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Monday, December 27, 2021

Energy policy of the United States

From Wikipedia, the free encyclopedia
 

The energy policy of the United States is determined by federal, state, and local entities in the United States, which address issues of energy production, distribution, and consumption, such as building codes and gas mileage standards. Energy policy may include legislation, international treaties, subsidies and incentives to investment, guidelines for energy conservation, taxation and other public policy techniques.

Several mandates have been proposed over the years, such as "gasoline will never exceed $1.00/gallon" [DJS-adjusted for inflation?] (Nixon) ($0.26 per liter), and "the United States will never again import as much oil as it did in 1977" (Carter), but no comprehensive long-term energy policy has been proposed, although there has been concern over this failure. Energy policy acts have been passed in 1992, 2005, 2007, 2008, and 2009 which include many provisions for conservation, such as the Energy Star program, and energy development, with grants and tax incentives for both renewable energy and non-renewable energy.

There is also criticism that federal energy policies since the 1973 oil crisis have been dominated by crisis-mentality thinking, promoting expensive quick fixes and single-shot solutions that ignore market and technology realities. Instead of providing stable rules that support basic research while leaving plenty of scope for American entrepreneurship and innovation, congresses and presidents have repeatedly backed policies which promise solutions that are politically expedient, but whose prospects are doubtful, without adequate consideration of the dollar costs, environmental costs, or national security costs of their actions. By 2018, the US is on the verge of achieving energy security or self-sufficiency as the total export of coal, natural gas, crude oil and petroleum products are exceeding imports. The US had a trade surplus in the energy sector by 2018. In the second half of 2019, the US is the top producer of oil and gas in the world. After becoming net exporter of crude oil and its products for a brief period of less than one year, US is expected to become net importer of crude oil and its products in 2020 due to fall in price of crude oil.

State-specific energy efficiency incentive programs also play a significant role in the overall energy policy of the United States. The United States refused to endorse the Kyoto Protocol, preferring to let the market drive CO2 reductions to mitigate global warming, which will require CO2 emission taxation. The administration of Barack Obama proposed an aggressive energy policy reform, including the need for a reduction of CO2 emissions, with a cap and trade program, which could help encourage more clean renewable, sustainable energy development. With new technologies such as fracking, the United States has in 2014 resumed its former role as the top oil producer in the world. On June 1, 2017, President Trump announced that the US would cease all participation in the 2015 Paris Agreement on climate change mitigation. In 2020, Joe Biden announced that the US would resume its participation of the Paris Agreement once more. EIA predicts that the dent in energy consumption in the year 2020 due to Covid 19 pandemic would take many years to recover.

History

US energy use (values in quad/year, each equal to 290 TWh/year)
 
US oil reserves increased until 1970, then began to decline.
 
Grand Coulee Dam in Washington State.

In the Colonial era the energy policy of the United States was for free use of standing timber for heating and industry. In the 19th century, new emphasis was placed on access to coal and its use for transport, heating and industry. Whales were rendered into lamp oil. Later, coal gas was fractionated for use as lighting and town gas. Natural gas was first used in America for lighting in 1816, and has grown in importance for use in homes, industry, and power plants, but natural gas production reached its US peak in 1973, and the price has risen significantly since then.

Coal provided the bulk of the US energy needs well into the 20th century. Most urban homes had a coal bin and a coal-fired furnace. Over the years these were replaced with oil furnaces, not because of it being cheaper but because it was easier and safer. Coal remains far cheaper than oil. The biggest use of oil has come from the development of the automobile.

Oil became increasingly important to the United States, and, from the early 1940s, the US government and oil industry entered into a mutually beneficial collaboration to control global oil resources. By 1950, oil consumption exceeded that of coal. The abundance of oil in California, Texas, Oklahoma, as well as in Canada and Mexico, coupled with its low cost, ease of transportation, high energy density, and use in internal combustion engines, lead to its increasing use.

Following World War II, oil heating boilers took over from coal burners along the Eastern Seaboard; diesel locomotives took over from coal-fired steam engines under dieselisation; oil-fired electricity plants were built; petroleum-burning buses replaced electric streetcars in a GM driven conspiracy, for which they were found guilty, and citizens bought gasoline-powered cars. Interstate Highways helped make cars the major means of personal transportation. As oil imports increased, US foreign policy was inexorably drawn into Middle East politics, supporting oil-producing Saudi Arabia and patrolling the sea lanes of the Persian Gulf.

Hydroelectricity was the basis of Nikola Tesla's introduction of the US electricity grid, starting at Niagara Falls, New York, in 1883. Electricity generated by major dams like the Jensen Dam, TVA Project, Grand Coulee Dam and Hoover Dam still produce some of the lowest-priced ($0.08/kWh), clean electricity in America. Rural electrification strung power lines to many more areas.

Utilities have their rates set to earn a revenue stream that provides them with a constant 10% – 13% rate of return based on operating costs. Increases or decreases of the operating costs of electricity production are passed directly through to the consumers.

The federal government provided substantially larger subsidies to fossil fuels than to renewables in the 2002–2008 period. Subsidies to fossil fuels totaled approximately $72 billion over the study period, representing a direct cost to taxpayers. Subsidies for renewable fuels, totaled $29 billion over the same period.

In some cases, the US has used its energy policy as a means to pursue other international goals. Richard Heinberg, a professor from Santa Rosa, California argues that a declassified CIA document shows that the US used oil prices as leverage against the economy of the Soviet Union. Specifically, he argues that the US intentionally worked with Saudi Arabia during the Reagan administration to keep oil prices low, thus decreasing the purchasing power of the Soviet Union's petroleum export industry. When combined with other US efforts to drain Soviet resources, this was eventually a major cause in the dissolution of the Soviet Union.

Energy imports

United States oil product imports by country
The trend of net energy imports into the United States (US Energy Information Administration).
 
US oil production peaked in 1970, then began to decline. In 2005 imports peaked at 60% of consumption.

As of 2019, the United States receives approximately 80% of its energy from fossil fuels. This energy is used for transport, industry, commercial and domestic use. The remaining non fossil fuel portion comes primarily from Hydro, Wind and Nuclear stations. Americans constitute less than 5% of the world's population, but consume 26% of the world's energy to produce 26% of the world's industrial output. They account for about 25% of the world's petroleum consumption, while producing only 6% of the world's annual petroleum supply.

Almost all of Canada's energy exports go to the United States, making it the largest foreign source of US energy imports. Canada is the top source of US imports of oil, gas. and electricity.

Petroleum

In 2012, the US produced 60% of the petroleum it used, the remainder being imported. The largest sources of imported oil were Canada, Saudi Arabia, Mexico, Venezuela, and Russia. Oil imports into the US peaked in 2006, when imports supplied nearly 12 million barrels/day which is 60% of US consumption; they have declined since, due both to increased domestic oil production, and reduced consumption. By April 2018, net imports of crude oil and petroleum products has fallen to 2.634 million barrels/day as shale oil production improved drastically. By the early 2020, the US is expected to be net exporter of crude oil and petroleum products. The US is also expected to be top producer of crude oil by 2019. US accounted for 98% of all global oil production growth in 2018.

The 1973 oil embargo highlighted the vulnerability of the United States to oil supply disruptions when it depends on imports from nations that are either politically unstable or opposed to US interests. Perceived remedies include measures to reduce demand for petroleum (such as conservation or alternative fuels), increase the supply of petroleum (by increasing domestic production, or maintaining petroleum reserves), or enhance the reliability of foreign imports (through foreign policy). The Federal Department of Energy was started to direct the various approaches.

Conservation

A National Maximum Speed Limit of 55 mph (88 km/h) was imposed to help reduce consumption, and Corporate Average Fuel Economy (aka CAFE) standards were enacted to downsize automobile categories. Year-round Daylight Saving Time was imposed, the United States Strategic Petroleum Reserve was created and the National Energy Act of 1978 was introduced. Alternative forms of energy and diversified oil supply resulted.

Re-design of cities, telecommuting, mass transit, higher housing density and walking could also reduce automobile fuel consumption. Carpooling, flexcars, Smart cars, and shorter commutes could all reduce fuel use.

Increasing supply

The United States Strategic Petroleum Reserve was created to augment supply in case of a national emergency.

Alternative fuels

Two-thirds of US oil consumption is in the transportation sector. The US – an important export country for food stocks – converted approximately 18% of its grain output to ethanol in 2008. Across the US, 25% of the whole corn crop went to ethanol in 2007. The percentage of corn going to biofuel is expected to go up. In 2006, US senators introduced the BioFuels Security Act.

The proposal has been made for a hydrogen economy, in which cars and factories would be powered by hydrogen fuel cells. However, energy would have to be used to produce the hydrogen, and hydrogen cars have been called one of the least efficient, most expensive ways to reduce greenhouse gases. Other plans include making society carbon neutral and using renewable energy, including solar, wind, and methane sources.

It has been suggested that automobiles could be powered by the following forms of energy: 60% by grid electricity, 20% by biofuels, and 20% by direct solar. Re-design of cities, telecommuting, mass transit, higher housing density and walking could also reduce automobile fuel consumption.

Enhance reliability of foreign sources

One purpose of American foreign policy, especially in the Middle East, is commonly seen as securing the continued flow of petroleum exports from the region.

The proposed Keystone XL pipeline from Canada is a way to enhance the security of US petroleum supply. The Keystone XL pipeline project was later cancelled in June 2021, as a result of the Biden Administration enacting Executive Order 13990 on January 20th, 2021, which blocked and revoked permits for the project due to climate change concerns and mass opposition from nearby Native American tribes, climate activists, and Democrats.

Natural gas

The United States is a net importer of natural gas, most of it by pipeline from Canada, with a smaller amount of LNG from other sources. Net gas imports into the US peaked in 2007, when the country imported 16.4 percent of the natural gas it consumed, and was the world's largest net importer of natural gas. By 2013, despite growing use of natural gas in the US, net imports had fallen to 5.0 percent of consumption.

Coal

The United States mines more coal than it uses, and is an exporter of coal.

Electricity

The United States is a net importer of electricity from Canada, and a net exporter to Mexico. Overall, in 2012 the US had net electricity imports of 47 thousand gigawatt-hours, which was less than 1.2% of the electrical power generated within the US.

Nuclear power in the United States depends largely on imported uranium. In 2011, US uranium mining provided 8 percent of the uranium concentrate loaded into nuclear reactors. The remainder was imported. Principal sources of imported uranium were Russia, Canada, Australia, Kazakhstan, and Namibia.

The US Energy Information Administration (EIA) groups the five largest consumers of energy in the United States, by sector. Their shares of total primary energy consumption in 2017 were:

  • Electric power—38.1%
  • Transportation—28.8%
  • Industrial—22.4%
  • Residential—6.2%
  • Commercial—4.5%

The electric power sector generates most of the electricity used in the US. The other four sectors consume most of that electricity.

Energy consumption

The primary sectors of US energy consumption in 2019.
  •   Residential: 15.7%
  •   Commercial: 12.4%
  •   Industrial: 34.8%
  •   Transportation: 37.1%

The per capita primary energy consumption is 6.6 tons of oil equivalent in 2017. Energy consumption can vary widely from state to state in the US. In 2012 for example, there was a large gap in electricity consumption by state between the top three states - Louisiana (1254 kWh/mo.), Tennessee (1217 kWh/mo.) and Mississippi (1193 kWh/mo.) - and the bottom three states - Maine (531 kWh/mo.), Hawaii (544 kWh/mo.) and Vermont (565 kWh/mo.).

Buildings and their construction consume more energy than transportation or industrial applications, and because buildings are responsible for the largest portion of greenhouse emissions, they have the largest impact on anthropic climate change. The AIA has proposed making buildings carbon neutral by 2030, meaning that the construction and operation of buildings will not require fossil fuel energy or emit greenhouse gases, and having the US reduce CO2 emissions to 40 to 60% below 1990 levels by 2050.

When President Carter created the US Department of Energy in 1977, one of their first successful projects was the Weatherization Assistance Program. During the last 30 years, this program has provided services to more than 5.5 million low-income families. On average, low-cost weatherization reduces heating bills by 31% and overall energy bills by $358 per year at current prices. Increased energy efficiency and weatherization spending has a high return on investment.

The "Energy Independence and Security Act of 2007" has a significant impact on US energy policy. It includes funding to help improve building codes, and will make it illegal to sell incandescent light bulbs, as they are less efficient than fluorescents and LEDs.

Technologies such as passive solar building design and zero energy buildings (ZEB) have demonstrated significant new-construction energy bill reductions. The "Energy Independence and Security Act of 2007" includes funding to increase the popularity of ZEBs, photovoltaics, and even a new solar air conditioning program. Many energy-saving measures can be added to existing buildings as retrofits, but others are only cost-effective in new construction, which is why building code improvements are being encouraged. The solution requires both improved incentives for energy conservation, and new energy sources.

The Energy Independence and Security Act of 2007 increases average gas mileage to 35 mpg by 2020. The Obama administration and 2007 legislation are encouraging the near-term use of plug-in electric cars, and hydrogen cars by 2020. Toyota has suggested that their third-generation 2009 Prius may cost much less than the current model. Larger advanced-technology batteries have been suggested to make it plug-in rechargeable. Photovoltaics are an option being discussed to extend its daytime electric driving range. Improving solar cell efficiency factors will continue to make this a progressively more-cost-effective option.

Sources

An offshore oil platform
 
The primary sources of US energy in 2019.
  •   Coal: 11.4Quad (11.4%)
  •   Hydro: 2.5Quad (2.5%)
  •   Geothermal: 0.209Quad (0.2%)
  •   Wind Power: 2.74Quad (2.7%)
  •   Solar: 1.04Quad (1.0%)
  •   Biomass: 4.98Quad (5.0%)
  •   Nuclear: 8.46Quad (8.4%)
  •   Natural Gas: 32.1Quad (32.1%)
  •   Oil: 36.7Quad (36.7%)

About 80% of all types of energy used in the United States is derived from fossil fuels. In 2019, the largest source of the country's energy came from petroleum (36.6%), followed by natural gas (32%), coal (11.4%), renewable sources (11.4%) and nuclear power (8.4%). Amory Lovins says that the sharp and steady cost reductions in solar power has been a "stunning market success". He says that solar, wind and cheap natural gas have significantly reduced the prospects of coal and nuclear power plants around the world. These costs have come down so far for solar photovoltaic electricity that CNBC pointed out that only 79 individuals could fund the US transition to solar. John Rowe, chair of Exelon (the largest nuclear power producer in the US), has said that the nuclear renaissance is dead.

Petroleum

US imports of crude oil and petroleum products (in thousands of barrels), 1981–2010.

In 2006, the US consumed 20.8 million bbl (3.31 million m3) of petroleum a day, of which 9 million bbl (1.4 million m3) is motor gasoline. Transportation is the largest consumer, accounting for approximately 68.9%, and 55% of oil use worldwide as documented in the Hirsch report. With approximately 5% of the world's population, the United States is responsible for approximately 25% of annual global oil consumption and according to 2008 estimates has a per-person daily consumption rate more than double that of the European Union. Automobiles are the single largest consumer of oil, consuming 40%, and are also the source of 20% of the nation's greenhouse gas emissions.

The US has about 22 billion bbl (3.5 billion m3) reserves while consuming about 7.6 billion bbl (1.21 billion m3) per year. This has created pressure for additional drilling. European gasoline prices reached $4 per U.S. gallon ($1.1 per liter) through taxation long before they reached the same price in the US, leading to higher consumption in the US.

Problems associated with oil supply include volatile oil prices, increasing world and domestic petroleum product demand, dependence on unstable imported foreign oil, falling domestic production (peak oil), and declining infrastructure, like the Alaska pipeline and oil refineries.

American dependence on imports grew from 10% in 1970 to 65% by the end of 2004. The Energy Information Administration projects that US oil imports will remain flat and consumption will grow, so net imports will decline to 54% of US oil consumption by 2030.


The subject of continued exploration for offshore drilling in the United States is a perennial debate, one which was heavily influenced in 2010 by the Deepwater Horizon oil spill in the Gulf of Mexico.

Coal

US coal production regions

America is self-sufficient in coal. Indeed, it has several hundred years' supply of it. The United States trend in coal use has been rising from 1950 through 2007, when coal production and consumption more than doubled. The population of the US has almost doubled in this time period as well, while the per capita energy use has been declining since 1978.

Coal in transit in Ohio

Most electricity (52% in 2000) in the country was historically generated from coal-fired power plants: in 2006, more than 90% of coal consumed was used to generate electricity. In 1950, about 19% percent of the coal consumed was for electricity generation. However, subsequent to 2007, coal-fired electricity began to decline, and in 2018, just 27.4% of US electricity was generated from coal.

In terms of the production of energy from domestic sources, from 1885 through 1951, coal was the leading source of energy in the United States. Crude oil and natural gas then vied for that role until 1982. Coal regained the position of the top domestic resource that year and again in 1984, and has retained it since. The US burns 1 billion tons of coal every year.

Concern for climate change has led to a call for a moratorium on all coal consumption, unless carbon capture is utilized. Coal is the largest potential source of CO2 emissions.

Integrated Gasification Combined Cycle (IGCC) is the cleanest currently operational coal-fired electricity generation technology. FutureGen is an experimental US research project to investigate the possibility of sequestering IGCC CO2 emissions underground.

Natural gas

Natural gas production and consumption quadrupled between 1950 and 1970 to 20×1012 cu ft (570 km3), but declined steadily to stabilize in 1986. Since then, the United States imports a rising share of its gas. In 2008 consumption of natural gas stood at 23.2×1012 cu ft (660 km3), while domestic production was at 20.6×1012 cu ft (580 km3). Approximately 3.0×1012 cu ft (85 km3) were imported, mainly by pipelines from Canada, which accounted for 90% of foreign supplies, while the remainder is delivered by liquefied natural gas (LNG) tankers carrying gas from five different countries.

The largest gas-producing states in 2007 were Texas (30%), Wyoming (10%), Oklahoma (9%) and New Mexico (8%), while 14% of the country's production came from the federal offshore lands in the Gulf of Mexico. Recent development in hydraulic fracturing and horizontal drilling have increased interest for shale gas across the United States in recent years. Leading fields are the Barnett Shale in Texas and the Antrim Shale in Michigan. Natural gas reserves in the United States were 35% higher in 2008 than two years earlier largely due to shale gas discoveries.

Rapid increase in shale gas production by 2018, has converted the country from a natural gas importer to an exporter and the largest producer of natural gas. LNG and CNG are being used in the transport sector to replace the costlier liquid fuels. Natural gas, which was earlier used as fuel mainly, is also diversifying in the form of feed stock in food sector to produce protein rich feed for cattle/fish/poultry. Cultivation of Methylococcus capsulatus bacteria culture by consuming natural gas produces high protein rich feed with tiny land and water foot print. Abundant natural gas availability in the US can also impart full global food security by producing highly nutrient food products without any water pollution. Natural gas/methane can also be converted cheaply in to hydrogen gas and carbon black using renewable electricity without emitting any green house gas for use in transport sector with fuel cell vehicle technology.

Nuclear power

The United States is the world's largest supplier of commercial nuclear power. As of 2010, the demand for nuclear power is softening in America, and some companies have withdrawn their applications for licenses to build. Ground has been broken on two new nuclear plants with a total of four reactors.

In August 2011, John Rowe, head of Exelon, America's largest nuclear utility, said that this was not the time to build new nuclear plants, not because of political opposition or the threat of cost overruns, but because of the low price of natural gas. "Shale [gas]", said he, "is good for the country, bad for new nuclear development".

Following the 2011 Japanese nuclear accidents, the US Nuclear Regulatory Commission has announced it will launch a comprehensive safety review of the 104 nuclear power reactors across the United States, at the request of President Obama. The Obama administration "continues to support the expansion of nuclear power in the United States, despite the crisis in Japan". Following the Japanese nuclear emergency, public support for building nuclear power plants in the US dropped to 43%, slightly lower than it was immediately after the Three Mile Island accident in 1979, according to a CBS News poll.

In his 2012 state-of-the-union address, Barack Obama said that America needs "an all-out, all-of-the-above strategy that develops every available source of American energy." President Obama boasted about a Michigan wind turbine factory, America's healthy supplies of natural gas and widespread oil exploration. He urged Congress to pass tax incentives for energy efficiency, clean energy, and an end to oil-company subsidies, but made no mention of nuclear power.

In 2013, four aging reactors in the US were permanently closed before their licenses expired because of high maintenance and repair costs at a time when natural gas prices have fallen: San Onofre 2 and 3 in California, Crystal River 3 in Florida, and Kewaunee in Wisconsin. The state of Vermont is trying to close Vermont Yankee, in Vernon. New York State is seeking to close Indian Point in Buchanan, 30 miles from New York City. Loss of nuclear-generating capacity is expected to be offset by the five new nuclear reactors currently under construction, with a proposed combined capacity of more than 5,000 MW.

As of 2020, support for nuclear energy from policymakers has been on the rise throughout the United States. President Joe Biden's administration has been said to have "one of the most explicitly pro-nuclear agendas", of any of his predecessors. A growing number of Democratic politicians like Senators Amy Klobuchar, Cory Booker, and John Delaney have expressed support for the expansion of nuclear power to combat climate change. Leaders in business and in government, like Jimmy Carter and Bill Gates, along with energy industry experts like Bret Kugelmass (founder of the Energy Impact Center) and Richard Martin (author of SuperFuel) have also openly supported the use of nuclear energy to curb and reverse the effects of climate change.

In October 2020, the US Department of Energy selected two US-based teams to receive $160 million in initial funding under the new Advanced Reactor Demonstration Program (ARDP). TerraPower and X-energy were each awarded $80 million to build two advanced nuclear reactors that can be operational within seven years. There are several other companies and institutions throughout the United States, like the Energy Impact Center's OPEN100 project, Commonwealth Fusion Systems, and Flibe Energy that are gaining attention from their nuclear power innovations and research efforts as well.

Renewable energy

Part of the 354 MW SEGS solar complex in northern San Bernardino County, California.
 
The Shepherds Flat Wind Farm is an 845 megawatt (MW) wind farm in the US state of Oregon.
 
The 550 MW Desert Sunlight Solar Farm in California.

Renewable energy in the United States accounted for 12.9 percent of the domestically produced electricity in 2013. Renewable energy reached a major milestone in the first quarter of 2011, when it contributed 11.7 percent of total US energy production at 2.245 quadrillion British thermal units (658 terawatt-hours), surpassing energy production from nuclear power at 2.125 quadrillion British thermal units (623 TWh). 2011 was the first year since 1997 that renewables exceeded nuclear in US total energy production.

Hydroelectric power is currently the largest producer of renewable power in the US. It produced around 6.2% of the nation's total electricity in 2010 which was 60.2% of the total renewable power in the US. The United States is the fourth largest producer of hydroelectricity in the world after China, Canada and Brazil. The Grand Coulee Dam is the 5th largest hydroelectric power station in the world.

US wind power installed capacity now exceeds 65,000 MW. For calendar year 2014, the electricity produced from wind power in the United States amounted to 181.79 terawatt-hours, or 4.44% of all generated electrical energy. Texas is firmly established as the leader in wind power development, followed by Iowa and California.

Several large solar thermal power stations have also been built. The largest of these solar thermal power stations is the SEGS group of plants in the Mojave Desert with a total generating capacity of 354 MW, making the system the largest solar plant of any kind in the world. As of 2015, the largest photovoltaic (PV) power plant in North America is Solar Star, a 579 megawatt photovoltaic power station near Rosamond, California. The Geysers in Northern California is the largest complex of geothermal energy production in the world.

With 2,957 MW of installed geothermal capacity, the United States remains the world leader with 30% of the online capacity total. As of early 2009, 120 new projects are underway. When developed, these projects could potentially supply up to 3,979 MW of power, meeting the needs of about 4 million homes. At this rate of development, geothermal production in the United States could exceed 15,000 MW by 2025.

The development of renewable energy and energy efficiency marks "a new era of energy exploration" in the United States, according to President Barack Obama. In a joint address to the Congress on February 24, 2009, President Obama called for doubling renewable energy within the next three years. In his 2012 State of the Union address, President Barack Obama restated his commitment to renewable energy and mentioned the long-standing Interior Department commitment to permit 10,000 MW of renewable energy projects on public land in 2012.

President Barack Obama's American Recovery and Reinvestment Act of 2009 included more than $70 billion in direct spending and tax credits for clean energy and associated transportation programs. This policy-stimulus combination represents the largest federal commitment in US history for renewable energy, advanced transportation, and energy conservation initiatives. As a result of these new initiatives, many more utilities are expected to strengthen their clean energy programs. In February 2011, the US Department of Energy launched its SunShot initiative, a collaborative national effort to cut the total cost of photovoltaic solar energy systems by 75% by 2020. Reaching this goal would make unsubsidized solar energy cost-competitive with other forms of electricity and get grid parity.

Biofuels

In recent years there has been an increased interest in biofuelsbioethanol and biodiesel – derived from common agricultural staples or waste. Increased domestic production of these fuels could reduce US expenditure on foreign oil and improve energy security if methods of producing and transporting the fuels do not involve heavy inputs of fossil fuels, as current agriculture does.

Most cars on the road today in the US can run on blends of up to 10% ethanol, and motor vehicle manufacturers already produce vehicles designed to run on much higher ethanol blends. In 2007, Portland, Oregon, became the first city in the United States to require all gasoline sold within city limits to contain at least 10% ethanol. Ford, Daimler AG, and GM are among the automobile companies that sell "flexible-fuel" cars, trucks, and minivans that can use gasoline and ethanol blends ranging from pure gasoline up to 85% ethanol (E85). By mid-2006, there were approximately 6 million E85-compatible vehicles on US roads.

The Renewable Fuels Association counts 113 US ethanol distilleries in operation and another 78 under construction, with capacity to produce 11.8 billion gallons within the next few years. The Energy Information Administration (EIA) predicts in its Annual Energy Outlook 2007 that ethanol consumption will reach 11.2 billion US gallons (42,000,000 m3) by 2012, outstripping the 7.5 billion US gallons (28,000,000 m3) required in the Renewable Fuel Standard that was enacted as part of the Energy Policy Act of 2005.

Expanding ethanol fuel (and biodiesel) industries provide jobs in plant construction, operations, and maintenance, mostly in rural communities. According to the Renewable Fuels Association, the ethanol industry created almost 154,000 US jobs in 2005 alone, boosting household income by $5.7 billion. It also contributed about $3.5 billion in tax revenues at the local, state, and federal levels.

In recent years, there has been criticism about the production of ethanol fuel from food crops. However, second generation biofuels are now being produced from a much broader range of feedstocks including the cellulose in dedicated energy crops (perennial grasses such as switchgrass and Miscanthus giganteus), forestry materials, the co-products from food production, and domestic vegetable waste. Produced responsibly they are sustainable energy sources that need not divert any land from growing food, nor damage the environment.

Energy efficiency

A spiral-type integrated compact fluorescent lamp, which has been popular among North American consumers since its introduction in the mid 1990s.
 
Tesla Roadster (2008) uses lithium ion batteries to achieve 220 mi (350 km) per charge, while also capable of going 0-60 in under 4 seconds.

There are many different types of energy efficiency innovation, including efficient water heaters; improved refrigerators and freezers; advanced building control technologies and advances in heating, ventilation, and cooling (HVAC); smart windows that adapt to maintain a comfortable interior environment; new building codes to reduce needless energy use; and compact fluorescent lights. Improvements in buildings alone, where over sixty percent of all energy is used, can save tens of billions of dollars per year.

Several states, including California, New York, Rhode Island, and Wisconsin, have consistently deployed energy efficiency innovations. Their state planning officials, citizens, and industry leaders, have found these very cost-effective, often providing greater service at lower personal and social cost than simply adding more fossil-fuel-based supply. This is the case for several reasons. Energy-efficient technologies often represent upgrades in service through superior performance (e.g. higher quality lighting, heating and cooling with greater controls, or improved reliability of service through greater ability of utilities to respond to time of peak demand). So these innovations can provide a better, less expensive service.

A wide range of energy-efficient technologies have ancillary benefits in improved quality of life, such as advanced windows that not only save on heating and cooling expenses, but also make the workplace or home more comfortable. Another example is more efficient vehicles, which not only save immediately on fuel purchases, but also emit fewer pollutants, improving health and saving on medical costs to the individual and to society.

In 1994, Amory Lovins developed the design concept of the Hypercar. This vehicle would have ultra-light construction with an aerodynamic body using advanced composite materials, low-drag design, and hybrid drive. Designers of the Hypercar claim it would achieve a three- to five-fold improvement in fuel economy, equal or better performance, safety, amenity, and affordability, compared with today's cars. Lovins says the commercialisation of the Hypercar began in 2014, with the production of the all-carbon electric BMW i3 family and the 313 miles per gallon Volkswagen XL1.

Energy budget, initiatives and incentives

An incentive resulting from US energy policy is a factor that provides motive for a specific course of action regarding the use of energy. In the US most energy policy incentives take the form of financial incentives. Examples of these include tax breaks, tax reductions, tax exemptions, rebates, loans and specific funding. Throughout US history there have been many incentives created through US energy policy.

Most recently the Energy Policy Act of 2005, Energy Independence and Security Act of 2007, and Emergency Economic Stabilization Act of 2008, each promote various energy efficiency improvements and encourage development of specific energy sources. US energy policy incentives can serve as a strategic manner to develop certain industries that plan to reduce America's dependence on foreign petroleum products and create jobs and industries that boost the national economy. The ability to do this depends upon which industries and products the government chooses to subsidize. In 2016, federal government energy-specific subsidies and supports for renewables, fossil fuels, and nuclear energy were $6,682 million, $489 million and $365 million, respectively. 

Budget

The 2012 budget that President Obama submitted to Congress calls for a 70 percent increase over the 2011 allocation for federal research and development activities related to renewable energy. The Office of Science in the Department of Energy would receive $2.0 billion for basic energy sciences to discover new ways to produce, store and use energy. Included in that amount are allocations of $457 million for solar energy; $341 million for biofuels and biomass R&D, including a new reverse auction to promote advanced biofuels; and more than doubling investment in geothermal energy to $102 million. The budget includes funding to accelerate the deployment of new models of energy research pioneered in the last several years, including $550 million for the Advanced Research Projects Agency–Energy, a program that supports breakthrough ideas.

Public investment

Public investment can enable the development of infrastructure projects through the use of public funds, grants, loans or other financing options. These funds provide a means for allocating the capital necessary for the development of renewable energy technologies.

Tax incentives

Federal tax incentives can be designed to accelerate market adoption, create jobs, encourage investment in a public good (reduced pollution) or encourage investment in renewable technology research and development. The Production Tax Credit (PTC) reduces the federal income taxes of qualified tax-paying owners of renewable energy projects based on the electrical output (measured in kWh) of grid-connected renewable energy facilities. The Investment Tax Credit (ITC) reduces federal income taxes for qualified tax-paying owners based on dollars of capital investment in renewable energy projects. The Advanced Energy Manufacturing Tax Credit (MTC) awards tax credits to new, expanded, or re-equipped domestic manufacturing facilities that support clean energy development.

Loan guarantees

The Department of Energy's Loan Guarantee Program, established by the Energy Policy Act of 2005 and enhanced by the American Recovery and Reinvestment Act of 2009, attempts to pave the way for investor support of clean energy projects by providing a guarantee of financing up to 80% of the project cost. The program is scheduled to end on September 30, 2011, unless Congress passes further legislation.

Renewable portfolio standard

A Renewable Portfolio Standard (RPS) is a mandate that requires electricity providers to supply to their customers a minimum amount of power from renewable sources, usually as a percentage of total energy use. As of June 2010, such standards have been enacted in 31 US states and the District of Columbia. For example, Governor Jerry Brown signed legislation requiring California's utilities to get 33 percent of their electricity from renewable energy sources by the end of 2020. Congress has considered a national RPS since 1997: the Senate has passed legislation three times, and the House once. As of April 2011, both houses have not acted in unison to pass legislation.

Biofuel subsidies

In the United States, biofuel subsidies have been justified on the following grounds: energy independence, reduction in greenhouse gas emissions, improvements in rural development related to biofuel plants and farm income support. Several economists from Iowa State University found "there is no evidence to disprove that the primary objective of biofuel policy is to support farm income."

Consumer subsidies

Consumers who purchase hybrid vehicles are eligible for a tax credit that depends upon the type of vehicle and the difference in fuel economy in comparison to vehicles of similar weights. These credits range from several hundred dollars to a few thousand dollars. Homeowners can receive a tax credit up to $500 for energy-efficient products like insulation, windows, doors, as well as heating and cooling equipment. Homeowners who install solar electric systems can receive a 30% tax credit and homeowners who install small wind systems can receive a tax credit up to $4000. Geothermal heat pumps also qualify for tax credits up to $2,000.

Other subsidies

Recent energy policy incentives have provided, among other things, billions of dollars in tax reductions for nuclear power, fossil fuel production, clean coal technologies, renewable electricity production, and conservation and efficiency improvements.

Federal leases

Ceasing to issue new leases for fossil fuel extraction on federal lands and waters, and avoiding renewals of existing leases for resources that are not yet producing would reduce global CO2 emissions by 100 million tonnes per year by 2030, and by greater amounts thereafter.

Net metering

Growth of net metering in the United States

Net metering is a policy by many states in the United States designed to help the adoption of renewable energy. Net metering was pioneered in the United States as a way to allow solar and wind to provide electricity whenever available and allow use of that electricity whenever it was needed, beginning with utilities in Idaho in 1980, and in Arizona in 1981. In 1983, Minnesota passed the first state net metering law. As of March 2015, 44 states and Washington, D.C. have developed mandatory net metering rules for at least some utilities. However, although the states' rules are clear few utilities actually compensate at full retail rates.

Net metering policies are determined by states, which have set policies varying on a number of key dimensions. The Energy Policy Act of 2005 required state electricity regulators to "consider" (but not necessarily implement) rules that mandate public electric utilities make available upon request net metering to their customers. Several legislative bills have been proposed to institute a federal standard limit on net metering. They range from H.R. 729, which sets a net metering cap at 2% of forecasted aggregate customer peak demand, to H.R. 1945 which has no aggregate cap, but does limit residential users to 10 kW, a low limit compared to many states, such as New Mexico, with an 80,000 kW limit, or states such as Arizona, Colorado, New Jersey, and Ohio which limit as a percentage of load.

Electricity distribution

The US power transmission grid consists of about 300,000 km (190,000 mi) of lines operated by approximately 500 companies. The North American Electric Reliability Corporation (NERC) oversees all of them.

Long distance electric power transmission results in energy loss, through electrical resistance, heat generation, electromagnetic induction and less-than-perfect electrical insulation. In 1995, these losses were estimated at 7.2%. Energy generation and distribution can be more efficient the closer it is to the point of use, if conducted in a high-efficiency generator, such as a CHP. In the generation and delivery of electrical power, system losses along the delivery chain are pronounced. Of five units of energy going into most large power plants, only about one unit of energy is delivered to the consumer in a usable form.

A similar situation exists in gas transport, where compressor stations along pipelines use energy to keep the gas moving, or where gas liquefaction/cooling/regasification in the liquiefied natural gas supply chain uses a substantial amount of energy, even though the scale of the loss is not as pronounced as it is in electricity.

Distributed generation and distributed storage are means of reducing total and transmission losses as well as reducing costs for electricity consumers.

Statistics

Electricity

Electricity production by source

Source 2012 production (TWh) Percentage of Total
Coal 1,709 41.5%
Petroleum 30 0.7%
Natural Gas 1,066 25.8%
Nuclear 813 19.7%
Renewable sources 486 11.8%
Other 21 0.5%
Total 4,120 100%

Electricity consumption by sector

Sector 2012 consumption (TWh) Percentage of total
Residential 1,413 36.5%
Commercial 1,323 34.2%
Industrial 986 25.5%
Transportation 7 0.2%
Direct use 138 3.6%
Total 3,867 100%

Oil

  • production: 9.688-million-barrels-per-day (1,540,300 m3/d) (2010 est.)
  • consumption: 19.15-million-barrels-per-day (3,045,000 m3/d) (2010 est.)

Heat engines are only 20% efficient at converting oil into work. Electric transmission (production to consumer) loses over 23% of the energy due to generation, transmission, and distribution.

Carbon dioxide emissions

Atmospheric carbon dioxide versus time

The EPA has the authority to regulate greenhouse gas emissions, under the Clean Air Act, and is one of the agency's seven priorities.

US carbon dioxide emissions (millions of metric tons of CO2)



Year CO2 Change from 1990
1990 5,100.5 0.00%
2005 6,107.6 19.75%
2006 6,019.0 18.01%
2007 6,118.6 19.96%
2008 5,924.3 16.15%
2009 5,500.5 7.84%
2010 5,706.4 11.88%

Public opinion

The summer 2006 issue of Ms. magazine examined how the oil industry impacts women's lives

The US results from the 1st Annual World Environment Review, published on June 5, 2007, revealed that:

  • 74% are concerned about climate change.
  • 80% think their Government should do more to tackle global warming.
  • 84% think that the US is too dependent on fossil fuels.
  • 72% think that the US is too reliant on foreign oil.
  • 79% think that the US Government should do more to increase the number of hybrid cars that are sold.
  • 67% think that the US Government should allow more offshore drilling.

The public is also quite clear on its priorities when it comes to promoting energy conservation versus increasing the supply of oil, coal, and natural gas. When asked which of these should be the higher priority, the public chooses energy conservation by a very wide 68 percent-to-21 percent margin. The public also predominantly believes that the need to cut down on energy consumption and protect the environment means increased energy efficiency should be mandated for certain products. Ninety-two percent of Americans now support such requirements.

However, when energy policy and climate change are compared to other issues, they are rated extremely low in terms of importance. A Pew Research Center poll on public priorities for 2011 found that global warming ranked last of twenty-two possible policy priorities. The same survey in 2012 found similar results.

Gallup found that from 2009 through the latest poll in March 2013, public opinion has been nearly evenly split on whether to give priority to the environment or to developing energy sources such as oil, gas, and coal. This represents a shift from poll results from 2001 through 2008, when clear pluralities of Americans wanted environmental concerns to take priority over developing fossil fuel resources. However, public opinion still heavily favors an emphasis on wind and solar energy (59 percent) over fossil fuels (31 percent).

General legislative policy, legislation and plans

The current head of the US Department of Energy under the Biden administration is Jennifer Granholm, who succeeded Dan Brouillette in February 2021.

As of September 2012, "The mission of the Energy Department is to ensure America's security and prosperity by addressing its energy, environmental and nuclear challenges through transformative science and technology solutions."

  • Catalyze the timely, material, and efficient transformation of the nation's energy system and secure US leadership in clean energy technologies.
  • Maintain a vibrant US effort in science and engineering as a cornerstone of our economic prosperity with clear leadership in strategic areas.
  • Enhance nuclear security through defense, nonproliferation, and environmental efforts.
  • Establish an operational and adaptable framework that combines the best wisdom of all Department stakeholders to maximize mission success.

In December 2009, the United States Patent and Trademark Office announced the Green Patent Pilot Program. The program was initiated to accelerate the examination of patent applications relating to certain green technologies, including the energy sector. The pilot program was initially designed to accommodate 3,000 applications related to certain green technology categories, and the program was originally set to expire on December 8, 2010. In May, 2010, the USPTO announced that it would expand the pilot program.

Greenhouse gas emissions

CO2 emission per capita per year per country

Although exceeded by China since 2007, the United States has historically been the world's largest producer of greenhouse gases. Some states are much more prolific polluters than others. The state of Texas produces approximately 1.5 trillion pounds of carbon dioxide yearly, more than every nation in the world except five outside of the United States: China, Russia, Japan, India, and Germany.

Despite signing the Kyoto Protocol, the United States has neither ratified nor withdrawn from it. In the absence of ratification, it remains non-binding on the US.

The Obama Administration has promised to take specific action towards mitigation of climate change. In addition, at state and local levels, there are currently a number of initiatives. As of March 11, 2007, mayors of 418 US cities in 50 states have endorsed the Kyoto protocol, after Mayor Greg Nickels of Seattle started a nationwide effort to get cities to agree to the protocol. As of January 18, 2007, eight Northeastern US states are involved in the Regional Greenhouse Gas Initiative (RGGI), a state level emissions capping and trading program.

On August 31, 2006, the California Legislature reached an agreement with Governor Arnold Schwarzenegger to reduce the state's greenhouse-gas emissions, which rank at 12th-largest carbon emitter in the world, by 25 percent by the year 2020. This resulted in the Global Warming Solutions Act which effectively puts California in line with the Kyoto limitations, but at a date later than the 2008–2012 Kyoto commitment period.

In the non-binding 'Washington Declaration' agreed on February 16, 2007, the United States, together with Presidents or Prime Ministers from Canada, France, Germany, Italy, Japan, Russia, United Kingdom, Brazil, China, India, Mexico and South Africa agreed in principle on the outline of a successor to the Kyoto Protocol. They envisage a global cap-and-trade system that would apply to both industrialized nations and developing countries, and hoped that this would be in place by 2009.

Chemistry Professor Nathan Lewis at Caltech estimates that to keep atmospheric carbon levels below 750 ppm, a level at which serious climate change would occur, by the year 2050, the United States would need to generate twice as much energy from renewable sources as is generated by all power sources combined today. However, current research indicates that even carbon dioxide concentrations in excess of 450 ppm would result in irreversible global climate change.

The book, Carbon-Free and Nuclear-Free, A Roadmap for U.S. Energy Policy, by Arjun Makhijani, argues that in order to meet goals of limiting global warming to 2 °C, the world will need to reduce CO2 emissions by 85% and the US will need to reduce emissions by 95%, which can be extended to within a few percent plus or minus of carbon free with little additional change. The book calls for phasing out use of oil, natural gas, and coal which does not use carbon sequestration by the year 2050. Effective delivered energy is projected to increase from about 75 Quadrillion Btu in 2005 to about 125 Quadrillion in 2050, but due to efficiency increases, the actual energy input is projected to increase from about 99 Quadrillion Btu in 2005 to about 103 Quadrillion in 2010 and then to decrease to about 77 Quadrillion in 2050. Petroleum use is projected to increase until 2010 and then linearly decrease to zero by 2050. The roadmap calls for nuclear power to decrease to zero at the same time, with the reduction also beginning in 2010.

In his book Hell and High Water, author Joseph Romm calls for the rapid deployment of existing technologies to decrease carbon emissions. In a follow-up article in Nature in June 2008, he argues that "If we are to have confidence in our ability to stabilize carbon dioxide levels below 450 p.p.m. emissions must average less than [5 billion metric tons of carbon] per year over the century. This means accelerating the deployment of the 11 wedges so they begin to take effect in 2015 and are completely operational in much less time than originally modeled by Socolow and Pacala."

In 2012, the National Renewable Energy Laboratory assessed the technical potential for renewable electricity for each of the 50 states, and concluded that each state has technical potential for renewable electricity, mostly from solar power and wind power, greater than its current electricity consumption. The report cautions: "Note that as a technical potential, rather than economic or market potential, these estimates do not consider availability of transmission infrastructure, costs, reliability or time-of-dispatch, current or future electricity loads, or relevant policies."

Space-based solar power

From Wikipedia, the free encyclopedia
 
NASA Integrated Symmetrical Concentrator SPS concept

Space-based solar power (SBSP) is the concept of collecting solar power in outer space and distributing it to Earth. Potential advantages of collecting solar energy in space include a higher collection rate and a longer collection period due to the lack of a diffusing atmosphere, and the possibility of placing a solar collector in an orbiting location where there is no night. A considerable fraction of incoming solar energy (55–60%) is lost on its way through the Earth's atmosphere by the effects of reflection and absorption. Space-based solar power systems convert sunlight to microwaves outside the atmosphere, avoiding these losses and the downtime due to the Earth's rotation, but at great cost due to the expense of launching material into orbit. SBSP is considered a form of sustainable or green energy, renewable energy, and is occasionally considered among climate engineering proposals. It is attractive to those seeking large-scale solutions to anthropogenic climate change or fossil fuel depletion (such as peak oil).

Various SBSP proposals have been researched since the early 1970s, but none are economically viable with present-day space launch infrastructure. Some technologists speculate that this may change in the distant future if an off-world industrial base were to be developed that could manufacture solar power satellites out of asteroids or lunar material, or if radical new space launch technologies other than rocketry should become available in the future.

Besides the cost of implementing such a system, SBSP also introduces several technological hurdles, including the problem of transmitting energy from orbit to Earth's surface for use. Since wires extending from Earth's surface to an orbiting satellite are neither practical nor feasible with current technology, SBSP designs generally include the use of some manner of wireless power transmission with its concomitant conversion inefficiencies, as well as land use concerns for the necessary antenna stations to receive the energy at Earth's surface. The collecting satellite would convert solar energy into electrical energy on board, powering a microwave transmitter or laser emitter, and transmit this energy to a collector (or microwave rectenna) on Earth's surface. Contrary to appearances of SBSP in popular novels and video games, most designs propose beam energy densities that are not harmful if human beings were to be inadvertently exposed, such as if a transmitting satellite's beam were to wander off-course. But the vast size of the receiving antennas that would be necessary would still require large blocks of land near the end users to be procured and dedicated to this purpose. The service life of space-based collectors in the face of challenges from long-term exposure to the space environment, including degradation from radiation and micrometeoroid damage, could also become a concern for SBSP.

SBSP is being actively pursued by Japan, China, Russia, India, the United Kingdom and the US.

In 2008, Japan passed its Basic Space Law which established space solar power as a national goal and JAXA has a roadmap to commercial SBSP.

In 2015, the China Academy for Space Technology (CAST) showcased their roadmap at the International Space Development Conference. In February 2019, Science and Technology Daily (科技日报, Keji Ribao), the official newspaper of the Ministry of Science and Technology of the People's Republic of China, reported that construction of a testing base had started in Chongqing's Bishan District. CAST vice-president Li Ming was quoted as saying China expects to be the first nation to build a working space solar power station with practical value. Chinese scientists were reported as planning to launch several small- and medium-sized space power stations between 2021 and 2025. In December 2019, Xinhua News Agency reported that China plans to launch a 200-tonne SBSP station capable of generating megawatts (MW) of electricity to Earth by 2035.

In May 2020 the US Naval Research Laboratory conducted its first test of solar power generation in a satellite. In August 2021, the California Institute of Technology (Caltech) announced that it planned to launch a SBSP test array by 2023, and at the same time revealed that Donald Bren and his wife Brigitte, both Caltech trustees, had been since 2013 funding the Institute's Space-based Solar Power Project, donating over $100 million.

History

A laser pilot beam guides the microwave power transmission to a rectenna

In 1941, science fiction writer Isaac Asimov published the science fiction short story "Reason", in which a space station transmits energy collected from the Sun to various planets using microwave beams. The SBSP concept, originally known as satellite solar-power system (SSPS), was first described in November 1968. In 1973 Peter Glaser was granted U.S. patent number 3,781,647 for his method of transmitting power over long distances (e.g. from an SPS to Earth's surface) using microwaves from a very large antenna (up to one square kilometer) on the satellite to a much larger one, now known as a rectenna, on the ground.

Glaser then was a vice president at Arthur D. Little, Inc. NASA signed a contract with ADL to lead four other companies in a broader study in 1974. They found that, while the concept had several major problems – chiefly the expense of putting the required materials in orbit and the lack of experience on projects of this scale in space – it showed enough promise to merit further investigation and research.

Concept Development and Evaluation Program

Between 1978 and 1986, the Congress authorized the Department of Energy (DoE) and NASA to jointly investigate the concept. They organized the Satellite Power System Concept Development and Evaluation Program. The study remains the most extensive performed to date (budget $50 million). Several reports were published investigating the engineering feasibility of such a project. They include:

Artist's concept of a solar power satellite in place. Shown is the assembly of a microwave transmission antenna. The solar power satellite was to be located in a geosynchronous orbit, 35,786 kilometres (22,236 mi) above the Earth's surface. NASA 1976
  • Resource Requirements (Critical Materials, Energy, and Land)
  • Financial/Management Scenarios
  • Public Acceptance
  • State and Local Regulations as Applied to Satellite Power System Microwave Receiving Antenna Facilities
  • Student Participation
  • Potential of Laser for SBSP Power Transmission
  • International Agreements
  • Centralization/Decentralization
  • Mapping of Exclusion Areas For Rectenna Sites
  • Economic and Demographic Issues Related to Deployment
  • Some Questions and Answers
  • Meteorological Effects on Laser Beam Propagation and Direct Solar Pumped Lasers
  • Public Outreach Experiment
  • Power Transmission and Reception Technical Summary and Assessment
  • Space Transportation

Discontinuation

The project was not continued with the change in administrations after the 1980 United States elections. The Office of Technology Assessment concluded that "Too little is currently known about the technical, economic, and environmental aspects of SPS to make a sound decision whether to proceed with its development and deployment. In addition, without further research an SPS demonstration or systems-engineering verification program would be a high-risk venture."

In 1997, NASA conducted its "Fresh Look" study to examine the modern state of SBSP feasibility. In assessing "What has changed" since the DOE study, NASA asserted that the "US National Space Policy now calls for NASA to make significant investments in technology (not a particular vehicle) to drive the costs of ETO [Earth to Orbit] transportation down dramatically. This is, of course, an absolute requirement of space solar power."

Conversely, Pete Worden of NASA claimed that space-based solar is about five orders of magnitude more expensive than solar power from the Arizona desert, with a major cost being the transportation of materials to orbit. Worden referred to possible solutions as speculative, and which would not be available for decades at the earliest.

On November 2, 2012, China proposed space collaboration with India that mentioned SBSP, "may be Space-based Solar Power initiative so that both India and China can work for long term association with proper funding along with other willing space faring nations to bring space solar power to earth."

Exploratory Research and Technology program

SERT Integrated Symmetrical Concentrator SPS concept.NASA

In 1999, NASA's Space Solar Power Exploratory Research and Technology program (SERT) was initiated for the following purposes:

  • Perform design studies of selected flight demonstration concepts.
  • Evaluate studies of the general feasibility, design, and requirements.
  • Create conceptual designs of subsystems that make use of advanced SSP technologies to benefit future space or terrestrial applications.
  • Formulate a preliminary plan of action for the U.S. (working with international partners) to undertake an aggressive technology initiative.
  • Construct technology development and demonstration roadmaps for critical space solar power (SSP) elements.

SERT went about developing a solar power satellite (SPS) concept for a future gigawatt space power system, to provide electrical power by converting the Sun's energy and beaming it to Earth's surface, and provided a conceptual development path that would utilize current technologies. SERT proposed an inflatable photovoltaic gossamer structure with concentrator lenses or solar heat engines to convert sunlight into electricity. The program looked both at systems in sun-synchronous orbit and geosynchronous orbit. Some of SERT's conclusions:

  • The increasing global energy demand is likely to continue for many decades resulting in new power plants of all sizes being built.
  • The environmental impact of those plants and their impact on world energy supplies and geopolitical relationships can be problematic.
  • Renewable energy is a compelling approach, both philosophically and in engineering terms.
  • Many renewable energy sources are limited in their ability to affordably provide the base load power required for global industrial development and prosperity, because of inherent land and water requirements.
  • Based on their Concept Definition Study, space solar power concepts may be ready to reenter the discussion.
  • Solar power satellites should no longer be envisioned as requiring unimaginably large initial investments in fixed infrastructure before the emplacement of productive power plants can begin.
  • Space solar power systems appear to possess many significant environmental advantages when compared to alternative approaches.
  • The economic viability of space solar power systems depends on many factors and the successful development of various new technologies (not least of which is the availability of much lower cost access to space than has been available); however, the same can be said of many other advanced power technologies options.
  • Space solar power may well emerge as a serious candidate among the options for meeting the energy demands of the 21st century.
  • Launch costs in the range of $100–$200 per kilogram of payload from low Earth orbit to Geosynchronous orbit are needed if SPS is to be economically viable.

Japan Aerospace Exploration Agency

The May 2014 IEEE Spectrum magazine carried a lengthy article "It's Always Sunny in Space" by Susumu Sasaki. The article stated, "It's been the subject of many previous studies and the stuff of sci-fi for decades, but space-based solar power could at last become a reality—and within 25 years, according to a proposal from researchers at the Tokyo-based Japan Aerospace Exploration Agency (JAXA)."

JAXA announced on 12 March 2015 that they wirelessly beamed 1.8 kilowatts 50 meters to a small receiver by converting electricity to microwaves and then back to electricity. This is the standard plan for this type of power. On 12 March 2015 Mitsubishi Heavy Industries demonstrated transmission of 10 kilowatts (kW) of power to a receiver unit located at a distance of 500 meters (m) away.

Advantages and disadvantages

Advantages

The SBSP concept is attractive because space has several major advantages over the Earth's surface for the collection of solar power:

  • It is always solar noon in space and full sun.
  • Collecting surfaces could receive much more intense sunlight, owing to the lack of obstructions such as atmospheric gasses, clouds, dust and other weather events. Consequently, the intensity in orbit is approximately 144% of the maximum attainable intensity on Earth's surface.
  • A satellite could be illuminated over 99% of the time, and be in Earth's shadow a maximum of only 72 minutes per night at the spring and fall equinoxes at local midnight. Orbiting satellites can be exposed to a consistently high degree of solar radiation, generally for 24 hours per day, whereas earth surface solar panels currently collect power for an average of 29% of the day.
  • Power could be relatively quickly redirected directly to areas that need it most. A collecting satellite could possibly direct power on demand to different surface locations based on geographical baseload or peak load power needs.
  • Reduced plant and wildlife interference.

Disadvantages

The SBSP concept also has a number of problems:

  • The large cost of launching a satellite into space. For 6.5 kg/kW, the cost to place a power satellite in GEO cannot exceed $200/kg if the power cost is to be competitive.
  • Microwave optic requires GW scale due to Airy disk beam spreading. Typically a 1 km transmitting disk at 2.45 GHz spreads out to 10 km at Earth distance.
  • Inability to constrain power transmission inside tiny beam angles. For example, a beam of 0.002 degrees (7.2 arc seconds) is required to stay within a one kilometer receiving antenna target from geostationary altitude. The most advanced directional wireless power transfer systems as of 2019 spread their half power beam width across at least 0.9 arc degrees.
  • Inaccessibility: Maintenance of an earth-based solar panel is relatively simple, but construction and maintenance on a solar panel in space would typically be done telerobotically. In addition to cost, astronauts working in GEO (geosynchronous Earth orbit) are exposed to unacceptably high radiation dangers and risk and cost about one thousand times more than the same task done telerobotically.
  • The space environment is hostile; PV panels (if used) suffer about eight times the degradation they would on Earth (except at orbits that are protected by the magnetosphere).
  • Space debris is a major hazard to large objects in space, particularly for large structures such as SBSP systems in transit through the debris below 2000 km. Collision risk is much reduced in GEO since all the satellites are moving in the same direction at very close to the same speed.
  • The broadcast frequency of the microwave downlink (if used) would require isolating the SBSP systems away from other satellites. GEO space is already well used and would require coordinating with the ITU-R.
  • The large size and corresponding cost of the receiving station on the ground. The cost has been estimated at a billion dollars for 5 GW by SBSP researcher Keith Henson.
  • Energy losses during several phases of conversion from photons to electrons to photons back to electrons.
  • Waste heat disposal in space power systems is difficult to begin with, but becomes intractable when the entire spacecraft is designed to absorb as much solar radiation as possible. Traditional spacecraft thermal control systems such as radiative vanes may interfere with solar panel occlusion or power transmitters.

Design

Artist's concept of a solar disk on top of a LEO to GEO electrically powered space tug.

Space-based solar power essentially consists of three elements:

  1. collecting solar energy in space with reflectors or inflatable mirrors onto solar cells or heaters for thermal systems
  2. wireless power transmission to Earth via microwave or laser
  3. receiving power on Earth via a rectenna, a microwave antenna

The space-based portion will not need to support itself against gravity (other than relatively weak tidal stresses). It needs no protection from terrestrial wind or weather, but will have to cope with space hazards such as micrometeors and solar flares. Two basic methods of conversion have been studied: photovoltaic (PV) and solar dynamic (SD). Most analyses of SBSP have focused on photovoltaic conversion using solar cells that directly convert sunlight into electricity. Solar dynamic uses mirrors to concentrate light on a boiler. The use of solar dynamic could reduce mass per watt. Wireless power transmission was proposed early on as a means to transfer energy from collection to the Earth's surface, using either microwave or laser radiation at a variety of frequencies.

Microwave power transmission

William C. Brown demonstrated in 1964, during Walter Cronkite's CBS News program, a microwave-powered model helicopter that received all the power it needed for flight from a microwave beam. Between 1969 and 1975, Bill Brown was technical director of a JPL Raytheon program that beamed 30 kW of power over a distance of 1 mile (1.6 km) at 9.6% efficiency.

Microwave power transmission of tens of kilowatts has been well proven by existing tests at Goldstone in California (1975) and Grand Bassin on Reunion Island (1997).

 

Comparison of laser and microwave power transmission. NASA diagram

More recently, microwave power transmission has been demonstrated, in conjunction with solar energy capture, between a mountain top in Maui and the island of Hawaii (92 miles away), by a team under John C. Mankins. Technological challenges in terms of array layout, single radiation element design, and overall efficiency, as well as the associated theoretical limits are presently a subject of research, as it was demonstrated by the Special Session on "Analysis of Electromagnetic Wireless Systems for Solar Power Transmission" held during the 2010 IEEE Symposium on Antennas and Propagation. In 2013, a useful overview was published, covering technologies and issues associated with microwave power transmission from space to ground. It includes an introduction to SPS, current research and future prospects. Moreover, a review of current methodologies and technologies for the design of antenna arrays for microwave power transmission appeared in the Proceedings of the IEEE.

Laser power beaming

Laser power beaming was envisioned by some at NASA as a stepping stone to further industrialization of space. In the 1980s, researchers at NASA worked on the potential use of lasers for space-to-space power beaming, focusing primarily on the development of a solar-powered laser. In 1989, it was suggested that power could also be usefully beamed by laser from Earth to space. In 1991, the SELENE project (SpacE Laser ENErgy) had begun, which included the study of laser power beaming for supplying power to a lunar base. The SELENE program was a two-year research effort, but the cost of taking the concept to operational status was too high, and the official project ended in 1993 before reaching a space-based demonstration.

In 1988, the use of an Earth-based laser to power an electric thruster for space propulsion was proposed by Grant Logan, with technical details worked out in 1989. He proposed using diamond solar cells operating at 600 degrees to convert ultraviolet laser light.

Orbital location

The main advantage of locating a space power station in geostationary orbit is that the antenna geometry stays constant, and so keeping the antennas lined up is simpler. Another advantage is that nearly continuous power transmission is immediately available as soon as the first space power station is placed in orbit, LEO requires several satellites before they are producing nearly continuous power.

Power beaming from geostationary orbit by microwaves carries the difficulty that the required 'optical aperture' sizes are very large. For example, the 1978 NASA SPS study required a 1-km diameter transmitting antenna, and a 10 km diameter receiving rectenna, for a microwave beam at 2.45 GHz. These sizes can be somewhat decreased by using shorter wavelengths, although they have increased atmospheric absorption and even potential beam blockage by rain or water droplets. Because of the thinned array curse, it is not possible to make a narrower beam by combining the beams of several smaller satellites. The large size of the transmitting and receiving antennas means that the minimum practical power level for an SPS will necessarily be high; small SPS systems will be possible, but uneconomic.

A collection of LEO (Low Earth Orbit) space power stations has been proposed as a precursor to GEO (Geostationary Orbit) space-based solar power.

Earth-based receiver

The Earth-based rectenna would likely consist of many short dipole antennas connected via diodes. Microwave broadcasts from the satellite would be received in the dipoles with about 85% efficiency. With a conventional microwave antenna, the reception efficiency is better, but its cost and complexity are also considerably greater. Rectennas would likely be several kilometers across.

In space applications

A laser SBSP could also power a base or vehicles on the surface of the Moon or Mars, saving on mass costs to land the power source. A spacecraft or another satellite could also be powered by the same means. In a 2012 report presented to NASA on space solar power, the author mentions another potential use for the technology behind space solar power could be for solar electric propulsion systems that could be used for interplanetary human exploration missions.

Launch costs

One problem for the SBSP concept is the cost of space launches and the amount of material that would need to be launched.

Much of the material launched need not be delivered to its eventual orbit immediately, which raises the possibility that high efficiency (but slower) engines could move SPS material from LEO to GEO at an acceptable cost. Examples include ion thrusters or nuclear propulsion.

To give an idea of the scale of the problem, assuming a solar panel mass of 20 kg per kilowatt (without considering the mass of the supporting structure, antenna, or any significant mass reduction of any focusing mirrors) a 4 GW power station would weigh about 80,000 metric tons, all of which would, in current circumstances, be launched from the Earth. This is, however, far from the state of the art for flown spacecraft, which as of 2015 was 150W/kg (6.7 kg/kW), and improving rapidly. Very lightweight designs could likely achieve 1 kg/kW, meaning 4,000 metric tons for the solar panels for the same 4 GW capacity station. Beyond the mass of the panels, overhead (including boosting to the desired orbit and stationkeeping) must be added.

Launch costs for 4GW to LEO

1 kg/kW 5 kg/kW 20 kg/kW
$1/kg (Minimum cost at ~$0.13/kWh power, 100% efficiency) $4M $20M $80M
$2000/kg (ex: Falcon Heavy) $8B $40B $160B
$10000/kg (ex: Ariane V) $40B $200B $800B

To these costs must be added the environmental impact of heavy space launch missions, if such costs are to be used in comparison to earth-based energy production. For comparison, the direct cost of a new coal or nuclear power plant ranges from $3 billion to $6 billion per GW (not including the full cost to the environment from CO2 emissions or storage of spent nuclear fuel, respectively).

Building from space

From lunar materials launched in orbit

Gerard O'Neill, noting the problem of high launch costs in the early 1970s, proposed building the SPS's in orbit with materials from the Moon. Launch costs from the Moon are potentially much lower than from Earth, due to the lower gravity and lack of atmospheric drag. This 1970s proposal assumed the then-advertised future launch costing of NASA's space shuttle. This approach would require substantial up front capital investment to establish mass drivers on the Moon. Nevertheless, on 30 April 1979, the Final Report ("Lunar Resources Utilization for Space Construction") by General Dynamics' Convair Division, under NASA contract NAS9-15560, concluded that use of lunar resources would be cheaper than Earth-based materials for a system of as few as thirty solar power satellites of 10 GW capacity each.

In 1980, when it became obvious NASA's launch cost estimates for the space shuttle were grossly optimistic, O'Neill et al. published another route to manufacturing using lunar materials with much lower startup costs. This 1980s SPS concept relied less on human presence in space and more on partially self-replicating systems on the lunar surface under remote control of workers stationed on Earth. The high net energy gain of this proposal derives from the Moon's much shallower gravitational well.

Having a relatively cheap per pound source of raw materials from space would lessen the concern for low mass designs and result in a different sort of SPS being built. The low cost per pound of lunar materials in O'Neill's vision would be supported by using lunar material to manufacture more facilities in orbit than just solar power satellites. Advanced techniques for launching from the Moon may reduce the cost of building a solar power satellite from lunar materials. Some proposed techniques include the lunar mass driver and the lunar space elevator, first described by Jerome Pearson. It would require establishing silicon mining and solar cell manufacturing facilities on the Moon.

On the Moon

Physicist Dr David Criswell suggests the Moon is the optimum location for solar power stations, and promotes lunar-based solar power. The main advantage he envisions is construction largely from locally available lunar materials, using in-situ resource utilization, with a teleoperated mobile factory and crane to assemble the microwave reflectors, and rovers to assemble and pave solar cells, which would significantly reduce launch costs compared to SBSP designs. Power relay satellites orbiting around earth and the Moon reflecting the microwave beam are also part of the project. A demo project of 1 GW starts at $50 billion. The Shimizu Corporation use combination of lasers and microwave for the Luna Ring concept, along with power relay satellites.

From an asteroid

Asteroid mining has also been seriously considered. A NASA design study evaluated a 10,000-ton mining vehicle (to be assembled in orbit) that would return a 500,000-ton asteroid fragment to geostationary orbit. Only about 3,000 tons of the mining ship would be traditional aerospace-grade payload. The rest would be reaction mass for the mass-driver engine, which could be arranged to be the spent rocket stages used to launch the payload. Assuming that 100% of the returned asteroid was useful, and that the asteroid miner itself couldn't be reused, that represents nearly a 95% reduction in launch costs. However, the true merits of such a method would depend on a thorough mineral survey of the candidate asteroids; thus far, we have only estimates of their composition. One proposal is to capture the asteroid Apophis into earth orbit and convert it into 150 solar power satellites of 5 GW each or the larger asteroid 1999 AN10 which is 50x the size of Apophis and large enough to build 7,500 5-gigawatt solar power satellites.

Gallery

Safety

The use of microwave transmission of power has been the most controversial issue in considering any SPS design. At the Earth's surface, a suggested microwave beam would have a maximum intensity at its center, of 23 mW/cm2 (less than 1/4 the solar irradiation constant), and an intensity of less than 1 mW/cm2 outside the rectenna fenceline (the receiver's perimeter). These compare with current United States Occupational Safety and Health Act (OSHA) workplace exposure limits for microwaves, which are 10 mW/cm2, - the limit itself being expressed in voluntary terms and ruled unenforceable for Federal OSHA enforcement purposes. A beam of this intensity is therefore at its center, of a similar magnitude to current safe workplace levels, even for long term or indefinite exposure. Outside the receiver, it is far less than the OSHA long-term levels Over 95% of the beam energy will fall on the rectenna. The remaining microwave energy will be absorbed and dispersed well within standards currently imposed upon microwave emissions around the world. It is important for system efficiency that as much of the microwave radiation as possible be focused on the rectenna. Outside the rectenna, microwave intensities rapidly decrease, so nearby towns or other human activity should be completely unaffected.

Exposure to the beam is able to be minimized in other ways. On the ground, physical access is controllable (e.g., via fencing), and typical aircraft flying through the beam provide passengers with a protective metal shell (i.e., a Faraday Cage), which will intercept the microwaves. Other aircraft (balloons, ultralight, etc.) can avoid exposure by observing airflight control spaces, as is currently done for military and other controlled airspace. The microwave beam intensity at ground level in the center of the beam would be designed and physically built into the system; simply, the transmitter would be too far away and too small to be able to increase the intensity to unsafe levels, even in principle.

In addition, a design constraint is that the microwave beam must not be so intense as to injure wildlife, particularly birds. Experiments with deliberate microwave irradiation at reasonable levels have failed to show negative effects even over multiple generations. Suggestions have been made to locate rectennas offshore, but this presents serious problems, including corrosion, mechanical stresses, and biological contamination.

A commonly proposed approach to ensuring fail-safe beam targeting is to use a retrodirective phased array antenna/rectenna. A "pilot" microwave beam emitted from the center of the rectenna on the ground establishes a phase front at the transmitting antenna. There, circuits in each of the antenna's subarrays compare the pilot beam's phase front with an internal clock phase to control the phase of the outgoing signal. This forces the transmitted beam to be centered precisely on the rectenna and to have a high degree of phase uniformity; if the pilot beam is lost for any reason (if the transmitting antenna is turned away from the rectenna, for example) the phase control value fails and the microwave power beam is automatically defocused. Such a system would be physically incapable of focusing its power beam anywhere that did not have a pilot beam transmitter. The long-term effects of beaming power through the ionosphere in the form of microwaves has yet to be studied, but nothing has been suggested which might lead to any significant effect.

Timeline

In the 20th century

  • 1941: Isaac Asimov published the science fiction short story "Reason," in which a space station transmits energy collected from the sun to various planets using microwave beams.
  • 1968: Peter Glaser introduces the concept of a "solar power satellite" system with square miles of solar collectors in high geosynchronous orbit for collection and conversion of sun's energy into a microwave beam to transmit usable energy to large receiving antennas (rectennas) on Earth for distribution.
  • 1973: Peter Glaser is granted United States patent number 3,781,647 for his method of transmitting power over long distances using microwaves from a large (one square kilometer) antenna on the satellite to a much larger one on the ground, now known as a rectenna.
  • 1978–81: The United States Department of Energy and NASA examine the solar power satellite (SPS) concept extensively, publishing design and feasibility studies.
  • 1987: Stationary High Altitude Relay Platform a Canadian experiment
  • 1995–97: NASA conducts a "Fresh Look" study of space solar power (SSP) concepts and technologies.
  • 1998: The Space Solar Power Concept Definition Study (CDS) identifies credible, commercially viable SSP concepts, while pointing out technical and programmatic risks.
  • 1998: Japan's space agency begins developing a space solar power system (SSPS), a program that continues to the present day.
  • 1999: NASA's Space Solar Power Exploratory Research and Technology program (SERT, see below) begins.
  • 2000: John Mankins of NASA testifies in the U.S. House of Representatives, saying "Large-scale SSP is a very complex integrated system of systems that requires numerous significant advances in current technology and capabilities. A technology roadmap has been developed that lays out potential paths for achieving all needed advances — albeit over several decades.

In the 21st century

  • 2001: NASDA (One of Japan's national space agencies before it became part of JAXA) announces plans to perform additional research and prototyping by launching an experimental satellite with 10 kilowatts and 1 megawatt of power.
  • 2003: ESA studies
  • 2007: The US Pentagon's National Security Space Office (NSSO) issues a report on October 10, 2007 stating they intend to collect solar energy from space for use on Earth to help the United States' ongoing relationship with the Middle East and the battle for oil. A demo plant could cost $10 billion, produce 10 megawatts, and become operational in 10 years.
  • 2007: In May 2007, a workshop is held at the US Massachusetts Institute of Technology (MIT) to review the current state of the SBSP market and technology.
  • 2010: Professors Andrea Massa and Giorgio Franceschetti announce a special session on the "Analysis of Electromagnetic Wireless Systems for Solar Power Transmission" at the 2010 Institute of Electrical and Electronics Engineers International Symposium on Antennas and Propagation.
  • 2010: The Indian Space Research Organisation and US' National Space Society launched a joint forum to enhance partnership in harnessing solar energy through space-based solar collectors. Called the Kalam-NSS Initiative after the former Indian President Dr APJ Abdul Kalam, the forum will lay the groundwork for the space-based solar power program which could see other countries joining in as well.
  • 2010: Sky's No Limit: Space-Based solar power, the next major step in the Indo-US strategic partnership?] written by USAF Lt Col Peter Garretson was published at the Institute for Defence Studies and Analysis.
  • 2012: China proposed joint development between India and China towards developing a solar power satellite, during a visit by former Indian President Dr APJ Abdul Kalam.
  • 2015: The Space Solar Power Initiative (SSPI) is established between Caltech and Northrop Grumman Corporation. An estimated $17.5 million is to be provided over a three-year project for development of a space-based solar power system.
  • 2015: JAXA announced on 12 March 2015 that they wirelessly beamed 1.8 kilowatts 50 meters to a small receiver by converting electricity to microwaves and then back to electricity.
  • 2016: Lt Gen. Zhang Yulin, deputy chief of the [PLA] armament development department of the Central Military Commission, suggested that China would next begin to exploit Earth-Moon space for industrial development. The goal would be the construction of space-based solar power satellites that would beam energy back to Earth.
  • 2016: A team with membership from the Naval Research Laboratory (NRL), Defense Advanced Projects Agency (DARPA), Air Force Air University, Joint Staff Logistics (J-4), Department of State, Makins Aerospace and Northrop Grumman won the Secretary of Defense (SECDEF) / Secretary of State (SECSTATE) / USAID Director's agency-wide D3 (Diplomacy, Development, Defense) Innovation Challenge with a proposal that the US must lead in space solar power. The proposal was followed by a vision video
  • 2016: Citizens for Space-Based Solar Power has transformed the D3 proposal into active petitions on the White House Website "America Must Lead the Transition to Space-Based Energy"and Change.org "USA Must Lead the Transition to Space-Based Energy" along with the following video.
  • 2016: Erik Larson and others from NOAA produce a paper "Global atmospheric response to emissions from a proposed reusable space launch system" The paper makes a case that up to 2 TW/year of power satellites could be constructed without intolerable damage to the atmosphere. Before this paper, there was concern that the NOx produced by reentry would destroy too much ozone.
  • 2016: Ian Cash of SICA Design proposes CASSIOPeiA (Constant Aperture, Solid State, Integrated, Orbital Phased Array) a new concept SPS Faculty Listing | Electrical and Computer Engineering
  • 2017: NASA selects five new research proposals focused on investments in space. The Colorado School of Mines focuses on "21st Century Trends in Space-Based Solar Power Generation and Storage."
  • 2019: Aditya Baraskar and Prof Toshiya Hanada from Space System Dynamic Laboratory, Kyushu University proposed Energy Orbit (E-Orbit), a small Space Solar Power Satellite constellation for power beaming between satellites in low earth orbit. A total of 1600 satellite to transmit 10 kilowatts of electricity in a 500 km radius at an altitude of 900 km. "
  • 2019: China creates a test base for SBSP, and announces plan to launch a working megawatt-grade 200-tonne SBSP station by 2035.

Non-typical configurations and architectural considerations

The typical reference system-of-systems involves a significant number (several thousand multi-gigawatt systems to service all or a significant portion of Earth's energy requirements) of individual satellites in GEO. The typical reference design for the individual satellite is in the 1-10 GW range and usually involves planar or concentrated solar photovoltaics (PV) as the energy collector / conversion. The most typical transmission designs are in the 1–10 GHz (2.45 or 5.8 GHz) RF band where there are minimum losses in the atmosphere. Materials for the satellites are sourced from, and manufactured on Earth and expected to be transported to LEO via re-usable rocket launch, and transported between LEO and GEO via chemical or electrical propulsion. In summary, the architecture choices are:

  • Location = GEO
  • Energy Collection = PV
  • Satellite = Monolithic Structure
  • Transmission = RF
  • Materials & Manufacturing = Earth
  • Installation = RLVs to LEO, Chemical to GEO

There are several interesting design variants from the reference system:

Alternate energy collection location: While GEO is most typical because of its advantages of nearness to Earth, simplified pointing and tracking, very small time in occultation, and scalability to meet all global demand several times over, other locations have been proposed:

  • Sun Earth L1: Robert Kennedy III, Ken Roy & David Fields have proposed a variant of the L1 sunshade called "Dyson Dots" where a multi-terawatt primary collector would beam energy back to a series of LEO sun-synchronous receiver satellites. The much farther distance to Earth requires a correspondingly larger transmission aperture.
  • Lunar surface: David Criswell has proposed using the Lunar surface itself as the collection medium, beaming power to the ground via a series of microwave reflectors in Earth Orbit. The chief advantage of this approach would be the ability to manufacture the solar collectors in-situ without the energy cost and complexity of launch. Disadvantages include the much longer distance, requiring larger transmission systems, the required "overbuild" to deal with the lunar night, and the difficulty of sufficient manufacturing and pointing of reflector satellites.
  • MEO: MEO systems have been proposed for in-space utilities and beam-power propulsion infrastructures. For example, see Royce Jones' paper.
  • Highly elliptical orbits: Molniya, Tundra, or Quazi Zenith orbits have been proposed as early locations for niche markets, requiring less energy to access and providing good persistence.
  • Sun-sync LEO: In this near Polar Orbit, the satellites precess at a rate that allows them to always face the Sun as they rotate around Earth. This is an easy to access orbit requiring far less energy, and its proximity to Earth requires smaller (and therefore less massive) transmitting apertures. However disadvantages to this approach include having to constantly shift receiving stations, or storing energy for a burst transmission. This orbit is already crowded and has significant space debris.
  • Equatorial LEO: Japan's SPS 2000 proposed an early demonstrator in equatorial LEO in which multiple equatorial participating nations could receive some power.
  • Earth's surface: Narayan Komerath has proposed a space power grid where excess energy from an existing grid or power plant on one side of the planet can be passed up to orbit, across to another satellite and down to receivers.

Energy collection: The most typical designs for solar power satellites include photovoltaics. These may be planar (and usually passively cooled), concentrated (and perhaps actively cooled). However, there are multiple interesting variants.

  • Solar thermal: Proponents of solar thermal have proposed using concentrated heating to cause a state change in a fluid to extract energy via rotating machinery followed by cooling in radiators. Advantages of this method might include overall system mass (disputed), non-degradation due to solar-wind damage, and radiation tolerance. One recent thermal solar power satellite design by Keith Henson and others has been visualized here. Thermal Space Solar Power concept A related concept is here: Beamed Energy Bootstrapping The proposed radiators are thin wall platic tube filled with low pressure (2.4 kPa) and temperature (20 deg C) steam.
  • Solar pumped laser: Japan has pursued a solar-pumped laser, where sunlight directly excites the lasing medium used to create the coherent beam to Earth.
  • Fusion decay: This version of a power-satellite is not "solar". Rather, the vacuum of space is seen as a "feature not a bug" for traditional fusion. Per Paul Werbos, after fusion even neutral particles decay to charged particles which in a sufficiently large volume would allow direct conversion to current.
  • Solar wind loop: Also called a Dyson–Harrop satellite. Here the satellite makes use not of the photons from the Sun but rather the charged particles in the solar wind which via electro-magnetic coupling generate a current in a large loop.
  • Direct mirrors: Early concepts for direct mirror re-direction of light to planet Earth suffered from the problem that rays coming from the sun are not parallel but are expanding from a disk and so the size of the spot on the Earth is quite large. Lewis Fraas has explored an array of parabolic mirrors to augment existing solar arrays.

Alternate satellite architecture: The typical satellite is a monolithic structure composed of a structural truss, one or more collectors, one or more transmitters, and occasionally primary and secondary reflectors. The entire structure may be gravity gradient stabilized. Alternative designs include:

  • Swarms of smaller satellites: Some designs propose swarms of free-flying smaller satellites. This is the case with several laser designs, and appears to be the case with CALTECH's Flying Carpets. For RF designs, an engineering constraint is the sparse array problem.
  • Free floating components: Solaren has proposed an alternative to the monolithic structure where the primary reflector and transmission reflector are free-flying.
  • Spin stabilization: NASA explored a spin-stabilized thin film concept.
  • Photonic laser thruster (PLT) stabilized structure: Young Bae has proposed that photon pressure may substitute for compressive members in large structures.

Transmission: The most typical design for energy transmission is via an RF antenna at below 10 GHz to a rectenna on the ground. Controversy exists between the benefits of Klystrons, Gyrotrons, Magnetrons and solid state. Alternate transmission approaches include:

  • Laser: Lasers offer the advantage of much lower cost and mass to first power, however there is controversy regarding benefits of efficiency. Lasers allow for much smaller transmitting and receiving apertures. However, a highly concentrated beam has eye-safety, fire safety, and weaponization concerns. Proponents believe they have answers to all these concerns. A laser-based approach must also find alternate ways of coping with clouds and precipitation.
  • Atmospheric waveguide: Some have proposed it may be possible to use a short pulse laser to create an atmospheric waveguide through which concentrated microwaves could flow.
  • Nuclear synthesis: Particle accelerators based in the inner solar system (whether in orbit or on a planet such as Mercury) could use solar energy to synthesize nuclear fuel from naturally occurring materials. While this would be highly inefficient using current technology (in terms of the amount of energy needed to manufacture the fuel compared to the amount of energy contained in the fuel) and would raise obvious nuclear safety issues, the basic technology upon which such an approach would rely on has been in use for decades, making this possibly the most reliable means of sending energy especially over very long distances - in particular, from the inner solar system to the outer solar system.

Materials and manufacturing: Typical designs make use of the developed industrial manufacturing system extant on Earth, and use Earth based materials both for the satellite and propellant. Variants include:

  • Lunar materials: Designs exist for Solar Power Satellites that source >99% of materials from lunar regolith with very small inputs of "vitamins" from other locations. Using materials from the Moon is attractive because launch from the Moon is in theory far less complicated than from Earth. There is no atmosphere, and so components do not need to be packed tightly in an aeroshell and survive vibration, pressure and temperature loads. Launch may be via a magnetic mass driver and bypass the requirement to use propellant for launch entirely. Launch from the Moon the GEO also requires far less energy than from Earth's much deeper gravity well. Building all the solar power satellites to fully supply all the required energy for the entire planet requires less than one millionth of the mass of the Moon.
  • Self-replication on the Moon: NASA explored a self-replicating factory on the Moon in 1980. More recently, Justin Lewis-Webber proposed a method of speciated manufacture of core elements based upon John Mankins SPS-Alpha design.
  • Asteroidal materials: Some asteroids are thought to have even lower Delta-V to recover materials than the Moon, and some particular materials of interest such as metals may be more concentrated or easier to access.
  • In-space/in-situ manufacturing: With the advent of in-space additive manufacturing, concepts such as SpiderFab might allow mass launch of raw materials for local extrusion.

Method of installation / Transportation of Material to Energy Collection Location: In the reference designs, component material is launched via well-understood chemical rockets (usually fully reusable launch systems) to LEO, after which either chemical or electrical propulsion is used to carry them to GEO. The desired characteristics for this system is very high mass-flow at low total cost. Alternate concepts include:

  • Lunar chemical launch: ULA has recently showcased a concept for a fully re-usable chemical lander XEUS to move materials from the Lunar surface to LLO or GEO.
  • Lunar mass driver: Launch of materials from the lunar surface using a system similar to an aircraft carrier electromagnetic catapult. An unexplored compact alternative would be the slingatron.
  • Lunar space elevator: An equatorial or near-equatorial cable extends to and through the lagrange point. This is claimed by proponents to be lower in mass than a traditional mass driver.
  • Space elevator: A ribbon of pure carbon nanotubes extends from its center of gravity in Geostationary orbit, allowing climbers to climb up to GEO. Problems with this include the material challenge of creating a ribbon of such length with adequate strength, management of collisions with satellites and space debris, and lightning.
  • MEO Skyhook: As part of an AFRL study, Roger Lenard proposed a MEO Skyhook. It appears that a gravity gradient-stabilized tether with its center of mass in MEO can be constructed of available materials. The bottom of the skyhook is close to the atmosphere in a "non-keplerian orbit". A re-usable rocket can launch to match altitude and speed with the bottom of the tether which is in a non-keplerian orbit (travelling much slower than typical orbital speed). The payload is transferred and it climbs the cable. The cable itself is kept from de-orbiting via electric propulsion and/or electromagnetic effects.
  • MAGLEV launch / StarTram: John Powell has a concept for a very high mass-flow system. In a first-gen system, built into a mountain, accelerates a payload through an evacuated MAGLEV track. A small on-board rocket circularizes the payload.
  • Beamed energy launch: Kevin Parkin and Escape Dynamics both have concepts for ground-based irradiation of a mono-propellant launch vehicle using RF energy. The RF energy is absorbed and directly heats the propellant not unlike in NERVA-style nuclear-thermal. LaserMotive has a concept for a laser-based approach.

In fiction

Space stations transmitting solar power have appeared in science-fiction works like Isaac Asimov's "Reason" (1941), that centers around the troubles caused by the robots operating the station. Asimov's short story "The Last Question" also features the use of SBSP to provide limitless energy for use on Earth.

Erc Kotani and John Maddox Roberts's 2000 novel The Legacy of Prometheus posits a race between several conglomerates to be the first to beam down a gigawatt of energy from a solar satellite in geosynchronous orbit.

In Ben Bova's novel PowerSat (2005), an entrepreneur strives to prove that his company's nearly completed power satellite and spaceplane (a means of getting maintenance crews to the satellite efficiently) are both safe and economically viable, while terrorists with ties to oil producing nations attempt to derail these attempts through subterfuge and sabotage.

Various aerospace companies have also showcased imaginative future solar power satellites in their corporate vision videos, including Boeing, Lockheed Martin, and United Launch Alliance.

The solar satellite is one of three means of producing energy in the browser-based game OGame.

In the 1978 anime TV series Future Boy Conan, SBSP enables the country of Industria to develop geomagnetic weapons, more powerful than nuclear weapons, that destroy entire continents.

Operator (computer programming)

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