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Sunday, August 9, 2020

Coal pollution mitigation

From Wikipedia, the free encyclopedia
 
Government Accountability Office diagram showing emissions controls at a coal fired power plant

Coal pollution mitigation, often called clean coal, is a series of systems and technologies that seek to mitigate the pollution and other environmental effects normally associated with the burning (though not the mining or processing) of coal, which is widely regarded as the dirtiest of the common fuels for industrial processes and power generation.

Approaches attempt to mitigate emissions of carbon dioxide (CO2) and other greenhouse gases, and radioactive materials, that arise from the use of coal, mainly for electrical power generation, using various technologies. Historical efforts to reduce coal pollution focused on flue-gas desulfurization starting in the 1850s and clean burn technologies. These efforts have been very successful in countries with strong environmental regulation, where emissions of acid-rain causing compounds and particulates have been reduced by up to 90% since 1995. More recent developments include carbon capture and storage, which pumps and stores CO2 emissions underground, and integrated gasification combined cycle (IGCC) involve coal gasification, which provides a basis for increased efficiency and lower cost in capturing CO2 emissions.

There are seven technologies deployed or proposed by the National Mining Association for deployment in the United States:
Of the 22 clean coal demonstration projects funded by the U.S. Department of Energy since 2003, none are in operation as of February 2017, having been abandoned or delayed due to capital budget overruns or discontinued because of excessive operating expenses.

Regulations

Since the 1970s, various policy and regulatory measures have driven coal pollution mitigation. In the US, the Clean Air Act was the primary driving force in reducing particulate emissions and acid rain from coal combustion. As regulations have increased the demand for coal pollution mitigation technologies, costs have fallen and performance has improved.

The widespread deployment of pollution-control equipment to reduce sulfur dioxide, NOx and dust emissions is just one example that brought cleaner air to many countries. The desire to tackle rising CO2 emissions to address climate change later introduced Carbon Capture and Storage (CCS).

Within the United States, Carbon Capture and Storage technologies, also sometimes referred to as carbon capture and sequestration, are mainly being developed in response to regulations by the Environmental Protection Agency—most notably the Clean Air Act—and in anticipation of legislation that seeks to mitigate climate change.

Loan guarantees and tax incentives have a long history of use in Australia, EU countries, and the US to encourage the introduction of coal pollution mitigation and other technologies to reduce environmental impact.

Environmental impact of coal

Greenhouse gases

Combustion of coal—which is mostly carbon—produces carbon dioxide as a product of combustion. According to the United Nations Intergovernmental Panel on Climate Change, the burning of coal, a fossil fuel, is a significant contributor to global warming. (See the UN IPCC Fourth Assessment Report). Burning 1 ton of coal produces 2.86 tons of carbon dioxide.

Carbon sequestration technology has yet to be tested on a large scale and may not be safe or successful. Sequestered CO2 may eventually leak up through the ground, may lead to unexpected geological instability or may cause contamination of aquifers used for drinking water supplies.

As a quarter of world energy consumption in 2019 was from coal, reaching the carbon dioxide reduction targets of the Paris Agreement will require modifications to how coal is used.

Measurement of pollution and availability of pollution data

In some countries, such as the EU, smokestack measurements from individual power plants must be published. Whereas in some countries, such as Turkey, they are only reported to the government not the public. However, since the late 2010s satellite measurements of some pollutants have been available.

Combustion By-products

By-products of coal combustion are compounds which are released into the atmosphere as a result of burning coal. Coal includes contaminants such as sulfur compounds and non-combustible minerals. When coal is burned, the minerals become ash (i.e. particulate matter or PM) and the sulfur forms sulfur dioxide (SO2). Since air is mostly nitrogen, combustion of coal often leads to production of nitrogen oxides. Sulfur dioxide and nitrogen oxides are primary causes of acid rain. For many years—before greenhouse gasses were widely understood to be a threat—it was thought that these by-products were the only drawback to using coal. These by-products are still a problem, but they have been greatly diminished in most advanced countries due to clean air regulations. It is possible to remove most of the sulfur dioxide (SO2), nitrogen oxides (NOx), and particulate matter (PM) emissions from the coal-burning process. For example, various techniques are used in a coal preparation plant to reduce the amount of non-combustible matter (i.e. ash) in the coal prior to burning. During combustion, fluidized bed combustion is used to reduce sulfur dioxide emissions. After burning, particulate matter (i.e. ash and dust) can be reduced using an electrostatic precipitator and sulfur dioxide emissions can be further reduced with flue-gas desulfurization. Trace amounts of radionuclides are more difficult to remove.

Coal-fired power plants are the largest aggregate source of the toxic heavy metal mercury: 50 tons per year come from coal power plants out of 150 tons emitted nationally in the US and 5000 tons globally. However, according to the United States Geological Survey, the trace amounts of mercury in coal by-products do not pose a threat to public health. A study in 2013 found that mercury found in the fish in the Pacific Ocean could possibly be linked to coal-fired plants in Asia.

Potential financial impact

Whether carbon capture and storage technology is adopted worldwide will "...depend less on science than on economics. Cleaning coal is very expensive." 

Cost of converting a single coal-fired power plant

Conversion of a conventional coal-fired power plant is done by injecting the CO
2
into ammonium carbonate after which it is then transported and deposited underground (preferably in soil beneath the sea). This injection process however is by far the most expensive. Besides the cost of the equipment and the ammonium carbonate, the coal-fired power plant also needs to use 30% of its generated heat to do the injection (parasitic load). A test-setup has been done in the American Electric Power Mountaineer coal-burning power plant.

One solution to reduce this thermal loss/parasitic load is to burn the pulverised load with pure oxygen instead of air.

Cost implications for new coal-fired power plants

Newly built coal-fired power plants can be made to immediately use gasification of the coal prior to combustion. This makes it much easier to separate off the CO
2
from the exhaust fumes, making the process cheaper. This gasification process is done in new coal-burning power plants such as the coal-burning power plant at Tianjin, called "GreenGen".

Costs for China

As of 2019 costs of retrofitting CCS are unclear and the economics depends partly on how the Chinese national carbon trading scheme progresses.

Costs for India

As of 2019 some argue that "with the right policy initiatives and market design" gasification with CCS would be cost effective for some coal plants.

Politics

Australia

In Australia, carbon capture and storage was often referred to by then Prime Minister Kevin Rudd as a possible way to reduce greenhouse gas emissions. (The previous Prime Minister John Howard had stated that nuclear power was a better alternative, as CCS technology may not prove to be economically feasible.)

Canada

In 2014 SaskPower a provincial-owned electric utility finished renovations on Boundary Dam's boiler number 3 making it the world's first post-combustion carbon capture storage facility. The renovation project ended up costing a little over $1.2 billion and can scrub out CO2 and toxins from up to 90 percent of the flue gas that it emits.

China

Since 2006, China releases more CO
2
than any other country. Researchers in China are focusing on increasing efficiency of burning coal so they can get more power out of less coal. It is estimated that new high efficiency power plants could reduce CO2 emission by 7% because they won't have to burn as much coal to get the same amount of power.

Japan

Following the catastrophic failure of the Fukushima I Nuclear Power Plant in Japan that resulted from the 2011 Tōhoku earthquake and tsunami, and the subsequent widespread public opposition against nuclear power, high energy, lower emission (HELE) coal power plants were increasingly favored by the Shinzō Abe-led government to recoup lost energy capacity from the partial shutdown of nuclear power plants in Japan and to replace aging coal and oil-fired power plants, while meeting 2030 emission targets of the Paris Agreement. 45 HELE power plants have been planned, purportedly to employ integrated gasification fuel cell cycle, a further development of integrated gasification combined cycle.

Japan had adopted prior pilot projects on IGCC coal power plants in the early-1990s and late-2000s.

United States

In the United States, "clean coal" was mentioned by former President George W. Bush on several occasions, including his 2007 State of the Union Address. Bush's position was that carbon capture and storage technologies should be encouraged as one means to reduce the country's dependence on foreign oil.

During the US Presidential campaign for 2008, both candidates John McCain and Barack Obama expressed interest in the development of CCS technologies as part of an overall comprehensive energy plan. The development of pollution mitigation technologies could also create export business for the United States or any other country working on it.

The American Reinvestment and Recovery Act, signed in 2009 by President Obama, allocated $3.4 billion for advanced carbon capture and storage technologies, including demonstration projects.

Former Secretary of State Hillary Clinton has said that "we should strive to have new electricity generation come from other sources, such as clean coal and renewables", and former Energy Secretary Dr. Steven Chu has said that "It is absolutely worthwhile to invest in carbon capture and storage", noting that even if the U.S. and Europe turned their backs on coal, developing nations like India and China would likely not.

During the first 2012 United States presidential election debate, Mitt Romney expressed his support for clean coal, and claimed that current federal policies were hampering the coal industry.

Office of Clean Coal and Carbon Management

The Office of Clean Coal and Carbon Management is part of the United States Department of Energy. It sponsors research into "clean coal" technology. 

Criticism of the approach

Environmentalists such as Dan Becker, director of the Sierra Club's Global Warming and Energy Program, believes that the term "clean coal" is misleading: "There is no such thing as clean coal and there never will be. It's an oxymoron." The Sierra Club's Coal Campaign has launched a site refuting the clean coal statements and advertising of the coal industry.

Complaints focus on the environmental impacts of coal extraction, high costs to sequester carbon, and uncertainty of how to manage end result pollutants and radionuclides. In reference to sequestration of carbon, concerns exist about whether geologic storage of CO2 in reservoirs, aquifers, etc., is indefinite/permanent.

The palaeontologist and influential environmental activist Tim Flannery made the assertion that the concept of clean coal might not be viable for all geographical locations.

Critics also believe that the continuing construction of coal-powered plants (whether or not they use carbon sequestration techniques) encourages unsustainable mining practices for coal, which can strip away mountains, hillsides, and natural areas. They also point out that there can be a large amount of energy required and pollution emitted in transporting the coal to the power plants.




The Reality Coalition, a US non-profit climate organization composed of the Alliance for Climate Protection, the Sierra Club, the National Wildlife Federation, the Natural Resources Defense Council, and the League of Conservation Voters, ran a series of television commercials in 2008 and 2009. The commercials were highly critical of attempts to mitigate coal's pollution, stating that without capturing CO2 emissions and storing it safely that it cannot be called "clean coal".


Greenpeace is a major opponent of the concept, because they view emissions and wastes as not being avoided but instead transferred from one waste stream to another. According to Greenpeace USA's Executive Director Phil Radford speaking in 2012, "even the industry figures it will take 10 or 20 years to arrive, and we need solutions sooner than that. We need to scale up renewable energy; 'clean coal' is a distraction from that."

Clean coal

The term Clean Coal in modern society often refers to the carbon capture and storage process. The term has been used by advertisers, lobbyists, and politicians such as Donald Trump.

Prior terminology

The industry term "clean coal" is increasingly used in reference to carbon capture and storage, an advanced theoretical process that would eliminate or significantly reduce carbon dioxide emissions from coal-based plants and permanently sequester them. More generally, the term has been found in modern usage to describe technologies designed to enhance both the efficiency and the environmental acceptability of coal extraction, preparation, and use.

U.S. Senate Bill 911 in April, 1987, defined clean coal technology as follows:
"The term clean coal technology means any technology...deployed at a new or existing facility which will achieve significant reductions in air emissions of sulfur dioxide or oxides of nitrogen associated with the utilization of coal in the generation of electricity."
Before being adopted in this fashion, historically "clean coal" was used to refer to clean-burning coal with low levels of impurities, though this term faded after rates of domestic coal usage dropped. The term appeared in a speech to mine workers in 1918, in context indicating coal that was "free of dirt and impurities." In the early 20th century, prior to World War II, clean coal (also called "smokeless coal") generally referred to anthracite and high-grade bituminous coal, used for cooking and home heating.

Clean coal technology is a collection of technologies being developed in attempts to lessen the negative environmental impact of coal energy generation and to mitigate worldwide climate change. When coal is used as a fuel source, the gaseous emissions generated by the thermal decomposition of the coal include sulfur dioxide (SO2), nitrogen oxides (NOx), mercury, and other chemical byproducts that vary depending on the type of the coal being used. These emissions have been established to have a negative impact on the environment and human health, contributing to acid rain, lung cancer and cardiovascular disease. As a result, clean coal technologies are being developed to remove or reduce pollutant emissions to the atmosphere. Some of the techniques that would be used to accomplish this include chemically washing minerals and impurities from the coal, gasification (see also IGCC), improved technology for treating flue gases to remove pollutants to increasingly stringent levels and at higher efficiency, carbon capture and storage technologies to capture the carbon dioxide from the flue gas and dewatering lower rank coals (brown coals) to improve the calorific value, and thus the efficiency of the conversion into electricity. Concerns exist regarding the economic viability of these technologies and the timeframe of delivery, potentially high hidden economic costs in terms of social and environmental damage, and the costs and viability of disposing of removed carbon and other toxic matter.

In its original usage, the term "Clean Coal" was used to refer to technologies that were designed to reduce emission of pollutants associated with burning coal, such as washing coal at the mine. This step removes some of the sulfur and other contaminants, including rocks and soil. This makes coal cleaner and cheaper to transport. More recently, the definition of clean coal has been expanded to include carbon capture and storage. Clean coal technology usually addresses atmospheric problems resulting from burning coal. Historically, the primary focus was on SO2 and NOx, the most important gases in causation of acid rain, and particulates which cause visible air pollution and have deleterious effects on human health.

Technology

Several different technological methods are available for the purpose of carbon capture as demanded by the clean coal concept:
  • Pre-combustion capture – This involves gasification of a feedstock (such as coal) to form synthesis gas, which may be shifted to produce a H2 and CO2-rich gas mixture, from which the CO2 can be efficiently captured and separated, transported, and ultimately sequestered, This technology is usually associated with Integrated Gasification Combined Cycle process configurations.
  • Post-combustion capture – This refers to capture of CO2 from exhaust gases of combustion processes.
  • Oxy-fuel combustion – Fossil fuels such as coal are burned in a mixture of recirculated flue gas and oxygen, rather than in air, which largely eliminates nitrogen from the flue gas enabling efficient, low-cost CO2 capture.
The Kemper County IGCC Project, a proposed 582 MW coal gasification-based power plant, was expected to use pre-combustion capture of CO2 to capture 65% of the CO2 the plant produces, which would have been utilized and geologically sequestered in enhanced oil recovery operations. However, after many delays and a cost runup to $7.5 billion (triple the initial budget), the coal gasification project was abandoned and as of late 2017, Kemper is under construction as a cheaper natural gas power plant.

The Saskatchewan Government's Boundary Dam Integrated Carbon Capture and Sequestration Demonstration Project will use post-combustion, amine-based scrubber technology to capture 90% of the CO2 emitted by Unit 3 of the power plant; this CO2 will be pipelined to and utilized for enhanced oil recovery in the Weyburn oil fields.

An oxyfuel CCS power plant operation processes the exhaust gases so as to separate the CO2 so that it may be stored or sequestered
 
An early example of a coal-based plant using (oxy-fuel) carbon-capture technology is Swedish company Vattenfall’s Schwarze Pumpe power station located in Spremberg, Germany, built by German firm Siemens, which went on-line in September 2008. The facility captures CO2 and acid rain producing pollutants, separates them, and compresses the CO2 into a liquid. Plans are to inject the CO2 into depleted natural gas fields or other geological formations. Vattenfall opines that this technology is considered not to be a final solution for CO2 reduction in the atmosphere, but provides an achievable solution in the near term while more desirable alternative solutions to power generation can be made economically practical.

Other examples of oxy-combustion carbon capture are in progress. Callide Power Station has retrofitted a 30-MWth existing PC-fired power plant to operate in oxy-fuel mode; in Ciuden, Spain, Endesa has a newly built 30-MWth oxy-fuel plant using circulating fluidized bed combustion (CFBC) technology. Babcock-ThermoEnergy's Zero Emission Boiler System (ZEBS) is oxy-combustion-based; this system features near 100% carbon-capture and according to company information virtually no air-emissions.

Other carbon capture and storage technologies include those that dewater low-rank coals. Low-rank coals often contain a higher level of moisture content which contains a lower energy content per tonne. This causes a reduced burning efficiency and an increased emissions output. Reduction of moisture from the coal prior to combustion can reduce emissions by up to 50 percent.

Demonstration projects in the United States

In the late 1980s and early 1990s, the U.S. Department of Energy (DOE) began conducting a joint program with the industry and State agencies to demonstrate clean coal technologies large enough for commercial use. The program, called the Clean Coal Technology & Clean Coal Power Initiative (CCPI), has had a number of successes that have reduced emissions and waste from coal-based electricity generation. The National Energy Technology Laboratory has administered three rounds of CCPI funding and the following projects were selected during each round:
  • Round 1 CCPI Projects
    • Advanced Multi-Product Coal Utilization By-Product Processing Plant
    • Demonstration of Integrated Optimization Software at the Baldwin Energy Complex
    • Gilberton Coal-to-Clean Fuels and Power Co-Production Project
    • Increasing Power Plant Efficiency: Lignite Fuel Enhancement
    • TOXECON Retrofit for Mercury and Multi-Pollutant Control on Three 90-MW Coal-Fired Boilers
    • Western Greenbrier Co-Production Demonstration Project
    • Commercial Demonstration of the Airborne Process
    • Integration of Advanced Emission Controls to Produce Next-Generation Circulating Fluid Bed Coal Generating Unit
  • Round 2 CCPI Projects
    • Airborne Process Commercial Scale Demonstration Program
    • Demonstration of a Coal-Based Transport Gasifier
    • Mercury Species and Multi-Pollutant Control Project
    • Mesaba Energy Project
  • Round 3 CCPI Projects
These programs have helped to meet regulatory challenges by incorporating pollution control technologies into a portfolio of cost-effective regulatory compliance options for conventional and developmental coal-fired power plants. This portfolio has positioned the U.S. as a top exporter of clean coal technologies such as those used for SOx, NOx and mercury, and more recently for carbon capture, consistent with a goal of deploying advanced coal-based power systems in commercial service with improved efficiency and environmental performance to meet increasingly stringent environmental regulations and market demands, leading to widespread, global deployment which will contribute to significant reductions in greenhouse gas emissions. The DOE continues its programs and initiatives through regional sequestration partnerships, a carbon sequestration leadership forum and the Carbon Sequestration Core Program, a CCS research and development program.

According to a report by the assistant secretary for fossil energy at the U.S. Department of Energy, clean coal technology has paid measurable dividends. Technological innovation introduced through the CCT Program now provides consumers cost-effective, clean, coal-based energy.

Clean coal and the environment

According to United Nations Intergovernmental Panel on Climate Change, the burning of coal, a fossil fuel, is a major contributor to global warming. (See the UN IPCC Fourth Assessment Report). As 26% of the world's electrical generation in 2004 was from coal-fired generation (see World energy resources and consumption), reaching the carbon dioxide reduction targets of the Kyoto Protocol will require modifications to how coal is utilized.

Coal, which is primarily used for the generation of electricity, is the second largest domestic contributor to carbon dioxide emissions in the US. The public has become more concerned about global warming which has led to new legislation. The coal industry has responded by running advertising touting clean coal in an effort to counter negative perceptions and claiming more than $50 billion towards the development and deployment of "traditional" clean coal technologies over the past 30 years; and promising $500 million towards carbon capture and storage research and development. There is still concern about clean coal technology being perceived as more environmentally friendly than it is, and the term "Clean Coal" has been used as an example of "greenwashing". According to the Sierra Club, "Despite the industry's hype, there's no such thing as 'clean coal.' But new technologies and policies can help reduce coal plants' deadly emissions."

Conjunction with enhanced oil recovery and other applications; commercial-scale CCS is currently being tested in the U.S. and other countries. Proposed CCS sites are subjected to extensive investigation and monitoring to avoid potential hazards, which could include leakage of sequestered CO2 to the atmosphere, induced geological instability, or contamination of water sources such as oceans and aquifers used for drinking water supplies.

The Great Plains Synfuels plant supports the technical feasibility of carbon dioxide sequestration. Carbon dioxide from the coal gasification is shipped to Canada where it is injected into the ground to aid in oil recovery. A drawback of the carbon sequestration process is that it is expensive compared to traditional processes.

Mountaintop removal mining

From Wikipedia, the free encyclopedia

Mountaintop removal site
 
Mountaintop removal site in Pike County, Kentucky

Mountaintop removal mining (MTR), also known as mountaintop mining (MTM), is a form of surface mining at the summit or summit ridge of a mountain. Coal seams are extracted from a mountain by removing the land, or overburden, above the seams. This method of coal mining is conducted in the Appalachian Mountains in the eastern United States. Explosives are used to remove up to 400 vertical feet (120 m) of mountain to expose underlying coal seams. Excess rock and soil is dumped into nearby valleys, in what are called "holler fills" ("hollow fills") or "valley fills". Less expensive to execute and requiring fewer employees, mountaintop removal mining began in Appalachia in the 1970s as an extension of conventional strip mining techniques. It is primarily occurring in Kentucky, West Virginia, Virginia, and Tennessee.

The practice of mountaintop removal mining has been controversial. The coal industry cites economic benefits and claims that mountaintop removal is safer than underground mining.

Overview

Mountaintop removal mining (MTR), also known as mountaintop mining (MTM), is a form of surface mining that involves the topographical alteration and/or removal of a summit, hill, or ridge to access buried coal seams. 

The MTR process involves the removal of coal seams by first fully removing the overburden lying atop them, exposing the seams from above. This method differs from more traditional underground mining, where typically a narrow shaft is dug which allows miners to collect seams using various underground methods, while leaving the vast majority of the overburden undisturbed. The overburden from MTR is either placed back on the ridge, attempting to reflect the approximate original contour of the mountain, and/or is moved into neighboring valleys.

Excess rock and soil containing mining byproducts are disposed into nearby valleys, in what are called "holler fills" or "valley fills".

MTR in the United States is most often associated with the extraction of coal in the Appalachian Mountains, where the United States Environmental Protection Agency (EPA) estimates that 2,200 square miles (5,700 km2) of Appalachian forests will be cleared for MTR sites by the year 2012. Sites range from Ohio to Virginia. It occurs most commonly in West Virginia and Eastern Kentucky, the top two coal-producing states in Appalachia. At current rates, MTR in the U.S. will mine over 1.4 million acres (5,700 km²) by 2010, an amount of land area that exceeds that of the state of Delaware. More than 500 mountains in the US have been destroyed by this process, resulting in the burial of 3,200 km (2,000 mi) of streams.

Mountaintop removal has been practiced since the 1960s. Increased demand for coal in the United States, sparked by the 1973 and 1979 petroleum crises, created incentives for a more economical form of coal mining than the traditional underground mining methods involving hundreds of workers, triggering the first widespread use of MTR. Its prevalence expanded further in the 1990s to retrieve relatively low-sulfur coal, a cleaner-burning form, which became desirable as a result of amendments to the U.S. Clean Air Act that tightened emissions limits on high-sulfur coal processing.

Process

US EPA diagram of mountaintop mining:

"Step 1. Layers of rock and dirt above the coal (called overburden) are removed."
"Step 2. The upper seams of coal are removed with spoils placed in an adjacent valley."
"Step 3. Draglines excavate lower layers of coal with spoils placed in spoil piles."
"Step 4. Regrading begins as coal excavation continues."
"Step 5. Once coal removal is completed, final regrading takes place and the area is revegetated."

Land is deforested prior to mining operations and the resultant lumber is either sold or burned. According to the Surface Mining Control and Reclamation Act of 1977 (SMCRA), the topsoil is supposed to be removed and set aside for later reclamation. However, coal companies are often granted waivers and instead reclaim the mountain with "topsoil substitute". The waivers are granted if adequate amounts of topsoil are not naturally present on the rocky ridge top. Once the area is cleared, miners use explosives to blast away the overburden, the rock and subsoil, to expose coal seams beneath. The overburden is then moved by various mechanical means to areas of the ridge previously mined. These areas are the most economical area of storage as they are located close to the active pit of exposed coal. If the ridge topography is too steep to adequately handle the amount of spoil produced then additional storage is used in a nearby valley or hollow, creating what is known as a valley fill or hollow fill. Any streams in a valley are buried by the overburden.

A front-end loader or excavator then removes the coal, where it is transported to a processing plant. Once coal removal is completed, the mining operators back stack overburden from the next area to be mined into the now empty pit. After backstacking and grading of overburden has been completed, topsoil (or a topsoil substitute) is layered over the overburden layer. Next, grass seed is spread in a mixture of seed, fertilizer, and mulch made from recycled newspaper. Depending on surface land owner wishes the land will then be further reclaimed by adding trees if the pre-approved post-mining land use is forest land or wildlife habitat. If the land owner has requested other post-mining land uses the land can be reclaimed to be used as pasture land, economic development or other uses specified in SMCRA.

Because coal usually exists in multiple geologically stratified seams, miners can often repeat the blasting process to mine over a dozen seams on a single mountain, increasing the mine depth each time. This can result in a vertical descent of hundreds of extra feet into the earth.

Economics

As of 2015, approximately one third of the electricity generated in the United States is produced by coal-fired power plants. MTR accounted for less than 5% of U.S. coal production as of 2001. In some regions, however, the percentage is higher, for example, MTR provided 30% of the coal mined in West Virginia in 2006.

Historically in the U.S. the prevalent method of coal acquisition was underground mining which is very labor-intensive. In MTR, through the use of explosives and large machinery, more than two and a half times as much coal can be extracted per worker per hour than in traditional underground mines, thus greatly reducing the need for workers. In Kentucky, for example, the number of workers has declined over 60% from 1979 to 2006 (from 47,190 to 17,959 workers). The industry overall lost approximately 10,000 jobs from 1990 to 1997, as MTR and other more mechanized underground mining methods became more widely used. The coal industry asserts that surface mining techniques, such as mountaintop removal, are safer for miners than sending miners underground.

Proponents argue that in certain geologic areas, MTR and similar forms of surface mining allow the only access to thin seams of coal that traditional underground mining would not be able to mine. MTR is sometimes the most cost-effective method of extracting coal.

Several studies of the impact of restrictions to mountaintop removal were authored in 2000 through 2005. Studies by Mark L. Burton, Michael J. Hicks and Cal Kent identified significant state-level tax losses attributable to lower levels of mining (notably the studies did not examine potential environmental costs, which the authors acknowledge may outweigh commercial benefits). Mountaintop removal sites are normally restored after the mining operation is complete, but "reclaimed soils characteristically have higher bulk density, lower organic content, low water-infiltration rates, and low nutrient content".

Legislation in the United States

In the United States, MTR is allowed by section 515(c)(1) of the Surface Mining Control and Reclamation Act of 1977. Although most coal mining sites must be reclaimed to the land's pre-mining contour and use, regulatory agencies can issue waivers to allow MTR. In such cases, SMCRA dictates that reclamation must create "a level plateau or a gently rolling contour with no highwalls remaining".

Different organizations have tried to revise a stream buffer rule placed in 1977. The rule states that certain conditions must be met, or the mining operation must take place “within 100 feet of a stream”.  The Obama Administration, in July 2015, wrote up a draft "Stream Protection Rule". This draft adds “more protections to downstream waters”, but it will also debilitate the current buffer requirements.

In February 2017, President Trump signed a bill that did away with the stream protection rule previously administered by the Obama Administration.

Permits must be obtained to deposit valley fill into streams. On four occasions, federal courts have ruled that the US Army Corps of Engineers violated the Clean Water Act by issuing such permits. Massey Energy Company is currently appealing a 2007 ruling, but has been allowed to continue mining in the meantime because "most of the substantial harm has already occurred," according to the judge.

The Bush administration appealed one of these rulings in 2001 because the Act had not explicitly defined "fill material" that could legally be placed in a waterway. The EPA and Army Corps of Engineers changed a rule to include mining debris in the definition of fill material, and the ruling was overturned.

On December 2, 2008, the Bush Administration made a rule change to remove the Stream Buffer Zone protection provision from SMCRA allowing coal companies to place mining waste rock and dirt directly into headwater waterways.

A federal judge has also ruled that using settling ponds to remove mining waste from streams violates the Clean Water Act. He also declared that the Army Corps of Engineers has no authority to issue permits allowing discharge of pollutants into such in-stream settling ponds, which are often built just below valley fills.

On January 15, 2008, the environmental advocacy group Center for Biological Diversity petitioned the United States Fish and Wildlife Service (FWS) to end a policy that waives detailed federal Endangered Species Act reviews for new mining permits. Under current policy, as long as a given MTR mining operation complies with federal surface mining law, the agency presumes conclusively, despite the complexities of intra- and inter-species relationships, that the instance of MTR in question is not damaging to endangered species or their habitat. Since 1996, this policy has exempted many strip mines from being subject to permit-specific reviews of impact on individual endangered species. Because of the 1996 Biological Opinion by FWS making case-by-case formal reviews unnecessary, the Interior's Office of Surface Mining and state regulators require mining companies to hire a government-approved contractor to conduct their own surveys for any potential endangered species. The surveys require approval from state and federal biologists, who provide informal guidance on how to minimize mines' potential effects to species. While the agencies have the option to ask for formal endangered species consultations during that process, they do so very rarely.

On May 25, 2008, North Carolina State Representative Pricey Harrison introduced a bill to ban the use of mountaintop removal coal from coal-fired power plants within North Carolina. This proposed legislation would have been the only legislation of its kind in the United States; however, the bill was defeated.

A Memorandum of Understanding (MOU) and Interagency Action Plan (IAP) were signed by officials of EPA, the Corps, and the Department of the Interior on June 11, 2009. The MOU and IAP outlined different administrative actions that would help decrease “the harmful environmental impacts of mountaintop mining”. The plan also includes near and long-term actions that highlight “specific steps, improved coordination, and greater transparency of decisions”.

The U.S. Energy Information Administration (EIA) stated that the Clean Water Rule was completed on May 27, 2015 by the U.S. Environmental Protection Agency (EPA) and the U.S. Army.  The Clean Water Rule “more precisely defines waters protected under the Clean Water Act”. The EIA also stated that the Office of Surface Mining Reclamation and Enforcement (OSMRE), the EPA and the U. S. Army Corps of Engineers are collaborating with each other to make an environmental impact statement (EIS) “analyzing environmental impacts of coal surface mining in the Appalachian region”.

On Tuesday, April 9, 2019, the Subcommittee on Energy and Mineral Resources held a legislative hearing, "Health and Environmental Impacts of Mountaintop Removal Mining". This hearing involved the H.R. 2050 (Rep. Yarmuth ) bill. This bill stated that “until health studies are conducted by the Department of Health and Human Services", there will be a suspension on permitting for mountaintop removal coal mining.

Environmental and health impacts

The Hobet mine in West Virginia taken by NASA LANDSAT in 1984
 
The Hobet mine in West Virginia taken by NASA LANDSAT in 2009

Critics

Critics contend that MTR is a destructive and unsustainable practice that benefits a small number of corporations at the expense of local communities and the environment. Though the main issue has been over the physical alteration of the landscape, opponents to the practice have also criticized MTR for the damage done to the environment by massive transport trucks, and the environmental damage done by the burning of coal for power.

Blasting at MTR sites also expels dust and fly-rock into the air, which can disturb or settle onto private property nearby. This dust may contain sulfur compounds, which corrodes structures and is a health hazard.

2010 report

A January 2010 report in the journal Science reviews current peer-reviewed studies and water quality data and explores the consequences of mountaintop mining. It concludes that mountaintop mining has serious environmental impacts that mitigation practices cannot successfully address. For example, the extensive tracts of deciduous forests destroyed by mountaintop mining support several endangered species and some of the highest biodiversity in North America. There is a particular problem with burial of headwater streams by valley fills which causes permanent loss of ecosystems that play critical roles in ecological processes.

In addition, increases in metal ions, pH, electrical conductivity, total dissolved solids due to elevated concentrations of sulfate are closely linked to the extent of mining in West Virginia watersheds. Declines in stream biodiversity have been linked to the level of mining disturbance in West Virginia watersheds.

Published studies

Published studies also show a high potential for human health impacts. These may result from contact with streams or exposure to airborne toxins and dust. Adult hospitalization for chronic pulmonary disorders and hypertension are elevated as a result of county-level coal production. Rates of mortality, lung cancer, as well as chronic heart, lung and kidney disease are also increased. A 2011 study found that counties in and near mountaintop mining areas had higher rates of birth defects for five out of six types of birth defects, including circulatory/respiratory, musculoskeletal, central nervous system, gastrointestinal, and urogenital defects.

These defect rates were more pronounced in the most recent period studied, suggesting the health effects of mountaintop mining-related air and water contamination may be cumulative. Another 2011 study found "the odds for reporting cancer were twice as high in the mountaintop mining environment compared to the non mining environment in ways not explained by age, sex, smoking, occupational exposure, or family cancer history".

Impact statement

A United States Environmental Protection Agency (EPA) environmental impact statement finds that streams near some valley fills from mountaintop removal contain higher levels of minerals in the water and decreased aquatic biodiversity. Mine-affected streams also have high selenium concentrations, which can bioaccumulate and produce toxic effects (e.g., reproductive failure, physical deformity, mortality), and these effects have been documented in reservoirs below streams. Because of higher pH balances in mine-affected streams, metals such as selenium and iron hydroxide are rendered insoluble, bringing attendant chemical changes to the stream.

The statement also estimates that 724 miles (1,165 km) of Appalachian streams were buried by valley fills between 1985 and 2001. On September 28, 2010, the U.S. Environmental Protection Agency’s (EPA) independent Science Advisory Board (SAB) released their first draft review of EPA’s research into the water quality impacts of valley fills associated with mountaintop mining, agreeing with EPA’s conclusion that valley fills are associated with increased levels of conductivity threatening aquatic life in surface waters.

Reclamation

Established in 1977, the Surface Mining Control and Reclamation Act set up a program “for the regulation of surface mining activities and the reclamation of coal-mined lands”. Although U.S. mountaintop removal sites by law must be reclaimed after mining is complete, reclamation has traditionally focused on stabilizing rock formations and controlling for erosion, and not on the reforestation of the affected area. However, the Surface Mining Control and Reclamation Act of 1977 list "the restoration of land and water resources" as a priority. Fast-growing, non-native flora such as Lespedeza cuneata, planted to quickly provide vegetation on a site, compete with tree seedlings, and trees have difficulty establishing root systems in compacted backfill.

Consequently, biodiversity suffers in a region of the United States with numerous endemic species. In addition, reintroduced elk (Cervus canadensis) on mountaintop removal sites in Kentucky are eating tree seedlings.

Advocates

Advocates of MTR claim that once the areas are reclaimed as mandated by law, the area can provide flat land suitable for many uses in a region where flat land is at a premium. They also maintain that the new growth on reclaimed mountaintop mined areas is better suited to support populations of game animals.

While some of the land is able to be turned into grassland which game animals can live in, the amount of grassland is minimal. The land does not retake the form it had before the MTR. As stated in the book Bringing Down the Mountains: "Some of the main problems associated with MTR include soil depletion, sedimentation, low success rate of tree regrowth, lack of successful revegetation, displacement of native wildlife, and burial of streams." The ecological benefits after MTR are far below the level of the original land.

Art, entertainment, and media

Documentaries

Non-fiction books

  • In April 2005, a group of Kentucky writers traveled together to see the devastation from mountaintop removal mining, and Wind Publishing produced the resulting collection of poems, essays and photographs, co-edited by Kristin Johannesen, Bobbie Ann Mason, and Mary Ann Taylor-Hall in Missing Mountains: We went to the mountaintop, but it wasn't there.
  • Dr. Shirley Stewart Burns, a West Virginia coalfield native, wrote the first academic work on mountaintop removal, titled Bringing Down The Mountains (2007), which is loosely based on her internationally award-winning 2005 Ph.D. dissertation of the same name.
  • Dr. Burns was also a co-editor, with Kentucky author Silas House and filmmaker Mari-Lynn Evans, of Coal Country (2009), a companion book for the nationally recognized feature-length film of the same name.
  • House, Silas & Howard, Jason (2009). Something's Rising: Appalachians Fighting Mountaintop Removal.
  • Howard, Jason (Editor) (2009). We All Live Downstream: Writings about Mountaintop Removal.
  • Dr. Rebecca Scott, another native West Virginian, examined the sociological relationship of identity and natural resource extraction in central Appalachia in her book, Removing Mountains (2010).
  • Hedges, Chris; Sacco, Joe (2012). Days of Destruction, Days of Revolt. Chapter 3. "Days of Devastation: Welch, West Virginia."
  • Cultural historian Jeff Biggers published The United States of Appalachia, which examined the cultural and human costs of mountaintop removal.
Additionally, many personal interest stories of coalfield residents have been written, including:

Fiction books

  • Mountaintop removal is a major plot element of Jonathan Franzen's best-selling novel Freedom (2010), wherein a major character helps to secure land for surface mining with the promise that it will be restored and turned into a nature reserve.
  • Same Sun Here by Silas House and Neela Vaswani is a novel for middle grade readers that deals with issues of mountaintop removal and is set over the course of one school year 2008-2009.
  • In John Grisham's novel Gray Mountain (2014), Samantha Kofer moves from a large Wall Street law firm to a small Appalachian town where she confronts the world of coal mining.

Music

Environmental issues in the United States

Per capita anthropogenic greenhouse gas emissions by country for the year 2000 including land-use change.
 
World CO2 emission by country 2006.svg

Environmental issues in the United States include climate change, energy, species conservation, invasive species, deforestation, mining, nuclear accidents, pesticides, pollution, waste and over-population. Despite taking hundreds of measures, the rate of environmental issues is increasing rapidly instead of reducing.

Movements and ideas

20th century

Both Conservationism and Environmentalism appeared in political debate in forests about the Progressive Era in the early 20th century. There were three main positions. The laissez-faire position held that owners of private property—including lumber and mining companies, should be allowed to do anything they wished for their property.

The Conservationists, led by President Theodore Roosevelt and his close ally Gifford Pinchot, said that the laissez-faire approach was too wasteful and inefficient. In any case, they noted, most of the natural resources in the western states were already owned by the federal government. The best course of action, they argued, was a long-term plan devised by national experts to maximize the long-term economic benefits of natural resources.




Environmentalism was the third position, led by John Muir (1838–1914). Muir's passion for nature made him the most influential American environmentalist. Muir preached that nature was sacred and humans are intruders who should look but not develop. He founded the Sierra Club and remains an icon of the environmentalist movement. He was primarily responsible for defining the environmentalist position, in the debate between Conservation and environmentalism.


Environmentalism preached that nature was almost sacred, and that man was an intruder. It allowed for limited tourism (such as hiking), but opposed automobiles in national parks. It strenuously opposed timber cutting on most public lands, and vehemently denounced the dams that Roosevelt supported for water supplies, electricity and flood control. Especially controversial was the Hetch Hetchy dam in Yosemite National Park, which Roosevelt approved, and which supplies the water supply of San Francisco.

Climate change

United States projected Köppen climate classification map for 2071 to 2100
 
Climate change in the United States refers to historical changes in the climate of the United States, as well as the regional climactic, economic, and cultural responses to global warming.

The current effects of global warming in the United States are widespread and varied. In 2012, the United States experienced its warmest year on record. As of 2012, the thirteen warmest years for the entire planet have all occurred since 1998, transcending those from 1880. Different regions experience widely different climatic changes. Changes in climate in the regions of the United States appear significant. For example, drought conditions appear to be worsening in the southwest while improving in the northeast. Some research has warned against possible problems due to American climate changes such as the spread of invasive species and possibilities of floods as well as droughts. Climate change is seen as a national security threat to the United States.

The United States is among the most significant emitters of greenhouse gasses in the world. In terms of both total and per capita emissions, it is among the largest contributors.

As of April 2019, 69% of Americans think that climate change is happening and 55% think that it is mostly human caused.

In 2015, according to The New York Times and others, oil companies knew that burning oil and gas could cause global warming since the 1970s but, nonetheless, funded deniers for years. 2016 was a historic year for billion-dollar weather and climate disasters in U.S.

Energy

Satellite image showing the light output at night in the United States

Since about 26% of all types of energy used in the United States are derived from fossil fuel consumption it is closely linked to greenhouse gas emissions. The energy policy of the United States is determined by federal, state and local public entities, which address issues of energy production, distribution, and consumption, such as building codes and gas mileage advancements. The production and transport of fossil fuels are also tied to significant environmental issues.

Species conservation

Many plant and animal species became extinct in North America soon after first human arrival, including the North American megafauna; others have become nearly extinct since European settlement, among them the American bison and California condor.

The last of the passenger pigeons died in 1914 after being the most common bird in North America. They were killed as both a source of food and because they were a threat to farming. Saving the bald eagle, the national bird of the U.S., from extinction was a notable conservation success.

As of 13 December, 2016, the International Union for the Conservation of Nature's Red List shows the United States has 1,514 species on its Threatened list (Critically Endangered, Endangered and Vulnerable categories).

Invasive species

Invasive species are a significant problem, some of the most notable being zebra mussels, Burmese pythons, kudzu, brown tree snakes and European starlings. Economic damages are estimated at $120 billion per year.

Deforestation

In 1620

Deforestation in the United States is an ongoing process in the United States. Like Deforestation in the rest of the world, it is a complex environmental issue caused by both social and economic pressures.

Prior to the arrival of European-Americans, about one half of the United States land area was forest, about 1,023,000,000 acres (4,140,000 km2) estimated in 1630. Recently, the Forest Service reported total forestation as 766,000,000 acres (3,100,000 km2) in 2012. The majority of deforestation took place prior to 1910 with the Forest Service reporting the minimum forestation as 721,000,000 acres (2,920,000 km2) around 1920. The forest resources of the United States have remained relatively constant through the 20th century. A 2017 study estimated 3 percent loss of forest between 1992-2001.

The 2005 Food and Agriculture Organization (FAO) Global Forest Resources Assessment ranked the United States as seventh highest country losing its old growth forests, a vast majority of which were removed prior to the 20th century.

Mining

Mining in the United States has been active since the beginning of colonial times, but became a major industry in the 19th century with a number of new mineral discoveries causing a series of mining rushes. In 2015, the value of coal, metals, and industrial minerals mined in the United States was US $109.6 billion. 158,000 workers were directly employed by the mining industry.

The mining industry has a number of impacts on communities, individuals and the environment. Mine safety incidents have been important parts of American occupational safety and health history. Mining has a number of environmental impacts. In the United States, issues like mountaintop removal, and acid mine drainage have widespread impacts on all parts of the environment. As of January 2020. the EPA lists 142 mines in the Superfund program.

Nuclear

The locations across the U.S. where nuclear waste is stored

The most notable accident involving nuclear power in the United States was Three Mile Island accident in 1979. Davis-Besse Nuclear Power Station has been the source of two of the top five most dangerous nuclear incidents in the United States since 1979.

Nuclear safety in the United States is governed by federal regulations and continues to be studied by the Nuclear Regulatory Commission (NRC). The safety of nuclear plants and materials controlled by the U.S. government for research and weapons production, as well those powering naval vessels, is not governed by the NRC.

The anti-nuclear movement in the United States consists of more than eighty anti-nuclear groups which have acted to oppose nuclear power and/or nuclear weapons in the USA. The movement has delayed construction or halted commitments to build some new nuclear plants, and has pressured the Nuclear Regulatory Commission to enforce and strengthen the safety regulations for nuclear power plants. Anti-nuclear campaigns that captured national public attention in the 1970s and 1980s involved the Calvert Cliffs Nuclear Power Plant, Seabrook Station Nuclear Power Plant, Diablo Canyon Power Plant, Shoreham Nuclear Power Plant, and Three Mile Island.

Pesticides

Pesticide use in the United States is predominately by the agricultural sector, which in 2012 comprised 89% of conventional pesticide usage in the United States.

The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) was first passed in 1947, giving the United States Department of Agriculture responsibility for regulating pesticides. In 1972, FIFRA underwent a major revision and transferred responsibility of pesticide regulation to the Environmental Protection Agency and shifted emphasis to protection of the environment and public health.

Pollution

Pollution from the Exxon Valdez oil spill.
 
As with many countries, pollution in the United States is a concern for environmental organizations, government agencies and individuals.

Pollution from U.S. manufacturing has declined massively since 1990 (despite an increase in production). A 2018 study in the American Economic Review found that environmental regulation is the primary driver of the reduction in pollution.

Air pollution

Looking down from the Hollywood Hills, with Griffith Observatory on the hill in the foreground, air pollution is visible in downtown Los Angeles on a late afternoon.

Air pollution is the introduction of chemicals, particulate matter, or biological materials into the atmosphere, causing harm or discomfort to humans or other living organisms, or damaging ecosystems. Air pollution can cause health problems including (but not limited to) infections, behavioral changes, cancer, organ failure, and premature death. These health effects are not equally distributed across the U.S population; there are demographic disparities by race, ethnicity, socioeconomic status, and education. Air pollution has affected the United States since the beginning of the Industrial Revolution.

According to a 2009 report, around "60 percent of Americans live in areas where air pollution has reached unhealthy levels that can make people sick". Analyzing data from 2016–2018, the American Lung Association found major declines in air quality, including increases in ground-level ozone.

In 2016, a study found that levels of nitrogen oxides had plummeted over the previous decade, due to better regulations, economic shifts, and technological innovations. NASA reported a 32% decrease of nitrogen dioxide in New York City and a 42% decrease in Atlanta between the periods of 2005–2007 and 2009–2011.

Water pollution

Topsoil runoff from farm, central Iowa, USA (2011).

Water pollution in the United States is a growing problem that became critical in the 19th century with the development of mechanized agriculture, mining, and industry, although recent regulation has drastically reduced water pollution throughout the nation. Extensive industrialization and rapid urban growth exacerbated water pollution as a lack of regulation allowed for discharges of sewage, toxic chemicals, nutrients and other pollutants into surface water.

In the early 20th century, communities began to install drinking water treatment systems, but control of the principal pollution sources—domestic sewage, industry, and agriculture—was not effectively addressed in the US until the later 20th century.

These pollution sources can affect both groundwater or surface water depending on their mode of contamination, which could include point source, nonpoint source, or transboundary pollution. Multiple incidents such as the Deepwater Horizon oil spill, have left lasting impacts on water quality, ecosystems, and public health in the United States.

Multiple solutions to water pollution in the United States can be implemented to curtail water pollution. This includes municipal wastewater treatment, agricultural and industrial wastewater treatment, erosion and sediment control, and the control of urban runoff. The continued implementation of pollution prevention, control and treatment measures are used to pursue the goal of maintaining water quality within levels specified in federal and state regulations. However, many water bodies across the country continue to violate water quality standards.

Solid waste

At 760 kg per person the United States generates the greatest amount of municipal waste. As of 2017, municipal waste totalled 267.8 million tons in total, or 4.51 pounds per person per day.

Policy

Solid waste policy in the United States is aimed at developing and implementing proper mechanisms to effectively manage solid waste. For solid waste policy to be effective, inputs should come from stakeholders, including citizens, businesses, community based-organizations, non governmental organizations, government agencies, universities, and other research organizations. These inputs form the basis of policy frameworks that influence solid waste management decisions. In the United States, the Environmental Protection Agency (EPA) regulates household, industrial, manufacturing, and commercial solid and hazardous wastes under the 1976 Resource Conservation and Recovery Act (RCRA). Effective solid waste management is a cooperative effort involving federal, state, regional, and local entities. Thus, the RCRA's Solid Waste program section D encourages the environmental departments of each state to develop comprehensive plans to manage nonhazardous industrial and municipal solid waste.
Electronic waste
Computer monitors being packed for shipping

Electronic waste or e-waste in the United States refers to electronic products that have reached the end of their operable lives, and the United States is beginning to address its waste problems with regulations at a state and federal level. Used electronics are the quickest-growing source of waste and can have serious health impacts. The United States is the world leader in producing the most e-waste, followed closely by China; both countries domestically recycle and export e-waste. Only recently has the United States begun to make an effort to start regulating where e-waste goes and how it is disposed of.

The United States does not have an official federal e-waste regulation system, yet certain states have implemented state regulatory systems. The National Strategy for Electronic Stewardship was co-founded by the Environmental Protection Agency (EPA), the Council on Environmental Quality, and the General Services Administration (GSA), and was introduced in 2011 to focus on federal action to establish electronic stewardship in the United States. E-waste management is critical due to the toxic chemicals present in electronic devices. According to the United States EPA, toxic substances such as lead, mercury, arsenic, and cadmium are often released into the environment and endanger whole communities; these toxic contaminants can have detrimental effects on the health of ecosystems and living organisms. United States e-waste management includes recycling and reuse programs, domestic landfill dumping, and international shipments of domestically produced e-waste. The EPA estimates that in 2009, the United States disposed of 2.37 million tons of e-waste, 25% of which was recycled domestically.

Hazardous waste

A household hazardous waste collection center in Seattle, Washington, U.S.

Under United States environmental policy, hazardous waste is a waste (usually a solid waste) that has the potential to:
  • cause, or significantly contribute to an increase in mortality or an increase in serious irreversible, or incapacitating reversible illness; or
  • pose a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported, or disposed of, or otherwise managed.
Under the 1976 Resource Conservation and Recovery Act (RCRA), a facility that treats, stores or disposes of hazardous waste must obtain a permit for doing so. Generators of and transporters of hazardous waste must meet specific requirements for handling, managing, and tracking waste. Through RCRA, Congress directed EPA to issue regulations for the management of hazardous waste. EPA developed strict requirements for all aspects of hazardous waste management including the treatment, storage, and disposal of hazardous waste. In addition to these federal requirements, states may develop more stringent requirements or requirements that are broader in scope than the federal regulations.

EPA authorizes states to implement the RCRA hazardous waste program. Authorized states must maintain standards that are equivalent to and at least as stringent as the federal program. Implementation of the authorized program usually includes activities such as permitting, corrective action, inspections, monitoring and enforcement.

Population

The total U.S. population crossed the 100 million mark around 1915, the 200 million mark in 1967, and the 300 million mark in 2006 (estimated on Tuesday, October 17). The U.S. population more than tripled during the 20th century — a growth rate of about 1.3 percent a year — from about 76 million in 1900 to 281 million in 2000. This is unlike most European countries, especially Germany, Russia, Italy and Greece, whose populations are slowly declining, and whose fertility rates are below replacement.

Population growth is fastest among minorities, and according to the United States Census Bureau's estimation for 2005, 45% of American children under the age of 5 are minorities. In 2007, the nation’s minority population reached 102.5 million. A year before, the minority population totaled 100.7 million. Hispanic and Latino Americans accounted for almost half (1.4 million) of the national population growth of 2.9 million between July 1, 2005, and July 1, 2006.

Based on a population clock maintained by the U.S. Census Bureau, the current U.S. population, as of 5:55 GMT (EST+5) 27 April 2012 is 316,237,337. A 2004 U.S. Census Bureau report predicted an increase of one third by the year 2050. A subsequent 2008 report projects a population of 439 million, which is a 44% increase from 2008.

Conservation and environmental movement

Today, the organized environmental movement is represented by a wide range of organizations sometimes called non-governmental organizations or NGOs. These organizations exist on local national and international scales. Environmental NGOs vary widely in political views and in the amount they seek to influence the government. The environmental movement today consists of both large national groups and also many smaller local groups with local concerns. Some resemble the old U.S. conservation movement - whose modern expression is the Nature Conservancy, Audubon Society and National Geographic Society - American organizations with a worldwide influence.

Butane

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