Three-phase electric power

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Three-phase transformer with four wire output for 208Y/120 volt service: one wire for neutral, others for A, B and C phases

Three-phase electric power (abbreviated 3φ) is a common type of alternating current used in electricity generation, transmission, and distribution. It is a type of polyphase system employing three wires (or four including an optional neutral return wire) and is the most common method used by electrical grids worldwide to transfer power.

Three-phase electrical power was developed in the 1880s by multiple people. Three-phase power works by the voltage and currents being 120 degrees out of phase on the three wires. As an AC system it allows the voltages to be easily stepped up using transformers to high voltage for transmission, and back down for distribution, giving high efficiency.

A three-wire three-phase circuit is usually more economical than an equivalent two-wire single-phase circuit at the same line to ground voltage because it uses less conductor material to transmit a given amount of electrical power. Three-phase power is mainly used directly to power large induction motors, other electric motors, and other heavy loads. Small loads often use only a two-wire single-phase circuit, which may be derived from a three-phase system.

Terminology

The conductors between a voltage source and a load are called lines, and the voltage between any two lines is called line voltage. The voltage measured between any line and neutral is called phase voltage. For example, for a 208/120 volt service, the line voltage is 208 Volts, and the phase voltage is 120 Volts.

History

Polyphase power systems were independently invented by Galileo Ferraris, Mikhail Dolivo-Dobrovolsky, Jonas Wenström, John Hopkinson, William Stanley Jr., and Nikola Tesla in the late 1880s.

The first AC motor developed by Italian physicist Galileo Ferraris. This was a two-phase motor and required four wires.

Three phase power evolved out of electric motor development. In 1885, Galileo Ferraris was doing research on rotating magnetic fields. Ferraris experimented with different types of asynchronous electric motors. The research and his studies resulted in the development of an alternator, which may be thought of as an alternating-current motor operating in reverse, so as to convert mechanical (rotating) power into electric power (as alternating current). On 11 March 1888, Ferraris published his research in a paper to the Royal Academy of Sciences in Turin.

Two months later Nikola Tesla gained U.S. Patent 381,968 for a three-phase electric motor design, application filed October 12, 1887. Figure 13 of this patent shows that Tesla envisaged his three-phase motor being powered from the generator via six wires.

These alternators operated by creating systems of alternating currents displaced from one another in phase by definite amounts, and depended on rotating magnetic fields for their operation. The resulting source of polyphase power soon found widespread acceptance. The invention of the polyphase alternator is key in the history of electrification, as is the power transformer. These inventions enabled power to be transmitted by wires economically over considerable distances. Polyphase power enabled the use of water-power (via hydroelectric generating plants in large dams) in remote places, thereby allowing the mechanical energy of the falling water to be converted to electricity, which then could be fed to an electric motor at any location where mechanical work needed to be done. This versatility sparked the growth of power-transmission network grids on continents around the globe.

Mikhail Dolivo-Dobrovolsky developed a three-phase electrical generator and a three-phase electric motor in 1888 and studied star and delta connections. His three-phase three-wire transmission system was displayed in Europe at the International Electro-Technical Exhibition of 1891, where Dolivo-Dobrovolsky used the system to transmit electric power at the distance of 176 km with 75% efficiency. In 1891 he also created a three-phase transformer and short-circuited (squirrel-cage) induction motor. He designed the world's first three-phase hydroelectric power plant in 1891.

Principle

Normalized waveforms of the instantaneous voltages in a three-phase system in one cycle with time increasing to the right. The phase order is 1‑2‑3. This cycle repeats with the frequency of the power system. Ideally, each phase's voltage, current, and power is offset from the others’ by 120°.

 

Three-phase electric power transmission lines

 

Three-phase transformer (Békéscsaba, Hungary): on the left are the primary wires and on the right are the secondary wires

In a symmetric three-phase power supply system, three conductors each carry an alternating current of the same frequency and voltage amplitude relative to a common reference, but with a phase difference of one third of a cycle (i.e. 120 degrees out of phase) between each. The common reference is usually connected to ground and often to a current-carrying conductor called the neutral. Due to the phase difference, the voltage on any conductor reaches its peak at one third of a cycle after one of the other conductors and one third of a cycle before the remaining conductor. This phase delay gives constant power transfer to a balanced linear load. It also makes it possible to produce a rotating magnetic field in an electric motor and generate other phase arrangements using transformers (for instance, a two phase system using a Scott-T transformer). The amplitude of the voltage difference between two phases is ${\displaystyle {\sqrt {3}}}$ (1.732...) times the amplitude of the voltage of the individual phases.

The symmetric three-phase systems described here are simply referred to as three-phase systems because, although it is possible to design and implement asymmetric three-phase power systems (i.e., with unequal voltages or phase shifts), they are not used in practice because they lack the most important advantages of symmetric systems.

In a three-phase system feeding a balanced and linear load, the sum of the instantaneous currents of the three conductors is zero. In other words, the current in each conductor is equal in magnitude to the sum of the currents in the other two, but with the opposite sign. The return path for the current in any phase conductor is the other two phase conductors.

Constant power transfer and cancelling phase currents are possible with any number (greater than one) of phases, maintaining the capacity-to-conductor material ratio that is twice that of single-phase power. However, two phases results in a less smooth (pulsating) current to the load (making smooth power transfer a challenge), and more than three phases complicates infrastructure unnecessarily.

Three-phase systems may have a fourth wire, common in low-voltage distribution. This is the neutral wire. The neutral allows three separate single-phase supplies to be provided at a constant voltage and is commonly used for supplying multiple single-phase loads. The connections are arranged so that, as far as possible in each group, equal power is drawn from each phase. Further up the distribution system, the currents are usually well balanced. Transformers may be wired to have a four-wire secondary and a three-wire primary, while allowing unbalanced loads and the associated secondary-side neutral currents.

Phase sequence

Wiring for the three phases is typically identified by colors which vary by country. The phases must be connected in the right order to achieve the intended direction of rotation of three-phase motors. For example, pumps and fans do not work in reverse. Maintaining the identity of phases is required if two sources could be connected at the same time; a direct interconnect between two different phases is a short circuit.

Advantages

As compared to a single-phase AC power supply that uses two conductors (phase and neutral), a three-phase supply with no neutral and the same phase-to-ground voltage and current capacity per phase can transmit three times as much power using just 1.5 times as many wires (i.e., three instead of two). Thus, the ratio of capacity to conductor material is doubled. The ratio of capacity to conductor material increases to 3:1 with an ungrounded three-phase and center-grounded single-phase system (or 2.25:1 if both employ grounds of the same gauge as the conductors). This leads to higher efficiency, lower weight, and cleaner waveforms.

Three-phase supplies have properties that make them desirable in electric power distribution systems:

• The phase currents tend to cancel out one another, summing to zero in the case of a linear balanced load. This makes it possible to reduce the size of the neutral conductor because it carries little or no current. With a balanced load, all the phase conductors carry the same current and so can be the same size.
• Power transfer into a linear balanced load is constant. In motor/generator applications, this helps to reduce vibrations.
• Three-phase systems can produce a rotating magnetic field with a specified direction and constant magnitude, which simplifies the design of electric motors, as no starting circuit is required.

Most household loads are single-phase. In North American residences, three-phase power might feed an apartment block, while the household loads are connected as single phase. In lower-density areas, a single phase might be used for distribution. In areas such as the United States where standard single-phase power uses 120V, some high-power domestic appliances such as electric stoves and clothes dryers are powered by a split phase system at 240 volts or from two phases of a three phase system at 208 volts.

Generation and distribution

See also: Mains electricity by country

 

Animation of three-phase current

 

Top image: elementary six-wire three-phase alternator with each phase using a separate pair of transmission wires. Bottom image: elementary three-wire three-phase alternator showing how the phases can share only three wires.

At the power station, an electrical generator converts mechanical power into a set of three AC electric currents, one from each coil (or winding) of the generator. The windings are arranged such that the currents are at the same frequency but with the peaks and troughs of their wave forms offset to provide three complementary currents with a phase separation of one-third cycle (120° or 2π⁄3 radians). The generator frequency is typically 50 or 60 Hz, depending on the country.

At the power station, transformers change the voltage from generators to a level suitable for transmission in order to minimize losses.

After further voltage conversions in the transmission network, the voltage is finally transformed to the standard utilization before power is supplied to customers.

Most automotive alternators generate three-phase AC and rectify it to DC with a diode bridge.

Transformer connections

A "delta" connected transformer winding is connected between phases of a three-phase system. A "wye" transformer connects each winding from a phase wire to a common neutral point.

A single three-phase transformer can be used, or three single-phase transformers.

In an "open delta" or "V" system, only two transformers are used. A closed delta made of three single-phase transformers can operate as an open delta if one of the transformers has failed or needs to be removed. In open delta, each transformer must carry current for its respective phases as well as current for the third phase, therefore capacity is reduced to 87%. With one of three transformers missing and the remaining two at 87% efficiency, the capacity is 58% (2⁄3 of 87%).

Where a delta-fed system must be grounded for detection of stray current to ground or protection from surge voltages, a grounding transformer (usually a zigzag transformer) may be connected to allow ground fault currents to return from any phase to ground. Another variation is a "corner grounded" delta system, which is a closed delta that is grounded at one of the junctions of transformers.

Three-wire and four-wire circuits

Wye (Y) and delta (Δ) circuits

There are two basic three-phase configurations: wye (Y) and delta (Δ). As shown in the diagram, a delta configuration requires only three wires for transmission but a wye (star) configuration may have a fourth wire. The fourth wire, if present, is provided as a neutral and is normally grounded. The three-wire and four-wire designations do not count the ground wire present above many transmission lines, which is solely for fault protection and does not carry current under normal use.

A four-wire system with symmetrical voltages between phase and neutral is obtained when the neutral is connected to the "common star point" of all supply windings. In such a system, all three phases will have the same magnitude of voltage relative to the neutral. Other non-symmetrical systems have been used.

The four-wire wye system is used when a mixture of single-phase and three-phase loads are to be served, such as mixed lighting and motor loads. An example of application is local distribution in Europe (and elsewhere), where each customer may be only fed from one phase and the neutral (which is common to the three phases). When a group of customers sharing the neutral draw unequal phase currents, the common neutral wire carries the currents resulting from these imbalances. Electrical engineers try to design the three-phase power system for any one location so that the power drawn from each of three phases is the same, as far as possible at that site. Electrical engineers also try to arrange the distribution network so the loads are balanced as much as possible, since the same principles that apply to individual premises also apply to the wide-scale distribution system power. Hence, every effort is made by supply authorities to distribute the power drawn on each of the three phases over a large number of premises so that, on average, as nearly as possible a balanced load is seen at the point of supply.

A delta-wye configuration across a transformer core (note that a practical transformer would usually have a different number of turns on each side).

For domestic use, some countries such as the UK may supply one phase and neutral at a high current (up to 100 A) to one property, while others such as Germany may supply 3 phases and neutral to each customer, but at a lower fuse rating, typically 40–63 A per phase, and "rotated" to avoid the effect that more load tends to be put on the first phase.

A transformer for a "high-leg delta" system used for mixed single-phase and three-phase loads on the same distribution system. Three-phase loads such as motors connect to L1, L2, and L3. Single-phase loads would be connected between L1 or L2 and neutral, or between L1 and L2. The L3 phase is 1.73 times the L1 or L2 voltage to neutral so this leg is not used for single-phase loads.

Based on wye (Y) and delta (Δ) connection. Generally, there are four different types of three-phase transformer winding connections for transmission and distribution purposes.

• wye (Y) - wye (Y) is used for small current and high voltage.
• Delta (Δ) - Delta (Δ) is used for large currents and low voltages.
• Delta (Δ) - wye (Y) is used for step-up transformers i.e., at generating stations.
• wye (Y) - Delta (Δ) is used for step-down transformers i.e., at the end of the transmission.

In North America, a high-leg delta supply is sometimes used where one winding of a delta-connected transformer feeding the load is center-tapped and that center tap is grounded and connected as a neutral as shown in the second diagram. This setup produces three different voltages: If the voltage between the center tap (neutral) and each of the top and bottom taps (phase and anti-phase) is 120 V (100%), the voltage across the phase and anti-phase lines is 240 V (200%), and the neutral to "high leg" voltage is ≈ 208 V (173%).

The reason for providing the delta connected supply is usually to power large motors requiring a rotating field. However, the premises concerned will also require the "normal" North American 120 V supplies, two of which are derived (180 degrees "out of phase") between the "neutral" and either of the center tapped phase points.

Balanced circuits

In the perfectly balanced case all three lines share equivalent loads. Examining the circuits we can derive relationships between line voltage and current, and load voltage and current for wye and delta connected loads.

In a balanced system each line will produce equal voltage magnitudes at phase angles equally spaced from each other. With V₁ as our reference and V₃ lagging V₂ lagging V₁, using angle notation, and V_LN the voltage between the line and the neutral we have:

${\displaystyle {\begin{aligned}V_{1}&=V_{\text{LN}}\angle 0^{\circ },\\V_{2}&=V_{\text{LN}}\angle {-120}^{\circ },\\V_{3}&=V_{\text{LN}}\angle {+120}^{\circ }.\end{aligned}}}$

These voltages feed into either a wye or delta connected load.

Wye (or, star; Y)

Three-phase AC generator connected as a wye or star source to a wye or star connected load

The voltage seen by the load will depend on the load connection; for the wye case, connecting each load to a phase (line-to-neutral) voltages gives:

${\displaystyle {\begin{aligned}I_{1}&={\frac {V_{1}}{\left|Z_{\text{total}}\right|}}\angle (-\theta ),\\[2pt]I_{2}&={\frac {V_{2}}{\left|Z_{\text{total}}\right|}}\angle \left(-120^{\circ }-\theta \right),\\[2pt]I_{3}&={\frac {V_{3}}{\left|Z_{\text{total}}\right|}}\angle \left(120^{\circ }-\theta \right),\end{aligned}}}$

where Z_total is the sum of line and load impedances (Z_total = Z_LN + Z_Y), and θ is the phase of the total impedance (Z_total).

The phase angle difference between voltage and current of each phase is not necessarily 0 and is dependent on the type of load impedance, Z_y. Inductive and capacitive loads will cause current to either lag or lead the voltage. However, the relative phase angle between each pair of lines (1 to 2, 2 to 3, and 3 to 1) will still be −120°.

A phasor diagram for a wye configuration, in which V_ab represents a line voltage and V_an represents a phase voltage. Voltages are balanced as:

• V_ab = (1∠α − 1∠α + 120°) √3 |V|∠α + 30°
• V_bc = √3 |V|∠α − 90°
• V_ca = √3 |V|∠α + 150°

(α = 0 in this case.)

By applying Kirchhoff's current law (KCL) to the neutral node, the three phase currents sum to the total current in the neutral line. In the balanced case:

${\displaystyle I_{1}+I_{2}+I_{3}=I_{\text{N}}=0.}$

Delta (Δ)

Three-phase AC generator connected as a wye source to a delta-connected load

In the delta circuit, loads are connected across the lines, and so loads see line-to-line voltages:

${\displaystyle {\begin{aligned}V_{12}&=V_{1}-V_{2}=\left(V_{\text{LN}}\angle 0^{\circ }\right)-\left(V_{\text{LN}}\angle {-120}^{\circ }\right)\\&={\sqrt {3}}V_{\text{LN}}\angle 30^{\circ }={\sqrt {3}}V_{1}\angle \left(\phi _{V_{1}}+30^{\circ }\right),\\[3pt]V_{23}&=V_{2}-V_{3}=\left(V_{\text{LN}}\angle {-120}^{\circ }\right)-\left(V_{\text{LN}}\angle 120^{\circ }\right)\\&={\sqrt {3}}V_{\text{LN}}\angle {-90}^{\circ }={\sqrt {3}}V_{2}\angle \left(\phi _{V_{2}}+30^{\circ }\right),\\[3pt]V_{31}&=V_{3}-V_{1}=\left(V_{\text{LN}}\angle 120^{\circ }\right)-\left(V_{\text{LN}}\angle 0^{\circ }\right)\\&={\sqrt {3}}V_{\text{LN}}\angle 150^{\circ }={\sqrt {3}}V_{3}\angle \left(\phi _{V_{3}}+30^{\circ }\right).\\\end{aligned}}}$

(Φ_v1 is the phase shift for the first voltage, commonly taken to be 0°; in this case, Φ_v2 = −120° and Φ_v3 = −240° or 120°.)

Further:

${\displaystyle {\begin{aligned}I_{12}&={\frac {V_{12}}{\left|Z_{\Delta }\right|}}\angle \left(30^{\circ }-\theta \right),\\[2pt]I_{23}&={\frac {V_{23}}{\left|Z_{\Delta }\right|}}\angle \left(-90^{\circ }-\theta \right),\\[2pt]I_{31}&={\frac {V_{31}}{\left|Z_{\Delta }\right|}}\angle \left(150^{\circ }-\theta \right),\end{aligned}}}$

where θ is the phase of delta impedance (Z_Δ).

Relative angles are preserved, so I₃₁ lags I₂₃ lags I₁₂ by 120°. Calculating line currents by using KCL at each delta node gives:

${\displaystyle {\begin{aligned}I_{1}&=I_{12}-I_{31}=I_{12}-I_{12}\angle 120^{\circ }\\&={\sqrt {3}}I_{12}\angle \left(\phi _{I_{12}}-30^{\circ }\right)={\sqrt {3}}I_{12}\angle (-\theta )\end{aligned}}}$

and similarly for each other line:

${\displaystyle {\begin{aligned}I_{2}&={\sqrt {3}}I_{23}\angle \left(\phi _{I_{23}}-30^{\circ }\right)={\sqrt {3}}I_{23}\angle \left(-120^{\circ }-\theta \right),\\[2pt]I_{3}&={\sqrt {3}}I_{31}\angle \left(\phi _{I_{31}}-30^{\circ }\right)={\sqrt {3}}I_{31}\angle \left(120^{\circ }-\theta \right),\end{aligned}}}$

where, again, θ is the phase of delta impedance (Z_Δ).

A delta configuration and a corresponding phasor diagram of its currents. Phase voltages are equal to line voltages, and currents are calculated as:

• I_a = I_ab − I_ca = √3 I_ab∠−30°
• I_b = I_bc − I_ab
• I_c = I_ca − I_bc

The overall power transferred is:

• S_3Φ = 3V_phaseI*_phase

Inspection of a phasor diagram, or conversion from phasor notation to complex notation, illuminates how the difference between two line-to-neutral voltages yields a line-to-line voltage that is greater by a factor of √3. As a delta configuration connects a load across phases of a transformer, it delivers the line-to-line voltage difference, which is √3 times greater than the line-to-neutral voltage delivered to a load in the wye configuration. As the power transferred is V²/Z, the impedance in the delta configuration must be 3 times what it would be in a wye configuration for the same power to be transferred.

Single-phase loads

Except in a high-leg delta system and a corner grounded delta system, single-phase loads may be connected across any two phases, or a load can be connected from phase to neutral. Distributing single-phase loads among the phases of a three-phase system balances the load and makes most economical use of conductors and transformers.

In a symmetrical three-phase four-wire, wye system, the three phase conductors have the same voltage to the system neutral. The voltage between line conductors is √3 times the phase conductor to neutral voltage:

${\displaystyle V_{\text{LL}}={\sqrt {3}}V_{\text{LN}}.}$

The currents returning from the customers' premises to the supply transformer all share the neutral wire. If the loads are evenly distributed on all three phases, the sum of the returning currents in the neutral wire is approximately zero. Any unbalanced phase loading on the secondary side of the transformer will use the transformer capacity inefficiently.

If the supply neutral is broken, phase-to-neutral voltage is no longer maintained. Phases with higher relative loading will experience reduced voltage, and phases with lower relative loading will experience elevated voltage, up to the phase-to-phase voltage.

A high-leg delta provides phase-to-neutral relationship of V_LL = 2 V_LN , however, LN load is imposed on one phase. A transformer manufacturer's page suggests that LN loading not exceed 5% of transformer capacity.

Since √3 ≈ 1.73, defining V_LN as 100% gives V_LL ≈ 100% × 1.73 = 173%. If V_LL was set as 100%, then V_LN ≈ 57.7%.

Unbalanced loads

When the currents on the three live wires of a three-phase system are not equal or are not at an exact 120° phase angle, the power loss is greater than for a perfectly balanced system. The method of symmetrical components is used to analyze unbalanced systems.

Non-linear loads

With linear loads, the neutral only carries the current due to imbalance between the phases. Gas-discharge lamps and devices that utilize rectifier-capacitor front-end such as switch-mode power supplies, computers, office equipment and such produce third-order harmonics that are in-phase on all the supply phases. Consequently, such harmonic currents add in the neutral in a wye system (or in the grounded (zigzag) transformer in a delta system), which can cause the neutral current to exceed the phase current.

Three-phase loads

See also: Industrial and multiphase power plugs and sockets

 

Three-phase electric machine with rotating magnetic fields

An important class of three-phase load is the electric motor. A three-phase induction motor has a simple design, inherently high starting torque and high efficiency. Such motors are applied in industry for many applications. A three-phase motor is more compact and less costly than a single-phase motor of the same voltage class and rating, and single-phase AC motors above 10 HP (7.5 kW) are uncommon. Three-phase motors also vibrate less and hence last longer than single-phase motors of the same power used under the same conditions.

Resistance heating loads such as electric boilers or space heating may be connected to three-phase systems. Electric lighting may also be similarly connected.

Line frequency flicker in light is detrimental to high speed cameras used in sports event broadcasting for slow motion replays. It can be reduced by evenly spreading line frequency operated light sources across the three phases so that the illuminated area is lit from all three phases. This technique was applied successfully at the 2008 Beijing Olympics.

Rectifiers may use a three-phase source to produce a six-pulse DC output. The output of such rectifiers is much smoother than rectified single phase and, unlike single-phase, does not drop to zero between pulses. Such rectifiers may be used for battery charging, electrolysis processes such as aluminium production or for operation of DC motors. "Zig-zag" transformers may make the equivalent of six-phase full-wave rectification, twelve pulses per cycle, and this method is occasionally employed to reduce the cost of the filtering components, while improving the quality of the resulting DC.

Three phase plug used in the past on electric stoves in Germany

One example of a three-phase load is the electric arc furnace used in steelmaking and in refining of ores.

In many European countries electric stoves are usually designed for a three-phase feed with permanent connection. Individual heating units are often connected between phase and neutral to allow for connection to a single-phase circuit if three-phase is not available. Other usual three-phase loads in the domestic field are tankless water heating systems and storage heaters. Homes in Europe and the UK have standardized on a nominal 230 V between any phase and ground. (Existing supplies remain near 240 V in the UK.) Most groups of houses are fed from a three-phase street transformer so that individual premises with above-average demand can be fed with a second or third phase connection.

Phase converters

Phase converters are used when three-phase equipment needs to be operated on a single-phase power source. They are used when three-phase power is not available or cost is not justifiable. Such converters may also allow the frequency to be varied, allowing speed control. Some railway locomotives use a single-phase source to drive three-phase motors fed through an electronic drive.

A rotary phase converter is a three-phase motor with special starting arrangements and power factor correction that produces balanced three-phase voltages. When properly designed, these rotary converters can allow satisfactory operation of a three-phase motor on a single-phase source. In such a device, the energy storage is performed by the inertia (flywheel effect) of the rotating components. An external flywheel is sometimes found on one or both ends of the shaft.

A three-phase generator can be driven by a single-phase motor. This motor-generator combination can provide a frequency changer function as well as phase conversion, but requires two machines with all their expenses and losses. The motor-generator method can also form an uninterruptible power supply when used in conjunction with a large flywheel and a battery-powered DC motor; such a combination will deliver nearly constant power compared to the temporary frequency drop experienced with a standby generator set gives until the standby generator kicks in.

Capacitors and autotransformers can be used to approximate a three-phase system in a static phase converter, but the voltage and phase angle of the additional phase may only be useful for certain loads.

Variable-frequency drives and digital phase converters use power electronic devices to synthesize a balanced three-phase supply from single-phase input power.

Testing

Verification of the phase sequence in a circuit is of considerable practical importance. Two sources of three-phase power must not be connected in parallel unless they have the same phase sequence, for example, when connecting a generator to an energized distribution network or when connecting two transformers in parallel. Otherwise, the interconnection will behave like a short circuit, and excess current will flow. The direction of rotation of three-phase motors can be reversed by interchanging any two phases; it may be impractical or harmful to test a machine by momentarily energizing the motor to observe its rotation. Phase sequence of two sources can be verified by measuring voltage between pairs of terminals and observing that terminals with very low voltage between them will have the same phase, whereas pairs that show a higher voltage are on different phases.

Where the absolute phase identity is not required, phase rotation test instruments can be used to identify the rotation sequence with one observation. The phase rotation test instrument may contain a miniature three-phase motor, whose direction of rotation can be directly observed through the instrument case. Another pattern uses a pair of lamps and an internal phase-shifting network to display the phase rotation. Another type of instrument can be connected to a de-energized three-phase motor and can detect the small voltages induced by residual magnetism, when the motor shaft is rotated by hand. A lamp or other indicator lights to show the sequence of voltages at the terminals for the given direction of shaft rotation.

Alternatives to three-phase

Split-phase electric power

Used when three-phase power is not available and allows double the normal utilization voltage to be supplied for high-power loads.

Two-phase electric power

Uses two AC voltages, with a 90-electrical-degree phase shift between them. Two-phase circuits may be wired with two pairs of conductors, or two wires may be combined, requiring only three wires for the circuit. Currents in the common conductor add to 1.4 times the current in the individual phases, so the common conductor must be larger. Two-phase and three-phase systems can be interconnected by a Scott-T transformer, invented by Charles F. Scott. Very early AC machines, notably the first generators at Niagara Falls, used a two-phase system, and some remnant two-phase distribution systems still exist, but three-phase systems have displaced the two-phase system for modern installations.

Monocyclic power

An asymmetrical modified two-phase power system used by General Electric around 1897, championed by Charles Proteus Steinmetz and Elihu Thomson. This system was devised to avoid patent infringement. In this system, a generator was wound with a full-voltage single-phase winding intended for lighting loads and with a small fraction (usually 1/4 of the line voltage) winding that produced a voltage in quadrature with the main windings. The intention was to use this "power wire" additional winding to provide starting torque for induction motors, with the main winding providing power for lighting loads. After the expiration of the Westinghouse patents on symmetrical two-phase and three-phase power distribution systems, the monocyclic system fell out of use; it was difficult to analyze and did not last long enough for satisfactory energy metering to be developed.

High-phase-order systems

Have been built and tested for power transmission. Such transmission lines typically would use six or twelve phases. High-phase-order transmission lines allow transfer of slightly less than proportionately higher power through a given volume without the expense of a high-voltage direct current (HVDC) converter at each end of the line. However, they require correspondingly more pieces of equipment.

DC

AC was historically used because it could be easily transformed to higher voltages for long distance transmission. However modern electronics can raise the voltage of DC with high efficiency, and DC lacks skin effect which permits transmission wires to be lighter and cheaper and so high-voltage direct current gives lower losses over long distances.

Color codes

See also: Electrical wiring § Colour code

Conductors of a three-phase system are usually identified by a color code, to allow for balanced loading and to assure the correct phase rotation for motors. Colors used may adhere to International Standard IEC 60446 (later IEC 60445), older standards or to no standard at all and may vary even within a single installation. For example, in the U.S. and Canada, different color codes are used for grounded (earthed) and ungrounded systems.

Country		Phases						Neutral, N		Protective earth, PE
		L1		L2		L3
Australia and New Zealand (AS/NZS 3000:2007 Figure 3.2, or IEC 60446 as approved by AS:3000)			Red, or brown		White; prev. yellow		Dark blue, or grey		Black, or blue			Green/Yellow-striped; (Installations prior to 1966, Green.)
Canada	Mandatory		Red		Black		Blue		White, or grey			Green perhaps yellow-striped, or uninsulated
	Isolated systems		Orange		Brown		Yellow		White, or grey			Green perhaps yellow-striped
European CENELEC (European Union and others; since April 2004, IEC 60446, later IEC 60445-2017), United Kingdom (since 31 March 2004), Hong Kong (from July 2007), Singapore (from March 2009), Russia (since 2009; GOST R 50462), Argentina, Ukraine, Belarus, Kazakhstan, South Korea (from Jan. 2021)			Brown		Black		Grey		Blue			Green/yellow-striped
Older European (prior to IEC 60446, varied by country)
UK (before April 2006), Hong Kong (before April 2009), South Africa, Malaysia, Singapore (before February 2011)			Red		Yellow		Blue		Black			Green/yellow-striped; before c. 1970, green
India			Red		Yellow		Blue		Black			Green perhaps yellow-striped
Chile - NCH 4/2003			Blue		Black		Red		White			Green perhaps yellow-striped
Former USSR (Russia, Ukraine, Kazakhstan; before 2009), People's Republic of China (GB 50303-2002 Section 15.2.2)			Yellow		Green		Red		Sky blue			Green/yellow-striped
Norway (before CENELEC adoption)			Black		White/grey		Brown		Blue			Yellow/green-striped; prev. yellow, or uninsulated
United States	Common practice		Black		Red		Blue		White, or grey			Green perhaps yellow-striped, or uninsulated
	Alternative practice		Brown		Orange (delta)		Yellow		Grey, or white			Green
					Violet (wye)

Political ecology

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Political_ecology 

 

Political ecology studies the complex interaction between economics, politics, technology, social tradition and the biological environment. These terraced rice fields in Yunnan, China, evidence how the environment is shaped by and shapes economy and society.

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Political ecology is the study of the relationships between political, economic and social factors with environmental issues and changes. Political ecology differs from apolitical ecological studies by politicizing environmental issues and phenomena.

The academic discipline offers wide-ranging studies integrating ecological social sciences with political economy in topics such as degradation and marginalization, environmental conflict, conservation and control, and environmental identities and social movements.

Origins

The term "political ecology" was first coined by Frank Thone in an article published in 1935. It has been widely used since then in the context of human geography and human ecology, but with no systematic definition. Anthropologist Eric R. Wolf gave it a second life in 1972 in an article entitled "Ownership and Political Ecology", in which he discusses how local rules of ownership and inheritance "mediate between the pressures emanating from the larger society and the exigencies of the local ecosystem", but did not develop the concept further. Other origins include other early works of Eric R. Wolf, Michael J. Watts, Susanna Hecht, and others in the 1970s and 1980s.

The origins of the field in the 1970s and 1980s were a result of the development of development geography and cultural ecology, particularly the work of Piers Blaikie on the sociopolitical origins of soil erosion. Historically, political ecology has focused on phenomena in and affecting the developing world; since the field's inception, "research has sought primarily to understand the political dynamics surrounding material and discursive struggles over the environment in the third world".

Scholars in political ecology are drawn from a variety of academic disciplines, including geography, anthropology, development studies, political science, economics, sociology, forestry, and environmental history.

Petra Kelly is one of the founding figures of political ecologist parties throughout Germany and Europe.

Overview

Political ecology's broad scope and interdisciplinary nature lends itself to multiple definitions and understandings. However, common assumptions across the field give the term relevance. Raymond L. Bryant and Sinéad Bailey developed three fundamental assumptions in practising political ecology:

• First, changes in the environment do not affect society in a homogenous way: political, social, and economic differences account for uneven distribution of costs and benefits.
• Second, "any change in environmental conditions must affect the political and economic status quo."
• Third, the unequal distribution of costs and benefits and the reinforcing or reducing of pre-existing inequalities has political implications in terms of the altered power relationships that then result.

In addition, political ecology attempts to provide critiques and alternatives in the interplay of the environment and political, economic and social factors. Paul Robbins asserts that the discipline has a "normative understanding that there are very likely better, less coercive, less exploitative, and more sustainable ways of doing things".

From these assumptions, political ecology can be used to:

• inform policymakers and organizations of the complexities surrounding environment and development, thereby contributing to better environmental governance.
• understand the decisions that communities make about the natural environment in the context of their political environment, economic pressure, and societal regulations
• look at how unequal relations in and among societies affect the natural environment, especially in context of government policy.

Scope and influences

Political ecology's movement as a field since its inception in the 1970s has complicated its scope and goals. Through the discipline's history, certain influences have grown more and less influential in determining the focus of study. Peter A. Walker traces the importance of the ecological sciences in political ecology. He points to the transition, for many critics, from a ‘structuralist’ approach through the 1970s and 1980s, in which ecology maintains a key position in the discipline, to a 'poststructuralist' approach with an emphasis on the 'politics' in political ecology. This turn has raised questions as to the differentiation with environmental politics as well as the field's use of the term of 'ecology'. Political ecological research has shifted from investigating political influence on the earth's surface to the focus on spatial-ecological influences on politics and power—a scope reminiscent of environmental politics.

Much has been drawn from cultural ecology, a form of analysis that showed how culture depends upon, and is influenced by, the material conditions of society (political ecology has largely eclipsed cultural ecology as a form of analysis according to Walker.) As Walker states, "whereas cultural ecology and systems theory emphasize[s] adaptation and homeostasis, political ecology emphasize[s] the role of political economy as a force of maladaptation and instability".

Political ecologists often use political economy frameworks to analyze environmental issues. Early and prominent examples of this were Silent Violence: Food, Famine and Peasantry in Northern Nigeria by Michael Watts in 1983, which traced the famine in northern Nigeria during the 1970s to the effects of colonialism, rather than an inevitable consequence of the drought in the Sahel, and The Political Economy of Soil Erosion in Developing Countries by Piers Blaikie in 1985, which traced land degradation in Africa to colonial policies of land appropriation, rather than over-exploitation by African farmers.

Relationship to anthropology and geography

Originating in the 18th and 19th centuries with philosophers such as Adam Smith, Karl Marx, and Thomas Malthus, political economy attempted to explain the relationships between economic production and political processes. It tended toward overly structuralist explanations, focusing on the role of individual economic relationships in the maintenance of social order. Eric Wolf used political economy in a neo-Marxist framework which began addressing the role of local cultures as a part of the world capitalist system, refusing to see those cultures as "primitive isolates". But environmental effects on political and economic processes were under-emphasised.

Conversely, Julian Steward and Roy Rappaport's theories of cultural ecology are sometimes credited with shifting the functionalist-oriented anthropology of the 1950s and 1960s and incorporating ecology and environment into ethnographic study.

Geographers and anthropologists worked with the strengths of both to form the basis of political ecology. PE focuses on issues of power, recognizing the importance of explaining environmental impacts on cultural processes without separating out political and economic contexts.

The application of political ecology in the work of anthropologists and geographers differs. While any approach will take both the political/economic and the ecological into account, the emphasis can be unequal. Some, such as geographer Michael Watts, focus on how the assertion of power impacts on access to environmental resources. His approach tends to see environmental harm as both a cause and an effect of “social marginalization”.

Political ecology has strengths and weaknesses. At its core, it contextualizes political and ecological explanations of human behavior. But as Walker points out, it has failed to offer “compelling counter-narratives” to “widely influential and popular yet deeply flawed and unapologetic neo-Malthusian rants such as Robert Kaplan's (1994) 'The coming anarchy' and Jared Diamond's (2005) Collapse (385). Ultimately, applying political ecology to policy decisions – especially in the US and Western Europe – will remain problematic as long as there is a resistance to Marxist and neo-Marxist theory.

Andrew Vayda and Bradley Walters (1999) criticize political ecologists for pre-supposing “the importance ... of certain kinds of political factors in the explanation of environmental changes” (167). Vayda and Walter's response to overly political approaches in political ecology is to encourage what they call “event ecology”, focusing on human responses to environmental events without presupposing the impact of political processes on environmental events. The critique has not been taken up widely. One example of work that builds on event ecology, in order to add a more explicit focus on the role of power dynamics and the need for including local peoples' voices is Penna-Firme (2013) "Political and Event Ecology: critiques and opportunities for collaboration".

Relationship to conservation

There is a divergence of ideas between conservation science and political ecology. With conservationists establishing protected areas to conserve biodiversity, "political ecologists have devoted some energy to the study of protected areas, which is unsurprising given political ecology's overall interest in forms of access to, and control over resources". The arguments against enclosure of land for conservation is that it harms local people and their livelihood systems, by denying them access. As Dove and Carpenter state, "indigenous people have important environmental knowledge which could contribute to conservation". The objection by political ecologists is that land use regulations are made by NGOs and the government, denying access, denying the ability of local people to conserve species and areas themselves, and rendering them more vulnerable through dispossession.

In a few cases, perhaps especially tragic local groups have been displaced to create national parks and reserves to ‘conserve’ the forest. Fortunately, most conservation bodies are now aware that, if a group has been using and managing a forest for several thousand years, throwing it off the land is more apt to destroy the forest ecosystem than to preserve it. (Sutton 2004: 302)

Power perspective in political ecology

Power is inevitable at the core of political ecology. Political ecology in the view Greenberg and Park is a way of creating a synergy between a political economy that aligns power distribution with ecological analysis and economic activities in a wider version of bio-environmental relations. Political ecology explained by Bryant is the dynamic in politics that is associated with "discursive struggle" and material in the environment of less developed nations, showing how unequal relation in power makes up a political environment. In the view of Robbins, empirical exploration that shows the changes occurring in an environment in clear connection to power is termed political ecology.

With power taking the central role in political ecology, there is a need to clarify the perspectives of power and the contributors to these perspectives, as well as the way political ecologies form situated ecocultural identities.

Actor-oriented power perspectives:

According to the actor-oriented power perspectives, power is exercised by actors which are contrary to the presumption of power being perceived as a force likely to pass individuals with no consciousness. Fredrick Engelstad, a Norwegian sociologist explained the concept of power as the combination of relationality, causality, and intentionality. The implication of this is that actors are perceived as power carriers in a significant way by which through action a certain intention (intentionality) is achieved, action occurs between at least two actors (relationality), and intended results are produced by action (causality). Viewing the power perspective from the angle of actor-oriented, Dowding submitted that power is linked to the agency, and this does not take away the importance of structure. Rather, while seen actor's use of power as a constraint, it is also propelled by structures.

The contributions made by actor-oriented power theory are given by Max Weber (1964) where he explained power to be people’s ability to the realization of their wills irrespective of the resistance posed by others. An instance given by Robert Dahl is the case where actor A exercises power over actor B by getting actor B to execute a task that actor B will otherwise not do. The extreme case of this is when some group of individuals is mandated to carry out the task contrary to their thought or will.

Svarstad, Benjaminsen, and Overå held that the theory of actor-oriented power help in providing conceptual distinctions with useful insight into the theoretical elements that are vital in studying political ecology. While there are actors who either exercise or try to put power into use in diverse ways, there are also actors who encounter resistance from their oppositions and other forces. An instance of these forces is the resisting the fulfilment of actors' intentions by other opposition who are more powerful. It can also come in the form of institutional structural constraints emanating from the outcome of intended actions.

The use of power by actors who exercise environmental interventions and actors who resist such interventions are oftentimes the emphasis of scholars of political ecology. However, when environmental interventions result in environmental degradations, scholars of political ecology throw their support to actors who resist such exercise of environmental interventions. Actors exercising environmental interventions include corporate organizations, governmental and non-governmental organizations while actors that resist them include groups such as peasants, fishermen, or pastoralists, by exercising counter-power using various kinds of resistance, or active involvement.

Neo-Marxist power perspectives

Amongst the foundations of political ecology is the political economy thought of Marxist which centered on the inequalities that emerged from global capitalism. However, the power perspectives of Marx are most likely highlighted even though there are several perspectives of power in political ecology influenced directly or indirectly by Marx. The Marxist main focus under capitalism is in relation to class and the stability of reproducing this class relation. Marx also placed human agency as the most important of his power concept with the human agency being socially conditioned as seen in his quote below:

"Men make their history, but they do not make it as they please; they do not make it under self-selected circumstances, but under circumstances existing already, given and transmitted from the past (Marx 1852:5)".

Thus, Marx's power theory which formed his perspective of power is the understanding of human agency as being constrained by social structure. As structure produces the potential and extent for power exertion, the human agency is reproducing the structure. This is illustrated by Isaac (1987) using the powerful David Rockefeller (1915 to 2017). is quoted below:

"But a social theory of power must explain what kinds of social relations exist and how power is distributed by these relations, such that it is possible for David Rockefeller to have the power that he has. To do this is not to deny that it is he who possesses this power, nor to deny those personal attributes determining the particular manner in which he exercises it. It is simply to insist that the power individuals possess has social conditions of existence and that it is these conditions that should be the primary focus of theoretical analysis".

Poststructuralist power perspectives

The poststructuralist power perspective is the domain of Michel Foucault’s work with its application in political ecology. The poststructuralist power perspectives can be in three dimensions such as; biopower, governmentality, and discursive power.

Biopower indicates that to secure life, governments are concerned with the improvement of health and quality of life among populations. Foucault in his work explained how through the knowledge of power, people have learned how they should behave. In so doing, Foucault separates sovereign power from bio-power. Where sovereign power is termed "take life or let live", the bio-power "make life or let die". While human as specie is continuously elaboration in conformity to nature, the superior one will intervene, acting on the environmental condition if the species of human are to be altered. Therefore, bio-power aim in terms of governance and knowledge is to ascertain environmental issues as core concerns.

Political ecology emphasized that understanding how power works in environmental governance follows Foucault’s notion of “governmentality”. Foucault sees governmentality as the means employed by the government to make its citizens behave in line with the priorities of government. Fletcher separates governmentality into four kinds. First is "discipline" which ensures that the citizens internalize specific manners like ethical standards and social norms. The second is the "truth" which is a way of governing citizens using truth-defining standards like religion. The third is "Neoliberal rationality" which is a motivational structure formed and used to improve outcomes. The fourth is "Sovereign power" used to govern based on rules and punishment for faulting the rules. According to Fletcher, these governmentalities may conflict, work alone, or overlap. Also, the first two are dependent on humans believing government priorities, the second two do not but are seen as of importance.

Lastly, "discursive power" manifest when actors (corporate organization, governmental, and non-governmental organizations) make people or groups imbibe and add to the reproduction of the discourses they produce. Unlike in other fields, in political ecology, discourses are studied in line with a critical realist epistemology. There are instances where the formation of discursive power is traced to a state’s colonial era when efforts are made in the appropriation of new territories. Going by the basis of Foucault's political-ecological discursive power, it becomes imperative to mention that, there exist various perspectives to those of Foucault with wider space for human agency.

Comparing between bio-power, governmentality, and discursive power, both governmentality, and discursive power can be regarded as a theoretical perspective with significant importance while bio-power can be regarded as a topical concern identified by Foucault as the core of modern-day governments.

Political ecologists

Some prominent contemporary scholars include:

• Anthony Bebbington
• Piers Blaikie
• Murray Bookchin
• Harold Brookfield
• Raymond L. Bryant
• Michael R. Dove
• Robyn Eckersley
• Arturo Escobar
• Andre Gorz
• Félix Guattari
• Susanna Hecht
• Ivan Illich
• Giorgos Kallis
• Alain Lipietz
• William Moseley
• Richard Peet
• Paul Robbins
• Ariel Salleh
• Farhana Sultana
• Erik Swyngedouw
• Bhaskar Vira
• Michael Watts
• Karl Zimmerer

Related journals

Scholarly journals that have been key to the development (and critique) of this field include:

• Annals of the Association of American Geographers
• Antipode
• Capitalism Nature Socialism
• Development and Change
• Journal of Peasant Studies
• Ecological Economics
• Ecology
• Economic Geography
• Environment and Planning
• Futures
• Gender, Place & Culture
• Geoforum
• Human Ecology
• Journal of Political Ecology
• New Left Review
• Progress in Human Geography
• Progress in Physical Geography
• Oryx (journal)

Environmental policy in China

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Environmental_policy_in_China 

Environmental policy in China is set by the National People's Congress and managed by the Ministry of Environmental Protection of the People's Republic of China. The Center for American Progress has described China's environmental policy as similar to that of the United States before 1970. That is, the central government issues fairly strict regulations, but the actual monitoring and enforcement are largely undertaken by local governments that have a greater interest in economic growth. The environmental work of non-governmental forces, such as lawyers, journalists, and non-governmental organizations, is limited by government regulations. Under the Ministry of Environmental Protection of the People's Republic of China, the Department of Policies, Laws, and Regulations is in charge of establishing and strengthening basic laws and policies such as environmental laws, administrative policies and economical regulations. It is also responsible for the development of national environmental protection policy and macro strategy.

China's rapid economic expansion combined with the country's relaxed environmental oversight has caused a number of ecological problems. In response to public pressure, the national government has undertaken a number of measures to curb pollution in China and improve the country's environmental situation. However, the government's response has been criticized as inadequate. Encouraged by national policy that judges regions solely by their economic development, corrupt and unwilling local authorities have hampered enforcement. Nonetheless, in April 2014, the government amended its environmental law to better fight pollution.

Since the 2010s, the government has given greater attention to environmental protection through policy actions such as the signing of the Paris climate accord, the 13th Five-Year Plan and the 2015 Environmental Protection Law reform  From 2006 to 2017, sulphur dioxide levels in China were reduced by 70 percent, and air pollution has decreased from 2013 to 2018 In 2017, investments in renewable energy amounted to US$279.8 billion worldwide, with China accounting for US$126.6 billion or 45% of the global investments. China has since become the world's largest investor, producer and consumer of renewable energy worldwide, manufacturing state-of-the-art solar panels, wind turbines and hydroelectric energy facilities as well as becoming the world’s largest producer of electric cars and buses.

Policy jurisdiction

The Ministry of Environmental Protection (MEP), formerly the State Environmental Protection Administration (SEPA), is a cabinet-level ministry in the executive branch of the Chinese Government that is responsible for implementing environmental policies, as well as the enforcement of environmental laws and regulations. The Ministry is tasked with protecting China's air, water, and land from pollution and contamination. Directly under the State Council, it is empowered and required by law to implement environmental policies and enforce environmental laws and regulations. Complementing its regulatory role, it funds and organizes research and development. There are 20 offices and departments under MEP including General Office, Department of Planning and Finance, Department of Policies, Laws and Regulations, Department of Human Resources Management and Institutional Arrangement, Department of Science, Technology and Standards Department of Environmental Impact Assessment, Department of Environmental Monitoring, Department of Water Environment Management, Department of Air Environment Management, Department of Soil Environment Management, Department of Nature and Ecology Conservation, Department of Nuclear Facility Safety Regulation, Department of Nuclear Power Safety Regulation, Department of Radiation Source Safety Regulation Bureau of Environmental Supervision and Inspection, Department of International Cooperation, Department of Education and Communications, The MEP Committee of Communist Party of China, Office of the CPC Central Commission for Discipline Inspection at MEP.^[13] All 20 offices are at the judicial level in the government ranking system. They carry out regulatory tasks in different areas and make sure that the agency is functioning accordingly. Since 2006, there have been five regional centers to help with local inspections and enforcement.

History

In 1972, Chinese representatives attended the first United Nations Conference on the Human Environment. The next year, the Environmental Protection Leadership Group was established. In 1983, the Chinese government announced that environmental protection would become a state policy. In 1998, China went through a disastrous year of serious flooding, and the Chinese government upgraded the Leading Group to a ministry-level agency, which then became the State Environmental Protection Administration.

According to the Chinese government website, the Central Government invested more than 40 billion yuan between 1998 and 2001 on protection of vegetation, farm subsidies, and conversion of farm to forests. Between 1999 and 2002, China converted 7.7 million hectares of farmland into forest.

From 2001 to 2005, Chinese environmental authorities received more than 2.53 million letters and 430,000 visits by 597,000 petitioners seeking environmental redress. Meanwhile, the number of mass protests caused by concerns over environmental issues grew steadily from 2001 to 2007. The increased attention on environmental matters caused the Chinese government to display an increased level of concern towards environmental issues. For example, in his 2007 annual address Wen Jiabao, the Premier of the People's Republic of China, made 48 references to "environment," "pollution," and "environmental protection", and stricter environmental regulations were subsequently implemented. Subsidies for some polluting industries were cancelled, while other polluting industries were shut down. However, many internal environmental targets were missed.

After the 2007 address, the influence of corruption was a hindrance to effective enforcement, as local authorities ignored orders and hampered the effectiveness of central decisions. In response, CPC General Secretary Hu Jintao implemented the "Green G.D.P." project, where China's gross domestic product was adjusted to compensate for negative environmental effects; however, the program quickly lost official influence due to unfavorable data. The project's lead researcher claimed that provincial leaders "do not like to be lined up and told how they are not meeting the leadership’s goals ... They found it difficult to accept this." The government attempted to hold national "No Car Days" where cars were banned from central roads, but the action was largely ignored. In 2008, the State Environmental Protection Administration was official replaced by the Ministry of Environmental Protection during the March National People's Congress sessions in Beijing.

Citizen activism regarding government decisions that are perceived as environmentally damaging increased in the 2010s. In April 2012, protests occurred in the southern town of Yinggehai following the announcement of a power plant project. The protesters initially succeeded in halting the project, worth 3.9 billion renminbi (£387m). Another town was selected for the location of the plant, but when the residents in the second location also resisted the authorities returned to Yinggehai. A second round of protests occurred in October 2012 and police clashed with protester, leading to 50 arrests and almost 100 injuries. In response to a waste pipeline for a paper factory in the city of Qidong, several thousand demonstrators protested in July 2012. Sixteen of the protesters were sentenced to between twelve and eighteen months in prison; however, thirteen were granted a reprieve on the grounds that they had confessed and repented. In total, more than 50,000 environmental protests occurred in China during 2012.

In response to an increasing air pollution problem, the Chinese government announced a five-year, US$277 billion plan to address the issue in 2013. Northern China will receive particular attention, as the government aims to reduce air emissions by 25 percent by 2017, compared with 2012 levels.

In March 2014, CPC General Secretary Xi Jinping "declared war" on pollution during the opening of the National People's Congress. After extensive debate lasting nearly two years, the parliament approved a new environmental law in April. The new law empowers environmental enforcement agencies with great punitive power, defines areas which require extra protection, and gives independent environmental groups more ability to operate in the country. The new articles of the law specifically address air pollution, and call for additional government oversight. Lawmaker Xin Chunying called the law "a heavy blow [in the fight against] our country's harsh environmental realities, and an important systemic construct". Three previous versions of the bill were voted down. The bill is the first revision to the environmental protection law since 1989.

In 2019, China launched the Belt and Road Initiative International Green Development Coalition.

In 2020, Chinese Communist Party general secretary Xi Jinping announced that China aims to peak emissions before 2030 and go carbon-neutral by 2060 in accordance with the Paris climate accord. According to Climate Action Tracker, if accomplished it would lower the expected rise in global temperature by 0.2 - 0.3 degrees - "the biggest single reduction ever estimated by the Climate Action Tracker".

In 2020, a sweeping law was passed by the Chinese government to protect the ecology of the Yangtze River. The new laws include strengthening ecological protection rules for hydropower projects along the river, banning chemical plants within 1 kilometer of the river, relocating polluting industries, severely restricting sand mining as well as a complete fishing ban on all the natural waterways of the river, including all its major tributaries and lakes.

Current law

When the new environmental protection provisions go into effect in January 2015, the government's environmental agencies will be allowed to enforce strict penalties and seize property of illegal polluters. Companies that break the law will be "named and shamed", with company executives subject to prison sentences of 15 days. There will be no upper limit on fines; previously, it was often cheaper for companies to pay the meager fines provisioned by the law than install anti-pollution measures. In all, the new law has 70 provisions, compared to the 47 of the existing law. More than 300 different groups will be able to sue on the behalf of people harmed by pollution. It remains to be seen whether these changes to the law will overcome some of the traditional problems with environmental litigation in China, such as difficulty getting cases accepted by the court, trouble gathering evidence and interference from local government.

Under the new law, local governments will be subject to discipline for failing to enforce environmental laws. Regions will no longer be judged solely on their economic progress, but instead must balance progress with environmental protection. Additionally, local governments will be required to disclose environmental information to the public. Individuals are encouraged to "adopt a low-carbon and frugal lifestyle and perform environmental protection duties" such as recycling their garbage under the law.

In June 2017, the Chinese government made a second amendment to the Water Pollution Prevention Act. Based on the first regulation of Water Pollution Prevention Act in 1996, the amendment will increase the punishment for water pollution and the penalty ceiling may be raised to 1 million yuan. According to the statement of the Minister of Environmental Protection, the second revised version further strengthened the responsibilities of local governments, and refined and improved the drinking water safety protection system. Since the legislation in 1984, this law has made a significant and positive contribution to improving the water environment in China. However, the quality of water environment in China is still not promising.

Protected areas

See also: List of protected areas of China

A number of different classes of protected areas are recognized under Chinese law. National, provincial, and local governments all have the power to designate areas as protected. Regardless of designation, most enforcement is made at the local level.

On January 1, 2019 the Chinese government promulgated the "Soil Pollution Prevention and Control Law". 1. The new law has guidelines for performing mergers and acquisitions environmental due diligence Phase II and III and HHRA (Human Health Risk Assessments) 2. Chinese government will not accept ASTM E1903 - 11 Standard Practice for Environmental Site Assessments: Phase II Environmental Site Assessment Process 3. Following the new Chinese law Phase II sampling guidance will cost 30-40% more than the ASTM methodology a. In part due to the requirements in the Chinese guidance that requires up-gradient and down gradient ground water testing and other technical guidance. b. Phase II due diligence sampling under the new Chinese regulation will become “Public Record” – accessible to any company or Chinese citizen. This transparency could damage global companies' reputation if a site under their control is publicly declared "polluted" c. The Chinese Technical guideline will necessarily add significant time to the process of due diligence – M&A (sale-deals need to factor this into transaction timelines - expect up to a year longer time line in cases where property in on a watch list or deemed by the government to be a PSPF (Priority Soil contamination Prevention and control Facility.) 4. Starting immediately ALL ACQUISITIONS NEED TO BE PREDICATED UPON A CHINESE POLLUTION LAW GUIDELINE COMPLIANT BASELINE – this requirement will add to the acquisition execution time line significantly. 5. Acquisitions need to establish contractual warranty and environmental escrow following the principles of the Chinese Regulation (Investor company legal counsel needs to change their acquisition agreement template to align with Chinese law guidance.) 6. If a target site has recently been found to be polluted under the regulation – M&A should cease until expert panel rules on remediation plans/proposals… buyers should not enter agreement to purchase until scope and cost to remediate have been approved by the expert panel and an escrow can be established along with warrantee language in the purchase agreement. 7. It is highly recommended that companies with property having historical recognized environmental conditions (HRECS) perform routine sampling that follows the Chinese guidelines a. If a company has facilities that fall into certain “High Risk Sectors” they are entered automatically in to the Watch List – including: i. Chemical ii. Pharma iii. Manufacturing iv. Oil & Gas v. Non Ferrous Metals b. Also a company can be listed on the Watch List if certain triggers are met: i. Store, Handle manager hazardous material ii. Generate >100 tonnes of Hazardous Waste per year iii. Located near sensitive areas (residential, water bodies) c. Sale or closure of any property on the “Watch List” must be accompanied by Phase II Assessments that follow the guideline d. Contaminated property discovery must be reported to the government – added to the “Watch List” which will be updated and released annually. 8. Where divestiture/purchase contracts include “indemnification” language protecting the seller or buyer – the new law provides these contractual provisions can be overridden by the Chinese Government. 9. Watch List site closure or sale (divestiture) requires Phase II report per the Chinese Pollution Law guideline – becomes public record – CAN HAVE NEGATIVE IMPACT TO COMPANY REPUTATION 10. Even though the new Chinese Law follows the principle of “polluter pays” - ERM sited client case studies where the “buyer” did not contribute to contamination – and yet ended up sharing the remediation cost with the seller. 11. Whenever a site has been found to be contaminated under the guidelines of the law – the owner must seek guidance from an “Expert Panel” who will make judgements/decisions about HHRA as well as remediation.

Current issues

Main article: Environmental issues in China

 

Air pollution caused by industrial plants

China has many environmental issues, severely affecting its biophysical environment as well as human health.

Water Shortage

China is facing three major water resources problems: water pollution, shortage of water resources and waste of water resources. The problem with water resources will be China's obstacles to achieve sustainable development in the 21st century. The government has begun to deal with water resources problems since the 1970s, establishing water pollution control and environmental protection agencies.

China ranks 5th globally in terms of water resources but the water resource per capita is less than 1/3 the world average. The Chinese government implemented two policies to alleviate the water shortage issues;supporting the South-North Water Diversion Project and improving water use efficiency. The government has provided funding for the South-North Water Diversion Project, which aims to bring 44.8 billion cubic meters of water to Beijing and other northern parts of China. The project will cause disruption to local inhabitants forcing the migration of nearly one million people. The total cost of this project is estimated at $62 billion. In 2010, the Communist Party of China and the State Council set policies to change ways of using water and improve water use efficiency. The central government had invested 1.8 trillion yuan to enable efficient water use by upgrading both agriculture irrigation systems and clean water systems in rural areas.

Water pollution is also an issue in China.

Besides the water shortage, the water quality is also an issue which has influenced public health and led to political disputes. Only less than half of all water resources meets the safe drinking water standards in China. Besides political oppositions between regions, the current government structure is also a barrier for water pollution control.

The Ministry of Ecology and Environment of the People's Republic of China is a relatively young ministry. It is assigned relatively less power and fewer employees than other existing ministries, which results in its heavy dependence on local environmental protection bureaus (EPB). The problem is that local EPBs do not only get controlled by higher EPB but also by local governments whose performance is assessed mainly by economic development. Therefore, the local governments have loose policies on companies that producing water pollution. Additionally, the financial support of EPBs comes from pollution fines instead of the Ministry of Ecology and Environment, which makes it difficult for the ministry to manage local EPBs.

Air pollution

Various forms of pollution have increased as China has industrialized, causing widespread environmental and health problems. In January 2013, fine airborne particulates rose as high as 993 micrograms per cubic meter in Beijing, compared with World Health Organization guidelines of no more than 25. Heavy industry, dominated by state-owned enterprises, has been promoted since the beginning of central planning and still has many special privileges such as access to cheap energy and loans. The industry possesses considerable power to resist environmental regulation.

At the end of October 2018, the Chinese government has issued the Atmospheric Pollution Prevention and Control Law (2018 Amendment), which will be implemented starting immediately. Experts believe that although the law is inevitably flawed in some aspects, if 80% of the law can be implemented, it is going to significantly improve the air quality. This law has been scrutinized three times. The new amendment has clearly stated out that enterprises of iron and steel, building materials, non-ferrous metals, petroleum, and chemical industry that discharge dust, sulfide, and nitrogen oxides in the course of production shall adopt cleaner production processes, construct dust-removing, desulfurization, and denitrification equipment in a complete set, or adopt technological transformation and other measures to control the discharge of air pollutants. Compared to the revised Air Pollution Control Law in 2000, the new version doubled the entries. Almost all the laws in the current version have been amended and revised to fit the current situation.

Based on 2015's China Environmental Bulletin published by the Chinese government, in 2015 the national urban air quality is getting better. The first implementation of the new air quality standards has made the PM 2.5 average concentration decreased by 14.1% compared to the year of 2014. The Ministry of Finance established a fund of 10.6 billion Yuan to improve the air quality and to control the air pollution around the Beijing-Tianjin-Hebei and the surrounding areas, Yangtze River, and other key areas. The government is also actively promoting renewable energy vehicles with an annual production of 390,000, four times more than the production in 2014.

Soil pollution

Soil pollution satellite image

Soil pollution problems, which is the land surface degradation caused by the abuse of resources and land caused by human activities, together with corresponding protection measures in China have occurred in recent decades. In total, nearly 16.1% of China's soil was polluted. These pollutions have caused a serious impact on the growth of crops and the health of the people. In terms of related policies, the Chinese government decided to draw on the successful examples of other countries and integrate China's national conditions to maintain long-term governance of soil pollution problems. From the 1980s to the 1990s, China began to work on soil environmental research by starting the Modern conservation tillage research with the support of Australia. From 2000 to now, the problem of soil pollution in China has become increasingly serious. The government has gradually put the prevention and control of soil pollution issues and other environmental protection issues in the first place by charging fines for polluted factories.

China conducted a large-scale soil quality sampling analysis nationwide from 2005 to 2013, and according to the National Soil Pollution Survey Bulletin promulgated by the Ministry of Environmental Protection of China in 2014, the total national soil exceedance rate (the percentage that exceeds the upper limit value) was 16.1%, of which slight, slight, moderate and heavy degree of pollution spot is 11.2%, 2.3%, 1.5% and 1.1%, respectively. From the point of view of pollution distribution, soil pollution in the south is heavier than in the north. The soil pollution problems in some regions such as the Yangtze River Delta, the Pearl River Delta, and the old industrial base in Northeast China are more severe. The soil in the southwest and south-central regions has exceeded the upper limit of heavy metals tolerance. The contents of the four inorganic pollutants such as cadmium, mercury, arsenic, and lead have gradually increased from northwest China to southeast China and from northeast China to southwest China. As far as the current state of legislation is concerned, China already has air pollution prevention and control law and water pollution control law, but it still lacks a soil pollution control law. In June 2017, the Ministry of Environmental Protection pointed out that China will establish a more refined working mechanism, continue to carry out investigation of soil pollution, promote the improvement of the legislative system, and fully cooperate with the National People's Congress in the legislation on soil pollution control law.

Desertification

Land desertification is another pressing environmental issue. A land survey conducted by the State Forestry Administration of China from 2013 to 2016 shows that 2.61 × 10⁶ km² of the national land, accounting for more than a quarter of China’s overall territory, is desertified. Arid, semi-arid, and sub-humid lands located in Northern and North-Western China make up for the majority of the affected territory. Desertification has long reaching consequences, resulting in ecological degradation, halting local economic development, as well as damaging the health of residents in the affected area. Desertified land facilitates the creation of sandstorms which threaten the health of residents in the nearby rural and urban areas alike. As the desert expands, it turns more and more land non-arable and unsuitable for development, creating poverty and food shortage. The current issue is a result of the combination of various anthropogenic and ecological factors. Devegetation brought about by unfavourable hydrologic conditions, climate change induced droughts, as well as unsustainable human activities such as overgrazing, agriculture, and deforestation, exposes the soil to frequent water and wind erosion, creating desert.

To combat land desertification, China has implemented a range of legislative policies as well as restorative programs. Laws are passed to prevent logging, agriculture, and animal grazing in locations of high desertification risk, establishing these areas as ecological function reserves. In areas surrounding desertified land, a large scale of protective forests and shelterbelts are created by programs such as the Three-Norths Shelter Forest Construction Program to reduce the effect of wind erosion. Since 1999, The Ministry of Forestry has been providing monetary rewards for farmers who plant trees instead of crops, as well as auctioning away national land to individuals to rehabilitate for economic gains. In 2002, The Sand Prevention and Control Law was introduced to encourage sustainable development in desertified areas, encouraging afforestation and establishment of green industries such as water efficient pasture and natural pharmaceutical production. This policy is met with wide support from the residents in these areas as it also stimulates local economic growth. Residents in the Kubuqi Desert, for example, have had their annual income increased from $56 to $2000 in less than 30 years.

Impact

China's lax environmental oversight had contributed to its environmental problems. Sixteen of the world's twenty most polluted cities were found in China in 2013, but has since reduced to just one at 19th place Government response has been criticized as inadequate. An official report released in 2014, found that 20% of the country's farmland, and 16% of its soil overall, is polluted. An estimated 60% of the groundwater is polluted.

According to the U.S. Environmental Protection Agency, China has shown great determination to "develop, implement, and enforce a solid environmental law framework" However, the impact of such efforts is not yet clear. The harmonization of Chinese society and the natural environment is billed as one of the country's top national priorities.

International groups called the law revision passed in April 2014 a positive development, but cautioned seeing the laws through to implementation would be a challenge.

Because China does not have a fully established legal system, enterprise executives base their environmental practices largely on perceptions about regulators rather than concerns for legal issues, according to a 2014 study published in Journal of Public Administration Research and Theory. One executive interviewed said that China's environmental regulations were “comprehensive” but yet “vague,” leaving local officials with large discretion in terms of enforcement. If executives think local officials may arbitrarily target their enterprises for enforcement, they are likely to adopt proactive practices, such as “developing certifiable environmental management systems,” but not basic ones, such as waste recycling.