Emissions reduction |


The US EPA’s new power plant rules: a World Resources Institute perspective


In April, the US Environmental Protection Agency and Biden administration announced four major regulations for power plants designed to slash multiple forms of toxic and planet-warming pollution. These rules represent the first legal limits on heat-trapping pollution from coal-fired power plants and will accelerate emissions reductions from the US power sector


When combined with other policies like tax credits from the Inflation Reduction Act, the new rules should be able to reduce power plant emissions by an estimated 75% below 2005 levels by 2035, and 83% by 2040. The new rules are critical for reducing uncertainty in decision-making by utilities, regulators and others about investments in the power sector in the coming years. In addition to new standards that address carbon dioxide emissions, EPA also announced new rules covering mercury, wastewater and coal ash disposal at power plants.


Here are four important things to know about the EPA’s new power plant rules:


• What do the EPA’s power plant rules require?


The new rules require existing coal plants and future natural gas plants to address carbon dioxide emissions in coming years. The requirements placed on coal plants depend on how long they expect to operate. For new gas plants, the required emissions controls will depend on how much they operate over the course of a year.


Coal plants that expect to operate beyond 2039 will have to reduce their carbon dioxide emissions by 90% by 2032, using carbon capture or other means, two years later than what was initially proposed in the draft rule released in May 2023.


Coal plants closing by 2039 will have to reduce their emissions 16% by 2030 (based on what’s achievable using 40% gas co-firing, though plants can use any technology they want to achieve the necessary reductions). Those plants scheduled to retire before 2032 are exempt from reducing emissions, but do have reporting requirements. If fully implemented, these rules could lead to the closure of most of the USA’s coal plants — the country’s most polluting source of electricity — before 2040.


It is, however, important to recognise that coal-fired electricity generation has plummeted in the USA during the last few decades, from just over 50% of total generation in 1990 to 17% in 2022, due to both a surge in natural gas, wind and solar generation, as well as the introduction of regulations requiring cleaner generation. In the final rules, the EPA brought forward the retirement date that triggers the need for emissions controls for coal plants from


2040 to 2039, requiring a larger set of plants to control emissions if they extend their lifetimes beyond 2039.


While requirements for existing natural gas plants, which are responsible for more than 40% of US electricity generation today, will be addressed in a forthcoming rule covering a wider set of air pollutants, the current rule addresses three categories of new natural gas plants based on their hours of operation over the course of a year:


For “baseload” plants that operate more than 40% of the time, EPA will require reductions that are the equivalent to 90% carbon capture and sequestration by 2032.


For “intermediate” natural gas plants that operate 20%-40% of the time, the rules require them to meet a performance threshold corresponding to an efficient simple cycle plant, or 1150 pounds of CO2


per MWh.


For peaker plants that operate less than 20% of the time, the rules require the use of lower- emitting fuels such as natural gas, which is already common practice, rather than diesel or high-emitting alternatives.


In addition to the greenhouse gas rule, EPA also finalised new rules strengthening and updating the Mercury and Air Toxics Standards (MATS) for coal-fired power plants, reducing pollutants discharged through wastewater from coal-fired power plants, and requiring the safe management of toxic coal ash left after burning coal for electricity.


• How can power plants comply with the new rules? Since the US Supreme Court ruled in Massachusetts vs EPA in 2007 that the agency was responsible for regulating the emissions of carbon dioxide and other greenhouse gases as pollution under the Clean Air Act, EPA has attempted to craft regulations that are based on the “best system of emission reduction” (BSER) to comply with this directive.


The first attempt was in 2015 with the Obama-era Clean Power Plan, which proposed a systemwide approach to require carbon emissions reductions. Those regulations were halted by court challenges before full implementation and replaced by the Trump administration’s inaccurately named Affordable Clean Energy Rule in 2019. That rule proposed to raise pollution limits and lower efficiency measures, which would have resulted in more damage to human and environmental health. But it was also halted by the courts before taking effect.


The new rules put forward by the EPA focus on reducing emissions from individual facilities by employing traditional, at-the-source pollution control measures for carbon as well as other forms of pollution. At present, the best way to control carbon emissions at individual power plants is through carbon capture and storage (CCS).


Utilities planning to operate a plant beyond the 2030s can comply with the rule by using


Summary of new EPA rules for coal plants and new natural gas plants Type of coal power plant


EPA rule, April 2024 Long-lived plants (operating beyond 2039)


Medium-term retirement (retiring between 2032 and 2039)


Near-term retirement (retiring before 2032) Type of natural gas power plant Peaker/low load (operates < 20% of hours in a year) Intermediate (operates 20%-40% of hours in a year) Baseload (operates >40% of hours in a year) Source: EPA


Emissions reductions equivalent to 90% carbon capture and storage by 2032


Reductions equivalent to 40% gas co-firing by 2030 Reporting requirement only EPA rule, April 2024


Emissions based on using lower emitting fuels (eg, natural gas rather than diesel)


Emissions based on efficient simple cycle plant operation (~1150 lb of CO2


/MWh)


Reductions equivalent to 90% carbon capture and storage by 2032


10 | June 2024| www.modernpowersystems.com


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