On 25 and 26 April the US Environmental Protection Agency issued final carbon pollution standards for power plants that set carbon dioxide (CO2) limits for new gas-fired combustion turbines and CO2 emission guidelines for existing coal, oil and gas-fired steam generating units, in order to secure important climate benefits and protect public health.
Alongside the measures aimed at GHG emissions directly from combustion the new Rule includes measures aimed at reducing the quantity of polluted wastewater from coal plants, including seepage from combustion ash storage into the water supply, tighter regulation of the presence of toxic metals, and also of mercury pollution from lignite plants.
As a nod towards a sector that is making long-term investments in the transition to clean energy, EPA said the rules are designed to work with power companies’ planning processes. Regulators say they project the rules will result in reductions of 1.38 billion metric tons of carbon pollution overall through 2047.
The EPA’s final rule heavily relies on carbon capture and sequestration/storage (CCS) as the best system of emission reduction for the longest-running existing coal-fired units and most heavily utilised new gas turbines. Unlike the original proposal from nearly a year ago, decarbonising these plants through clean hydrogen co-firing is not a factor in the new Rule. Rules for existing natural gas-fired plants aren’t expected to come out until after the November presidential election.
Compliance and exemptions
Under EPA’s final rule, coal plants which plan to stay open beyond 2039 would have to be reducing or capturing 90% of their carbon dioxide emissions by 2032.
Initially, the compliance date to implement CCS for this subcategory of coal plants was January 1, 2030, but the EPA said it been told by stakeholders that this deadline did not provide adequate lead time.
Under the final rule, coal plants that are scheduled to close by 2039 would have to cut their emissions 16% by 2030. In this case, EPA said the BSER (best available technology) for this subcategory is co-firing with natural gas, at a level of 40 % of the unit’s annual heat input. EPA said more than half (100 GW) of still-operating coal-fired units have already announced retirement dates or conversion to gas-fired units before 2039.
Coal plants that are set to retire by 2032 would be exempted from the new rule.
Standards and methods
The new rules, finalised under separate authorities including the Clean Air Act, Clean Water Act, and Resource Conservation and Recovery Act, are aimed at ensuring that all long-term coal-fired plants and base load new gas-fired plants control 90% of their carbon pollution. Existing coal-fired power plants are the largest source of GHGs from the power sector. New natural gas-fired combustion turbines are some of the largest new sources of GHG being built today and these final standards are intended to ensure that they are constructed to minimise their GHG emissions.
Consistent with EPA’s traditional approach to establishing pollution standards under the Clean Air Act, the final limits and emission guidelines are based on proven pollution control technologies that can be applied directly to power plants and can achieve substantial reductions in carbon pollution at reasonable cost. Emission guidelines for the longest-running existing coal units and performance standards for new base load combustion turbines are based on the use of carbon capture and sequestration/storage (CCS) – which EPA says is an available and cost-effective control technology that can be applied directly to power plants.
EPA has evaluated the emissions reductions, benefits, and costs of the final carbon pollution standards in a Regulatory Impact Analysis. The RIA projects reductions of 1.38 billion metric tons of CO2 system-wide through to 2047 along with tens of thousands of tons of PM2.5, (particulate matter under 2.5 microns) SO2, and NOx – all harmful air pollutants that are known to endanger public health.
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