Greenhouse Gas Emission Reductions From Existing Power Plants: Options to Ensure Electric System Reliability

The report argues that EPA's regulation of greenhouse gas (GHG) emissions from existing power plants under Section 111(d) of the Clean Air Act will not jeopardize electric system reliability. Unlike the unit-specific MATS rule, Section 111(d) employs a 'cooperative federalism' model, allowing states to develop State Implementation Plans (SIPs) with significant flexibility. This includes 'inside the fence' options like heat-rate improvements and 'outside the fence' options such as emission-averaging, carbon budgets, and demand-side reductions. The author notes that current industry conditions—including low natural gas prices, underutilized natural-gas-fired combined-cycle (NGCC) capacity, flat electricity demand, and the growth of renewables—provide a buffer that supports reliable compliance. The report concludes that as long as EPA, states, and industry engage in timely planning, the regulatory framework provides sufficient latitude to maintain power system adequacy and security.

• The regulatory framework of Section 111(d) of the Clean Air Act is fundamentally different from other EPA rules like the MATS rule because it uses a 'cooperative federalism' model that provides states with wide latitude in how they achieve emissions reductions through State Implementation Plans (SIPs).
• Compliance options for states are categorized as 'inside the fence' (engineering-based improvements at the unit level) and 'outside the fence' (system-wide changes in dispatch, demand, and market mechanisms).
• As of March 2014, approximately 3,084 existing electric utility steam generating units (EGUs) and NGCC units are likely to be affected by Section 111(d), representing about 532.4 GW of generating capacity, or 70 percent of U.S. fossil generating capacity.
• The report identifies that electricity demand has remained relatively flat, which provides 'breathing room' for the industry to manage changes in the generation mix without compromising reliability.
• The loss of zero-carbon nuclear generation due to economic pressures could increase CO2 emissions and pressure states to include mechanisms in their SIPs to retain these resources.
• The report argues that reliability concerns are misplaced because the industry has a proven track record of responding to environmental rules without causing system failures.
• Market-based 'outside the fence' approaches, such as tradable performance standards, are estimated to be significantly more cost-effective than purely engineering-based 'inside the fence' actions.

APA

Tierney, S. F. (2014). Greenhouse Gas Emission Reductions From Existing Power Plants: Options to Ensure Electric System Reliability. Clean Air Task Force. https://cdn.catf.us/wp-content/uploads/2019/10/21093241/tierney_report_electric_reliability_and_ghg_emissions.pdf

Chicago

Tierney, Susan F. Greenhouse Gas Emission Reductions From Existing Power Plants: Options to Ensure Electric System Reliability. Clean Air Task Force, 2014. https://cdn.catf.us/wp-content/uploads/2019/10/21093241/tierney_report_electric_reliability_and_ghg_emissions.pdf.

Wikipedia

{{cite report |last1=Tierney |first1=Susan F. |title=Greenhouse Gas Emission Reductions From Existing Power Plants: Options to Ensure Electric System Reliability |publisher=Clean Air Task Force |date=May 2014 |url=https://cdn.catf.us/wp-content/uploads/2019/10/21093241/tierney_report_electric_reliability_and_ghg_emissions.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{tierney2014greenhouse, author = {Tierney, Susan F.}, title = {{Greenhouse Gas Emission Reductions From Existing Power Plants: Options to Ensure Electric System Reliability}}, institution = {Clean Air Task Force}, year = {2014}, month = may, url = {https://cdn.catf.us/wp-content/uploads/2019/10/21093241/tierney_report_electric_reliability_and_ghg_emissions.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }