The Environmental Protection Agency (EPA) thinks it's reasonable to expect coal-fired power plants can make an improvement of at least 4% in their heat rates and, as a result, curb carbon dioxide emissions.
This is one of the points made in the proposed Clean Power Plan, which EPA issued earlier this month. The proposed rule for existing plants seeks to have states draft implementation plans designed to reduce CO2 30% below 2005 levels by 2030.
The 645-page rule proposal also mentions increasing usage of combined-cycle natural gas plants built in the past 15 years to 70% rather than the current 45%. EPA says completion of five existing nuclear reactors now under construction are also important - as are greater use of renewables, energy efficiency and regional emissions trading.
The current weighted-average annual heat rate of U.S. coal-fired electric generating units (EGUs) in the range of 400 to 600 MW is approximately 10,434 Btu per net kWh, EPA said in the rule proposal.
Several studies have examined the opportunities to employ heat rate improvements as a means of reducing CO2 emissions from coal-fired power plants. There was a 2009 study from Sargent & Lundy that noted improvements could be made from equipment upgrades, upgrades to boilers, steam turbines and control systems.
Such tweaks could provide total heat rate improvements in the range of 4% to 12%, EPA says. “We believe a reasonable estimate for the purposes of developing state-specific goals” is a 4% improvement in heat rate, EPA said.
“The total of the estimated potential heat rate improvements from adoption of best practices to reduce heat rate variability and implementation of equipment upgrades as discussed above is six percent (6%),” EPA said.
“Because of the close relationship between an EGU's fuel consumption and its CO2 emissions, a six percent heat rate improvement would be associated with a reduction in CO2 emissions of approximately six percent,” EPA said.
Improving the heat rate at coal plants should bring about a reduction in fuel spending, which would help offset the cost of the plant upgrades, EPA said.
“As summarized below, we estimate that, on average, the savings in fuel cost associated with a six percent heat rate improvement would be sufficient to cover much of the associated costs,” EPA said.
“The [Sargent and Lundy] study estimated that for a range of heat rate improvements from 415 to 1205 Btus per kWh, corresponding to percentage heat rate improvements of 4 to 12 percent for a typical coal-fired EGU, the required capital costs would range from $40 to $150 per kW,” EPA said.
EPA has announced the proposed rule under Section 111(d) of the Clean Air Act.
This article was republished with permission from GenerationHub.