President Obama’s recent climate change address could foreshadow a further shift from coal to natural gas-fueled generation in order to lower greenhouse gas (GHG) emissions, according to a July 1 commentary by Bernstein Research.
The review was led by Bernstein Research Senior Analyst Hugh Wynne. The July 1 evaluation builds upon an earlier assessment of the Obama carbon policy by the same analyst.
“Even a 10% cut in the CO2 emissions of the fossil fuel fleet would require a reduction in utility coal burn of ~175 million tons, or the equivalent of 17% of U.S. coal production, and an 8 Bcf/d increase in utility gas burn, or the equivalent of ~12% of U.S. natural gas production,” according to the research arm of Sanford C. Bernstein & Co.
Power generation accounts for the largest chunk of greenhouse gas emissions in the United States with 33% of the total and 40% of “addressable emissions.” Residential and commercial buildings are really too small to regulate.
Coal emissions then account for 80% of total CO2 emissions of the power sector. Gas-fired units, by contrast, only account for 19%, Wynne noted.
In addition, the average rate of CO2 emissions per MWh from U.S. combined cycle turbines is 60% less than that the average rate from the coal fleet. In addition the combined-cycle fleet is “technically capable of doubling its 2011 power output of some 834 million MWh,” Wynne said in the report.
Were such an increase in the power output of the combined-cycle fleet to replace coal fired generation, the corresponding decline in CO2 emissions of the power sector would be 500 million metric tons (834 million MWh x 0.6 metric tons per MWh). This is equivalent to more than 20% of the CO2 emissions of the power sector in 2011.
There are a couple of promising technologies for capturing CO2 from existing coal plants, the firm notes in the assessment.
Both the amine capture and oxy-fuel technologies, however, are “highly energy-intensive,” according to the Bernstein analysis. The energy required to operate the emissions controls creates a large parasitic load on the output of the retrofitted power plant, reducing net power output by over 30%.
The EPA could, however, go with a less far-reaching approach – like mandating improvements in the heat rates of existing plants. But “no series of steps to improve energy efficiency can be assumed to have universal applicability,” according to the Bernstein analysis.