Subsurface Sequestration of CO2 in the U.S: Is it Money Best Spent?

Abstract

The continuously decreasing average coal rank (heating value), inadequate investment, and ever stricter air-emission controls have caused the average efficiency of electricity generation from coal in the U.S. to plummet to a mere 32% by the year 2008. The U.S. gas-fired powerplants are 30% more efficient than the coal-fired ones, with average efficiency of 43% in 2008. Replacing each 1,000 MWe generated by an average coal-fired powerplant with an average gas-fired powerplant would avoid today 7 million tonnes of CO2 emissions, 1.2 million tonnes of toxic ash, and significant issues with water contamination. The parallel upgrades to the more efficient supercritical steam turbines would decrease current emissions by up to 50% (from the current average plant efficiency of 32% to over 45%). The CO2 captured in the new combined-cycle powerplants might be used to enhance oil recovery in local fields, where feasible. The CO2 enhanced oil recovery (EOR) can never become the main sink for the gigantic CO2 volume generated each year by electric powerplants. Currently, EOR could absorb only 1% of that volume.