While carbon capture and storage (CCS) research is frequently associated with coal-fired power plants, there is also significant interest in using CO2 control technology for electric generation from natural gas.
Electric Power Research Institute (EPRI) Director of Generation R&D Director Revis James discussed carbon capture for natural gas power plants during a briefing in Washington, D.C. during December for the United States Energy Association (USEA).
CCS for natural gas power plants is likely to be necessary in the future, according to material that the EPRI official presented at the Dec. 16 briefing.
In 2012 the electric power sector accounted for 36% of all U.S. natural gas consumption, James pointed out in his prepared materials. Natural gas accounted for 27% of total electric generation in 2012 and the gas share is expected to increase significantly by 2040.
EPRI has been evaluating the performance and cost impact of applying post-combustion capture today’s natural gas combined-cycle power plants, James said. The research looked at CCS feasibility for 556-MW combined-cycle plants – both a “new build” plant and retrofitting an existing plant.
New build analysis includes both a new power plant designed with capture as well as a new plant designed with carbon capture and exhaust gas recycle (EGR). One post-combustion capture technology studied includes advanced amine solvent from Aker Clean Carbon.
As might be expected, the cost of retrofitting is more expensive than an integrated design. Major factors affecting costs include engineering, procurement and construction (EPC); unit capacity factor and the overall levelized cost of electricity (which is a bigger issue than avoided CO2 cost).
The ERPI slides presented by James suggest that combined-cycle power plants with carbon capture currently cost more than double the price of a standard combined-cycle plant without carbon capture.
The cost of new build combined-cycle plants designed with post-combustion carbon capture could cost in the neighborhood of $1,676/kW (based on 2011 dollars). By contrast, the standard combined-cycle plant without carbon capture would cost an estimated $780/kW, according to the EPRI materials.
EGR technology would cost an estimated $1,586/kW. A combined-cycle gas plant subsequently retrofitted with carbon capture would cost $1,736/kW.
The growth in natural gas-fired power generation continues to be driven by relatively low gas prices, as well as existing and expected environmental regulations affecting coal.
Other emerging factors will affect this growth include increasing needs for operational flexibility and the potential need to capture CO2 from gas-fired generation units.
Growing variability in dispatch of firm assets as a result of increasing renewables deployments, distributed generation, and load management makes natural-gas fired generation attractive. Potential long-term goals for CO2 emissions mitigation are likely to require reducing emissions from gas-fired generation, but CO2 capture could limit operational flexibility and economy of operations.