Is Carbon Capture and Storage Technology Really Necessary?
By Jim Vess
Today, electric generation from coal makes up about 35% of the total electric generation in the United States. Coal is abundant and inexpensive, but it’s dirty. Many utilities are finding it cheaper to retire older coal-fired plants than to upgrade them to meet the U.S. Environmental Protection Agency’s (EPA) current carbon dioxide (CO2) emission requirements.
Currently the most efficient coal-fired power plants are the ultra-supercritical plants which operate at high steam temperatures of 1100°F and emit approximately 1760 pounds of CO2 per megawatt-hour (MWh).
Last August, EPA set the standard for new coal plant at 1400 pounds of CO2 per MWh. This new standard is assumed to require carbon capture and storage (CCS) technology in order to meet the 20% reduction in CO2 emissions. However, current CCS technologies are very expensive and can negatively affect plant performance. Also, many locations worldwide lack suitable geology for CO2 storage.
In a new white paper, the Electric Power Research Institute (EPRI) poses the question: “Is technology available or in development that would enable power plants fueled solely by coal to operate so efficiently that a CO2 emission standard of 636 kg/MWh (1400 lb/MWh) or less could be met without CCS?”
The white paper, Can Future Coal Power Plants Meet CO2 Emission Standards Without Carbon Capture and Storage? (EPRI report 3002006770) analyzes current and anticipated U.S. and international CO2 emission standards for coal plants and identifies key challenges associated with CCS deployment. The paper also provides detailed descriptions of coal-only technologies that, while not ready for commercial deployment, provide significant opportunities to reduce CO2 emissions.
EPRI looked at several technology options for increasing the thermal efficiency of the processes for generating electricity with coal, such as: Rankine cycles (used by most of today’s coal plants) with higher steam temperatures; cogeneration; and coal gasification integrated with one of four systems – combined cycles (gas turbine plants), supercritical CO2 Brayton cycles (which use the CO2 instead of water or steam as the working fluid), solid oxide fuel cells (SOFCs), and “triple cycles” (a combination of combined cycles and SOFCs).
Currently, none of the options considered in the analysis are commercially available, economically viable, or suitable for broad deployment. Research and development programs making progress in the development of these technologies, but additional public-private investment will be needed to accelerate this development.
While the use of renewables – wind and solar – is gaining ground, experts agree that we will also need to rely on fossil fuels for decades into the future in order to meet the world’s growing demand for energy. Coal is readily available and new technologies can clean it up.
“It’s critically important for the electric power industry to have as many generation technology and fuel options as possible,” said EPRI Vice President of Generation Tom Alley in an EPRI press release. “Reducing emissions will be one of the key drivers as the industry makes decisions about existing assets and about the designs and fuels used in the next generation of power plants. EPRI research like this can be invaluable in informing those decisions.”