Generating electricity in plants that are more efficient. For example, a new supercritical pulverized coal plant requires less than 9,000 Btu (British thermal units) of coal energy input to generate 1 kWh of electricity (>38 percent efficiency) compared to the current average of more than 10,000 Btu/kWh of electricity (<34 percent efficiency).
Switching to a less carbon-intensive fossil fuel. For example, generating 1 million Btu of energy as heat from coal combustion releases about 200 pounds of CO2, whereas generating the same amount of energy as heat from natural gas releases about 120 pounds of CO2.
Combining fuel switching and more efficient generating plants. For example, a new natural gas-fired combined cycle (NGCC) power plant requires only about 6,800 Btu of energy input to generate 1 kWh of electricity (~50 percent efficiency). Hence, to generate 100 kWh of electricity, a NGCC plant would emit about 80 pounds of CO2 compared to the average coal plant that emits 200 pounds per 100 kWh, or a more efficient PC plant that emits 180 pounds per 100 kWh.
Generating electricity without using fossil fuels, for example, by using renewable resources or nuclear power.
Capturing and sequestering (storing) CO2 produced by fossil fuel combustion or gasification.
The technologies currently offered commercially to capture power plant CO2 emissions can achieve net emission reductions of 85 to 90 percent at new PC or IGCC power plants (IPCC, 2005). Such technologies are widely used in a variety of industrial processes, mainly in the petroleum and petrochemical industries, but are not yet deployed commercially in the electric power sector. Although post-combustion CO2 capture systems employing amine sorbents have demonstrated effective removal of CO2 from flue gas streams from gas-fired and coal-fired boilers, they have not yet been applied at the larger scales typical of modern power plants (e.g., plants that generate several hundred megawatts of electricity). The same is true for the “pre-combustion” capture technologies used commercially at gasification-based processes. Various types of oxyfuel combustion systems2 also are being developed to facilitate CO2 capture, but these have not yet been proven. A variety of advanced gas separation methods are being developed by national and international R&D efforts to selectively and more cost-effectively remove CO2 from flue gas and other gas streams. However, large-scale demonstrations of CO2 capture and sequestration at the 100 MW scale are needed before such systems can be implemented on a large scale.
Oxyfuel combustion systems involve the combustion of pulverized coal in a mixture of oxygen and recirculated flue gas in order to reduce the net volume of flue gases from the process and to substantially increase the concentration of CO2 in the flue gases compared to the normal pulverized coal combustion in air (CCSD, 2007).