Natural gas is substantially cleaner than coal when it comes to carbon emissions. But that's just the beginning of its clean-energy profile. Natural gas also has 80% fewer NOx emissions-and virtually no sulfur dioxide, mercury or particulate pollution.
Coal-fired electricity generating facilities are the largest single source of greenhouse gas emissions in the United States. In fact, coal-fired power plants currently account for 80% of all the CO2 emissions from the U.S. electric power industry and about 33% of all U.S. CO2 emissions.
Natural gas offers significant reductions in these pollutants and substantially eases impact on human health and the environment. Natural gas emits just over half of the CO2 per megawatt-hour (MWh) of a coal plant and modern natural gas combined cycle turbines emit 60 percent less CO2 per MWh than a typical coal plant.
According to the Congressional Research Service, if we doubled the utilization of combined cycle natural gas capacity to 85%, we could displace about 19% of the CO2 emissions associated with coal power, or approximately 636 million metric tons of CO2. This amounts to an 8.8% reduction of all CO2 emissions in the U.S.
Cost-Effective
Electric power producers and users are always concerned about costs. Regulated utilities work hard to hold down customer bills, and participants in the wholesale electric market operate in a highly competitive environment. Operators must be concerned about the total cost of the unit from construction through decades of operation.
Natural gas plants have attractive "life cycle" economics compared with other fuels. Faster and cheaper construction and better operating efficiency with natural gas can mean lower rates for electric power consumers.
According to a 2008 Electric Power Research Institute study, a conventional combined-cycle natural gas plant costs about $1,000 per kilowatt of capacity constructed. A coal-fired plant costs more than $2,500 per KW hour to build. The cost of a new nuclear plant is more than $4,000 per KW of capacity. Wind generation costs are about double natural gas installation costs. A new solar plant in Florida is projected at about $6,600 per KW.
Another benefit: natural gas plants can be approved and built in months, not years as with coal, or a decade in the case of new nuclear plants. And when converting from coal to natural gas, there are fewer permitting issues, and lower emissions control costs.
Steve Mitnick, former chief energy advisor to the Governor of New York, said when you add in the increased operations and maintenance costs of old coal-fired power plants and environmental control retrofit costs that may be required as well as other system operational factors, the "coal-to-gas gap is virtually closed."
Efficient
Not only is natural gas twice as clean as coal, it's also significantly more efficient. According to Black & Veatch, the average combined cycle natural gas plant is approximately 39% more efficient than the oldest 50% of existing coal generation capacity-and 58% more efficient than the oldest 10% of coal-fired plants. What does that mean for consumers? For the oldest power-generating facilities, you need to burn 60% more coal to generate equivalent power from cleaner and more efficient natural gas.
Yet each new generation of natural gas-fueled power plants has been more efficient than the last. Today's combined-cycle natural gas power plants integrate several stages in the generation process to capture and re-use energy and heat. The result is a reduction in both the cost of electricity and emissions.
Natural gas-fueled generating equipment also provides efficiency value because it can more easily be sized to fit the need, and output can be ramped up and scaled back quickly when electric demand is at its peak on hot or cold days and used to provide uninterrupted service.
