Coal-fired power plants play an important role in providing energy at low prices. The reality is that coal is abundant, efficient and less expensive than most other energy options, and will remain an important part of our energy future. Coal accounts for about 50% of electricity production in the United States, and, as shown in Figure 1, it remains a low-cost energy source for U.S. residences. However, coal-fired plants do emit carbon dioxide (CO2), a greenhouse gas (GHG), into the atmosphere, and efforts are underway to improve coal’s environmental performance so that we can take full advantage of this plentiful resource.
“Clean coal technology” describes a new generation of energy processes, some currently available and others being developed, that have the ability to sharply reduce air emissions and other pollutants. These new technological breakthroughs make it possible for new and older coal-burning power plants to produce power in an economical and environmentally responsible manner.
Figure 1. Coal accounts for about 50% of electricity production in the United States, and, as shown in Figure 1, it remains the lowest cost energy source for U.S. residences.
Among the key options under development for use alone or in combination are:
- Optimizing existing plants so they reduce emissions and increase the amount of electricity produced with the same amount of coal.
- Continuing to develop and refine best-available combustion technology, including circulating fluidized-bed (CFB) technology, which includes supercritical and ultra supercritical combustion. This option may also include burning biomass as a fuel, thus reducing the level of CO2 emissions, and oxy-combustion for collecting CO2-rich flue gas.
- Gasification — turning coal into a gas and removing impurities from the coal gas before it is combusted.
- Carbon capture and storage (CCS) — capturing the carbon dioxide from the flue gas and storing it underground or reusing it.
Clean coal is a key component of U.S. energy strategies
The Obama-Biden administration has stated that coal must play a part in our nation’s energy strategy. The White House Energy and the Environment Agenda includes an initiative to develop and deploy clean coal technology. At his Senate confirmation hearing, Dr. Steven Chu, the Obama administration’s Secretary of Energy, stated, “Coal is an abundant resource in the world ... It is imperative that we figure out a way to use coal as cleanly as possible.”
To stimulate the kind of innovative thinking needed to find ways to use coal cleanly, the government funds numerous research projects through the U.S. Department of Energy (DOE) and has pledged to work towards advancing clean coal technologies.
That pledge comes in the form of government co-financing for new coal technologies that help utilities cut pollutants from power plants and demonstrate ways to reduce GHGs by boosting efficiency. Most recently, recognizing that carbon sequestration and storage (CCS) technologies hold enormous potential to reduce GHG emissions from coal-fired power plants, DOE has begun funding projects that use CCS technologies and/or beneficial reuse of carbon dioxide.
The DOE is funding an initiative to equip multiple new clean coal power plants with advanced CCS technology, stating, “As technological advancements have been realized in the last five years, the United States is eager to demonstrate carbon capture and storage technology on commercial plants that when operational, will be the cleanest coal-fired plants in the world.” In addition, the DOE is also participating in a number of international CCS efforts, including projects in Canada, Germany, Australia, Algeria and China.
It is clear that government and its industry partners place high hopes that these public-private partnerships will lead to technology breakthroughs allowing coal-fired plants to continue to provide safe, affordable energy.
Major clean coal technologies under development
Scientists and engineers in the U.S. and abroad are conducting research and demonstration projects to prove that coal can be used to produce energy efficiently and responsibly and, in the process, provide clear evidence that clean coal can in fact play a significant role in our energy future for many years to come.
Optimizing existing coal-fired power plants
Optimizing existing plants is the “low-hanging fruit” of technologies because it makes the best possible use of what we already have. In the United States, optimization includes using sophisticated software to help plants reduce emissions, increase efficiency, lower costs and improve reliability. One example is an integrated online optimization system at a coal-fired plant located in Baldwin, Ill., that led to a 12-14% reduction in nitrogen oxide (NOx) emissions, reduction of ammonia consumption by 15-20%, increase in fuel efficiency and available megawatt hours, and reduction in GHGs, mercury, and particulates.
In the developing world where many coal-fired plants operate far below their design efficiencies because of poor-quality coals, poor plant maintenance, and lack of diagnostic tools and instrumentation, optimization programs could include implementation of low-cost best practices that would save millions of tons of coal, avoid millions of tons of CO2 emissions, and improve the plants’ financial performance. Refurbished power plants would be more efficient and emit less CO2. Plants could also be upgraded with new pollution control equipment to emit less sulfur dioxide, nitrogen oxide, particulates and other emissions, including mercury. Although some demonstration projects have been implemented, much more work is needed in this area, because the economic and environmental payoff would be so significant.