Focus on Coal 


Te Obama-Biden administration has stated that coal must play a part in our nation’s energy strategy. Te 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 US Department of Energy (DOE) and has pledged to work towards advancing clean coal technologies. Tat 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, recognising 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. 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.


Scientists and engineers in the US 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. Optimising 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, optimisation includes using sophisticated software to help plants reduce emissions, increase efficiency, lower costs, and improve reliability. One example is an integrated online optimisation system at a coal- fired plant located in Baldwin, Illinois, that led to a 12–14 per cent reduction in nitrogen oxide (NOx) emissions, reduction of ammonia consumption by 15–20 per cent, 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, optimisation programs could include implementation of low cost best practices that would save millions of tons of coal, avoid million 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 sulphur 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. Circulating fluidised-bed (CFB) technology is an existing available technology, already being used to burn coal and other fuels to produce energy in a clean, environmentally responsible way. CFB is a clean coal combustion platform with a unique low temperature combustion process that can burn both traditional fuels and carbon-neutral fuels, including biomass, waste coals, tires, and processed waste materials. Te


technology can be used to significantly reduce CO2 emissions to the atmosphere. Unlike conventional steam generators that burn the fuel in a high-temperature flame, CFB technology does not have burners or a flame within its furnace. CFB uses fluidisation technology to mix and circulate fuel particles with limestone as they burn in a low temperature combustion process. Te limestone captures the sulphur oxides as they are formed, while the low-burning temperature minimises the formation of nitrogen oxides.


Te fuel and limestone particles are recycled over


and over back to the process, which results in high efficiency for burning the fuel, capturing pollutants, and for transferring the fuel’s heat energy into high- quality steam to produce power. Te CFB technology is now being integrated


with vertical-tube, once-through unit (OTU) supercritical steam technology, which provides the best combination of features for efficient, cost effective, and environmentally responsible power production. Te innovative boiler design uses BENSON vertical-tube supercritical once through steam technology for the evaporator steam circuit. Foster Wheeler is the leader in the design and


development of CFB technology and has begun to upscale its output by firing at an unmatched capacity. With more than 350 units already sold, research is now underway on an important enhancement to the basic CFB technology that will allow it to become part of a practical CCS solution. New or retrofitted coal-fired power plants could operate in oxy-combustion (carbon capture) mode, which would produce a CO2


rich flue


gas that can be practically captured and stored. Costs to run in this carbon neutral oxy-combustion mode are substantially higher than normal mode, but the plants can be built in stages so power generators can defer


www.engineerlive.com 41


“As one of the nation’s lowest-cost


electric power sources for the foreseeable future, coal will remain a


necessary and important part of US energy production.”


Robert S Giglio Director of Global


Marketing and Strategy,


Foster Wheeler Global Power Group


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