Cleaner burning coal power plants in the works

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Tuesday, 26 June 2012 11:33

June 26, 2012

Global engineering giants and utilities around the world are joining together to demonstrate how two new technologies can help clean up coal-burning plants, Technology Review reports.

The two new advancements revolve around lowering the cost of capturing carbon dioxide emitted from coal-burning power plants and helping utilities comply with current and proposed environmental regulations. Both technologies focus on how to efficiently burn coal in the presence of pure oxygen rather than air, which is mostly made up of nitrogen. In the next few months, the earliest pilot projects are expected to be up and running, according to the news source.

Burning fossil fuels in pure oxygen is an idea that has actually been around for some time, however companies have avoided the method due to the excessive costs when compared with conventional coal plant technology. The new developments show promise to help utilities reduce at least some of these high costs by improving efficiency and lowering capital costs in other parts of the plant.

One of the technologies was developed by ThermoEnergy and Italy's ITEA S.p.A., who are working together to promote, finance, design and construct a 50-megawatt pilot plant and a 320-megawatt commercial facility to test the new technology. The companies say the ultimate goal is to create coal-fired emissions-free electricity generation plants, and also be able to retrofit current plants with the clean-burning technology.

"We believe our collaboration with ThermoEnergy through Unity Power Alliance will lead to faster commercialization of pressurized oxy-combustion technology in the power industry," Alvise Bassignano, managing director of ITEA, said in a recent press release. "We look forward to starting work on our 50 MW plant next year."

Simply put, the technology improves the clean-up of flue gases, according to the Technology Review. For example, certain pollutants will be able to be captured in glass form after a high-temperature combustion process. It also allows power output to be quickly changed, rising from 10 percent to 100 percent of its generating capacity in as little as 30 minutes. This is compared with current coal plants that take several hours to perform the same activity.

Together, all of the advantages are expected to improve efficiency such that it will make it about as cost-effective to build the new plant as it is to retrofit a coal plant with current technology to meet requirements set by the Environmental Protection Agency.

According to the news provider, the other technology is being developed by Net Power in partnership with many other major companies including Toshiba, power company Exelon and engineering firm Shaw. The innovation is touted to make coal plants significantly more efficient than they are at present - as much as 50 percent more so, compared with the 30 percent efficiency-improvement some current technologies are expected to deliver.

The most efficient plants today use a gas turbine together with a steam turbine that runs off the exhaust of the first turbine. The new technology puts the exhaust given off the the gas turbine to work by forcing it to direct part of the carbon dioxide in the exhaust stream back into the gas turbine, negating the need for a steam turbine.

Ahmed Ghoniem, who does mechanical engineering research at MIT, said the technologies indeed look "plausible on paper," however he will remain skeptical "until things get demonstrated." Ghoniem stated that the economics of the project are still uncertain as well, as it is "an open question" how much money the technology could actually save over current power plants.

The demonstrations, which are anticipated to be a major benchmark for the technology, are expected to begin in 2013.

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