Researchers clear the air

MAJOR advances by researchers in the USA are helping to improve coal-fired power plant efficiency and reduce emissions, according to one of the researchers.

Emily Roberts

The Energy & Environmental Research Centre and the University of North Dakota have jointly developed a process that involves burning a combination of pure oxygen and coal to generate electricity.


Material used in a demonstration plant - the same alloy used to make F-16 fighter jet engines - is said to be a first for a coal-fired power system.


As part of a demonstration project, a high-temperature heat exchanger was tested in a natural gas and coal-fired system. Using indirect-firing combined cycle technology, the system heats air to a higher temperature in the heat exchanger and uses hot air to turn a turbine. The EERC said it had used the system's heat exchanger to produce air at 2000 degrees Fahrenheit.


"Results of previous demonstrations while firing with air prove that the efficiency of a power plant using this technology could improve by about 30%, resulting in cheaper, cleaner energy," EERC senior research manager John Hurley said.


"If a time comes when taxes are imposed on carbon dioxide emissions, it will be very important to remove the carbon dioxide from the gas stream and sequester it, and that will be much easier if the system is fired with oxygen rather than air."


The system could also be configured to use biomass, liquid and other fuels, EERC said.


Through the Xcel Energy Renewable Development Fund, the EERC has recently completed tests using 20% biomass. In addition to the Xcel funding, the majority of the work is funded through the US Department of Energy and managed through the DOE National Energy Technology Laboratory.