Lehigh’s Energy Research Center (ERC) has developed a variety of technologies that improve the operating efficiency of power plants while reducing emissions of toxic substances and greenhouse gases.
Recently, the ERC received a DOE grant to develop methods of recovering and reusing heat generated by the carbon-dioxide (CO2) compression process in a carbon capture and sequestration (CCS) system.
A CCS system makes it possible to generate electric power from coal without emitting significant amounts of CO2 to the atmosphere. The system separates CO2 from power-plant flue gas and compresses the CO2 to high pressure. The compressed CO2 can be transported by pipeline and is now used to help extract oil from underground reservoirs in a process known as enhanced oil recovery. Scientists are also evaluating the feasibility of injecting compressed CO2 below the earth’s surface into saline aquifers whose geological features would sequester, or store, the CO2.
The goal of the current project, says ERC director Edward Levy, is to recover heat that is generated when CO2 is compressed and to use that heat to improve the efficiency of the power plant’s operation. The ERC is developing computational models of the methods used to capture and compress CO2 and estimating the increases in efficiency that will result from each.
“It requires a tremendous amount of pressure, about 2,200 pounds per square inch or close to 150 atmospheres, to compress CO2 to a supercritical state,” says Levy. “In the compression process, CO2 heats up, creating the potential for heat to be recovered and used beneficially within the power plant.
“All carbon capture schemes reduce power plant efficiency and increase the cost of generating electricity. We’re trying to mitigate this. We’re looking at different types of compressors to see how much heat can be recovered and what we can do with this heat to improve power plant efficiency.”
The ERC has conducted other research projects that promoted the reduction of carbon emissions. One involved the recovery of water from flue gas and another removed water from high-moisture coals. Both resulted in improvements in power plant efficiency and reduction in the rates of CO2 formation.
The project is funded through DOE’s National Energy Technology Laboratory.