Transforming Waste Heat to Power through Development of a CO2 - Based Power Cycle

Abstract

With global demand for energy expected to increase 60% by 2030, concerns about energy affordability, security, and greenhouse gas emissions have heightened interest in energy efficiency and grid demand reduction. In the U.S., legislators are striving to regulate GHG emissions through market-based mechanisms, efficiency programs, demand reduction, and economic incentives. Most of the world’s electrical power is generated by heat engines that convert heat from fuel combustion into mechanical energy which is then converted into electricity. The U.S. DOE estimates that 280,000 MW discharged annually in the U.S. as waste heat could be recycled to provide 20% of U.S. electricity needs while slashing GHG by 20% and saving USD $70-150B per year on energy costs. Various sources of independent data suggest that this waste heat recovery opportunity is valued at over USD $600B (1). Similar, large opportunities exist worldwide. In response to this opportunity, Echogen Power Systems (Akron, OH U.S.A.) is developing power generation technologies that transform heat from waste and renewable energy sources into electricity and process heat. The thermal engine technology is based on a waste heat to power cycle using a supercritical carbon dioxide working fluid in a closed loop. Supercritical carbon dioxide is environmentally benign, non-toxic, with favorable heat and mass transport properties that make it energy dense. Compared to organic and steam-based waste heat recovery systems, supercritical CO2 can achieve high efficiencies over a wide temperature range of heat sources with compact components resulting in a smaller system footprint. This paper presents an overview on the Echogen system technology and associated leading applications. Results are reported on field testing currently underway for an Echogen 250 kW thermal engine at American Electric Power’s Dolan Research Laboratory.