- Landfill Gas to Energy with Waste Heat Recovery (CHP)
Burns & McDonnell provided permitting, architectural, engineering, procurement and construction services to Gundersen Lutheran in La Crosse County, Wis., for the design and construction of a 1.137-megawatt landfill gas-fired power plant. The system captures waste heat generated from a Jenbacher JMC416 engine to provide building and domestic hot water heating for two four-story buildings at the client's Onalaska campus. The power generated is sold to utility Xcel Energy.
Various members of the GE Jenbacher family of gensets with the potential to fit the electrical and thermal needs of the project were considered. Candidates for selection included the JGC320 (1,059 kW), the JGC416 (1.137 kW) and a pair of JGC312 units (1,266 kW total). Based on Burns & McDonnell's pro forma analysis, the JGC416 genset emerged as the best choice.
Unless otherwise recovered, the JMC 416 engine wastes the heat rejected into the atmosphere by its cooling water circuit via the engine's high-temperature exhaust. The addition of a decoupling heat exchanger inserted in the cooling water circuit provides a means of rejecting that waste heat to an external water circuit, where the heat is put to beneficial use. Additionally, the waste heat from the engine exhaust is recovered from the genset to double the thermal recovery by recovering heat from the engine exhaust gas via a heat recovery unit. The recovery of waste heat from the JMC 416 engine significantly enhances the overall project payback.