Gundersen Lutheran, the third largest healthcare organization in Wisconsin, has set a goal through its Project Envision to meet 100 percent of its energy needs by 2014. Its focus is on energy efficiency and renewable energy efforts. Burns & McDonnell is helping the organization achieve this goal by designing and building a landfill gas-fueled combined heat and power (CHP) facility at its Onalaska campus in LaCrosse County, Wis.
Burns & McDonnell is providing design-build, air permitting, startup and commissioning services for the project, which features a GE Jenbacher JGC416 genset, complete with accessories for engine waste heat recovery.
- Air permitting
The centerpiece of this project is a 1,137-kW containerized reciprocating engine-generator set (genset). It is fueled by landfill gas generated and collected at the county's landfill almost 2 miles away. The gas is transported via an underground pipeline to the Onalaska campus.
Electricity is generated at 480V, then stepped-up to 13.8-kV for direct interconnection to the Xcel Energy (local utility) grid. A decoupling heat exchanger in the engine hot water circuit captures the intercooler, lube oil and jacket water heat wasted by the engine, transferring 2 million Btu/hour of heat into Gundersen Lutheran's glycol-water heat recovery loop.
Likewise, an exhaust heat recovery unit collects heat wasted in the engine exhaust, transferring an additional 2 million Btu/hour of heat into the same heat recovery loop. Pumps circulate the almost 200-degree hot water through 2,600 feet of underground piping into the mechanical rooms of the five-story main clinic and a three-story support services building.
There, additional heat exchangers transfer this heat into the existing building heating and domestic hot water heating systems. The heat transferred is sufficient to idle the existing natural gas-fueled boilers and hot water heaters on all but the very coldest winter days. A small utility building is also provided adjacent to the genset to house the hot water circulation pumps and controls, storage tanks for fresh and used engine lube oil, glycol storage in drums and small tools and spare parts storage.