KGRA Energy LP, a U.S.-based waste heat recovery developer, has signed a contract with Weyerhaeuser Co. KGRA's subsidiary Ayden HTP Partners LLC will design and construct the 800 kW waste heat recovery system at Weyerhaeuser's Greenville, N.C., lumber mill.

The system, which is scheduled to come online in the summer of 2011, will recover waste heat from Weyerhaeuser's biomass-based thermal drying system to generate 4.5 million kWh of CO2-free electricity per year. KGRA's system will displace the equivalent of more than 9 million pounds of carbon dioxide each year.

The system from Lake Forest, Ill.-based KGRA Energy uses the organic Rankine cycle to recover waste heat from viable sources such as furnaces, boilers, kilns and combustion engine exhausts, converting it into usable CO2-free electricity. At the Weyerhaeuser lumber mill, heat will be recovered from a kiln where cut lumber enters the drying process.

KGRA's systems are modular and scalable, providing the ability to produce power from smaller and lower temperature heat sources previously deemed unsuitable for standard cogeneration.