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NREL Ignites New Renewable Fuels Heating Plant

November 20, 2008

Golden, Colo. - With the spark from a high intensity road flare, engineers at the U.S. Department of Energy's National Renewable Energy Laboratory lit its new, smoke-free Renewable Fuels Heating Plant today.

The $3.3 million project is the Laboratory's latest step toward operating as a net-zero energy facility.

The RFHP will heat NREL’s South Table Mountain Campus laboratory buildings by burning woody biomass, including wood chips from trees lost to the region's mountain pine beetle epidemic and waste wood.

Operating smoke-free and odor-free, the plant will offset about 4.8 million pounds of carbon dioxide each year and as much as 75 percent of the 50,000 million Btus of natural gas used annually to heat the STM campus.

"This project has been carefully scrutinized to deliver environmental and economic benefits," said RFHP project manager Chris Gaul. "It has met all of the challenges. Wood chips are NREL's best resource for large scale, on-site renewable energy."

The new heat plant is financed under an innovative Energy Savings Performance Contract with Ameresco Federal Solutions Inc., an energy services company, in compliance with U.S. Department of Energy's Transformational Energy Action Management (TEAM) Initiative.

An ESPC is an alternative financing tool that allows federal operations to accomplish energy-related improvements without making capital investments from Congressional appropriations.

Under the terms of the heat plant's ESPC, Ameresco will bear the project's costs and purchases, provide the fuel and guarantee the plant's operation. NREL will repay the company from annual cost savings of wood over natural gas — projected in the first year to be more than $400,000. Ameresco also will perform verification analyses to ensure the plant is achieving the guaranteed energy savings.

The wood chips for the boiler cost $29 per ton or $2.42 per million BTUs — about one-quarter of the cost of natural gas.

The ESPC is one alternative financing mechanism that facilities can use to meet the DOE goal to reduce energy use by 30 percent across the Department's nationwide operations by 2015.

The DOE's TEAM initiative seeks to  dramatically transform DOE's energy, environmental and transportation management by a variety of measures, including acquiring up to 7.5 percent of all energy from renewable sources and attaining at least a  Leadership in Energy and Environmental Design (LEED) Gold standard certification on all new buildings.

DOE designed the TEAM Initiative to be a replicable model to be used by other Federal agencies. On Oct. 22, Gaul represented NREL in Washington, D.C. in receiving a DOE Federal Energy Management Program TEAM award for the RFHP project.

The new heat plant is behind the Field Test Laboratory Building (FTLB.) New underground hot water piping connects it to the Science & Technology Facility (ST&F), the Solar Energy Research Facility (SERF), the FTLB and other campus buildings.

Lighting the heat plant follows a deliberate process.

The wood chips are screened to remove rocks and debris, and then automatically fed into the furnace's combustion chamber using a mechanical auger. Technicians lit a large flare attached to a long steel bar like a giant match. Then they pushed the burning flare into the chamber to light the fuel.

Once the chips ignite, the fire is managed so it grows evenly and progressively.  The boiler must be warmed slowly to prevent its ceramic refractory from cracking.  It could take eight hours to reach full operating temperature.

 The wood chips are roasted to the point where they are gasified. The wood gases then are mixed with air for complete combustion in the heat recovery boiler. Temperatures in the two-stage process reach 1700° F (930°C), and leave very little ash or soot.

The system uses a multiclone separator to remove 85 percent of the remaining particulates from the boiler flue gas. Inside each of the separator's multiple chambers, dual cyclones are generated to capture and spin dust particles from the gas. The particles are hurled against the walls of the chambers and fall into a hopper.

The RFHP's ultra-efficient combustion process allows the facility to meet state requirements while burning biomass to reduce the lab's carbon footprint. The RFHP has a state air emissions permit.

During cold weather, the plant is expected to burn a truckload of wood chips per day and produce 600 gallons of hot water per minute. Gaul projects it will burn 3,600 tons of wood chips in a year.

The plant's fuel reservoir will hold four days of wood chip fuel. The fuel supplier, A-1 Organics, is just two miles away and operates a 1,000-horsepower wood chipper that can grind a three-month fuel supply in a single day. Existing natural gas boilers have been retained to provide replacement heat in case the RFHP encounters fuel supply or operational problems.

The RFHP is one of several renewable energy projects under construction and development at NREL. Combined, they are part of the Sustainable NREL initiative to replace the laboratory’s use of fossil energy with renewable energy and reduce greenhouse gas emissions.

NREL is the U.S. Department of Energy's primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for DOE by The Alliance for Sustainable Energy, LLC.

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