Riverview, Michigan

DTE Biomass Energy designed, constructed and operates Michigan's first landfill gas combustion turbine facility.

Project Background
Located in the community of Riverview, about 20 miles south of downtown Detroit, the Riverview Land Preserve has received municipal refuse since 1968.

Today, the land-filled waste materials occupy nearly 180 acres with about 120 acres dedicated to gas recovery. The landfill is expected to operate for another 25 years. Each day 5,000 cubic yards of waste is deposited. At the end of each day, six inches of soil and/or shredded wood are added to the top of the pile. This daily cover deters scavengers, reduces gas odor and prevents litter. This cover starts the process of creating gas. As the waste decomposes, without oxygen, bacteria produces methane gas, a useful form of energy.

The gas recovery project was constructed in 1987 for over $8 million. Constructed in less than five months, power sales to Detroit Edison began in January 1988. The gas collection system includes more than 115 vertical gas collection wells ranging from 50 to 100 feet deep, and four horizontal gas collection wells totaling more than 4,600 feet.

DTE Biomass Energy technicians are stationed onsite to monitor the gas collection system, the landfill gas-fired combustion turbines and provide day-to-day environmental services.

Performance
Today the gas collection system recovers more than 4.2 million cubic feet of gas per day. Two Solar T-4500 gas turbines operate 24 hours a day to use the landfill gas and generate electricity for sale to Detroit Edison customers. The 6.6 megawatt facility produces enough "clean" electricity to continuously power over 5,000 homes.

Environmental Impact
While the project's production of electricity is a small portion of Detroit Edison's power needs, the environmental significance of this operation is impressive. By capturing over 4 million cubic feet per day of landfill gas, the Riverview landfill gas recovery system has reduced over 1,200 tons of sulfur dioxide emissions which would have been produced by fossil-fueled power generation. Each day the project converts methane into a viable energy source. Over 20 billion cubic feet of gas has been beneficially recovered since 1988.

The landfill was constructed on top of a naturally occurring 10-foot thick clay liner. Recently constructed cells incorporate a synthetic liner and a 2-foot thick sand drainage layer. Berms, trees and other natural landscaping help minimize the noise from the site, which is closely surrounded by residential development. An additional 14 acres of wetland has been reserved as natural habitat for waterfowl, deer, and other native creatures. Local residents now golf on the landfill unaware of the gas collection and energy project adjacent to the golf course.

Community Enrichment
Annual revenues to the city of Riverview from the operation of the landfill and gas collection system are substantial. This income ensures that Riverview has one of the best Public Works Departments in the Metro-Detroit area, and one of the lowest tax bases. Fire, police, waste collection, and other public programs are supported by the landfill revenue.

In addition to funding, the landfill provides recreational activities to the local residents. From 1979 to 1996, the Riverview Land Preserve played host to one of the first winter sports hills built on layers of solid waste. The site has two driving ranges and three executive-type golf holes adjacent to the existing 27-hole municipal golf course.

Orlando, Florida

Project Background
The Orange County Solid Waste Facility is situated on a 1,500-acre site in Orange County, Florida, southeast of downtown Orlando. Opened in 1971, this integrated modern solid waste facility has received over 9 million tons of municipal solid waste from residents and commercial facilities in Orange County.

The landfill gas utilization project is owned and operated by Orlando Gas Producers (OGP), Inc., a subsidiary of DTE Biomass Energy, Inc. Designed to extract up to 7.9 million cubic feet per day (MmCFD), landfill gas is processed and piped directly to the Orlando Utilities Commission Stanton Energy Center where it is co-fired with coal to create steam and produce electricity. The gas generates about 17 megawatts of the plants 900 megawatt capacity, displacing about 2.5 percent of the total annual coal purchases of the energy center. The project began operations on April 1, 1998.

Landfill Gas Recovery System
OGP obtained the gas rights in December 1996 through a competitive proposal process initiated by Orange County Utilities Division and their consultant CH2M/G&R, an environmental engineering firm. In exchange for a lump sum payment, the county and OGP signed a construction contract for the design and installation of a gas collection system. This arrangement qualified the project for federal tax credits available to the landfill gas industry.

The gas collection system includes 148 vertical gas collection wells averaging 65 feet deep, three horizontal gas collection wells totaling 3,600 feet, and four centrifugal blowers.

Challenges
The facility design responded to numerous unique project challenges including:

• The retrofit of existing vent wells in Cells A-K, a 100-acre section of the landfill;
• Condensate handling in Cells A-K and the gas transmission main;
• A combined blower/flare station designed to deliver the gas to OUC, while providing backup flaring to maintain compliance with NSPS requirements;
• Installation of the gas collection system after the placement of the geomembrane cover system; and
• Injection of medium grade landfill gas through the use of center fired gas burners installed into existing pulverized coal injection ports.

Conclusion
Every landfill gas recovery and utilization project has unique characteristics which create numerous challenges requiring resolution. The Orange County Landfill Gas recovery project was no exception. The effective removal, pumping, and disposal of condensate from system components, from wells to collection piping to the blower station and delivery pipeline continues to be the challenge to maximizing production.

DTE Biomass Energy has embraced the challenges of this project and continues its successful partnership with the Orange County Utilities Division and the Orlando Utilities Commission.

Explore the full potential of your locally available energy resources by enlisting the support of DTE Biomass Energy. Call 800.216.3338 x32080 today, to discuss how we can help you answer your energy needs, generate additional revenue and play your part in preserving today's environment for future generations.