May 23, 2007 | General

Fueling Up On Landfill Gas

BioCycle May 2007, Vol. 48, No. 5, p. 55
Solid Waste Authority of Central Ohio launches into a multiphase public/private partnership to convert landfill gas into biofuels and other high-value end products.
Nora Goldstein

THE Solid Waste Authority of Central Ohio (SWACO) operates a 142-acre municipal solid waste landfill to service the Columbus, Ohio metro region. The Franklin County landfill, which opened in 1985 and receives about 3,500 tons/day of MSW, has another 221 acres of expansion capacity. Because of the size of its landfill, SWACO was required to install a landfill gas collection system and a flare, the Maximum Achievable Control Technology (MACT) as required by the U.S. Environmental Protection Agency. While the flare addressed the MACT requirement, it created an air quality concern.
“Like so many things we do, solving one environmental problem creates others,” says Michael Long, SWACO’s Executive Director. “When we burn the flare, we release carbon monoxide (CO) and NOX into the atmosphere, and there is no energy recovery. Upon analyzing the situation, we recognized that we were dealing with a couple of valuable resources – methane and carbon dioxide – and decided to explore options that would enable us to utilize those resources, send a minimum amount of BTUs to the flare to destroy the NMOC (nonmethane organic compounds), and minimize the production of NOX and CO.”
A traditional landfill gas to energy recovery system was a challenge because of access to the electric grid. “Just because the technology exists to produce electricity doesn’t mean the landfill will always have easy access to the end user,” adds Long. “We are in the service area of the electric utility, and we can’t run a parallel wire to them to distribute power. There also were tariffs, and the issue of how much the utility would pay for the electricity.”
That reality led SWACO to look around for other end uses for the landfill gas. Underlying the search was the mindset that the solution(s) had to offer flexibility in the end products generated to take advantage of market and regulatory fluctuations. “We didn’t want to make a major commitment of capital to one technology that may be viewed now as a winner,” he explains. “During the energy crisis of the 1970s, the City of Columbus built a waste-to-energy power plant. Every prediction was wrong at that time, from interest rates and electricity prices to construction costs and running out of landfill space. Everything that pointed toward that project being feasible was not correct. So when we are talking about significant capital investments today, we need to be smarter about our approach, especially with landfill gas. We were looking for a project that generated a variety of products, where we can shift from one end product to another, depending on the end markets.”
SWACO learned about the landfill gas recovery initiatives at the Burlington County, New Jersey Resource Recovery Complex. The Resource Recovery Complex includes an active bioreactor landfill (and a closed landfill), a biosolids composting operation, a greenhouse heated and powered with landfill gas, and a wood recycling operation. Also colocated at the site is the Rutgers University EcoComplex, a business incubator for environmentally-based companies. (See “Landfill Gives Birth To Ecoindustrial Complex,” December 2004 (Part I), and March 2005 (Part II)). One tenant of the incubator was Acrion Technologies, Inc. (based in Cleveland, Ohio), which developed a carbon dioxide wash system to clean up landfill gas for multiple uses, including food grade liquid CO2, and methane that can be converted to vehicle fuel as liquid (LNG) or compressed natural gas (CNG), methanol or pipeline quality natural gas.
“We toured the EcoComplex in 2003, and met with Acrion, and what we saw was an opportunity to have multiple markets for our landfill gas,” explains Long. “We also saw the advantage of working with a private partner who has the ability to change that mix of end products according to market demand and new opportunities. As a local government agency, we do not have the expertise or the resources to do all of these things. We created a private sector partnership with Acrion and FirmGreen Energy (FirmGreen™), a California company that is a licensee of the patented Acrion CO2 Wash® technology. Together, the public-private partnership has a mission to utilize more than 750 billion BTUs of thermal energy from our landfill in an environmentally responsible way.”
Acrion’s CO2 Wash technology removes hydrogen sulfides, VOCs and siloxanes out of the raw landfill gas. Carbon dioxide, recovered from the landfill gas and converted to liquid form, is used to wash out the impurities. CO2 Wash product, a contaminant-free mix of roughly 70 percent methane and 30 percent CO2, can be used directly as fuel to generate electricity or as feedstock for synthetic chemicals such as methanol. Further separation of CO2 produces methane suitable for pipeline injection or vehicle fuel. A second product, ultra pure CO2 , has many uses including food freezing, chemical reagent, inerting gas, greenhouse plant nutrient, and dry ice manufacture.
SWACO’s first stop on its renewable energy journey is the Green Energy Center, located next to the Franklin County landfill. A groundbreaking ceremony for the Green Energy Center, which is being developed in three phases, took place in June 2005. Components of the Center include: CO2 Wash®; Carbon Dioxide Sequestration; Electrical Generation (via microturbine); Methanol Synthesis (reforming methane to synthesis gas for conversion to methanol, which then can be used to produce biodiesel): CNG and Biodiesel for Vehicle Fuel; Optional Gas to Pipeline; Optional IC (internal combustion) Engine Electrical Generation; Greenhouse Operation using the CO2; and Hydrogen Fuel Research and Development.
Phase I, which is now under construction, is expected to be operational by this fall. SWACO will own and operate Phase I. “It involves taking a small amount of the landfill gas and running it through a 300 cfm CO2 wash,” says Long. “Some of the methane will be compressed into CNG and used to power our fleet of vehicles. The remainder of the natural gas will be run into a 250 kW Ingersoll Rand microturbine with waste heat recovery. We will use the outputs of the microturbine at our administration and maintenance buildings. We believe that we will save about 10 percent on our electric bill, 15 percent on our propane use, and produce the CNG necessary to eventually operate our truck fleet and potentially sell excess CNG to local governments. The current 300 cfm design is capable of producing up to 650 gallons of diesel equivalent energy content CNG per day. Our goal with Phase I is to demonstrate that the technology works and we are going to get some immediate benefit.”
Long adds that SWACO identified a company in Atlanta that can retrofit its fleet of trucks to run on CNG. Four tanks each hold the equivalent of 40 gallons of diesel. The tanks get placed behind the truck cab. Last year, SWACO took delivery of a 2005 Ford Sterling truck with a 12.7-Detroit series 60 diesel engine that was retrofitted to be a dual-fuel system powered by CNG and biodiesel. The current price of CNG is about $2/diesel gallon equivalent; SWACO expects its net costs will be about $1/diesel gallon equivalent. Between the buildings and the vehicles, he anticipates a direct savings in energy and fuel costs of over $150,000/year from this Phase I project.
Phase II, to be developed and owned by FirmGreen, will involve installation of two CO2 Wash units for a total of 2,500 cfm of landfill gas processing capacity. The methane will be reformed into methanol; production capacity is up to 20 million gallons/year. A portion of the methanol has been presold to Mitsubishi Gas Chemical America, Inc. The remainder of the methanol will be converted into biodiesel. FirmGreen has a contract with a soybean farmers cooperative located south of Columbus. The co-op will crush the beans and bring the soybean oil to the landfill for reacting with the methanol to create biodiesel. The 100 percent biodiesel will be blended to produce an estimated 100 million gallons/year of B-20 fuel, according to FirmGreen. Construction of Phase II is scheduled for fall of 2007, with completion in the last quarter of 2008.
Phase III of the project involves installing IC engines (6.5 MW) and a greenhouse at the landfill to utilize pure CO2 from the wash process. “At the Rutgers EcoComplex greenhouse, we saw that injecting CO2 into the greenhouse causes a significant increase in productivity of the crop, in this case tomatoes,” says Long. “Another possible end product is dry ice, which is being used increasingly as a refrigerant in the trucking industry to reduce fuel use and the load on the truck.” In Phase III, FirmGreen will also increase electricity production from the landfill gas for sale to the grid.
Permitting for Phase I has gone relatively smoothly, in part because the units being installed are small and are exempt from air quality regulations. Building and construction permits are in hand. Phase II permitting is more complicated due to the methanol plant, and Phase III will be equally complex because of the electricity generation and grid connections. The air permits for Phases I and II have been approved.
An anticipated overall benefit in terms of air quality is the reduction of hazardous air pollutants. The landfill is limited to 250 tons/year of carbon monoxide emissions. “We were pushing that limit last year, even with installation of an enclosed flare in 2005,” says Rick Dodge, SWACO’s Director of Environmental Compliance. “But with the installation of the CO2 Wash system, we expect to reduce carbon monoxide emissions to the point where we will never exceed that limit.” Long adds that SWACO, as the enforcement agency, will be overseeing air emissions compliance, so will know immediately if the wash system is effective at reducing CO in the flare.
With its $18 million Green Energy Center on its way to becoming a reality, SWACO has its sights on other environmentally sustainable initiatives. The former waste-to-energy plant site built by the City of Columbus is being transformed into an ecoindustrial complex. One of the first tenants will be Rastra Technologies Inc., a building products company that plans to locate a factory to manufacture building panels out of ground polystyrene and cement. The panels are used for home and commercial construction. Over 80 percent of the Rastra panels are made from recycled product. SWACO’s Franklin County Landfill receives at least five tractor-trailer loads of polystyrene daily, which adds up to almost 87,000 cubic yards annually or 6 percent of the total yearly capacity at the landfill, according to SWACO.
Also on the site will be an expansion of The Grossman Group’s paper recycling operation, currently located in the last remaining trash plant building. This expansion will add another 28,000 square feet to the 14,000 square feet already in use. Grossman Group’s recycling operation diverts over 50 tons/day of paper from the landfill.
Energy to power the new businesses will also come from “green” sources. Kurtz Brothers plans to build an anaerobic digester on SWACO property next to the site. The digester will take organic materials, including biosolids, food residuals and yard waste, and turn the mix into energy.
“Everyone benefits from this initiative,” says Long. “When we consider all possibilities, we can better our environment, help our economy, and provide new energy.”

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