Landfills emit methane, a greenhouse gas (GHG) at least 21 times more potent than carbon dioxide over a 100-year time frame. In 1994, to reduce methane emissions, the USEPA launched an innovative voluntary partnership and assistance program named the Landfill Methane Outreach Program (LMOP). LMOP’s primary goal continues to this day: encouraging the recovery and beneficial use of landfill gas (LFG) to mitigate landfill methane emissions while also capturing the energy potential of this renewable resource. Because LFG is composed of about 50% methane, it has approximately half the energy value of natural gas-and those 500 British thermal units per standard cubic foot (Btu/scf) are valuable.
After 19 years (Figure 1 shows a timeline of milestones), LMOP continues to deliver technical, informational, and outreach support to municipalities and counties, large corporations and small businesses, utilities and electric cooperatives, industry veterans and startups, universities and colleges, state and federal agencies, and many other organizations along the LFG energy spectrum. LMOP helps these groups throughout the project development process and offers a variety of services, including:
- Analysis of LFG as an energy resource (gas modeling)
- Preliminary economic feasibility assessments (LMOP’s LFGcost model)
- Identification of potential matches between landfills and end users (LMOP’s Locator tool)
- Detailed landfill data (LMOP’s national database of landfills and projects)
- Training workshops and annual conference
- Dissemination of pertinent information via timely listserv e-mails
- Ribbon-cutting posters and flyers
LMOP’s approach has focused on promoting the dual benefit of LFG energy: environmentally beneficial and economically sound. To serve a maturing LFG energy industry, the program has evolved to provide the level and types of assistance and information that are most needed to advance LFG energy projects. For example, over the years LMOP has proactively provided an increasing amount of information and tools via its website (epa.gov/lmop) to better assist and equip the industry. As LMOP begins its 20th year, the program reflects on the history of LFG energy projects in the United States and what the future may bring.
Since 1995, LMOP’s first full year in existence, the number of LFG energy projects in operation in this country has increased by 330%, from ~145 in 1995 to ~630 in November 2013 (USEPA LMOP, LMOP Landfill and LFG Energy Project Database, as of November 7, 2013). Collectively, the projects currently in operation provide enough energy to power or heat more than 1.9 million homes this year and reduce GHG emissions equivalent to the carbon sequestered annually by more than 90 million acres of US forests. The number of new projects built per year (Figure 2 shows 1981 through 2012) has fluctuated and some projects ceased operating for various reasons, but the overall growth of the industry attests to the significant successes that these projects have achieved: GHG emission reductions; cleaner air, an economic boost, and access to a local source of renewable energy for the community; and financial benefits (i.e., inherent value of fuel, particularly a renewable fuel) for the landfill owner and other involved parties.
Renewable energy in general garnered increasing attention through the 1990s and especially the 2000s, when many states passed legislation requiring utilities to meet certain renewable energy percentage requirements. Of the 41 states and US territories that have passed a renewable portfolio standard or goal to date, 73% did so between 2001 and 2009 (Database of State Incentives for Renewables and Efficiency [DSIRE]. http://www.dsireusa.org/. Accessed November 8, 2013). This push at the state level for new sources of renewable power contributed to many “matches” between landfill owners looking to offset the costs of controlling LFG and utilities seeking reliable green energy.
Rising natural gas prices during the same period, with a peak of $13.06 per thousand cubic feet in July 2008 (US Department of Energy Natural Gas Industrial Pricing. http://www.eia.gov/dnav/ng/hist/n3035us3m.htm), spurred the growth of what LMOP refers to as “direct use” projects in which LFG replaces fossil fuels in equipment such as a boiler or kiln, or is cleaned to pipeline quality (high-Btu gas) by removing carbon dioxide and contaminants. Only 25 direct-use projects existed in 1995, but the number grew to 125 projects in 2011, a 400% increase (US EPA LMOP, LMOP Landfill and LFG Energy Project Database, as of November 7, 2013). A wide variety of businesses as well as government agencies have found LFG to be a good fit, economically and logistically, for their energy needs [see a sampling at www.epa.gov/lmop/documents/pdfs/companies.pdf].
LMOP’s comprehensive database of LFG energy projects has revealed trends in the industry over time, such as high-Btu projects becoming more prevalent and an increase in the use of combined heat and power technologies. Recent data indicate three more positive developments.
Low LFG flow? There’s a technology for that: As many of the landfills with moderate to large LFG energy potential already have LFG energy recovery in place or planned for the future, opportunities for smaller amounts of LFG have become more apparent. Existing projects may have excess LFG available for energy use although not enough to warrant a major modification, while other pre-project landfills simply have an available LFG amount on the lower end of the project scale due to landfill size and other factors.
Figure 3: Two LFG-fueled, 100-kilowatt engines
generate power for the transfer and recycling
facility in Watauga County, North Carolina.
Several communities have found innovative direct uses for their small LFG flows, ranging from paint evaporation to infrared heaters to glass blowing. Most small electricity projects (<600 kW) have historically been limited to microturbines, although lately more options are cropping up (Ibid.).
From 2011 to mid-2013, eight engine projects have come online with an installed capacity of 500 kW or less. Four of these projects (one shown in Figure 1) are located in rural North Carolina; in all, they combust LFG in a total of six modified truck engines to generate a combined 500 kW. The other four projects generate between 225 and 450 kW each, using differing engine types (Ibid.). As interest has grown in generating electricity from smaller amounts of biogas, the equipment manufacturing industry responded. Several LMOP Industry Partners (www.epa.gov/lmop/partners/industry.html) supply LFG electricity-generating equipment with lower size ranges of 20 kW, 30 kW, 45 kW, 150 kW, or 180 kW.
Let’s go! Vehicle fuel from LFG-The first full-scale US project to convert LFG into vehicle fuel, specifically compressed natural gas (CNG), began in 1993 at the Puente Hills Landfill in California and lasted 14 years. Los Angeles County vehicles, including rideshare vans and water trucks, benefited from the on-site fuel supply created from 250 cubic feet per minute (cfm) of LFG (Sanitation Districts of Los Angeles County. Converting Landfill Gas to Vehicle Fuel: The Results of Over 30 Months of Operation. March 1996. http://goo.gl/tt0WwR).
Due to recent increased production and low prices of natural gas, waste management companies and communities throughout the country are converting their vehicle fleets to run on CNG, and often are providing at least a portion of the fuel from their own LFG supplies. Five LFG-to-CNG projects (in California, Georgia, Louisiana, Michigan, and Wisconsin) were developed between 2009 and 2013, using as little as 20 cfm of LFG to generate 100 gallons of gasoline equivalent per day of CNG (US EPA LMOP, LMOP Landfill and LFG Energy Project Database, as of November 7, 2013).
Natural-gas-powered vehicles in the United States now number 112,000 (US Department of Energy, Energy Efficiency and Renewable Energy, Alternative Fuels Data Center. www.afdc.energy.gov/vehicles/natural_gas.html. Accessed November 13, 2013.), and natural gas is predicted to be the fastest growing fuel in the transportation sector, particularly for heavy-duty vehicles, through 2040 (US Energy Information Administration. Annual Energy Outlook 2013. DOE/EIA-0383, 2013. April 2013. http://www.eia.gov/forecasts/aeo/pdf/0383(2013).pdf). With the federal Renewable Fuel Standard requiring 36 billion gallons of renewable fuels to be blended into the transportation fuel supply by 2022, many more landfills are expected to explore their potential to create renewable natural gas to fuel vehicles (USEPA Office of Transportation and Air Quality [OTAQ]. Renewable Fuel Standard http://www.epa.gov/otaq/fuels/renewablefuels/. Accessed November 13, 2013).
Do-it-yourself projects-LMOP’s database tracks whether projects are developed by a third party or self-developed by the landfill owner or end user of the LFG or electricity. Both options have their advantages, and no one cookie-cutter approach is best for every project situation. LMOP’s Project Development Handbook (http://www.epa.gov/lmop/documents/pdfs/pdh_chapter6.pdf) details factors to consider when structuring a project team.
LMOP’s data indicate that, prior to 2000, 18% of projects were self-developed, whereas 33% of the projects that started up between 2000 and 2012 were self-developed (US EPA LMOP, LMOP Landfill and LFG Energy Project Database, as of November 7, 2013). This shows a trend that self-development has ticked upward in popularity in recent years. Two of LMOP’s 2012 award winners (http://www.epa.gov/lmop/partners/award/2012.html) were do-it-yourself projects: a small electricity project in North Carolina (Figure 3) and a small vehicle fuel project in Louisiana (Figure 4). Both sites indicated that keeping costs down was a major factor in their decision to manage and own their project with help from contractors and consultants.
Figure 4: Fueling station for 250-gasoline gallon equivalent LFG-to-CNG project in St. Landry Parish, LA.