While the sun's energy fills solar cells, and nature's breath spins wind turbines, such natural resources can't fuel generation of alternative energy as consistently as another abundant but much less palatable component of everyday life.
That would be trash — buried, decaying, we-don't-ever-want-to-see-that-stuff-again trash.
"It's a good form of renewable electricity, in that it's baseload electricity," says Scott Martin, an engineer at Burns & McDonnell who works on projects that convert landfill gas to energy. "Landfill gas flow is consistent: It's being generated in the morning, in the afternoon, in the evening. It's being generated when you're sleeping. The sun doesn't have to shine for you to be generating electricity. The wind doesn't have to blow.
"It's reliable, renewable energy that works."
These days, landfill gas — that's the methane produced when organic matter in landfills decomposes — is feeding a market need, as a variety of projects strive to meet renewable energy demands from governments, utilities and their customers.
The feedstock certainly is out there. Methane rises from some 2,400 landfills that handle municipal solid waste throughout the United States, with varied sets of rules and regulations governing how and how much of the gas is to be collected. Some sites simply allow the gas to escape naturally. Others gather the methane through collection piping and convey the gas to flare stations, where it is burned off. Methane is considered a greenhouse gas, one that traps heat at a rate at least 21 times that of carbon dioxide, another landfill byproduct.
That's why a growing number of landfills are serving as opportunistic power plants, or at least as fuel-producing fields. Municipalities, utilities and manufacturers increasingly regard the pervasive gas as a valuable raw material, capable of addressing energy needs through its conversion into electricity and its use as thermal heat.
Nearly 600 landfill gas-to-energy projects are operational across the country, according to the Environmental Protection Agency. At least another 550 landfills are candidates for having their methane recovered and harvested for utilization, which would be expected to provide enough power for another 716,000 homes.
Professionals at Burns & McDonnell are experienced in assessing, designing, permitting, equipping and building landfill gas-to-energy systems, a broad market whose clients include municipalities, manufacturers, utilities and others working to balance operational efficiencies, environmental needs and economic returns.
A Healthy Partnership
Case in point: the Gundersen Health System and La Crosse, Wis., where a landfill turns its gas into revenue while the health system builds on its model of generating clean, renewable energy. The synergy creates cost savings and increased environmental awareness for the effort's partners, customers and constituents.
"This partnership and this project alone is really, I think, the poster child for how to do things right," says Cathy Stepp, secretary of the Wisconsin Department of Natural Resources. "I mean, this is really what people care about - what we are doing to sustain, going forward, for our children and grandchildren. This is a great example of that."
When it came online early last year, the project began converting its landfill's source stream — about 300 cubic feet of methane per minute — into enough electricity and thermal heat to meet the full energy needs of Gundersen's Onalaska Campus, including:
- A six-story clinic for physicians' offices, patient visits, outpatient surgeries and related services.
- A four-story office building for staffers in support services — human resources, accounting, maintenance and others.
Together the buildings encompass 350,000 square feet of space, and every inch is heated, illuminated and otherwise empowered by electricity and heat drawn from a Jenbacher JMC 416 reciprocating engine running on landfill gas.
Rather than continuing to light off its unwanted methane on site using a flare station — akin to a giant Bic lighter that never goes out — the La Crosse County Landfill now collects, cools and transports the gas 1.5 miles under and across Interstate 90, so that it can be piped into the heavy-duty engine for power generation. Heat generated by the engine also is used to heat water, which then circulates throughout the health campus.
"The flaring gas was just wasted," says Jeff Rich, executive director for Envision®, Gundersen's program and portfolio of renewable energy products and energy service offerings. "Now the campus produces more energy than the entire campus uses."
Burns & McDonnell provided the health system with turnkey front-end planning, engineering and construction services on the project, which was honored as a 2012 Project of the Year by the EPA's Landfill Methane Outreach Program. The award recognizes projects that contribute to job creation, provide energy savings and generate green power.
Medical campuses offer plenty of opportunity for the growth of such green-energy systems. The nation's 8,000 hospitals are among the most energy-intensive commercial buildings around, using more than 2.5 times the energy — and, therefore, producing 2.5 times the emissions — of typical commercial office buildings, according to the Department of Energy. And with U.S. hospitals already spending more than $5 billion each year on energy, it's no wonder budgeting officials are looking for relief from the rising financial pain.
Gundersen Health System's environmental program, Envision®, already is seeing improvement as Gundersen pursues an overall goal to be completely energy independent by 2014, a standard that calls for producing about 220 million cubic feet of natural gas and 45 million kilowatt-hours of electricity per year.
The landfill gas-to-energy project in La Crosse already has made the Onalaska Campus energy independent and has accounted for 11 percent of the needs for the entire system, which has more than 50 clinics and is affiliated with three hospitals and four nursing homes serving patients and clients in Iowa, Minnesota and Wisconsin.
"Projects like this one are improving the environment in the communities we serve, helping to lower the cost of healthcare by reducing our energy costs, and are good for our community's future," Rich says.
Such client commitment is critical for such projects to succeed, says Martin, who manages Burns & McDonnell's work for Gundersen Health System. Also key: favorable market conditions, including utility and regulatory support from local, state and federal governments.
The project is expected to pay for itself within eight years.
"This has proven to be an outstanding partnership," says Hank Koch, solid waste director for La Crosse County. "We're proud that we can show other communities across the country just what a public-private partnership can achieve."
Another, larger project also is meeting the needs of a collection of partners, this time more than 400 miles to the southwest in St. Joseph, Mo.
KCP&L completed the system — one of the first utility-grade generating projects of its type and size in the Midwest — in 2011. It generates 1.6 megawatts of electricity using methane drawn from the St. Joseph Sanitary Landfill. Burns & McDonnell provided engineering, permitting, design and construction services.
The project added 47 new collection wells to an existing network of 17. The perforated polyvinyl chloride (PVC) wells are connected to a network of high-density polyethylene (HDPE) piping, together working in concert to pull landfill methane from more than 70 acres of landfill.
"Today, the plant actually generates enough electricity to power nearly 1,000 homes annually," says Laurie Gates, manager of category management for KCP&L. "This project has taken what normally is an undesirable byproduct and turned it into a very real asset."
The gas fuels a Caterpillar 3520C engine generator, in turn providing a consistent power load to KCP&L's power grid. The project reduces greenhouse gas emissions by at least 50,000 metric tons of carbon dioxide per year, says Keith Connor, Environmental Engineering Department manager at Burns & McDonnell.
"Using landfill gas for energy is a proven renewable energy technology that Burns & McDonnell brings to our solid waste and utility clients," says Connor, who served as project manager in St. Joseph.
The city of St. Joseph finds a beneficial reuse for an inescapable waste stream. The utility generates green energy. The overall community welcomes cleaner air and reduced expenses for a basic municipal service.
"Greenhouse gases are a worldwide concern," says J. Bruce Woody, city manager of St. Joseph. "This project provides the dual benefit of collecting and destroying methane gas and producing revenue to keep the gate fees at the St. Joseph landfill the lowest in the state."
Martin, who served as lead project engineer on the St. Joseph project, cautions that converting landfill gas to energy isn't for everyone. Some landfills simply are too small to yield cost-efficient projects. Others can't keep costs down enough to compete with other forms of renewable electricity. In some instances, government and utility incentives for alternative energy aren't sufficient to draw landfill owners, utilities or others into considering landfill gas a viable option.
But conditions change. Technologies evolve. Public sentiment builds.
Some of the most market-sensitive businesses on the planet already use landfill gas to fuel manufacturing operations, including BMW, Ford Motor Co. and General Motors. Interest is accelerating, always with eyes down the road.
"A lot of unique factors go into this, into being able to put a project together," Martin says. "But there are a lot of facilities, a lot of manufacturers, that are starting to look at co-locating next to landfills because of this untapped resource. It's a real opportunity."
For more information, contact J. David Langford, 816-822-3175.
Rubbish to Resource: Landfill Gas to Energy
Methane gas is an inevitable byproduct of natural decay, during which both methane and carbon dioxide are generated from organic materials "cooking" below the landfill surface. "It's an anaerobic process, or decomposition without oxygen," says Scott Martin, of Burns & McDonnell.
Perforated PVC well piping is placed in bore holes — some reaching 120 feet deep — to collect gas before it can escape. Wells are connected to a piping network near the surface, in which the gas moves thanks to a blower that creates a mild vacuum.
Gas cools as it moves through the pipes, often leaving condensation behind. That's why closed systems include collection sites at low points for the condensate, or water, to be cleared using sump pumps.
Methane gas is delivered, as fuel, to a reciprocating engine, which in turn generates electricity. An engine's exhaust — at 900 degrees — also can be captured and used to heat water for distribution.