Yards underneath a patch of land at Fort Benning, Ga., a layer of festering garbage from an old dump was producing methane gas.
The noxious — and potentially flammable — fumes were migrating underground to nearby facilities, so technicians installed vents, added propane to the mix, and burned the gas off. The energy dissipated and the process released greenhouse gasses into the atmosphere. Fort officials also had to pay for the propane.
Today, a small power station has been attached to the vents and is producing enough electricity to power about 250 homes.
The Defense Department has set lofty goals for its facilities when it comes to renewable energies. It wants to produce 3 gigawatts of renewable energy by 2025, with each service branch kicking in one more gigawatt. Each gigawatt can power about 250,000 homes.
Renewables are traditionally thought of as solar, wind and geothermal. The gas produced by microbes breaking down organic material buried in old garbage dumps is not in that category. It is a finite resource. But once the landfill is full and dirt is placed over it as a cap, it may produce methane for as long as a century, said Brad Hancock, director of federal programs at FlexEnergy, an Irvine, Calif.-based company that makes the power station.
“If you look at the lifespan of a landfill being about 100 years, we can produce electricity basically the entire 100 years,” Hancock said.
The amount of methane produced by a landfill placed on a chart looks like a perfect bell curve, he explained. For the first few years, very little gas is produced. Then it peaks for 20 to 30 years as it emits large amounts of high-quality gas. It then begins to tail off.
During the peak years, a regular turbine engine can be hooked up to the vents and electricity can be produced easily, although there will be so-called greenhouse gasses released, Hancock said.
The company’s FlexPowerstation can generate electricity in the beginning and end stages of the landfill’s lifespan, he said. “Our value is really on the wings out there in the years nobody else can do it,” he said.
The power station marries two technologies and was the brainchild of company founder, Edan Prabhu, who was familiar with catalytic oxidizers, which are commonly used to break down such things as the compounds in chemical weapons when they must be safely disposed. The process does not release any substances into the air.
Prabhu thought he could wed the oxidizer to a turbine engine that burns off combustible gasses. Hancock likens the idea to modern-day luggage. There were wheels and there were suitcases. But it was a long time before someone got the obvious idea to put wheels on the suitcases.
Prabhu developed the technology using Department of Energy grants then secured some venture capital in 2009. The turbine he chose was being manufactured by Ingersoll Rand Energy Systems. In 2009, FlexEnergy bought the division from the industrial giant and merged the operations. Overnight, the startup added hundreds of employees.
Next, it had to prove the viability of its product, and the Army provided the venue.
The Department of Defense Environmental Security Technology Certification Program sent out a broad agency announcement seeking innovative and cost-effective technologies to address energy requirements. The program had its roots tackling the environmental cleanup problems on military bases, but was expanding into renewable energy.
“There are a lot of these landfills around the nation, where they are either venting the methane into the air or collecting it and flaring it,” Hancock said. Many of them are on military installations.
The turbine was selected for the program, and the small landfill at Fort Benning was chosen. FlexEnergy, in partnership with Southern Research Institute, installed one of the power stations on the landfill in the spring of 2011. SRI is an independent, third party that is monitoring the project and verifying the data it collects. The plan is for SRI to write a full report this fall.
The Fort Benning dump is an older, smaller landfill that has been closed for more than 10 years. It produces enough methane to run one machine and will continue to do so for the foreseeable future, Hancock said. The electricity is being fed onto the base’s grid. It isn’t directly feeding 250 homes, but providing the equivalent in free electricity to Fort Benning. Part of the contract is that FlexEnergy will leave the machine onsite for the base to use after the pilot project ends.
“Fort Benning is absolutely critical to us to get the third-party verified data out of it that shows our system works,” he said.
“We’ve got a lot of people waiting on the sidelines, saying, ‘as soon as you show me the data from Fort Benning, then I am on board to buy these,’” he said.
The engine also works on digesters at waste water treatment plants where utility companies have to store pools of sludge as the organic matter breaks down. In the commercial sector, the company has signed a deal with a large landfill in Orange County in California that will use six of the turbines. The profits from the electricity sold will be split between the landfill and FlexEnergy.
“The landfill goes from the cost of flaring off its methane to a net revenue being generated and power that will help the community out,” Hancock said.
The catch is that the power station is not economically viable unless the landfill owners have installed collection systems to flare off the methane. There are tens of thousands of old dumps in the United States, he estimated. They don’t all have collection systems, but since methane is a potent greenhouse gas, he believes more landfills will be required to collect and burn it off.
“Because it is not burning anything and it is using the oxidizer, it doesn’t produce emissions. The FlexPower station can get permitted where other systems have trouble,” he said.
Richard Kidd, deputy assistant secretary of the Army for energy and sustainability, said in a statement: “We are converting what was once a waste stream, a pollutant, a contaminant, and a liability, into what will be a resource going forward.”
Meanwhile, other non-military entities are stepping in to help bases reach the 2025 goal.
At Fort Hood, Texas, a private company that maintains military housing went outside the Army’s renewable energy programs and had a field of solar panels installed at its own expense.
Universal Services-Fort Hood is the contractor that maintains the base’s Liberty Village complex, where some 300 families live.
It took advantage of federal and state tax credits to put together a project that will provide 1 million kilowatt hours of electricity, about 20 percent of its annual consumption, said Jim Stein, vice president of government affairs for Schott Defense, the maker of the solar panels.
The contractor had to ask Fort Hood for four acres to install 3,000 panels.
For the base, it was an easy call since Army installations are part of the requirement calling for 25 percent renewable energy consumption by 2025, Stein said. Universal Services put the $3 million deal together without requiring funding from the fort. It hired an engineering company to set up the project, and it will now have a steady flow of electricity for at least the next 25 years — and one that will not rise in price during that span, unlike fossil fuels.
Giving up land in order to reach the Defense Department renewable energy goals will be a trend in the future, Stein predicted.
And as was the case at Fort Hood, the military shouldn’t have to invest any of its own funds.
Setting up solar, geo-thermal and wind farms on bases can be done independently. The investors set up power purchase agreements where the military service agrees to buy the power generated. The developer owns and maintains the wind, solar or geo-thermal farm.
Military bases are already secure locations, so there doesn’t need to be any security costs, he noted. There are problems with wind farms at some facilities. Their rotating blades can interfere with radar systems.
The Defense Logistics Agency reported in a statement that it has signed $400 million worth of energy savings performance contracts (ESPCs) so far.
In the past, many bases had their own power plants, Stein noted. Then they began to get their electricity from nearby utilities.
“Now, they’re looking to get some independence from the grid,” he said. In the aftermath of 9/11, Hurricane Katrina and other disasters commanders want to keep operations going even if the rest of the community has no power.
“It’s kind of a great model and a win-win for everybody because the Army wants the grid security and the energy security and Universal Services gets warranty security and investment security,” he said.
CORRECTION: The original version of this story stated that the Defense Logistics Agency awarded $400 million worth of PPA contracts, instead of ESPC contracts.