JB Elmendorf - Richardson turns landfill gas into energy

  • Published
  • By David Bedard
During an especially cold December afternoon, a swirling formation of obsidian ravens hovered over a gray chimney, the structure pushing out hot air in the form of burned methane gas and oxygen combusted into water and carbon dioxide. Perhaps the black birds liked the heat. Perhaps they liked the extra lift. Chances are, it was the tantalizing combination of both that attracted the feathered acrobats.

Currently, the Anchorage Municipal Solid Waste Landfill, adjacent to Joint Base Elmendorf-Richardson, collects and burns landfill gas to comply with EPA regulations. The gas is primarily methane -- a rather simple molecule composed of a single carbon atom bonded to four surrounding hydrogen atoms.

With an eye to the future, officials at JB Elmendorf, the Municipality of Anchorage and Doyon Utilities put their heads together to find a way to convert the landfill gas from a diversion for ravens into usable energy for the military base.

The JB Elmendorf Landfill Gas Waste to Energy Plant is scheduled to begin operations January 2013 and is projected to generate more than 56,000 megawatt hours or 26.2 percent of JB Elmendorf's electrical load, said Tim Berg, 673rd Civil Engineer Squadron asset optimization chief.

"Here (the municipality was) flaring the gas and getting no benefit other than maybe the ravens like to soar in the plume," Berg said. "Now, we're turning it into electricity for the base to use."

Mark Madden, manager of planning and engineering, Municipality of Anchorage Solid Waste Services, said he has been eager to convert the costly flare into a profitable enterprise for the municipality.

"For the past five years, we have been just burning this gas," Madden explained. "And it's costing us about $60,000 per year to get rid of it. With this project, we don't burn the gas off, we sell it. The base gets electricity, we get rid of our gas."

Berg said once it was determined the gas would be sold rather than burned, the municipality put out a bid for a customer. Because military construction projects can take years to plan and execute, and the federal government cannot bid on its own behalf for such projects, Berg said the policy of privatization was beneficial to ensure JB Elmendorf would have access to the methane gas for energy use.

"It was advantageous for us to have a privatized utility contractor ... who could take those steps in partnership with the military as well as the municipality and the state," he said.
Leveraging a $2 million grant from the Alaska Energy Authority and a 30 percent tax benefit from the federal government, Berg said the project will become cash positive in the third or fourth year of operation and save an estimated $50 million during the 46-year life of the project.

Perhaps more crucially, Berg said the plant ensures JB Elmendorf will more than exceed renewable energy goals established by Executive Orders 13423 and 13514 as well as Section 203, Energy Policy Act of 2005. These mandates require federal agencies use renewable energy to meet at least 7.5 percent of total electric consumption beginning 2013. Because the generator plant is located at JB Elmendorf, the installation is able to double count credit at 52.4 percent, or nearly seven times the goal.

"(The plant) is important from a regulatory standpoint," Berg said. "It's mandated by our commander in chief. But also it's just the right thing to do."

Marvin Riddle, Doyon Utilities consultant, said the plant is a system of systems beginning at the landfill where a network of pipes feed into a central point through suction of a blower.

"Right now, that gas is being pushed straight into a chimney flare that basically burns all of those (British thermal units)," Riddle said. "The new system is going to divert that into a processing skid."

The skid -- or gas processing module -- sits along side of the flare, which will be idled once the plant is fully operational. Once the gas hits the skid, it is discharged at approximately 9 psi, picking up heat. The heat is taken out by an inline cooler and the process also removes moisture. The gas goes through another pre-heater and another heat exchanger where more water comes out.

Each time water comes out, it removes sulfur and siloxane, impurities that would be harmful to the engines in the plant.

The gas is then pushed down to the generator plant to a header where the gas pressure is reduced to approximately 1.5 psi for ingestion into the plant's current complement of four 20-cylinder generators.

The engines are designed to run primarily on methane, but they can also run on natural gas or a mixture of both if there is an interruption of supply.

"(The gases) can be automatically blended as the engines are running," Riddle said. "So if you lose either fuel, the base should not lose any power."

Berg said the plant will expand to five generators by late 2013 because there is enough methane production. Today, there is enough garbage composting in the landfill to provide methane for the life of the unit. The plant will be tied to the existing JB Richardson grid through electric distribution.

Additionally, the plant is large enough to accommodate an array of Organic Rankine cycle heat-recovery units capable of adding 1 megawatt to the plant's electric-production capability should the addition of the units prove to be economically viable.

Madden said the plant is a boon for JB Elmendorf, the municipality and utilities privatization.

"At the end of the day, this really proved to be the best fit for everyone all the way around," he said. "We're neighbors. We have a lot of shared interests in the ground we're standing on."