Doyon testing JBER landfill gas plant

New plant using gas from Anchorage Regional Landfill garbage to produce electricity; without a use, municipality has to flare gas

Kristen Nelson

Petroleum News

A combination of increasing electric rates at Fort Richardson in Southcentral Alaska and a requirement that the Anchorage Regional Landfill flare methane gas generated by garbage have produced a project to use landfill gas to produce electricity for the Fort Richardson portion of Joint Base Elmendorf-Richardson, JBER, near Anchorage.

Four of five generators for the project are currently in the test phase.

Aimee Oravec, attorney for project developer Doyon Utilities LLC, told the Regulatory Commission of Alaska Aug. 15 that after years of working on the issue, the Municipality of Anchorage solicited proposals for a project in 2010, a bid won by Doyon Utilities.

Oravec said the main terms of the contract between Doyon Utilities and the municipality include Doyon Utilities designing, building, operating and maintaining a gas process module with associated pipelines on the Anchorage Regional Landfill, with the municipality owning the landfill properties.

Doyon Utilities, she said, is required to ensure that the gas processing module meets regulatory and environmental requirements.

Doyon Utilities has also built a landfill gas-fired electric generation plant on JBER, helping JBER meet requirements under federal legislation that 7.5 percent of its energy be from a renewable source.

The project allows JBER to replace more than 25 percent of its total usage, Oravec said, and Doyon Utilities has been able to beat the Municipal Light & Power price for electric power and in July was authorized to increase the size of the project.

From four generators to five

“So basically the federal government wants us to generate more than we had originally bid and current with that, we have discovered that the landfill generates more landfill gas than was originally known at the time of the bid,” she said.

The net present value of the project to the municipality is $51 million over 20 years and to the federal government $32 million over the same period.

There is room in the Doyon Utilities building on JBER for six generators, but right now the project is being designed for five, she said.

Marvin Riddle, Doyon Utilities project manager, said the generators are General Electric Jenbachers, built in Jenbacher, Austria, specifically for a dual-fuel combustion engine.

“They’re designed to burn natural gas or landfill gas,” Riddle said.

There are probably 500 to 600 of the generators installed worldwide, he said: “It’s not new technology; the Germans have been doing it for quite a while.”

Landfill gas the priority fuel

“Right now the Municipality of Anchorage is flaring 1,760 cubic feet a minute of gas” with a heat value of 500 Btu per cubic foot.

Riddle said the gas compression skid at the landfill is designed to handle 2,500 cubic feet of gas a minute. It’s basically a dehumidification and filtering skid.

“The landfill gas comes out of the landfill at 100 percent relative humidity — basically, saturated gas,” he said.

Saturated gas is harder for the engines to burn and because it has to be moved 6,000 feet to the JBER power plant there’s a problem with icing or precipitants dropping out in cooler weather, “so we want to remove as much moisture as we can.”

The other advantage of removing moisture is that is a way to get rid of a lot of the contaminants, he said.

Water which is removed at the landfill is handled by the municipality.

Depending on the time of year, Doyon Utilities can generate 30 to 50 percent of the requirements for the Fort Richardson side of JBER, Riddle said.

The engines are dual fuel and Doyon also has access to Enstar gas “so if we have a problem with one fuel it switches to the other fuel,” he said.

Riddle said they’re in the testing phase right now on the four generators; the fifth unit, added recently to the plant plan, won’t be delivered until next year.