The conversion of landfill methane gas to liquefied natural gas (LNG) for use in fueling trash trucks and other heavy equipment is similar in its technical processes and economics, according to a New Jersey-based executive getting ready to open a landfill-LNG plant later this year at a Northern California trash site. But Linde North America, a project partner with Houston-based Waste Management Corp., has no interest in global, baseload-size LNG projects, according to Byran Luftglass, Linde’s energy segment manager.

“Other than the scaling it is pretty much the same kind of process [for liquefaction], and given it is the same kind of process, the economics wouldn’t be that dissimilar,” Luftglass said. “But we’re not doing this on a massive scale and transporting massive LNG quantities long distances for injection into the nation’s pipeline system.”

The California project in the Altamont Pass southeast of San Francisco-Oakland’s East Bay Area is touted by Luftglass and his firm’s partners as a model for what can be replicated at landfills and dairy farms across the nation, wherever enough biomethane can be captured, cleaned and liquefied. Waste Management operates 277 landfills nationwide and operates many of its trash trucks on LNG, a spokesperson told NGI.

Altamont is one of several LNG-biomethane projects around the world in which Linde is participating, according to Luftglass who spoke with NGI Friday. More generally, German-based Linde is a supplier of industrial, specialty and medical gases and engineering products and services.

“Biomethane is a truly renewable and readily available green source of high-quality fuel,” Luftglass said. Acknowledging that it is still an emerging commodity, he said the fuel’s “economic and environmental value is rapidly being recognized.”

When commercially operable later this year, the Altamont project on a site of less than an acre in size will produce 3 MMcf/d of landfill gas that is turned into 13,000 gal/d of LNG, or the equivalent of more than 1 MMcf/d for transportation fuel to supply up to 300 trucks. The LNG produced annually will amount to 4 million gal.

Luftglass downplayed the added cleaning involved in liquefying landfill gas, as opposed to pipeline-quality gas. “We use a clean-up system that is tailored to the application. In the case of Altamont, once it is cleaned up to liquefier specifications, it goes into a heat exchanger, just as it would for global-scale LNG,” he said.

Any transportation LNG liquefaction facility has to have a clean-up step, according to Luftglass. “You cannot just take pipeline gas and liquefy it; you have to clean it up, too, with absorbent-type systems, or amine systems. So they have to have clean-up systems to bring the gas to the same quality specs that we have.”

Luftglass does acknowledge, however, that liquefying landfill gas is “more complicated, more difficult and trickier, and that is why landfill gas-to-LNG has been difficult for people to do.” He added that Linde has come with what he called “the right design to handle the vagaries of landfill gas.” He said Linde’s equipment is very “compact and energy efficient,” using a lot of components found in commercial heating-ventilation-cooling equipment.

In the Altamont project, LNG will be transported by tanker trucks to fueling stations throughout California where it will be used by trash collection trucks and other heavy-duty vehicles. “LNG burns in cleaner natural gas engines that have 20% less carbon emissions than diesel engines,” the landfill partners said. “This project will reduce carbon dioxide emissions by more than 30,000 tons annually.”

In the landfill gas-to-methane process trash-produced gas with about 50% methane is first cleaned through compression, chilling and absorption before the purified gas is fed through a liquefier taking the gas to its minus-260-degree F temperature that turns it into LNG. The LNG is then stored in a tank for trucks that come to haul it to various fueling stations.

“We’re doing this in a virtual closed loop system,” said Luftglass, noting the landfill gas is fueling the refuse trucks that helped create the landfill to begin with. “It is pretty neat. The analogy would be fueling the global LNG tanker ships with LNG.”

Eventually as demand grows for the landfill LNG supplies for transportation, Luftglass predicts refueling of the trucks will take place at the landfill where production occurs. Thus, not all of the LNG will be transported to refueling stations.

“I suspect we’ll see refuse collection and transfer trucks refuel at this or other sites like it,” he said, noting that Linde is looking at a number of potential other sites and it has applied for both federal and state incentive funds for a second site in California in combination with Waste Management.

There are some emissions from the process, the proponents said, but they are minimal.

Linde plans to commission a similar plant later this summer outside of London.

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