DME Viability as Fuel Touted, but has ‘Steep Hill to Climb’

SAN DIEGO — Executives attending a dimethyl ether industry meeting here were told by trucking representatives that while the fuel has a number of desirable qualities, the jury is still out on its practicality as a transportation fuel.

The International DME Association heard from key players in the industry, including Volvo Group, which endorses the fuel, and American Trucking Associations, which maintains the fuel has “a steep hill to climb” to gain acceptance but that trucking is not opposed to it.

In 2007, Gothenburg, Sweden-based Volvo Group began a serious study of seven alternatives to diesel, “and DME came out on top,” said Susan Alt, a senior vice president for the original equipment manufacturer. It’s the parent company of Volvo Trucks and Mack Trucks, both based in Greensboro, North Carolina.

Volvo prefers DME — a molecule made of carbon, hydrogen and oxygen — to natural gas in the long term because DME has properties similar to diesel and is easier to transport, Alt said.

She spoke at the DME meeting on Oct. 7. Joining her was ATA attorney Glen Kedzie, who works on environmental and energy issues for the federation.

Kedzie said truck operators are “finicky” and will not switch on a casual basis. He said DME is in its infancy and cited a Department of Energy forecast from earlier this year through 2040 that does not list DME as a fuel of any significance.

He said choosing a fuel has profound ramifications for a fleet, as it affects vehicles, engines, technician training and purchasing networks.

The DME conference took place here as ATA’s Management Conference & Exhibition was coming to a close.

Alt said Volvo Group is particularly keen on DME in North America and expects actual results will prove the DOE forecast wrong. Volvo is working with Safeway Inc. and Oberon Fuels on a test program where the grocer uses tractors powered by DME made from biomass.

Alt said the major payoff for DME would come when it gets produced from natural gas that would be turned first into methanol and then DME. She characterized Oberon’s biomass approach as “small batch,” but switching to a methanol base means there is “a potential for huge volumes of fuel.”

The fuel is also very similar to propane in that it can be stored at room temperature and modest pressure in any vessel suitable for propane. In contrast, when natural gas is used as transportation fuel, it must either be compressed to 3,600 pounds per square inch or liquefied at minus-260 degrees Fahrenheit.

DME is “easy to use and transport,” Alt said.

She also said DME is a clean fuel that does not include carbon-to-carbon molecular bonds, as do gasoline and diesel. Carbon-carbon bonds produce particulate matter, or soot, when burned. Therefore, she said, a DME truck would not need a diesel particulate filter, but selective catalytic reduction would still be necessary.

Emmanuel Varenne, a Volvo engineering manager who works on alternative fuels, said DME engines work with combustion from pressure rather than spark ignition in gasoline or natural-gas engines. Varenne said a DME engine has an 18:1 compression ratio, the same as a diesel truck engine. He addressed the DME conference Oct. 8.

A high compression ratio leads to the large torque levels that are favored by haulers of heavy freight.

Robert Fanick, who researches engines for Southwest Research Institute, told the group the same day that their fuel “has a lot of advantages as a transportation fuel” as well as some problems, such as low lubricity, or natural lubricating properties.

Fanick said the problems that have been found so far should be able to be overcome through further research.

Kedzie said the trucking federation is not opposed to DME.

“Fleets would welcome other fuel-choice opportunities to challenge the three primary fuels being used in our industry right now — diesel, gasoline and natural gas,” he said.

Beyond that general preference, though, Kedzie said most fleets will want to see a lot of sound evidence and thorough vehicle demonstrations before they invest heavily in a new fuel.

Alt said Volvo does not yet have a schedule for rolling out DME trucks on a mass-production scale.

But Volvo did recently say that it is putting a hold on development of a compression-ignition LNG engine for North America in favor of DME. Alt said that is not a worldwide decision because, in Europe, the company remains highly interested in LNG.