Washington State recently passed legislation to include an exciting and innovative new energy source into our definition of “alternative fuel.” Dimethyl ether, also known simply as DME, now qualifies by definition as a “clean alternative fuel” in Washington. This means that DME also qualifies under Washington Senate Bill 5987, which provides tax credits to businesses for the purchase or conversion of vehicles that are “principally powered by a clean alternative fuel.” Tax credits depend on gross vehicle weight rating (GVWR) and range from $5,000 – $20,000 per vehicle. Each company may claim up to $250,000 or credits for up to 25 vehicles annually. For more information regarding available funding, please refer to this link about the Alternative Fuel Commercial Vehicle Tax Credit.

This incentive, coupled with the fuel’s strong performance in heavy-duty vehicles, positions DME as a viable alternative fuel option for many vehicle fleets throughout Washington.

Introducing DME

“There’s no silver bullet” is a refrain often sung by those in the alternative fuel vehicle industry, as there isn’t one specific alternative fuel option that’s going to work for every kind of vehicle and fleet. Thus, there’s always room for innovation, and innovation can occur without kicking other fuels and technologies out of the market. This has opened the door for DME, which has unique benefits and has the potential to fill an important niche in the transportation industry.

Dimethyl ether is an isomer of ethanol, which means it has the same chemical makeup of ethanol but its molecules are arranged differently. Used in heating and industrial applications for decades, it is a popular source of energy in China, with large scale production existing or planned in Japan, Egypt, and Trinidad and Tobago. DME can be produced various feedstocks such as coal or natural gas as well as from renewable sources such as paper waste, forest and agricultural byproducts, municipal waste, and dedicated fuel crops.

Among the other currently available alternative fuels, DME most closely resembles liquid petroleum gas (LPG), otherwise known as propane. Due to their similar chemical properties, both are a gas under standard pressure but are easily liquefied under moderate pressure at room temperature. DME differs from LPG in that it can be compression ignited like diesel. In fact, diesel engines require only minor engine modifications to use DME, making it an attractive alternative fuel for engine manufacturers and fleets alike. Not only does this compression ignition make it easier for manufacturers to adapt their engines to run on DME, but the compression ignition cycle is well known for having the highest thermal efficiency among internal combustion engines used in on-road applications. That efficacy translates into high potential fuel economy and low maintenance.

DME can also be blended with LPG, which allows the DME-LPG blend to displace diesel fuel on compression engines. The DME and LPG industries recognize the importance of displacing petroleum consumption and are committed to working together. A recent LPGas article outlines how DME’s recent popularity might impact the LPG industry. Jesse Johnson, VP of Sales with Blossman Gas (an LPG company), posits that “as the market develops over the next 10 years, there’s going to be a role for the propane industry to become a distribution arm for DME because it’s compatible with propane.”

A dimethyl ether (DME) fuel pump located in Shanghai (Source: International DME Association)

A DME fuel storage tank, which is nearly identical to standard propane tanks. (Source: Volvo)

Where is DME headed?

The environmental benefits of dimethyl ether make it an attractive option for vehicles from an emissions perspective as well. When burned, DME emits zero particulate matter, and 95 percent fewer nitrogen oxides than diesel fuel. This allows engine manufacturers to skip the complex and costly emission control systems currently used on diesel engines. Finally, producing DME with renewables avoids emissions related to extracting resources from the ground, another crucial environmental benefit.

Oberon Fuels, a company out of California, is leading the way in DME production. Their pilot plant opened in 2013, and they currently have capacity to produce up to 10,000 gallons of DME per day. Oberon Fuels is committed to advancing DME production in the United States, so be sure to keep an eye on them over the coming months.

Production and fueling infrastructure remain in early stages, so it may be a while before you can fill’er up with DME. But keep an eye on this emerging fuel. These recent developments point toward a developing market for DME, which is increasingly positioned to become a relevant alternative fuel solution for fleets around the country. The benefits of DME are apparent though, and it won’t be long before you hear DME as often as you hear LPG or CNG!

For more information, check out the International DME Association’s website and the Alternative Fuels Data Center’s overview on DME. And as always, you can connect with us on Facebook, Twitter or via email with any questions.

- Western Washington Clean Cities Team