Petition seeking RFS credit for DME fuel could boost diesel alternative
Oberon Fuels, a La Jolla, California-based firm, formally petitioned the EPA on August 29, to allow credit for dimethyl ether (DME) under the agency’s renewable fuel standard (RFS), which proponents say could help boost the market for DME as an alternative to conventional diesel due to its ease of use, lower emissions and storage benefits.
Oberon is one of a number of companies and supporters working on a region-by-region strategy to get DME into a trucking market currently dominated by diesel fuel. Diesel fuel is favored because of its high efficiency and widespread availability. The companies held two briefings in Washington, D.C. on September 27, hoping to raise the profile and awareness of DME among legislators and regulators.
DME supporters say it can be made on a small-scale using natural gas feedstock produced from oil drilling or from biomass and wastewater treatment plants. The feedstocks are currently wasted because they are typically produced in small volumes or at remote locations. Advocates say the fuel could begin to replace diesel fuel in heavy-duty trucks without facing the distribution, storage, fueling and other infrastructure problems associated with other alternative fuels.
DME has some qualities that are similar to diesel fuel. Its high cetane number, a measure of combustion quality, means it can be used in high-efficiency compression engines. It has other qualities similar to natural gas, such as not requiring filters for particulate matter (PM) due to a reported lack of PM emissions when combusted.
With projected long-term low natural gas prices and untapped methane waste streams, interest in DME has grown according to its supporters. Oberon Fuels has previously said it is “working very closely” with the California Air Resources Board to certify DME as a fuel.
Now Oberon is petitioning the EPA for RFS credit for converting a high-methane-content feedstock from a nearby dairy farm into DME. Winning RFS recognition would mean that when it produces biogas-derived DME for use as a transportation fuel, the company could generate credits that could then be sold to refineries and other parties to help them meet RFS blending requirements.
The EPA has yet to post a notice on its website that it has received the petition, but an Oberon official says the company expects the process will take about a year.
RFS credit for biogas-derived DME would make “a huge impact” and encourage financing for projects that collect waste methane from biological processes, Oberon Fuels President Rebecca Boudreaux said, noting those projects are more capital-intensive than producing the fuel from a direct source of methane, such as a conventional natural gas pipeline.
Because DME can be derived from any source of methane, Boudreaux said it could also potentially get RFS credit as a cellulosic biofuel for methane derived from landfill gas, whereas methane from food waste and water treatment plants would qualify as an advanced biofuel and therefore meet the RFS targets for those fuels.
To promote DME and break into the transportation market, Oberon is working to install small-scale modules that can produce up to 10,000 gallons of DME per day, which officials say is enough to supply a small regional market or a company with fuel for a fleet of about 100 to 150 trucks.
(October 10, 2013)
