Just as natural gas is starting to gain a toehold in the Class 8 truck segment as a lower-cost, lower-pollution alternative to conventional diesel engines, comes a potentially even more promising option that retains the durability, power, and range for which diesel engines are known, without the need for extensive, expensive, and heavy exhaust after-treatment and without the special handling and storage needed with liquefied natural gas.
Sound too good to be true? America, meet dimethyl ether, one of the most promising alternative fuels for heavy trucks in recent decades, possibly ever. And what's sure to keep Chesapeake Energy, T. Boone Pickens, and the rest of the natural-gas boosters happy is that it can be produced from natural gas, as well as from other waste feedstocks, including animal, municipal, water treatment, and other sources of methane.
DME combusts without the need for spark or external ignition, meaning DME can be run in diesel engines with minimal modification to the engines or fueling systems. And unlike conventional diesel trucks, which now require urea aftertreatment to meet federal emissions standards, the DME-fueled trucks require no liquid catalyst for NOx; and because of the almost non-existent particulates, no diesel particulate filter is required either.
And unlike the ultra high-pressure and ultra low-temperature storage required with liquefied natural gas, the preferred fueling option in Class 8 trucks due to its longer range, DME has similar storage characteristics to propane, meaning a modest 75 psi storage pressure. DME is commonly used as a propellant in aerosol cans, and is considered non-toxic. When sourced from a sustainable feedstock like biomethane, it can result in up to a 95 percent reduction in total CO2 compared with conventional diesel fuel.
Oberon Fuels, a small startup based in San Diego, is developing on-site production units that can produce the fuel from pipeline natural gas or biogas, providing a fuel supply for small fleets that potentially circumvents the issue of infrastructure for local, short-haul fleets. However, like natural gas for Class 8 trucks, a comprehensive nationwide fueling infrastructure remains a potential hurdle for DME's mass-market adoption as a long-haul fueling alternative.
Volvo Trucks is currently in trials with Safeway Inc., the West Coast supermarket company that also owns the Vons and Pak 'n Save brands. The full production rollout of the DME option for Volvo's U.S. customers is expected to begin in 2015.
Source: Volvo Trucks