DME as Diesel Fuel Alternative Gaining Ground
DEERFIELD, IL --- Chemrec, a Sweden-headquartered energy company with American operations, said it is actively pursuing U.S. federal and state grants and loan guarantees to improve its ability to ramp up commercial-scale black liquor gasification biorefineries at U.S. pulp mills.
Chemrec said two recent developments -- testing of dimethyl ether (DME) as a diesel fuel alternative by the Volvo Group and Ford Europe, along with Chemrec AB's recently announced groundbreaking for a BioDME plant in Sweden -- are kindling renewed interest in this carbon-neutral motor fuel.
DME, made from a variety of renewable materials and fossil fuels, burns soot-free, produces almost no GHG upon combustion and is very energy efficient, Chemrec said. With a high cetane number (the measure of combustion of diesel fuel under compression) and with no particle formation during combustion, "DME provides a very cost-effective way to meet stringent exhaust emission targets," Chemrec said.
Unlike conventional DME produced from fossil-based feedstocks, BioDME made through the Chemrec black liquor gasification technology -- black liquor is a waste stream of the pulping process -- uses residual forestry biomass as its feedstock, thus no foodstocks or farmable acreage is used. "BioDME offers a very high reduction of carbon dioxide emissions -- around 95 percent -- compared to conventional diesel fuel, and it can be produced with very high conversion efficiency at relatively moderate capital cost," the company said.
Chemrec recently broke ground for a demonstration BioDME plant in Piteå, Sweden, and the plant is expected to be producing BioDME and methanol in 2010, said Chemrec CEO Richard J. LeBlanc.
"America has been slower than Europe and Asia to catch on to DME as a motor fuel, as DME technology research and development in those areas are mostly government funded, but it is the belief of DME supporters in the U.S. -- from government energy researchers, academics and industry -- that DME and in particular BioDME has an important role to play in America's security and energy sustainability," said LeBlanc, who is also CEO of Chemrec USA.
Alternative Fuel Technologies Inc., based in Redford, Mich., designs and manufactures common rail and injection systems designed for DME delivery in diesel engines. Jim McCandless, CEO of Alternative Fuel Technologies, said DME has unique advantages for truck lines, bus fleets, materials handling equipment and other vehicles that refuel at central refueling depots.
"Although DME's energy density is lower than diesel, the overall engine thermal efficiency is the same or higher," McCandless said. "Also, DME will cost less than diesel on an equal energy basis; 1.8 gallons of DME will cost less than 1 gallon of diesel, assuming $70/bbl or higher oil price."
DME is a liquefied gas, like propane, that becomes liquid under low pressure of 60 psi.
"It is an ideal diesel fuel because it has very high oxygen content, 35 percent by weight, and no carbon-carbon bonds," McCandless explained. "What that means is that it cannot produce soot particulates or black smoke. This permits the use of very high EGR or exhaust gas recirculation rates to lower NOx emissions without having to use exotic and expensive after-treatment devices like particulate traps and SCR catalysts that require the injection of urea to lower NOx."
Another positive factor is that fuel injection pressures can be much lower than those currently needed by diesel engines. DME engines need injection pressures of about 6,500 psi; diesel engines currently require pressures upward of 30,000 psi. "The lower pressure requirements greatly simplify the fuel injection equipment," McCandless said.
In a study of various biofuels from a range of feedstocks, Volvo showed that the production of DME from harvest forestry woody biomass using the black liquor gasification process yields the highest miles per acre per year than biofuels produced by most other processes. Other studies show that the technology also yields the highest well-to-wheel greenhouse gas reduction and energy efficiency.