Taking Pulp to the Pump

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Rudberg says that Chemrec worked closely with researchers at Oak Ridge National Laboratory to identify appropriate materials for testing in a gasification plant that has operated at a Weyerhaeuser mill in New Bern, NC, since 1996. This plant can process up to 15 percent of the mill's black liquor. Rudberg says that the refractory at New Bern has been operating for two years, which he believes is long enough to prove that its commercialization is viable.

That performance is clearly enough to convince Chemrec's backers to finance the next step: generating biofuel from the syngas. While Weyerhaeuser simply burns the syngas to generate heat at New Bern, Chemrec's small research plant in Pitea, Sweden, has demonstrated production of syngas pure enough for catalytic fuel synthesis. BioDME, Chemrec's EU-funded consortium, will turn that syngas into between four and five metric tons of DME per day.

Another BioDME partner, Haldor Topsoe, will build the DME synthesis plant, to start up in 2010. Göteborg-based Volvo Group (not to be confused with the Ford-owned luxury-car division, Volvo Cars) will adapt the fuel systems of 14 long-haul diesel trucks to run on DME. And Swedish oil company Preem is building four fueling stations to distribute the DME across Sweden.

At the same time, Chemrec is doing the engineering for two plants that would be 25 times larger, producing 40,000 tons of DME each year: one at Pitea, and one at the New Page mill in Michigan. Converting every pulp mill in the United States would, according to Rudberg, generate the equivalent of about 7.5 billion gallons of fuel--about one-fifth of the U.S. government's total target for 2020.

But it remains questionable whether demand would naturally follow. DME is currently used primarily as a substitute in aerosol spray cans, and clearly more than four fueling stations in Sweden will be needed for it to take off as a biofuel. Marc Londo, a senior research and biofuels expert at the Energy Research Center of the Netherlands, in Amsterdam, says that this chicken-and-egg dilemma is a major drawback. He believes that Chemrec's success would be better assured if it produced synthetic diesel from its syngas--a strategy pursued by German biomass gasification innovator Choren Industries. "The strong advantage of synthetic diesel is you can simply blend it with currently available diesel," says Londo. "For bio DME, you need dedicated distribution networks."

Londo says that synthetic diesel has another advantage: while it costs slightly more to produce from syngas than DME does, synthetic diesel has a higher energy density. A tank of diesel will take a long-haul truck twice as far as a tank of DME: "For long-haul trucks, energy density is a critical factor, and synthetic diesel is thus a more valuable fuel," he says.

BioDME project leader Per Salomonsson, an R&D manager with Volvo Group, says that it comes down to how much fuel an acre of land will produce. Synthetic diesel would be a lot easier for Volvo Group to drop into its vehicles, but according to their estimates, DME will deliver over 65 percent more miles of travel per acre cultivated; compared with conventional biodiesel produced from vegetal oil, the advantage is five to one. "There will be a shortage of biomass in the future," says Salomonsson. "In the long run, we can't afford to have anything but the most efficient process."