The higher temperatures also make for a better quality syngas. Conventional gasification typically produces a syngas mixture that’s half hydrogen and half carbon monoxide. Sundrop’s process achieves a hydrogen-to-CO ratio of two to one.
“I can tell you, the economics have been looked at quite extensively, and the idea of being able to produce gasoline at less than $2 a gallon without subsidies, we believe that’s a real number,” Weimer says. The financial upside is even greater if carbon pricing becomes a reality, because the solar-driven process results in a reduction in greenhouse-gas emissions compared to conventional fuel production. “The key now is to design a scalable solar reactor.”
Ajay Dalai, an associate professor of chemical engineering at the University of Saskatchewan, says powering gasification with solar energy has merit but could prove tricky. “When you’re transferring the heat into the pipe, how do you make sure that it is distributed thoroughly through the biomass?” Controlling heat transfer and temperature levels will be key, he says.
Wayne Simmons, chief executive officer of Sundrop Fuels,
doesn’t underestimate the challenges to commercializing the technology. He acknowledges, for example, that the greatest biomass resources aren’t located where the greatest solar resources are. Still, some woody biomass does exist in the U.S. Southwest, where Sundrop plans to build its first commercial plant. States such as New Mexico and Arizona, for example, regularly thin their forests to lower the risk of forest fires. But to access more feedstock, Sundrop is also looking at transporting energy crops, such as switchgrass, by rail from as far north as Kansas and as far east as Texas.
Construction on Sundrop’s first commercial facility is expected to begin this year. The company plans to couple its solar gasification plant with a pilot-scale biorefinery that can produce up to eight million gallons of transportation fuel annually. It’s targeting 2015 for a full-scale biorefinery that can produce 100 million gallons a year.
The company has attracted some key investors, including venture-capital firm Kleiner Perkins Caufield & Byers.