It’s a known fact that biomass can be used to produce fuel. It’s also known that to produce useful gasoline, the biomass needs energy-intensive treatments, that include transforming it into a synthetic gas, called “syngas”, at a temperature of 700 ºC, in the presence of steam.
Sundrop Fuels, a Louisville, CO, -based company has developed a method of using concentrated solar power to heat the biomass to 1200 or 1300 ºC, and even produce syngas more efficiently than the standard technology, which uses only 30 to 35 percent of the biomass.
Syngas is made of hydrogen and carbon monoxide, the two chemical building blocks for methanol, ethanol and gasoline.
The gasifier system consists of ceramic tubes that pass through a furnace. The gasifier is mounted atop a tower surrounded by a field of solar concentrating mirrors that reflect sunlight back to the furnace. As the biomass is dropped through the intensely hot ceramic tubes, it is vaporized into syngas.
Why Sundrop Fuels uses a higher temperature for developing the syngas is explained by Alam Weimer, a chemical engineering professor at the University of Colorado in Boulder: “It’s like a sledgehammer because of the (1,200 to 1,300 ºC) temperatures it operates at,” he says, explaining that conventional gasification uses lower temperatures to try to minimize the volume of biomass used to fuel the process. But keeping the temperature lower poses another problem. Gasification at temperatures below 1,000 ºC leaves behind tar. “And that tar is expensive to get rid of,” says Weimer. “If you leave it in there, it will end up killing your catalysts downstream when you try to reform your product into (liquid) fuel.”
Sundrop Fuels CEO, Wayne Simmons, also explains the economic part of their biomass processing technology: “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.”
Simmons is also looking at transporting the biomass from Kansas and Texas, by train, because not always biomass-rich areas are also fond with a lot of sun. This part, though, makes a larger CO2 footprint for the biomass-resulted fuel.
A 100 million gallons a year production facility is being prepared for opening in 2015.