When you heat dry biomass — like wood or crop waste — over 700ºC, in the presence of steam, it gasifies:
At those temperatures, most of the biomass is converted to a synthetic gas. This “syngas” is made up of hydrogen and carbon monoxide, which are the chemical building blocks for higher-value fuels such as methanol, ethanol, and gasoline.
If you burn a third of the biomass to produce the heat to gassify the rest, you have an obvious source of inefficiency. If you gasify the biomass with sunlight though, you get a better product that costs less to produce:
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.”