Technical Overview of Biomass‑to‑Syngas Biofuel Process

NAUTILUS EDUCATION | BETA PRODUCT avuncular and black-haired. His interests are broad: He spends his spare time writing and reading history, and has authored books on conflict in the Middle East and the role of Christian missionaries in China. A lifetime in fuels chemistry left Fang with one burning question: “What is the real solution to the energy crisis?” His career at oil companies BP and ExxonMobil, and engine manufacturer Cummins, spanned not just one but two major energy upheav- als—the oil crisis of the 1970s and then its sequel in the first decade of the 21st century, which is arguably still ongoing. These experiences impressed on Fang the importance of securing the fuel supply in such a way as to avoid despoiling the environment. The solution, says the bespectacled chemist, is “nature- sourced biomass or natural gas converted effectively to gas or diesel.” Primus’s original idea was simple: take scrap wood or other biomass, turn tt into pellets, and apply pres- sure and heat (700 degrees Celsius or more) to break it down into hydrogen and carbon monoxide. Then build this composite “syngas,” shorthand for “synthet- ic gas,” back up into whatever hydrocarbon product is desired—the molecules of eight carbon and 18 hydro- gen atoms known as iso-octane that are a measure of the quality of conventional gasoline, or the longer chains of similar hydrocarbons that comprise diesel or jet fuel. Because plant biomass absorbs carbon dioxide as it grows, the emissions produced by burning the biofuel should balance out overall—every molecule of CO2 emitted when the fuel is burned was previously absorbed by the plant that made the fuel. The story of the search for such green fuel 1s lit- tered with disappointments, however. Major compa- nies brew ethanol in large quantities in the United States. It is routinely added to gasoline (at levels of around 10 percent, on its way to 15 percent) as a way to improve combustion, reduce pollution, and support industrial corn farmers. But most ethanol is still made from the edible kernels of com plants, instead of the inedible cellulose that was promised in the heady days of the mid-2000s, when Congress passed a spate of laws promoting biofuel production. Since 1978, the ethanol industry has enjoyed subsidies and tax credits to the order of 40 cents per gallon, and now produces an annual dead zone at the mouth of the Mississippi 24 River each summer as a result of fertilizer washing off the endless cornfields of the Midwest. But ethanol is unlikely to ever fully replace conventional fossil fuels, since it is more difficult to transport, produces a frac- tion of the energy of oil, and would require engines to be refitted or replaced on a massive scale. Hence the interest in “drop-in” biofuels as a sub- stitute for conventional fuels in existing cars, planes, and trucks. The problem is not one of infrastructure, but chemistry: Companies must find a way to eco- nomically imitate and fast-track a process for which time and geology have done most of the work in con- ventional fossil fuels. The energy in these fuels is the pent-up power of ancient sunlight, which billions of photosynthetic microorganisms soaked up before dying, fossilizing, and turning into the hydrocarbon- rich stew we know as petroleum, and from which we refine gas, diesel, and jet fuel, among other products. In theory, then, it should be possible to turn the car- bohydrates and other chemicals that store energy for today’s living things into the hydrocarbons we rely on for transportation. Potential routes to such “green crude” include algae, other photosynthetic organisms, and specialty microbes engineered to spit out hydrocarbons. Biofuel company Solazyme has a contract to supply United Airlines with 20 million gallons of algal jet fuel, and teamed up with a green fuel-station network to offer biodiesel in a test run in San Francisco’s Bay Area. But it takes a lot of water—and a lot of energy to move that water around—in order to grow algae in large quan- tities, and tailor-making microbes is expensive at its current scale. As a result, companies are diversifying. Algal fuel producer Sapphire Energy is now focusing on isolating the genetic traits in the ancestors of all plants that might be usefully incorporated into other crops. Solazyme is making oils and specialty fats to sell at high margins to cosmetics and food companies, as is would-be microbial fuel-maker Amyris. The industry for “advanced biofuels is literally mm its infancy,” con- cedes Jonathan Wolfson, Solazyme CEO. The allure of Primus’s technology 1s its promise to harness waste wood and other inedible biomass that would otherwise be thrown into landfills, and turn it ito a renewable source of gasoline. Its “syngas to gasoline plus” process consists, essentially, of four HOUSE_OVERSIGHT_015484