Turning sawdust into gasoline

This is not science fiction: We actually can make gasoline from wood waste, switchgrass, algae and sugarcane. Maybe it won't be 'fossil fuel' anymore.

Thu, Dec 10 2009 at 4:02 PM EST

SAWDUST TO GAS: Dr. George Huber with a tiny vial of pre-gasoline. (Photo: Jim Motavalli)

Here’s the conventional wisdom: Oil was made from the slow crushing of ancient plants (and dinosaurs!) under the Earth over millions of years. That’s why we call it “fossil fuel,” and that’s why it’s not a renewable resource — the supply is finite, and we’re reaching the peak of that supply.

That’s the conventional wisdom. But it’s wrong.

We can actually make gasoline (as well as diesel and jet fuel) from sustainable sources, including fast-growing grasses, wood waste and even algae (I know, it sounds gross). The research is far along, and it’s actively being pursued not only in university labs, but in well-funded corporate projects.

Dr. George Huber, a professor of chemical engineering at the University of Massachusetts in Amherst, showed me how he makes small amounts of gasoline from sawdust in his lab ... on a tabletop. No, it’s not cold fusion: It’s science-fiction science that actually works.

Huber takes pine sawdust — the cheapest “feedstock” at $40 to $80 a dry ton, but he could use many other things — and runs it through a sieve to refine it. He then loads it into a hopper on his lab-scaled fluidized bed reactor (FBR). Very large versions of these reactors have been in use since 1942 to break petroleum down into its component parts. The FBR heats the oxygen-deprived sawdust to 750 to 1,100 degrees Fahrenheit, so it decomposes without burning. “Within seconds you have liquids starting to form,” says Dr. Huber.

The same process would work with paper mill waste, agricultural residue (from, for instance, sugarcane and corn production), and “energy crops” such as switchgrass and miscanthus.

Huber’s liquid is not gasoline yet, but a gasoline precursor that will need further processing. But the final product is chemically identical to gas, diesel or jet fuel, and the fact that it can be made price-competitive with gasoline at $40 to $50 a barrel is what has financed considerable research. Unlike hydrogen, ethanol and other alternatives, plant-based gasoline can go straight into our current network of 160,000 gas stations.

If this was a crackpot idea, would the Obama-era Renewable Fuel Standard of 2007 require the making of a billion gallons of diesel from biomass by 2012?

Gasoline production from biomass may not stay on the lab scale for long. Huber and UMass are commercializing it under the name Anellotech, and that company says it can produce “price parity” gasoline by 2019. A plant is due to be completed by 2014. That $30 million plant could theoretically produce 2 million gallons annually.

Anellotech CEO David Sudolsky says, “At this early stage, we’re concentrating on sawdust because we can get it right down the street and it’s available all over the country,” he said. “I’m very excited about it,” Sudolsky said.

The “Next Generation Hydrocarbon Biorefineries” report says trees, grasses and agricultural residues (among other non-food sources) constitute more than 80 percent of the total biomass in the U.S. If the 1.3 billion dry tons of ligno-cellulosic biomass cited in a federal study were converted to biofuel, it would have the energy equivalent of 3.8 billion barrels of oil, which is half of the U.S. consumption in 2006.

One of the lead scientists working on fundamental research to make gasoline and diesel fuel from sugars is James Dumesic of the University of Wisconsin. Dumesic estimates that 50 percent of the transportation fleet could be powered with ligno-cellulosic fuels, and he helped make that a reality by co-founding Virent Energy Systems, with Dr. Randy Cortright in 2002.

In an interview, Cortright said the company has spent three years taking its process from a very limited lab scale to a current gasoline yield of a half-gallon a day. In 2008, Shell entered into a new five-year partnership with Virent to research and develop technologies to convert plant sugars directly into gasoline. The financial arrangements were not disclosed, but Virent had previously collected $10 million in government grants and $40 million in venture capital. According to Dr. Cortright, other significant investors include Cargill and Honda.

A year later, Shell (the world’s largest buyer and blender of crop-based biofuels) said it would concentrate on biofuels and carbon sequestration at the expense of investment in other renewable technologies, including wind and solar, which it said did not offer attractive investment opportunities. According to Linda Cook, Shell’s executive director of gas and power, “We are businessmen and women. If there were renewables [which make money] we would put money into it.”

According to Dr. Lance Lobban, director of the University of Oklahoma School of Chemical, Biological and Materials Engineering, “green” fuel can be a big part of the world’s energy future. “Most biomass-based fuels can’t currently compete economically with $50 per barrel oil,” Dr. Lobban says. “But as oil becomes more expensive, and as it becomes more important to limit greenhouse gas emissions, we will look at ‘green gasoline’ because it would be essentially carbon neutral — its source is plants which remove CO2 from the atmosphere as they grow.”

There’s a lot more exciting research underway than will fit on this page. In future installments, I’ll look at the prospects for gasoline from algae and other unlikely sources.

MNN homepage photo: filo/iStockPhoto

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