Researchers turn waste into fuel

In a small lab at the back of Agriculture Engineering, a new method for creating biofuels without the use of grain has been tested and proven, at least on a small scale.

Dr. Lin Wei, an assistant professor in agricultural and biosystems engineering, has been developing a new method of producing biofuels for two years. That method uses a process called pyrolysis to turn biomass like corn stover and sawdust, which today is often considered waste, into biocrude oil. The oil is then refined into fuels that can “drop-in” to traditional gasoline, diesel or JP-8 jet fuel.

Wei said his research has been funded to the tune of about $2 million by three U.S. government agencies: the Department of Transportation, the Department of Energy and the Department of Defense. The DOD’s interest centers around the Navy’s green fleet program. That program, according to its website, seeks to reduce the Navy’s use of petroleum fuels 50 percent by 2020. The Navy also plans to sail what it calls “The Great Green Fleet” – a carrier strike group that will use, in addition to nuclear power, at least 50 percent bio-based fuels by 2016.

That funding was funneled through the Sun Grant Initiative. The initiative is a national network of land-grant universities dedicated to promoting a bio-based economy. According to Dr. Vance Owens, the interim director of the initiative’s North Central Regional Center, funding for Wei’s research has come from a number of sources in addition to the federal government.

“Right now the North Central Sun Grant Center has received funding from the DOD, DOE, United States Department of Agriculture and DOT,” Owens said.

As recently as two weeks ago, Wei received $390,000 from the DOD and another $110,000 from the state to study how non-food oilseeds could be used to produce fuel.

“It’s kind of weird when you think that we’re about as far from a coast as you can imagine, but we can provide great assistance to achieving that goal of becoming a great green fleet,” Owens said.

So far Wei has successfully created drop-in fuels from three different types of feedstock: corn stover, sawdust and non-food vegetable oil. Biofuels produced from vegetable oil have been of particular interest to the Navy as a supplement to JP-8, which is used in everything from jets to trucks.

“What we do here is upgrade vegetable oil to drop-in fuel, similar to what we do with corn stover, so that we can directly blend it with petroleum aviation fuel, or we can just send it to the refinery to blend it all together,” Wei said.

Wei’s method of producing biofuel is still in the laboratory scale phase and produces only about a quarter of a gallon of fuel per day. Wei said that within a year, though, his research could move on to the next step toward commercial production ­– the pilot scale phase, which could produce about 26 gallons per day.

“Then it will go to live demonstration scale, for example, in one or two more years. I would say within five years maybe we can go to commercial scale,” Wei said.

Wei’s process may be a bit late in going into commercial production to be a part of the Green Fleet’s first cruise, but it does have potential to impact fuel prices in the future. Biofuels will never be able to replace petroleum-based fuels entirely, Wei said, but they do have potential to act as a supplement.

“Many researchers believe biofuels can take over 30 to 40 percent of the transportation fuel industry. That’s an estimate from literature, not my research, but if we can commercialize this, maybe 30 percent is not unreasonable,” Wei said.

The emphasis of Wei’s research is on biomass that has been seen as waste in the past. SDSU has the potential to see substantial gains if Wei’s process does indeed go to commercial production. For his process to be successful, Wei had to invent a new kind of catalyst to help convert biocrude oil into fuel and a new kind of pyrolysis reactor to convert biomass into biocrude oil.

“We try to utilize all this waste to produce renewable liquid biofuels,” Wei said.

A patent has been filed for the catalyst, and it has been licensed to a small innovation company called Thermo Ag. Wei has also used the catalyst to refine non-food grade vegetable oil into JP-8. The catalyst is used to increase the amount of fuel produced from particular feedstocks. For vegetable oil, Wei has been able to attain a yield rate of 50 to 60 percent per liter. The two other types of feedstock Wei has used, sawdust and corn stover, have been able to reach a yield of about 10 percent.

“If we want to make the process work, we have to use some catalysts so we can get higher yields,” Wei said.

The Catalytic Fast Pyrolysis reactor that Wei invented is also licensed to Thermo Ag. Pyrolysis essentially uses heat with very low levels of oxygen to change biomass from one state into another. In the case of Wei’s reactor, biomass like sawdust or corn stover (essentially ground up corn stalks) is transformed into a foul smelling liquid called biocrude oil.

That oil is then processed through a hydrodeoxygenation reactor, which was also developed for Wei’s process. The HDO reactor upgrades the biocrude oil into drop-in fuel that looks and smells very much like gasoline. Though he has so far only worked with sawdust and corn stover, they are not, Wei said, the limit to potential types of feedstock.

“We can convert other feedstock as well,” Wei said. “For example, we got pretty good yield from sawdust; corn stover was a little bit lower. Maybe some type of grass will get higher or lower yields. We try to use everything.”

So far Wei’s work has contributed to as many as five patents that have already been filed.

“If we can commercialize this technology, the university can get license royalties which can directly benefit the university, I believe,” Wei said.

Biofuels research has also helped research in other areas. One of the by-products of Wei’s process is biochar, which is essentially the solid waste left over from pyrolysis. Biochar has been turned by Dr. Zhengrong Gu, an associate professor in agricultural and biosystems engineering, into high quality activated carbon. Gu said that the activated carbon produced from biochar could be used for a number of purposes, not the least of which is in super capacitors.

“We already have some super-activated carbon that can be used in super capacitors,” Gu said.

Biochar, which is very similar to charcoal, is also being researched by a team in the Plant Science Department for use in soil abatement. Dr. David Clay, a professor and member of the research team, said that similar products have been used by people throughout history to improve soil quality, most notably in South America.

“We’re trying to examine what types of properties the biochar has,” said Dr. Thomas Schumacher, a professor in the Plant Science Department who is also in on the research.

Wei’s research, according to Dr. James Julson, a professor in agricultural and biosystems engineering who is working on his own biofuels research project, has the potential to be used by the military for mobile fuel production. Essentially the military could use any locally available biomass to produce its own fuel while deployed.

“That’s a long ways off though,” Julson said.

The work that Wei has done is actually just one part of a much larger family of research at SDSU. That research ranges from feedstock development to transportation and products like super-capacitors and fuel.