University of Michigan professors are heating and squishing algae in a pressure-cooker that fast-forwards the crude oil making process from millennia to just minutes. It doesn’t have to be algae it could be any wet biomass.
Phillip Savage, an Arthur F. Thurnau Professor in the U-M Department of Chemical Engineering is principal investigator on the $2-million National Science Foundation grant that supports the project. The grant is funded under the American Recovery and Reinvestment Act.
This method is the raw and brutal way to take biomass to oil products. Savage says, “We’re trying to do what nature does when it creates oil, but we don’t want to wait millions of years. The hard part is taking the tar that comes out of the pressure cooker and turning it into something you could put in your car, changing the properties so it can flow more easily, and doing it in a way that’s affordable.”
The U-M researchers pressure-cooker runs contrary to the conventions in algae to fuel processing. The conventional technique involves cultivating special oily types of algae, drying the algae and then extracting its oil. The U-M pressurized hydrothermal process allows researchers to start with less-oily types of algae. The process also eliminates the need to dry it, overcoming two major barriers to large-scale conversion of algae to liquid fuels.
This just might work at scale. Savage said, “This research could play a major role in the nation’s transition toward energy independence and reduced carbon dioxide emissions from the energy sector.” Michigan being car country, the professors are working to understand and improve the process in an effort to speed up development of affordable biofuels that could replace fossil fuels and power today’s engines.
Savage points out the research is using microalgae, the microscopic species of algae: simple, floating plants that don’t have leaves, roots or stems. They break down more easily than other potential biofuel source plants because they don’t have tough cell walls. Algae-based biofuels are carbon-neutral. The algae feed on carbon dioxide in the air, and then return it when the biofuel is burned. Fossil fuel combustion puffs additional carbon into the air without ever taking any back. The process is a net to net planetary carbon cycle system.
“This research could play a major role in the nation’s transition toward energy independence and reduced carbon dioxide emissions from the energy sector,” Savage said.
Savage’s team is also examining the possibility of other new fuel sources such as E. coli bacteria that would feed on waste products from previous bio-oil batches. “The vision is that nothing would leave the refinery except oil. Everything would get reused. That’s one of the things that makes this project novel. It’s an integrated process. We’re combining hydrothermal, catalytic and biological approaches,” said Savage.
Savage describes how the process works – “We make an algae soup, heat it to about 300 degrees and keep the water at high enough pressure to keep it liquid as opposed to steam. We cook it for 30 minutes to an hour and we get a crude bio-oil.” The high temperature and pressure allows the algae to react with the water and break down. Not only does the native oil get released, but proteins and carbohydrates also decompose and add to the fuel yield.
The Michigan team is taking a broad and deep look at this process. They are investigating ways to use catalysts to bump up the energy density of the resulting bio-oil, thin it into a flowing material and also clean it up by reducing its sulfur and nitrogen content.
They’re examining the process from a life-cycle perspective, seeking to recycle waste products to grow new source material for future fuel batches. This doesn’t have to be algae, Savage said. It could be any “wet biomass.” They are working on growing in their experiments’ waste products E. coli that they could potentially use along with the algae in the process.
It’s a substantial team. A long impressive list covering several specialties –
Gregory Keoleian, professor of sustainable systems in the School of Natural Resources and Environment and in the Department of Civil and Environmental Engineering.
Adam Matzger professor in the Department of Chemistry.
Suljo Linic, assistant professor in the Department of Chemical Engineering.
Nina Lin, assistant professor in the departments of Chemical Engineering and Biomedical Engineering.
Nancy Love, professor and chair of the Department of Civil and Environmental Engineering.
Henry Wang, professor in the departments of Chemical Engineering and Biomedical Engineering.
This effort looks very good across the range of chemistry and engineering. It would seem that at the early stage getting scale wouldn’t be much of an issue. Introducing catalysts might complicate things; other innovations could have an impact on scale. But there doesn’t seem to be any major barriers to commercial sized function for now.
The issue of note is the tars that form and the native heavy oil type that the process yields. Both could be resolved at the refinery stage, but the better the quality of the product the better price it would yield. Perhaps there is a satisfying point the professors could find to make commercial scale efforts worth the effort and risk.
What’s not discussed in any detail is the cost to process. That alone would make the news much more valuable. From what’s been described though, the heating and pressurization isn’t going to huge, difficult to estimate expense. That would leave the production, harvesting and transport to a unit the unknown problem or opportunity.