Biofuel breakthrough: Quick cook method turns algae into oil

ANN ARBOR—It looks like Mother Nature was wasting her time with a
multimillion-year process to produce crude oil. Michigan Engineering
researchers can "pressure-cook" algae for as little as a minute and transform
an unprecedented 65 percent of the green slime into biocrude.

"We're trying to mimic the process in nature that forms crude oil with marine organisms," said Phil
Savage, an Arthur F. Thurnau professor and a professor of chemical engineering at the University of
Michigan.

The findings will be presented Nov. 1 at the 2012 American Institute of Chemical Engineers Annual
Meeting in Pittsburgh.

Savage's ocean-going organism of choice is the green marine micro-alga of the genus
Nannochloropsis.

To make their one-minute biocrude, Savage and Julia Faeth, a doctoral student in Savage's lab,
filled a steel pipe connector with 1.5 milliliters of wet algae, capped it and plunged it into 1,100-
degree Fahrenheit sand. The small volume ensured that the algae was heated through, but with only
a minute to warm up, the algae's temperature should have just grazed the 550-degree mark before
the team pulled the reactor back out.

Previously, Savage and his team heated the algae for times ranging from 10 to 90 minutes. They
saw their best results, with about half of the algae converted to biocrude, after treating it for 10 to 40
minutes at 570 degrees.

Why are the one-minute results so much better? Savage and Faeth won't be sure until they have
done more experiments, but they have some ideas.

"My guess is that the reactions that produce biocrude are actually must faster than previously
thought," Savage said.

Faeth suggests that the fast heating might boost the biocrude by keeping unwanted reactions at bay.

"For example, the biocrude might decompose into substances that dissolve in water, and the fast
heating rates might discourage that reaction," Faeth said.

The team points out that shorter reaction times mean that the reactors don't have to be as large.

"By reducing the reactor volume, the cost of building a biocrude production plant also decreases,"
Faeth said, though both she and Savage cautioned that they couldn't say for sure whether the new
method is faster and cheaper until the process is further developed.

Current commercial makers of algae-based fuel first dry the algae and then extract the natural oil.
But at over $20 per gallon, this fuel is a long way from the gas pump.

"Companies know that that approach is not economical, so they are looking at approaches for using
wet algae, as are we," Savage said.
One of the advantages of the wet method is that it doesn't just extract the existing fat from the algae
—it also breaks down proteins and carbohydrates. The minute method did this so successfully that
the oil contained about 90 percent of the energy in the original algae.

"That result is near the upper bound of what is possible," Savage said.

Before biocrude can be fed into the existing refinery system for petroleum, it needs pre-refining to
get rid of the extra oxygen and nitrogen atoms that abound in living things. The Savage lab also is
developing better methods for this leg of biofuel production, breaking the record with a biocrude that
was 97 percent carbon and hydrogen earlier this year. A paper on this work is currently under
review.

Once producing biofuel from algae is economical, researchers estimate that an area the size of New
Mexico could provide enough oil to match current U.S. petroleum consumption. And, unlike corn
produced for ethanol—which already accounts for half that area—the algae won't need to occupy
good farmland, thriving in brackish ponds instead.

The research, "The Effects of Heating Rate and Reaction Time on Hydrothermal Liquefaction of
Microalgae," was funded by the Emerging Frontiers in Research and Innovation program of the
National Science Foundation. The university is pursuing patent protection for the intellectual
property, and is seeking commercialization partners to help bring the technology to market.

Pressure-cooking algae into a better biofuel

Heating and squishing microalgae in a pressure-cooker can fast-forward the

University of Michigan professors are working to understand and improve this procedure in an effort
to speed up development of affordable biofuels that could replace fossil fuels and power today's
engines.

They are 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 Phillip Savage, an Arthur F. Thurnau
Professor in the U-M Department of Chemical Engineering and principal investigator on the $2-
million National Science Foundation grant that supports this project. The grant is funded under the
American Recovery and Reinvestment Act.

"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.
Microalgae are 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, Savage said.

Unlike fossil fuels, algae-based biofuels are carbon-neutral. The algae feed on carbon dioxide in the
air, and this gets released when the biofuel is burned. Fossil fuel combustion puffs additional carbon
into the air without ever taking any back.

The pressure-cooker method the U-M researchers are studying bucks the trend in algae-to-fuel
processing. The conventional technique involves cultivating special, oily types of algae, drying the
algae and then extracting its oil.

The hydrothermal process this project employs 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 microalgae to liquid fuels.

"We make an algae soup," Savage said. "We 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.

"We're trying to do what nature does when it creates oil, but we don't want to wait millions of years,"
Savage said. "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."

Savage and his colleagues are 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.

Furthermore, 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. colithat they could potentially use along with algae.

Other collaborators are: 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; and Henry Wang, professor in the departments of Chemical Engineering
and Biomedical Engineering.