Engineers develop fast method to convert algae to biocrude

March 4, 2019, University of Utah
University of Utah chemical engineering assistant professor Swomitra Mohanty, pictured with beakers of algae, is part of a team that has developed a new kind of jet mixer for turning algae into biomass that extracts the lipids with much less energy than the older extraction method. It is a key discovery that now puts this form of energy closer to becoming a viable, cost-effective alternative fuel. Credit: Dan Hixson/University of Utah College of Engineering

Biofuel experts have long sought a more economically-viable way to turn algae into biocrude oil to power vehicles, ships and even jets. University of Utah researchers believe they have found an answer. They have developed an unusually rapid method to deliver cost-effective algal biocrude in large quantities using a specially-designed jet mixer.

Packed inside the microorganisms growing in ponds, lakes and rivers are lipids, which are fatty acid molecules containing oil that can be extracted to power diesel engines. When extracted the lipids are called biocrude. That makes organisms such as microalgae an attractive form of biomass, organic matter that can be used as a sustainable fuel source. These lipids are also found in a variety of other single-cell organisms such as yeasts used in cheese processing. But the problem with using for biomass has always been the amount of it takes to pull the lipids or biocrude from the watery plants. Under current methods, it takes more energy to turn algae into biocrude than the amount of energy you get back out of it.

A team of University of Utah have developed a new kind of jet mixer that extracts the lipids with much less energy than the older extraction method, a key discovery that now puts this form of energy closer to becoming a viable, cost-effective alternative fuel. The new mixer is fast, too, extracting lipids in seconds.

The team's results were published in a new peer-reviewed journal, Chemical Engineering Science X. The article, "Algal Lipid Extraction Using Confined Impinging Jet Mixers," can be downloaded here.

"The key piece here is trying to get energy parity. We're not there yet, but this is a really important step toward accomplishing it," says Dr. Leonard Pease, a co-author of the paper. "We have removed a significant development barrier to make algal biofuel production more efficient and smarter. Our method puts us much closer to creating biofuels energy parity than we were before."

Right now, in order to extract the oil-rich lipids from the algae, scientists have to pull the water from the algae first, leaving either a slurry or dry powder of the biomass. That is the most energy-intensive part of the process. That residue is then mixed with a solvent where the lipids are separated from the biomass. What's left is a precursor, the biocrude, used to produce algae-based biofuel. That fuel is then mixed with diesel fuel to power long-haul trucks, tractors and other large diesel-powered machinery. But because it requires so much energy to extract the water from the plants at the beginning of the process, turning algae into biofuel has thus far not been a practical, efficient or economical process.

"There have been many laudable research efforts to advance algal biofuel, but nothing has yet produced a price point capable of attracting commercial development. Our designs may change that equation and put algal back in play," says University of Utah chemical engineering assistant professor Swomitra "Bobby" Mohanty, a co-author on the paper. Other co-authors are former U chemical engineering doctoral student Yen-Hsun "Robert" Tseng and U chemical engineering associate professor John McLennan.

The team has created a new mixing extractor, a reactor that shoots jets of the solvent at jets of algae, creating a localized turbulence in which the lipids "jump" a short distance into the stream of solvent. The solvent then is taken out and can be recycled to be used again in the process. "Our designs ensure you don't have to expend all that energy in drying the algae and are much more rapid than competing technologies," notes Mohanty.

This technology could also be applied beyond algae and include a variety of microorganisms such as bacteria, fungi, or any microbial-derived oil, says Mohanty.

In 2017, about 5 percent of total primary energy use in the United States came from biomass, according to the U.S. Department of Energy. Other forms of biomass include burning wood for electricity, ethanol that is made from crops such as corn and sugar cane, and food and yard waste in garbage that is converted to biogas. The benefit of algae is that it can be grown in ponds, raceways or custom-designed bioreactors and then harvested to produce an abundance of fuel. Growing algae in such mass quantities also could positively affect the atmosphere by reducing the amount of carbon dioxide in the air.

"This is game-changing," Pease says of their work on algae research. "The breakthrough technologies we are creating could drive a revolution in algae and other cell-derived biofuels development. The dream may soon be within reach."

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Jayarava
3 / 5 (1) Mar 04, 2019
"That fuel is then mixed with diesel fuel to power long-haul trucks, tractors and other large diesel-powered machinery."

It beggars belief that in 2019 we are scrambling to reduce CO2 emissions and pollution from vehicle exhausts (particularly particulates from diesel) and there are scientists trying to ensure that we fail by making cheaper alternatives to fossil fuels.

Da Schneib
1 / 5 (1) Mar 04, 2019
Meh. Until it's energy-positive there's no point. This is like a fusion experiment that "almost" breaks even.
BobSage
5 / 5 (1) Mar 04, 2019
Great, if it can go commercial. Much simpler to fuel existing engines than create electric or hydrogen infrastructure. Why even AOC should be happy with this. With this we can still fly in airplanes, drive our cars, and live in our existing houses.

Now let's hope someone finds a solution to cow farts as well.
unrealone1
3.7 / 5 (3) Mar 04, 2019
Nothing is cheaper than Natural Gas.
Da Schneib
1 / 5 (1) Mar 04, 2019
How about soybeans?
Captain Stumpy
3 / 5 (2) Mar 04, 2019
for anyone interested: "Algal lipid extraction using confined impinging jet mixers"
Yen-HsunTsenga, Swomitra K.Mohantya, John D.McLennana, Leonard F.Pease

https://www.scien...18300029
carbon_unit
5 / 5 (1) Mar 05, 2019
It beggars belief that in 2019 we are scrambling to reduce CO2 emissions and pollution from vehicle exhausts (particularly particulates from diesel)
The main thing is to stop using fossil fuels. Yes, diesel is a terrible technology that needs to go away.
Meh. Until it's energy-positive there's no point. This is like a fusion experiment that "almost" breaks even.
It is a work in progress, not ready for prime time. Why so down on it?? I'm not hep on diesel, but algae could be a good feedstock that can be grown in all sorts of places, even metro areas. I sort of envision the side of a buildings covered with tubes in which algae is grown (climate permitting.) Personally, I think batteries will win out, but they may have a hard time replacing aviation fuel, etc.
Nothing is cheaper than Natural Gas.
A fossil fuel with the associated externalized costs.
Da Schneib
not rated yet Mar 05, 2019
Why so down on it?
The hyperbole.

And the fact it's not at least energy neutral. Not much good making biocrude from algae if you're burning coal to make the electricity to do it.
carbon_unit
5 / 5 (1) Mar 05, 2019
Well, yeah, hype. Who says coal will be used to drive the conversion process? That would be silly. This looks like the kind of thing that could use excess wind or solar power.

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