SALT LAKE CITY — A team of University of Utah engineers have found a more efficient way to convert algae into biodiesel, something that could change the landscape of alternative energy.
The research, titled “Algal Lipid Extraction Using Confined Impinging Jet Mixers,” modified the approach to extraction, which saves more energy in the process.
The concept of converting algae into fuel has been around since the 1970s, when scientists would grow algae, dewater it, and extract the oil from lipids using a solvent, explained Swomitra Mohanty, co-author of the study and U. chemical engineering professor.
Lipids are fatty acid molecules that contain oil which can be extracted to make biocrude, the precursor to biodiesel used to fuel diesel-powered engines.
The team used a modified version of an impinging jet mixer that extracts the lipids faster and with significantly less energy usage than the traditional extraction method.
In traditional methods, the drying process used a considerable amount of heat and mechanical energy, and it used more energy in the extraction process than what was extracted from the algae.
In the new approach with impinging jet mixers, none of this energy is required, which reduces the cost and makes the process more eco-friendly.
The algae can go straight from the reactor to the mixer with solvent, at room temperature — eliminating the need for the drying.
"What that does, is that breaks apart the algae and allows the oils to be extracted into the solvent all at once," Mohanty said.
This is game-changing. 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.
–Leonard Pease, U. study co-author
Everything can now be done at ambient temperature, he explained.
That process creates the biocrude, which can then be converted into biodiesel or other fuels such as jet fuel.
"Our goal was to really figure out how to make this kind of process quicker and less expensive so you could use it for a number of applications," Mohanty said.
While using algae as fuel is environmentally friendly, alternative fuel isn't always economically friendly.
"Anything that's environmentally friendly tends to be very expensive," Mohanty said. "This is a piece in a larger puzzle. So what this does, this helps at least the extraction piece of that big puzzle."
Another piece of that puzzle is the algae growing process, something that can be time-consuming and expensive, Mohanty said.
"It's definitely an improvement over traditional methods for this part of the algae biofuel process," he said. "This is a piece of that which is useful in minimizing that cost. It can help reduce the cost of algae, at least the extraction portion."
Utah bodies of water have experienced outbreaks of dangerous algal blooms in recent years, and Mohanty says, in theory, that algae could be converted into biofuel.
Cyanobacteria, found in algae blooms, have lipid oil that could be used for biofuels, according to Mohanty. However, it's likely the toxins would still be in the water, so this method would need to be investigated further, he said.
The hope is to be able to offset dependence on fossil fuels in the future, Mohanty said.
“This is game-changing,” said Leonard Pease, a co-author of the paper, in a news release. “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.”
However, the research doesn't only apply to algae, Mohanty said.
"It's not just for algae, algae just happens to be what we were demonstrating it on," he clarified.
Mohanty said his department focuses on algae and that he doesn't have experience growing other organisms, but he said the reactor can be used for other microorganisms.
"The reactor can be used for more than just algae, you can actually use it in other microorganisms that have oil in it," Mohanty said. "You could take the same technology and extract oils from other things that might be cheaper."
In 2017, renewable energy provided about 11 percent of total U.S. energy consumption, and biomass fuels provided about 5 percent of total primary energy, according to U.S. Department of Energy.
Former U. chemical engineering doctoral student Yen-Hsun Tseng and U. chemical engineering associate professor John McLennan also co-authored the study.