A key to renewable energy could be locked in a tiny, slimy group of floating plants.
A multidisciplinary Kansas University team called the Feedstock to Tailpipe Initiative is striving to find a feasible way to turn algae, the water-dwelling plant common in lakes and ponds, into biofuels. With researchers from several fields coming together, associate professor of chemical and petroleum engineering Susan Williams said the initiative can examine every aspect of biofuel production for solutions.
“I think that’s what makes KU unique in this research,” Williams said.
She said most schools focus on one aspect, such as the creation of biofuels from plants, but not the whole system.
At the beginning of the process is ecosystem ecology professor Val Smith and the algae. In 2009 Smith proved that wastewater from the Lawrence Wastewater Treatment Plant could be used to grow algae. In six of the plant’s treatment tanks he showed that not only can algae be grown, but it actually helps purify the water.
“They’re like biological sponges soaking up what would otherwise go out in the water,” Smith said.
Now he has turned his attention to getting the greatest yield of biomass from the algae. Like any crop, algae have predators; tiny zooplankton are their biggest enemies, Smith said. But unlike farmers who spray their crops with pesticide, Smith can’t use poison to control the invertebrates. He said not only would the chemicals be costly, but they also pose a danger to birds that might land and feed in algae ponds.
“You can’t cover the water with screens,” he said. “So we have to use a bio-control” — a natural element introduced to control pests.
Smith’s recent research has been focused on finding a bio-control. He believes the answer is a tiny freshwater fish called mosquitofish.
“Tanks with fish had three to five times as much algae,” he said.
Treating the algae production as its own ecosystem rather than just as a crop enabled Smith to greatly increase the biomass yield. The fish prey on the zooplankton, which allows the algae to grow in abundance. He said treating the production as a system that can be controlled biologically is unique to the university’s research.
Biomass to biocrude
The next step is to turn the algae into biofuel. Williams said oil is extracted from the algae in two ways: either with chemical solvents that separate the oils or with a process called liquefaction.
“You can think about it as almost being like pressure-cooking the algae,” she said.
During liquefaction, algae and water are placed in a batch reactor and heated to a point where the water does the chemistry itself. At high temperatures, water is able to convert carbohydrates and other molecules inside the algae into oil. Williams said the process is much like how petroleum is created underground through centuries of extreme pressure, but in a much shorter amount of time.
“We get a product that looks very similar to crude,” she said.
Because the algae feedstock is different than what created regular petroleum, she said, it has higher levels of nitrogen and oxygen. Research in the engineering side of the Feedstock to Tailpipe spectrum is focused on the chemical profile of the algae oil. Williams said with the purchase of a new batch reactor, the team can start producing enough oil to study it extensively.
She said there are two options for producing fuel from the algae: The extra nitrogen and oxygen can be removed before the oil is sent to a petroleum refinery, or the oil can be blended with petroleum at the refinery and processed all at once.
“What you get out looks exactly like diesel or gas,” she said. “I would expect the emission profile would look the same.”
From a pollution standpoint algae fuel doesn’t seem like much of an improvement, but Williams said gasoline produced with biofuels tends to have a low level of sulfur, one of the major pollutants in gas.
Not just oil
Smith said algae at the treatment plant purify the water to levels above EPA standards by absorbing nitrogen phosphate from the water. When Williams and her team cook the algae, the compound comes out of the algae in the form of a solid they call biochar. That solid has the potential to also be useful.
“It can be used for fertilizers and other applications,” she said. “And certainly with Kansas being an agriculture state, availability of fertilizer is important.”
Williams said being able to generate multiple products is an attractive feature of the algae-processing technology because it produces a diverse portfolio of products for companies to sell.
“It’s not just the production of fuel. Now we have all these products that can come out of it,” she said.
Williams said with the size of the Lawrence Wastewater Treatment Plant, six to nine barrels of biocrude could be produced a day.
“It’s not a ton, but it’s more than test-tube size,” she said.
She said production of biofuels from algae would begin on a small scale. Algae production would have to use existing resources such as water treatment facilities and be located near bio-refineries that can separate the oil from the algae. Williams said she envisions algae biofuels being a part of a larger energy solution that includes wind, solar and other renewable energies.
“Even if it’s only a billion gallons, it’s a billion gallons helping reduce how much we use petroleum,” she said.