Hatcher Team Creates New Process to Boost Biofuel Production from Algae
Just when you're sure that algae are a good source of biodiesel fuel, along comes a new scheme to wring even more alternative energy from the green scum.
During the past five years, researchers at Old Dominion University have devised ways to cultivate and harvest microscopic algae, and then to convert them into a biodiesel fuel by a proprietary one-step process. Now they have discovered another process - which they also hope to patent - that produces a versatile, algae-based liquid similar to crude oil.
Patrick Hatcher, the ODU Batten Endowed Chair in Physical Sciences and the executive director of the Virginia Coastal Energy Research Consortium (VCERC), said in an interview Friday, Aug. 20, that this new oil he and collaborators are producing can be refined into gasoline and jet fuel, as well as diesel fuel.
Furthermore, Hatcher said the new oil is derived from a biopolymer in the algal cell wall, and not from the fatty lipids that are extracted for biodiesel fuel. In other words, from the same batch of algae, the researchers can extract a vegetable oil-like biodiesel fuel as well as another oily substance that is quite different.
"It's a twofer, actually a 'threefer,'" Hatcher said, referring to the way the one sample of algae can now turn out two types of liquid fuels, as well as a protein-rich by-product that can be used as animal feed.
Proteins, which can make up 25 to 50 percent of algal cellular matter, are an impediment to scientists looking for ways to produce oils from the microorganisms. Hatcher's research team is using a proprietary chemical treatment to strip the proteins from algal cells. "This technique is very commonly used in biomedical research to extract proteins so they can be studied," Hatcher explained.
So without having to use a lot of energy in an extra step to extract the proteins, the researchers are employing the chemical treatment to prepare the algae for a thermal process called pyrolysis, which frees the biofuels.
The result of their new process is a liquid much like high-quality crude oil, according to Hatcher. "It's actually better than the light sweet crude you get from Saudia Arabia. It doesn't have the nitrogen and sulfur molecules and is low in, or maybe free of, oxygen."
"An oil company would hug you if you shipped this oil" to its refinery, Hatcher added. "Nitrogen poisons refinery catalysts as well as catalytic converters (in automobile exhaust systems). Oil companies spend billions to reduce nitrogen in fuel."
Since 2006, the thrust of ODU's and VCERC's work with algae has been the extraction of lipids for conversion into a FAME (fatty acid methyl esters) biodiesel fuel. Most of the current commercial biodiesel fuels are FAME products made from soybeans, although a one-acre algae pond has been shown to produce more biofuels per year than one acre of soybeans.
A portion of the algae left behind after this conversion process is a biopolymer from the cell walls of algae called algaenan. It has some properties of plastic, or polyethylene. Hatcher believes it is actually a type of polyester. Whatever it is, it is the sturdy stuff - similar to a skeleton or shell - that enables algae to show up in the fossil record.
For three decades or so, researchers have known that algaenan exists in the cell walls of some, but not all, algae species. The type of algae that the Hatcher team has settled upon for its experiments - Scenedesmus spp.- does have the algaenan, although the species was chosen mostly because its lipid content is adequate and it is a hearty species found naturally in Virginia and North Carolina.
Researchers elsewhere also have shown that algaenan can be cooked in the presence of little or no oxygen - the technique called pyrolysis - producing gases that can be condensed into hydrocarbons. Before pyrolysis can be conducted, however, the algaenan needs to be separated from other parts of the algal biomass, such as proteins.
Ways previously published by other scientists to separate out the algaenan were found wanting by the Hatcher research team. That's when Isaiah Ruhl, a research associate on the Hatcher team, suggested the new chemical treatment, for which he and Elodie Salmon, also an ODU research associate, are preparing a patent application.
Hatcher said the new process overcomes a common problem with the pyrolysis of algae. "The pyro problem has been the tars, the crud, in the final product."
Another strong advantage of the new process is the fact that it can be applied to wet algae. In ongoing ODU/VCERC biodiesel experiments, the algae that the researchers have grown at the ODU algal farm near Hopewell has been dried before it was fed into a device called an algaenator that extracted the FAME products. Wet algae cells resist giving up their lipid content. Unfortunately, drying the algae is a time- and energy-consuming process that detracts from the economic viability of algae-to-biodiesel conversion.
Hatcher said the recent discoveries will not bring a phase-out of the original line of biodiesel research that focused only on FAME extraction from dried algae. The research team is in the process of upgrading the algaenator that is designed for that original work. "Our goal still is to get that algaenator set up and to measure the economics of FAME biodiesel production and evaluate that process thoroughly," he said.
It would be possible, he pointed out, to go through the FAME biodiesel-producing procedures and then to apply the new process to the algal biomass byproduct, which would separate out proteins and leave the researchers with algaenan. Then pyrolysis could turn the algaenan into the versatile oil.
This versatile oil, which so far at ODU has been produced only in quantities of a few ounces, is being tested this month on an instrument recently purchased by the university that simulates the distillation outcome for a particular oil. In other words, it shows the quality and types of products that a refinery could get from the oil. "So far, the results are very promising," Hatcher said.
The research team has begun conversations with the U.S. Department of Defense officials, who are eager to find alternative and sustainable sources of "green" fuels, including the jet fuel that could be refined from the versatile oil. "They were very excited by what we had to tell them," Hatcher said.
One aim of the ODU/VCERC research has been to get multiple benefits from the algae-to-biofuel process. With current technology, it is very difficult to produce biodiesel fuel that competes in price with $3 per gallon petrol diesel. But the "threefer" outcome described by Hatcher could go a long way toward changing that.
ODU/VCERC has also shown that algae can grow well in wastewater treatment plant effluent, taking in nutrients that could harm the environment if the effluent were released into open waters. Another benefit is that algae take in carbon dioxide as they grow, helping to sequester a gas that has been linked to global warming.
"A goal of our Virginia research consortium is to offer a value-added biofuel product by developing a commercial process in which the algae we need for biofuels are grown in nutrient-rich wastewater. We want to produce not only a 'green' fuel, but also marketable by-products that would help algal biofuels compete in the marketplace," Hatcher said in an interview last year. These by-products could include valuable carbon credits for carbon dioxide sequestered by the algae.
Therefore, the total product would be 1) renewable biofuels that would be produced locally and economically competitive with fossil fuels, 2) fuel that would produce carbon emissions lower than those for fossil fuels, with the aim of producing a zero net carbon emission fuel, 3) animal feed or fertilizer, 4) cleaner coastal waters and 5) marketable credits for removal of nutrients and carbon dioxide from discharges and emissions.
In addition to ODU, where VCERC is based, the consortium includes researchers from Hampton University, James Madison University, Norfolk State University, Virginia Tech, the University of Virginia, Virginia Commonwealth University and the College of William and Mary's Virginia Institute of Marine Science. For more information, visit www.vcerc.org.
Published on: August 20, 2010