Hatcher, Salmon Apply for Patent on Algae-Crude Technology
Sustainable, large-scale production of biofuels from algae is the quest of researchers all over the globe, and the technologies that win out are sure to be the ones that are the most streamlined and cost-effective. That's the commercial reality behind the patent applications filed over the last few years by geochemist Patrick Hatcher of Old Dominion University and ODU postdoctoral researcher Elodie Salmon, including one that was filed this month.
There are numerous innovations described in the most recent application, but perhaps one of the most important hinges on the word "water."
"No sooner did we file the latest patent application, than the influential online Biofuels Digest ran its list of eight transformational technologies that could 'rock' the biofuels world," Hatcher said. "One of the eight breakthroughs on the digest's dream list involves the problem of extracting algae from the water they grow in, and this is precisely what we have addressed. Our research shows that biofuels can be produced directly from algae-enriched water."
A drag on algae-biofuels production, according to Biofuels Digest, is "the problem of getting the algae out of the water, or the water out of the algae." The publication noted that processes currently used require the removal of 1,000 gallons of water to get a gallon of dry algal biomass. "So even if you are expending just a handful of BTUs per gallon to move the water, you're dangerously close to using more energy to produce algal fuels than the fuel contains," the digest article stated.
Hatcher leads a team of algae-biofuels researchers at ODU and, as executive director of the Virginia Coastal Energy Research Consortium (VCERC), has promoted algal biomass as an energy source. At ODU's Algal Farm near Hopewell, Va., almost three years of research has gone into growing the green, microscopic algae in a specially designed pond, and into harvesting and drying the crop.
Technologies for algae-to-biofuel conversion now focus on extracting the fatty lipids that make up about 15-to-40 percent of algal biomass. Because wet algal cells resist giving up their lipid content, the algae typically are skimmed from water and dried before going into the reactors that produce biodiesel fuel. Since 2006, ODU and VCERC's work with algae has involved almost exclusively the extraction of lipids from dried algae for conversion into a FAME (fatty acid methyl esters) biodiesel fuel. Much of the commercial biodiesel fuel available now is a FAME product made from soybeans.
Hatcher and Salmon expanded the ODU algae-biofuels research more than two years ago by experimenting with another component that is present in some algae, a protective outer wall called algaenan. This biopolymer material - similar to a plastic shell - makes up about 10-to-20 percent of the algal cell.
It has been shown in nature that high heat has converted algaenan into petroleum-like hydrocarbons. In fact, many scientists believe that this recalcitrant material collected in ocean sediments and was compacted and cooked over millions of years to create crude oil deposits. But Hatcher said that when other researchers have simulated the heat and pressure of these natural forces to convert algaenan into hydrocarbons, they have not come up with a product that can be refined into the various fuels that we now get from crude oil.
The ODU team has used a process by which water with enriched amounts of algae in it is "cooked" at about 350 degrees Celsius. This work was done in collaboration with Dr. Michael Lewan at the U.S. Geological Survey in Denver.
"We use a reactor that is something like a pressure cooker you would have in your kitchen,"
Hatcher explained. When the algae-water mixture emerges from the reactor, droplets of an algae-crude oil are floating on top. After the algae-crude is separated, the remaining water can be used as a fertilizer for field crops, he said.
As for the algae-crude, "It's a liquid much like high-quality crude oil, and our tests indicate that it can be refined into gasoline, jet fuel, diesel fuel and so forth," Hatcher added.
Extensive chemical analysis of the different algaenan found in various algae species, and of the hydrocarbons the ODU researchers have created from the algaenan, leads Hatcher to believe that this raw material can be "tuned," as he puts it, for best results. For example, growing conditions of algae might be varied to produce algaenan with a particularly favorable composition for the production of fuel hydrocarbons. The researchers also believe that genetic modification and several other pre-treatments of algaenan will make the resultant algae-crude more like the crude oil found in natural deposits.
Another branch of the algae-biofuels research at ODU continues with the harvesting and drying of algae, followed by the conversion of the algae's fatty lipids into biodiesel fuel. This is accomplished in a new $750,000 instrument that the algal research team has installed at the Algal Farm and dubbed the "Algaenator."
"We should have the commercial advantage of offering a 'threefer,' meaning we get three products from the algae," Hatcher explained. "We get biodiesel from the Algaenator, after which we extract the algaenan to produce algae-crude. Then we use the remaining byproduct from the Algaenator as a fertilizer." That byproduct is the proteins and carbohydrates that - along with lipids and algaenan - make up the algal cell.
An aim of the ODU/VCERC research right from the start was to derive multiple benefits from an algae-biofuel project. With current technology, it is very difficult to produce biodiesel fuel that competes in price with $3-$4 per gallon petroleum 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.