Science doesn't smell sweet in the lab used by Douglas Elliott at Pacific Northwest National Laboratory in Richland.
It has the odor that might be expected from a combination of rotting eggs, dirty socks and burning wood.
In Elliott's lab, a bucket of dark green algae slurry is pumped into a chemical reactor that reaches from floor to ceiling. The complex system of tubes uses intense heat and pressure to break apart solid elements, transforming algae into liquid crude oil in less than an hour.
The process of pressure cooking certain oily algae into biofuel, much as nature does over millions of years, is not a new idea for biofuel researchers. But engineers at PNNL are simulating the method at a much more rapid and continuous rate, churning out several liters of algae oil per day.
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That's hardly enough to make a dent in U.S. oil consumption, which last year reached almost 19 million barrels per day. But companies are showing interest in using PNNL's technology to ramp up to commercial-scale production.
With additional refining, crude oil from algae can be converted into mostly gasoline or diesel fuel. Elliott, the laboratory fellow who led team research on the project, said people should be excited about the long-term potential of fuels from alternative sources like algae.
"We won't be pumping oil forever. We have to figure out a renewable system," Elliott said. "That's what this biomass is all about."
A team of PNNL scientists and engineers, who were part of a consortium across laboratories across the nation, spent about three years exploring ways to efficiently make algae fuel. Cost is still a major hurdle, as most processes require expensive energy to first dry the material.
But the reactor built at PNNL works with a soupy algae paste that's made up of 80 percent to 90 percent water. The system runs at 350 degrees and 3,000 pounds per square inch of pressure to produce water and oil from the algae, a process called hydrothermal liquefaction.
In a sense, the process mimics what happens beneath the Earth's surface over millions of years as algae forced underground is heated and pressurized into petroleum.
And because the system runs continuously, Elliott said it is more energy and cost-efficient than processing dried algae in batches. Leftover water and nutrients can be recycled to grow more algae.
"It's not a perfectly efficient process, but we get a much higher yield of both liquid and gas fuels,"Elliott said. "We aren't adding any special chemicals. It's just heating it up under pressure."
Growing enough algae is another challenge entirely, Elliott said. Algae grows easily, but gathering enough feedstock to meet fuel requirements is difficult, he said.
The good news, Elliott said, is algae can be grown just about anywhere.
"This is the problem we have with biomass," he said. "Getting enough to have any impact, especially when we're just starting out, is very difficult."
PNNL recently published its findings, and a Utah-based company has licensed the technology to build a pilot plant. Genifuel Corp. also has worked with the lab to develop the complementary process turning algae or wastewater into natural gas, known as catalytic hydrothermal gasification.
"This really has been a fruitful collaboration," said Genifuel president Jim Oyler in a statement. "It's a formidable challenge to make biofuel that's cost-competitive with established petroleum-based fuels. This is a huge step in the right direction."