The day when planes, trucks and cars are commonly revved up on pond scum may be on the near horizon thanks to a technological advance that continuously turns a stream of concentrated algae into bio-crude oil. From green goo to crude takes less than an hour.
The goo contains about 10 percent to 20 percent algae by weight. The rest is water. This mixture is piped into a high-tech pressure cooker where temperatures hover around 660 degrees Fahrenheit and pressures of 3,000 pounds per square inch to keep the mixture in a liquid phase.
Inside the cooker are "some technology tricks that other people don't have" that help separate the plant oils and other minerals such as phosphorous from the water, Douglas Elliott, a fellow at the Department of Energy's Pacific Northwest National Laboratory in Richland, Wash., told NBC News.
An hour after being poured into the cooker, gravity separates the crude oil from the water as it flows out the other end.
"We can clean up that bio-crude and make it into liquid hydrocarbons that could well serve to displace the gas, diesel and jet [fuel] that we make from petroleum now," he added.
What's more, a further water-processing step recovers methane—essentially natural gas—from the leftover plant material. The remaining nitrogen-rich water and recovered phosphorous can be recycled to grow more algae.
Elliott and colleagues describe the process in a paper accepted for publication in the journal Algal Research. Utah-based biofuels company Genifuel has licensed the technology and is working with an industrial partner to build a pilot plant.
The so-called hydrothermal liquefaction technology that Elliott and his colleagues used to create the bio-crude was pioneered in the 1970s but fell out of favor as researchers focused on developing algae strains that yield high amounts of oil in the form of lipids.