Scientists in the United States have developed a new method for converting algae into crude oil which reduces the time required for the process to under 60 minutes, yet remains both cost-effective and convenient.
Researchers from the US Department of Energy's Pacific Northwest National Laboratory (PNNL) in Richland, Washington, have devised a new technology which essentially replicates the natural processes which led to the formation of the earth's fossil fuels, yet reduces the time span necessary from millions of years to under 60 minutes.
The hydrothermal liquefaction process they have developed involves mixing algae with water and channeling it continuously through a long tube which serves as an extreme pressure cooker, keeping the algae at a temperature of nearly 350 degrees Celsius and pressures of around 3,000 psi.
The algae-water mixture - ideally comprised of 20 per cent algae by weight - is stirred for just 30 minutes while in the tube, which serves to break down its chemical structure and convert it into a bio-oil.
The resulting oil is highly akin to light, sweet crude oil in its chemical composition,and can be subsequently refined into jet fuel, gasoline or diesel. The process also provides the added bonus of generating mineral byproducts which can be put to good use as fertilizers, such as nitrogen, phosphorus and potassium.
Douglas C. Elliott, who led the development of the technology, said the process essentially mimics natural processes which occur over "an unfathomable length of time."
While hydrothermal liquefaction itself is nothing new, having drawn a flurry of scientific attention in the 1970s during the oil crisis, Elliott says the new process that he and his colleagues have developed marks a major advance upon its predecessors in terms of cost and convenience.
Their system is capable of converting algae of varying quality into crude oil, obviating the need to specifically cultivate fuel-grade strains via expensive processes, which invariably require the use of large amounts of sugar and clear closed containers.
According to the PNNL studies, 100 kilograms of algae feedstock will produce 53 kilograms of green bio-oil. While the extreme pressure cooker required for the conversion process does require large amounts of power to operate, Elliott said that the technology still manages to achieve a significant net energy gain via the use of heat recovery features which maximize efficiency via power recycling.
The proprietary technology has already been licensed to Genifuel Corporation, a Utah-based start-up, which plans to swiftly scale-up its implementation to make it better suited to commercial purposes.