Scientists at the Department of Energy’s Pacific Northwest National Laboratory (PNNL) in Richland, Washington have figured out how to compress into under an hour a process that normally takes millions of years – the decomposition of organic matter into valuable fuels. With climate change intensifying algal blooms in many parts of the world, perhaps it’s good news that the material that proved perfect for this process was none other than concentrated pond scum.
In the PNNL process, a slurry of wet algae is pumped into the front part of a chemical reactor. The cooker uses temperatures of 660 degrees Fahrenheit and pressures of over 3,000 pounds per square inch to keep the mixture in a liquid phase while it extracts plant oil from the water. Less than an hour later, you have crude oil. The byproducts of the process include nitrogen-rich water and material that contains phosphorus, which can be used to regrow more algae. Additionally, the process can recover methane, or natural gas, from the leftover plant material. Though the cooker continuously processes only about 1.5L per hour right now, the researchers are confident that the technique can easily be scaled up. A biofuels company called Genicorp has licensed the technology and is working on building a pilot plant.
A previous incarnation of this technology, which is called hydrothermal liquefaction, was pioneered in the 1970′s, a time of heightened worries about fuel shortages. It involved drying the algae and adding chemicals to extract lipids, a process that was difficult, energy-intensive and expensive. However, this new technique isn’t perfect either; the fuels created are somewhat different chemically from different petroleum, and we still haven’t figured out how to grow sufficiently huge batches of algae for the energy production we need. And there’s no evidence that this algae’s petroleum burns any cleaner.
Images: PNNL Video