A faster and cost-effective method to convert algae to biocrude

A team of University of Utah chemical engineers has developed a new kind of jet mixer that extracts the lipids with much less energy than the older extraction method, a key discovery that now puts this form of energy closer to becoming a viable, cost-effective alternative fuel. The new mixer is fast, too, extracting lipids in seconds

Packed inside the microorganisms growing in ponds, lakes, and rivers are lipids, which are fatty acid molecules containing oil that can be extracted to power diesel engines. When extracted the lipids are called biocrude. That makes organisms such as microalgae an attractive form of biomass, organic matter that can be used as a sustainable fuel source. These lipids are also found in a variety of other single-cell organisms such as yeasts used in cheese processing. But the problem with using algae for biomass has always been the amount of energy it takes to pull the lipids or biocrude from the watery plants. Under current methods, it takes more energy to turn algae into biocrude than the amount of energy you get back out of it.

Right now, in order to extract the oil-rich lipids from the algae, scientists have to pull the water from the algae first, leaving either a slurry or dry powder of the biomass. That is the most energy-intensive part of the process. That residue is then mixed with a solvent where the lipids are separated from the biomass. What's left is a precursor, the biocrude, used to produce algae-based biofuel. That fuel is then mixed with diesel fuel to power long-haul trucks, tractors, and other large diesel-powered machinery. But because it requires so much energy to extract the water from the plants at the beginning of the process, turning algae into biofuel has thus far not been a practical, efficient or economical process.

The team has created a new mixing extractor, a reactor that shoots jets of the solvent at jets of algae, creating localized turbulence in which the lipids jump a short distance into the stream of solvent. The solvent then is taken out and can be recycled to be used again in the process. This technology could also be applied beyond algae and include a variety of microorganisms such as bacteria, fungi, or any microbial-derived oil.