Microalgae techniques developing for biofuels in Spain

[Spain] Andrew Mourant writes in RenewableEnergyFocus.com about three advancing microalgae research projects that hold promise for commercial applications. A five-year project based in Spain to create energy from algae grown using wastewater has attracted €7 million of EU funding
Coordinated by global water management company Aqualia, it involves partners from Germany, Austria and the Netherlands, and is driven by scientific research from the University of Southampton in the UK.

After anaerobic pre-treatment to maximize biogas production, wastewater is further purified by the growth of algal biomass. Harvested algae is treated for extraction of oils and other by-products, while the remaining algal biomass is turned into biomethane, CO2 and minerals, together with residual biomass from wastewater and/or agriculture.

“This current prototype confirms all the results we’ve had in the preliminary phases on the pilot ponds,” said Frank Rogalla, who serves as research coordinator and director of innovation and technology at Aqualia. “Now the whole chain will be integrated and (ready to power) the first car by the end of the year.”

Rogalla expects that each cultivated hectare will be able to fuel three cars “of average size” with algae biomethane, assuming each travels 15,000 kilometers a year. “We’re also producing biogas from raw sewage before the algae treatment, which should roughly double the methane production,” he added.

“After the end of the project, we hope that the client, the municipality of Chiclana, will continue to operate the facility, as it will be a self-sustainable system. This biofuel could also be transformed into electricity with a CHP (combined heat and power) engine.”

In the US, scientists at Iowa University’s Center for Sustainable Environmental Technologies (CSET) have pursued catalytic pyrolysis – a thermochemical conversion process – of microalgae as their way forward. They see it as a less energy-intensive and more economical method of producing petrochemicals and ammonia.

“We thought it interesting to evaluate microalgae as a feedstock for pyrolysis because it’s so different,” said Robert C. Brown, CSET Director at Iowa University. “Microalgae also contain significant levels of lipids and proteins, which occur in only low concentrations of lignocellulose.”

Brown’s research team was able to pyrolyze the microalgae, but the nitrogen from the protein ended up as undesirable compounds in the bio-oil, he explained. That’s when they decided to investigate catalytic pyrolysis. “We found it produced hydrocarbons that were both oxygen- and nitrogen-free, which is very attractive from the standpoint of production of fuels.”

Brown’s team chose to work with Chlorella vulgaris, a green microalga low in lipids. “When we discovered that it could convert virtually all microalgae components (including the protein) into hydrocarbons, we realized that what was important was overall yield — not simply lipid yield,” Brown explained. “It turns out that overall biomass yield goes down as lipid content goes up, so the best choice of feedstock is often lipid-lean microalgae.”

And in a program that began in 2007 at Scripps Institution of Oceanography, UC San Diego, Dr. Mark Hildebrand’s team of marine biology researchers have manipulated algae genetically to improve the yield of key components for biofuel production. The Scripps team believes that diatoms — among the most prevalent oceanic algae — are “uniquely suited” to biofuel production. That they can be grown in sea water is a big bonus in drought-prone areas such as California, for it relieves pressure on fresh water supplies.

Their key discovery is the possibility of “turning off” an enzyme in diatoms that breaks down lipids for energy. This enables algae to accumulate more lipids without slowing their growth. Hildebrand believes his team has conquered a major obstacle to algae biofuel production.

 

Photo caption: Aqualia wastewater treatment facility in Spain

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