Algae Asphalt & Fungus Fuel: Progress in Search for Petroleum Replacements

by Michael Keller

Our world is run on the backs of ancient dead things. Like it or not, petroleum is ever present in our lives, and projections show that will continue to be the case until at least 2040.

Around 36 percent of all energy consumed in the U.S. in 2013 came from burning petroleum, which is the naturally occurring flammable liquid found deep underground that is used to make a range of fuels. The country’s reliance on crude is expected to diminish only slightly to 33 percent by 2040, according to the Energy Information Administration’s 2015 forecast.

It’s not just fuel for planes, trains and automobiles that drives our demand for the stuff–it is also the source of chemicals used to make plastics, lubricants and even the binder in asphalt. But getting crude out of the ground can be a messy business that always carries a risk for the environment and human health. And burning it releases long-stored repositories of carbon, nitrogen and sulfur into the atmosphere to wreak havoc on health and climate.

A number of efforts are reporting success at finding sci-fi ways to fuel the future. Learn more about two new projects and see a video and pictures below.

Moving the petroleum demand needle even slightly still requires game-changing innovations on the alternative fuel supply side. Many researchers around the world are rising to the challenge, working to put a dent in petroleum demand by finding better replacements. There’s no such thing as a panacea in engineering, though, and each hopeful advance comes with challenges–the technology can’t be scaled to meet industrial levels of output; price to make the petroleum alternative is stuck above a ceiling that makes it unviable on the market; a new product can’t overcome the inertia of a deeply entrenched petroleum-based industry and infrastructure; or countless others.

Take one example: A large portfolio of advances have come from converting starches and sugars from crops into biofuels, but this path has proven to drive up demand for these crops and competition for fertile farmland. The unacceptable result is climbing food prices. Instead, some are looking to use non-crop plants like switchgrass that happily grow on marginal lands for biofuel feedstock. Others are trying to convert sunlight directly into hydrocarbons while still others are pushing the descendents of the ancient life that makes up fossil fuels–living bacteria, algae and fungi–to produce the valuable liquids.

Recently, two teams announced they’ve made initial progress on their petroleum alternatives projects. meanwhile, thousands of scientists are also continuing to pick away at the problem at labs around the world.

In the first, a group in France say they have produced asphalt using a genus of microscopic freshwater algae called Scenedesmus. This organism has long been used to make dyes for cosmetics and has recently been investigated as a biofuel producer. The team applied hot, pressurized water to residues left over from the cosmetics industry to produce a black, water-repelling and viscous material nearly identical to asphalt. They were able to achieve conversion efficiency of 55 percent.

The bioasphalt goes from liquid at 212 degrees Fahrenheit to an elastic binder when combined with aggregate and cooled. The work was detailed last month in the journal ACS Sustainable Chemistry & Engineering. It has only been tested in the lab so far, but cost-effectiveness studies and field tests are expected in the coming years, study coauthor and the National Center for Scientific Research’s Bruno Bujoli told Liberation.

An economical replacement for the petroleum used to make asphalt wouldn’t be just a drop in the bucket in reducing overall demand for crude. Around 2 percent–a little less than a gallon–of every barrel of oil is converted to asphalt oil. In the U.S. every year, production plants turn out up to 550 million tons of finished asphalt, according to the National Asphalt Pavement Association. The group says roughly 5 percent of its members’ product by weight is asphalt oil, translating to 2.75 million tons of the petroleum product consumed for American roads annually.

(Process for the production of bioasphalt from microalgae. Courtesy of Les films du Cercle Rouge.)

(Aggregate mineral coated and bound in the microalgae-based bioasphalt material. Courtesy of les films du cercle rouge.)

Meanwhile, a team at Washington State University say they’ve achieved initial success getting a genetically modified common black fungus to produce molecular components of jet fuel and other valuable petroleum products. They coaxed the altered Aspergillus carbonarius, a fungus found on fruits and vegetables and commonly in soil, to make hydrocarbons by feeding it an oatmeal diet. They were also able to get smaller amounts of fuel when feeding it things like wheat bran, switchgrass and leftovers from corn production. Interestingly, the oatmeal-based diet led the fungi to produce a wider range of hydrocarbons than the other diets.

Previous research showed that the fungus naturally produce complex hydrocarbons, likely as a chemical defense against bacterial enemies. By learning more about the metabolic pathways the fungus employs to make the hydrocarbons and using genetic engineering, they intend to ramp up production of the molecules.

Lead researcher Birgitte Ahring, the director of the Bioproducts, Sciences and Engineering Laboratory at WSU Tri-cities, says she hopes the process leads to economically viable production of aviation biofuels in five years. If it works, the scientists say, fungus-base fuel could be a low-cost alternative to other replacements because the organisms complete the entire molecular synthesis by themselves. Other microbe-based biofuel production requires several steps to make the finished product. The work was published in April in the journal Fungal Biology.

“It’s very promising,’’ said Ahring. “I think that the fungus-based fuels are something that is going to happen. It’s a tremendous opportunity. ’’



(Birgitte Ahring, director of the Bioproducts, Sciences and Engineering Laboratory at WSU Tri-cities, and Ph.D. student Malavika Sinha look at a new mutant of Aspergillus carbonarius. Courtesy Washington State University.)

Top Image: Process for the production of bioasphalt from microalgae. Courtesy of Les films du Cercle Rouge.