Aviation Biofuel Research Kicks Into High Gear

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Airlines around the world consume more than 5 million barrels of jet fuel each and every day. Each gallon of jet fuel creates 21.1 pounds of carbon dioxide, according to the Energy Information Administration. Since there are 42 gallons in a barrel, that works out to be more than 2 million tons a day being added to the atmosphere every day from airplanes. Clearly, reducing or eliminating all that carbon dioxide would be a good thing for the Earth and everyone on it.

One way to do that would be to transition to airplanes that use electricity rather than jet fuel. That’s not as farfetched as it sounds, with major manufacturers like Airbus and Boeing experimenting with electrically powered aircraft. But they are years away and the first ones will be limited to about 300 miles of range — perfect for short hop feeder routes but inappropriate for transcontinental or transoceanic flights.

Biofuel Research At JBEI

Researchers at the DOE’s Joint BioEnergy Institute have just published a paper in the journal Energy & Environmental Scienceentitled “Techno-economic analysis and life-cycle greenhouse gas mitigation cost of five routes to bio-jet fuel blendstocks.” The multi-disciplinary team at JBEI is focused on optimizing each stage of the bio-jet fuel production process.

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According to Science Daily, some researchers specialize in engineering ideal source plants — referred to as biomass — which create a high proportion of carbohydrates and a low proportion of lignin. Others are developing methods for efficiently isolating the carbohydrates in non-food biomass and breaking them into sugar molecules that bacteria can digest, or “bioconvert,” into a fuel molecule.

To obtain the highest possible yield from bioconversion, yet other JBEI researchers are examining which genetic and environmental factors make the modified bacteria more efficient. Once these stages are optimized, JBEI scientists can transition the technologies to commercial partners who may then modify and blend the fuels into ready-to-use products and devise strategies to industrialize the scale of production.

“It’s challenging to electrify aviation using batteries or fuel cells in part because of the weight restrictions on aircraft, so liquid biofuels have the potential to play a big role in greenhouse gas emissions reductions,” says lead author Corinne Scown. “The team at JBEI has been working on biological routes to advanced bio-jet fuel blends that are not only derived from plant-based sugars but also have attractive properties that could actually provide an advantage over conventional jet fuels.”

Biofuels Are More Efficient

One such attractive property is that bio-fuels allow airplanes to fly further on a gallon of fuel than they can using conventional jet fuel. The cost of fuel is the largest component in any carriers profitability equation. Anything that makes airplanes more efficient will be welcome news to airlines.

“Our hope is that early in the research stages, we can at least simulate what we think it would look like if you develop these fuel production routes to the point of maturity,” Scown says. “If you were to push them to the ethanol benchmark — the technology to create ethanol from plant material like corn stalks, leaves, and cobs has been around a long time, and we can ferment sugars with a 90% efficiency — how close would this get us to the market price of petroleum fuels? That is important to know now. Thankfully, the answer is they can be viable. And we’ve identified improvements that need to happen all along the conversion process to make that happen.”

Costs Are Dropping, But Need To Go Lower

At present, the theoretical cost of bio-jet fuel is $16 per gallon. That is far too high to be commercially viable at present, but here’s the good news. When the research began, the cost was more like $300,000 per gallon. Just as solar panels once cost several dollars per watt, the costs are coming down dramatically. Factor in more air miles per gallon and the math gets more attractive. Currently, airlines pay $2.50 per gallon on average for conventional jet fuel.

To explore how bio-jet fuel could bridge the remaining price gap, the research team used complex computer simulations that modeled the necessary technology and subsequent costs of scaled-up production pathways at different efficiency levels and with a range of biomass and chemical inputs. The authors simulated a total of five different production pathways to four distinct fuel molecules.

The results showed that all five pathways could indeed create fuel products at the target price of $2.50 per gallon if manufacturers are able to convert the leftover lignin into a valuable chemical — something JBEI researchers are currently working toward — that could be sold to offset the cost of biofuels. The net price of a gallon of biofuel could be lowered further if airlines were offered even a modest financial credit for emissions reduction.

Following some industry research, the team also found that airlines may be willing to pay a premium of as much as 50 cents per gallon because all four biofuels deliver more energy per unit volume, meaning a plane could fly farther on a tank of the same size.

“The development of plant-based compounds that have a performance advantage over their petroleum-based counterparts is an important factor in determining their marketplace viability,” said Blake Simmons, a co-author and the Chief Science and Technology Officer at JBEI.

The Importance Of Reducing Airplane Emissions

However, as promising as these findings are, getting the biofuel production technology to the gold-standard yields assumed in these simulations will require further advances. “It’s clear that, to get these fuels to commercial viability, we need all hands on deck,” Scown noted. “But this analysis highlights the importance of multi-institutional, integrative research centers like JBEI because no group working on one phase of the process alone can make it happen.”

Such basic research is precisely the kind of long range effort that governments are best at. Yet conservatives reactionaries complain bitterly about spending tax dollars on such investigations and the Trump maladministration has proposed slashing the DOE budget so it can build a wall along the US southern border.

Few things could be more important than finding a way to decarbonize air travel. Why do charter members of the Zero Intelligence Club insist such efforts are part of the “big government” boogeyman they have constructed to protect their vested interests?