As much as we love electric planes here CleanTechnica, a zero-emission flight on any significant scale is still years away. That is why aviation stakeholders are so interested in biofuels. Problems with costs and the supply chain are blocking the way, but a team of American researchers in the Northwest Pacific has just come up with a new solution that could also help the region’s paper industry solve the problem of reducing waste.
Biofuel and lignin, lignin, lignin
Lignin is the solid part of plants that makes them solid. It is also difficult to convert lignin into biofuels and other biologically based chemical products. However, the world is flooded with lignin, due to the process of making paper in which lignin is separated for disposal or reuse. If left inside, the final product turns yellow.
This is a problem because excess lignin is usually burned for fuel, releasing greenhouse gases into the atmosphere.
More lignin could hit the market in the coming years as the wood products industry turns to new, high-tech formulations. For example, back in 2018, a research team at the University of Maryland devised a process to remove lignin from balsa or other soft wood and compress the remaining material.
The resulting material is stronger than steel and could be used to make cars, so maybe the wooden parts of the plane will return one day.
Solving lignin problems with nature
An energy-intensive, chemically based process is a conventional way of breaking down lignin. Researchers are looking for more efficient bio-based systems to do the same thing. The idea is similar to biogas digesters that have become common in recent years. Digestors trigger the natural processes of microbes, which chew soft biomass and release gas.
Digestors, however, are intended for soft biomass such as manure and municipal sludge. Natural digestion is a relatively delicate process that does not affect lignin, so the challenge is to get systems to biology to function in the harsh conditions required to break down lignin.
This brings us to the latest news about lignin from a team of researchers from Washington State University and the Pacific Northwest National Laboratory, which is part of a large network of national laboratories of the US Department of Energy.
The research team came up with a kind of biomimicric solution to the problem. You can get all the juicy details in the diary Nature Communicationsbut for those of you on the move it involves an artificial robo-enzyme that mimics the natural process of breaking down lignin, only better, faster, stronger and longer.
The new enzyme is based on natural enzymes of fungi and bacteria, which are able to break down fallen logs in the forest, lignin and others. The challenge is to get them to pick up the pace and function efficiently in a man-made system, which is almost impossible in their natural state.
“Chemists have tried and failed for more than a century to make valuable lignin products. That record of frustration may change soon, “the laboratory said in a press release on May 31, emphasizing that the new research is based on generations of previous works that have revealed most of the secret life of enzymes.
How does it work?
One key element that the research team invited to play was a protein-like molecule called peptoid, which was developed in the 1990s. Peptoids are a designed version of natural peptides that are present at active sites of the enzyme.
“In the current study, researchers have replaced peptides that surround the active site of natural enzymes with protein-like molecules called peptoids. These peptoids then assembled themselves into nano-scale crystal tubes and sheets, ”the laboratory explained.
Peptoids are more stable and durable than their peptide cousins. As a result, instead of just one active site per enzyme, there may be many more. They can be organized and adjusted with great precision, and can withstand temperatures up to 60 degrees Celsius.
“If a new bio-mimetic enzyme can be further improved to increase conversion yield, to produce more selective products, it has the potential to increase to industrial scale. The technology offers new pathways to renewable materials for aviation biofuels and biofuel-based materials, among other applications, ”the laboratory noted.
So where is all the aviation biofuel?
For those of you leading the results at home, the two relevant study authors are PNNL affiliates and associate professors Xiao Zhang and Chun-Long Chen from WSU, with additional contributions from Tengyue Jian, Wenchao Yang, Peng Mu, PNNL’s Xin Zhang and Yicheng Zhou and Peipei Wang from WSU, through the WSU-PNNL Institute of Organic Products.
Speaking of biofuel for aviation, the flight on vegetable fuel has been coming for a long time. During the Obama administration, tobacco-based aviation fuel seemed ready for commercial development. Algae-based fuel was another upcoming one, and a “cocktail” of cornmeal and other ingredients was in preparation.
The US Department of Energy recently published a list of promising SAF (Sustainable Aircraft Fuel) routes, so keep an eye out for these research projects (list edited for brevity)
- SAF from wet waste: Carbon negative fuel from food waste, animal manure and other waste with high water content.
- Bio-based polycyclic alkane: Bio-acetone upgraded with ultraviolet light and catalysts, made from a range of biomass resources, such as corn stoves or bioenergy crops.
- SAF from carbon-rich waste gases: Waste carbon monoxide from industrial processes, trapped and upgraded by bacteria in ethanol for SAF “alcohol in a jet”.
Widespread commercial use of SAF is yet to come, but momentum is growing and the corn kiln is still in progress (the corn kiln has woody stems, shells and other leftovers left over from the harvest). Yesterday, Southwest Airlines became the latest aviation shareholder to jump into SAF’s corn wagon.
In a project that is a partner of the company with the Department of Energy, Southwest has invested in SAFFiRE Renewables, which comes under the auspices of D3MAX.
“SAFFiRE is expected to use technology developed by the National Renewable Energy Laboratory DOE (NREL) to convert cornstarch, a widely available waste material in the United States, into renewable ethanol that would then be upgraded to SAF,” explains Southwest.
Both of these companies are new to the market CleanTechnica radar. The more famous name appears in the upgrade part of the project, which will be taken over by LanzaJet, a spinoff of LanzaTech. Earlier this year, LanzaJet received $ 50 million from the Microsoft Climate Innovation Fund for its Freedom Pines Fuels plant in Soperton, Georgia, where it will process ethanol from Southwest corn if all goes according to plan. LanzaJet is also supported by the Ministry of Energy, so expect more information about them.
“According to NREL, this could produce significant amounts of cost-effective SAF that could provide an 84 percent reduction in carbon intensity compared to conventional life-cycle jet fuel,” Southwest said.
Lovers of electric planes, do not despair. Southwest predicts it will replace up to 5% of its jet fuel with SAF by 2030, leaving plenty of time for zero-emission airplanes of the future – fuel cells, batteries or both – to use the space for themselves.
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Photo: Lignin biofuel for sustainable waste reduction in the aviation and paper industries courtesy of the Pacific Northwest National Laboratory.
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