Peptoids Add Spice To New Biofuel Formula For Aircraft & More

As much as we love electric airplanes over here at CleanTechnica, zero emission flight at any significant scale is still years away. That’s why aviation stakeholders are so keen on biofuel. Cost and supply chain issues block the way, but a team of US researchers in the Pacific Northwest has just come up with a new solution that could also help the region’s paper industry solve its waste reduction problem.

Biofuel & Lignin, Lignin, Lignin

Lignin is the tough part of plants that makes them, well, tough. It’s also tough to convert lignin into biofuel and other bio-based chemical products. While, the world is awash in lignin, party due a paper-making process in which lignin is separated out for disposal or re-use. If left in, it turns the final product yellow.

That’s a problem because excess lignin is typically burned for fuel, releasing greenhouse gases into the atmosphere.

More lignin may surge into the market in future 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 came up with a process for removing the lignin from balsa wood or other soft woods, and compressing the remaining material.

The resulting material is stronger than steel and could be used to make cars, so perhaps wooden airplane parts will make a come back, some day.

Solving The Lignin Problem With Nature

An energy intensive, chemical-based process is the conventional way to break down lignin. Researchers have seeking more efficient bio-based systems for doing the same thing. The idea is similar to the biogas digesters that have become commonplace in recent years. Digesters deploy the natural processes of microbes, which chew through soft biomass and pop out gas.

Digesters, though, are meant for soft biomass like livestock manure and municipal sewage sludge. Natural digestion is a relatively gentle process that does not work on lignin, so the challenge is to get bio-based systems to function under the harsh conditions needed to break down lignin.

That brings us to the latest lignin news from a team of researchers with Washington State University and Pacific Northwest National Laboratory, which is part of the US Department of Energy’s sprawling network of national labs.

The research team has come up with a sort of biomimicry solution to the problem. You can get all the juicy details in the journal Nature Communicationsbut for those of you on the go it involves an artificial robo-enzyme that mimics the natural process of lignin breakdown, only better, faster, and stronger, and longer.

The new enzyme is based on the naturally occurring enzymes of fungi and bacteria, which are capable of making fallen logs decompose in the forest, lignin and all. The challenge is getting them to pick up the pace and function efficiency in a human-made system, which is all but impossible in their natural state.

“Chemists have tried and failed for more than a century to make valuable products from lignin. That track record of frustration may be about to change,” the lab enthused in a press release dated May 31, by a way of emphasizing that the new research builds on generations of previous work that exposed much of the secret life of enzymes.

How Does It Work?

One key element the research team called into play is a protein-like molecule called a peptoid, which was developed in the 1990s. Peptoids are an engineered version of the naturally occurring peptides that are present at the active sites of enzymes.

“In the current study, the researchers replaced the peptides that surrounded the active site of natural enzymes with protein-like molecules called peptoids. These peptoids then self-assembled into nanoscale crystalline tubes and sheets,” the lab explained.

Peptoids are more stable and durable than their peptide cousins. As a result, instead of just one active site per enzyme there can be many more. They can be organized and tuned with great precision, and they can withstand temperatures up to 60 degrees Celsius.

“If the new bio-mimetic enzyme can be further improved to increase conversion yield, to generate more selective products, it has potential for scale up to industrial scale. The technology offers new routes to renewable materials for aviation biofuel and biobased materials, among other applications,” the lab observed.

So, Where Is All The Aviation Biofuel?

For those of you keeping score at home, two corresponding authors on the study are PNNL affiliates and associate professors Xiao Zhang and Chun-Long Chen of WSU, with additional contributions from Tengyue Jian, Wenchao Yang, Peng Mu, Xin Zhang of PNNL and Yicheng Zhou and Peipei Wang of WSU, throu the WSU-PNNL Bioproducts Institute.

Speaking of aviation biofuel, plant-fueled flight has been a long time coming. During the Obama administration, tobacco-based aviation fuel seemed ready for commercial development. Algae-based fuel was another up-and-comer, and a “cocktail” of corn stover and other ingredients was also in the works.

The US Department of Energy recently posted a list of promising SAF (sustainable aviation fuel) pathways, so keep an eye on these research projects (list edited for brevity)

  • SAF from wet waste: A carbon-negative fuel from food waste, animal manure, and other wastes with high water content.
  • Bio-based polycyclic alkane: Bio-acetone Upgraded with ultraviolet light and catalysts, made from a range of biomass resources, like corn stover or bioenergy crops.
  • SAF from carbon-rich waste gases: Waste carbon monoxide from industrial processes, captured and upgraded with bacteria into ethanol for “alcohol-to-jet” SAF.

Widespread commercial use of SAF is still a long time coming, but the momentum is building and corn stover is still in the running (corn stove is the woody stalks, husks, and other debris left over from harvest). Just yesterday Southwest Airlines became the latest aviation stakeholder to hop on the corn stover SAF bandwagon.

In a project that partners the company with Energy Department, Southwest has invested in the firm SAFFiRE Renewables, which comes under the umbrella of D3MAX.

“SAFFiRE is expected to utilize technology developed by the DOE’s National Renewable Energy Laboratory (NREL) to convert corn stove, a widely available waste feedstock in the US, into renewable ethanol that then would be upgraded into SAF,” Southwest explains.

Both of those companies are new on the CleanTechnica radar. A more familiar name pops up in upgrading part of the project, which will be undertaken by LanzaJet, a spinoff of the company LanzaTech. Earlier this year LanzaJet received $50 million in funding from the Microsoft Climate Innovation Fund for its Freedom Pines Fuels plant in Soperton, Georgia, where it will process Southwest’s corn stover ethanol if all goes according to the plan. LanzaJet is also supported by the Department of Energy, so expect to hear more about them.

“According to NREL, this could produce significant quantities of cost-competitive SAF that could provide an 84 percent reduction in carbon intensity compared to conventional jet fuel on a lifecycle basis,” Southwest enthuses.

Electric aircraft fans, don’t despair. Southwest anticipates replacing up to 5% of its jet fuel with SAF by 2030, plenty of time for the zero emission aircraft of the future — fuel cell, battery, or both — to carve out space for themselves.

Follow me on Twitter @TinaMCasey.

Photo: Lignin biofuel for sustainable aviation and paper industry waste reduction courtesy of Pacific Northwest National Laboratory.



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