Synthetic fuels from renewable energies are necessary to achieve climate goals in transport.&nbsp;The so-called reFuels promise a CO 2 reduction of up to 90 percent&nbsp;compared to conventional fuels.&nbsp;In order to be able to cover future needs in heavy goods, air and ship traffic, as well as for the supply of basic materials to the chemical industry, we need appropriate industrial plants.&nbsp;In the REF4FU project, researchers at the Karlsruhe Institute of Technology (KIT) and their partners now want to find out how many reFuels are actually required and what the green refineries of the future will have to be like in order to provide them reliably.&quot;Even with increasing electromobility in the transport sector, liquid fuels will still be needed for a long time,&quot; says Professor Nicolaus Dahmen from the Institute for Catalysis Research and Technology (IKFT) at KIT, who heads the &quot;Refineries for Future&quot; (REF4FU) project.&nbsp;Because: &ldquo;Today, only 60 percent of the fuel flows into individual car traffic.&rdquo; Anyone who speaks of combustion engines is therefore only talking about car engines.&nbsp;That is why the project is now about developing, testing and standardizing completely renewable fuels for all areas of transport, which can also be used by the vehicles in the existing fleet on the road, on water and in the air.<h2>Renewable raw materials are the starting point</h2>The starting point is sustainably produced hydrogen, pyrolysis oil from organic residues such as straw or residual wood, methanol from renewable raw materials and Fischer-Tropsch oil, which corresponds to green crude oil.&nbsp;&quot;The advantage is that these products can be transported, stored and traded like crude oil is today,&quot; explains Dahmen.&nbsp;In addition, green crude oil is also used in the chemical industry, for example for the production of plastics.<h2>Market ramp-up scenarios</h2>ReFuels are already being manufactured, albeit on a pre-industrial scale: &quot;There are already corresponding processes and also large pilot plants that are technically mature and are already producing tons of synthetic fuel,&quot; says Dahmen.&nbsp;It is unclear how the fuels are to get onto the market and thus to the customers.&nbsp;&quot;We can&#39;t just stand on the side of the road with a barrel to sell it,&quot; says Dahmen.&nbsp;In order to find out when and where which amounts of synthetic petrol, diesel or kerosene are needed, the researchers work with scenarios.&nbsp;In doing so, they take into account, for example, the political goals regarding the electrification of car traffic or the expected development in the various transport sectors.&nbsp;&quot;Accordingly, petrol will probably be the first to disappear from the market,&quot;&nbsp;believes Dammen.&nbsp;This in turn will have an impact on the design of future production capacities.The REF4FU joint project coordinated by KIT is funded with around 7 million euros by the Federal Ministry for Digital Affairs and Transport. In addition to institutes of the KIT (IKFT, IMVT, EBI-ceb, IFKM, IIP), partners are the DLR - German Aerospace Center, the German Biomass Research Center (DBFZ), the Technical University Bergakademie Freiberg and the Chemical Plant Engineering Chemnitz, the BASF, EDL Anlagenbau and Ineratec; the refinery MiRO, Porsche and ASG are associated partners.

Renewable liquid fuels are urgently needed even with increasing electrification for heavy goods, air and ship traffic (Photo: Markus Breig, Amadeus Bramsiepe, KIT)

Alliance of science and industry designs processes and demand scenarios for mass production of synthetic fuels - Federal government provides funding of around 7 million euros

Renewable Fuels from Green Refineries

The study suggests a process for creating paper bags durable enough to be used multiple times and then broken down chemically by an alkaline treatment to be used as a source for biofuel production, according to researcher <a href="https://abe.psu.edu/directory/dec109" target="_blank">Daniel Ciolkosz</a>, associate research professor of agricultural and biological engineering.&ldquo;When the primary use of these paper products ends, using them for secondary purposes makes them more sustainable,&rdquo; he said. &ldquo;Recycling and reducing paper waste also helps in reducing total solid waste destined for landfills. This is a concept we think society should consider.&rdquo;<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1681253131928-paper-bag-pexels-lisa-fotios.jpg" style="width: 766px;" class="fr-fic fr-dib">Paper bags are a popular alternative to plastic bags to reduce the environmental impacts caused by using plastics, but paper bags have short lifespans due to their low durability, particularly when wet. Credit:&nbsp;Lisa Fotios/Pexals.&nbsp;All Rights Reserved.&nbsp;Lead researcher <a href="https://abe.psu.edu/directory/jxt380" target="_blank">Jaya Tripathi</a>, who will graduate from Penn State this spring with a doctoral degree in biorenewable systems and has accepted a position at the Joint BioEnergy Institute in California, devised an innovative process in which cellulose in paper is torrefied, or roasted in an oxygen-deprived environment, to greatly increase its tensile strength when wet.Paper bags are a popular alternative to plastic bags to reduce the environmental impacts caused by using plastics, she explained, but paper bags have short lifespans due to their low durability, particularly when wet. And a paper bag must be reused several times to reduce its global-warming potential to below that of the conventional high-density polyethylene bag, Tripathi added.&ldquo;Reuse is mainly governed by bag strength, and it is unlikely that a typical paper bag can be reused the required number of times due to its low durability upon wetting,&rdquo; she said. &ldquo;Using expensive chemical processes to enhance wet strength diminishes paper&#39;s ecofriendly and cost-efficient features for commercial application, so there is a need to explore non-chemical techniques to increase the wet strength of paper bags. Torrefaction could be the answer.&rdquo;<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1681253157554-bag-veggies-marco-verch-flickr-fixed.jpg" style="width: 766px;" class="fr-fic fr-dib">By switching to stronger, reusable paper shopping bags, a large volume of plastic waste could be eliminated, the researchers suggest..&nbsp;Credit:&nbsp;Marco Verch/Flickr.&nbsp;All Rights Reserved.&nbsp;Because torrefaction decreased the glucose yield in the paper, she then treated the paper with a solution of sodium hydroxide, also known as lye or caustic soda, that increased its glucose yield, making it a better source for biofuel production.In&nbsp;<a href="https://www.sciencedirect.com/science/article/abs/pii/S0921344923000198" target="_blank">findings recently published in Resources, Conservation and Recycling</a>, using filter paper as the medium, the researchers reported that the wet-tensile strength of the paper increased by 1,533%, 2,233%, 1,567% and 557% after torrefaction for 40 minutes at 392 degrees Fahrenheit, 428 F, 464 F and 500 F, respectively.Glucose yield decreased with increased torrefaction severity, but after treating torrefied paper samples with an alkaline sodium hydroxide solution, glucose yield increased, the researchers noted. For instance, the glucose yield of raw filter paper was 955 mg/g of substrate, whereas it was 690 mg/g of substrate for the same paper sample torrefied at 392 F. The glucose yield increased to 808 and 933 mg/g of substrate with 1% and 10% alkaline treatment, respectively.The need for a concept like the one demonstrated by the researchers to replace plastic bags is obvious, Tripathi pointed out. According to the U.N. Environment Programme,&nbsp;<a href="https://www.unep.org/interactives/beat-plastic-pollution/" target="_blank">5 trillion plastic bags are produced worldwide annually</a>. It can take up to 1,000 years for these bags to disintegrate completely. Americans throw away 100 billion bags annually &mdash; the equivalent to dumping nearly 12 million barrels of crude oil.&ldquo;By switching to stronger, reusable paper shopping bags, we could eliminate much of that waste,&rdquo; Tripathi said. &ldquo;The implications of a technology like the one we demonstrated in this research &mdash; if it can be perfected &mdash; including using the worn-out bags as a substrate for biofuel production, would be huge.&rdquo;Like many scientific discoveries, Tripathi learned about the synergy of torrefaction and alkaline treatment for increased paper capabilities by accident.&ldquo;I was looking into something else, studying how torrefaction impacts cellulose for glucose yield for use as a biofuel substrate,&rdquo; she said. &ldquo;But I noticed that the paper&rsquo;s strength was increasing as we torrefied the cellulose. That made me think that it probably would be good for packaging, an entirely different application.&rdquo;Contributing to the research was Daniel Sykes, teaching professor of chemistry.This research was supported by the U.S. Department of Agriculture&rsquo;s National Institute for Food and Agriculture.

As the world searches for ways to reduce the use of plastics such as single-use plastic bags, a novel study by Penn State researchers demonstrates a process to make paper bags stronger — especially when they get wet — to make them a more viable alternative.

Stronger paper bags, reused repeatedly then recycled for biofuel could be future

The transformation of the transportation sector for a sustainable future requires further reductions in CO2 emissions. This also calls for newer, more sustainable fuels. Such fuels can be subdivided into biofuels on the one hand, made from waste and refuse materials, and electricity-based fuels (eFuels) on the other, which are made from carbon dioxide (CO2) and water using renewable electric energy (Power-to-X technology). The objective of the Synergy&nbsp;Fuels&nbsp;project is to combine the production of biofuels with the production of eFuels and to develop the corresponding integrated refinery concept. This novel material-based and energy-based integration of existing concepts using biogenic waste materials, CO2&nbsp;and renewable energy is to make the production of sustainable fuels more efficient and thus to drive the future-oriented transformation of the transportation sector.<a target="_blank"></a><header><h2>&quot;There&#39;s no easy answer to sustainability&quot;</h2></header>TUMCS Rector Prof. Volker Sieber, member of the project as head of the Professorship for Chemistry of Biogenic Resources, explains why synergies among various technologies in the area of sustainable transportation development are decisive: &quot;Varying local circumstances and differing fields of application make it necessary for us to rely on more than one individual technology &ndash; there&#39;s no single silver bullet for moving sustainability ahead in the transportation sector. That&#39;s why we&#39;re focusing on the combination of thermochemical, electrochemical and biotechnological processes.&quot; The Synergy Fuels project focuses particularly on transportation areas in which the reduction of greenhouse gas emissions is difficult to achieve for a number of reasons, for example the difficulty involved in electrifying air transport. The collaboration among the project partners in this field is strongly accelerating technology and innovation transfer, so that project results can be ultimately applied in practice. &quot;The technological maturity needed for market entry and actual implementation is within the scope of our research and is ensured by the involvement of partners from the industrial sector,&quot; says Jakob Burger, who holds the Professorship for Chemical Process Engineering at the TUM Campus Straubing and is the acting project coordinator.<a target="_blank"></a><header><h2>TUM Campus in Straubing is the strongest project partner</h2></header>Six professorships at the TUM Campus in Straubing are receiving 5.7 million euros, the largest share of the funding. As a TUM Integrative Research Center, TUMCS covers interdisciplinary research and teaching on the realization of a sustainable resource and energy transformation and is thus ideal for this type of collaborative project. The joint work performed by the project partners is being institutionalized in the founding of a research center for renewable fuels.

In a laboratory at TUM Campus Straubing researchers are working on fermentation of renewable resources and to develop sutainable biofuel production processes.

Technical University of Munich (TUM) is working on alternative, climate-neutral fuels for use in transportation. Together with partners from industry and science, six TUM professorships at the TUM Campus Straubing for Biotechnology and Sustainability (TUMCS) have received funding from the German Federal Ministry of Transport and Digital Infrastructure for the Synergy Fuels project. Over a period of four years, the support will total of 13.6 million euros, 5.7 million euros of which are earmarked for TUM.

TUM researching climate-neutral fuels for the transportation sector

<section id="isPasted">&ldquo;I have food companies asking me: What can you make? My answer is: What do you want me to make? We can make anything.&rdquo;These are the words of Associate Professor Jos&eacute; L. Martinez, who conducts research and teaches precision fermentation at DTU, and he sums up the past decade&#39;s fast-paced development of a technology that can help the world to a more sustainable production of just about anything.Egg whites, cheese, yogurt, milk, vitamins, fragrances, colouring agents, flavour additives, vaccines, and cancer and malaria medicine are just some of the things that are manufactured today using components produced with precision fermentation.Fermentation is a word that most people probably associate with the process of producing beer, bread, sauerkraut or its &lsquo;hip&rsquo; counterpart of the East, kimchi. Fermentation utilizes microorganisms such as bacteria and yeasts that already exist in nature. And this is exactly where fermentation differs from precision fermentation. Because the microorganisms involved in precision fermentation are designed for the specific purpose, says Jos&eacute; L. Martinez:&ldquo;In precision fermentation, microorganisms such as bacteria, fungi, microalgae, or yeast cells are utilized to produce the substances we need. But in order to get the organisms to produce the substances, they must first undergo a couple years&rsquo; development work in a laboratory where they are specially designed using genetic engineering.&rdquo;<h2>CRISPR changed everything</h2>One of the most important tools for this redesign is CRISPR. Simply put, CRISPR can be used to &lsquo;cut&rsquo; out genes of a plant or another living organism and insert them into a new cell. The inserted gene contains the code for the substance to be manufactured. If the process is successful, the genetically modified cell can now produce the substance.Precision fermentation has been known for decades, and Novo Nordisk has long utilized it to produce insulin. But the field has skyrocketed over the past decade due to the CRISPR technology, which became available in 2012.&ldquo;Before CRISPR, genetic modification of a microorganism was a difficult, slow, and boring process, and only possible with a few organisms. With CRISPR, it suddenly became easier, and we can now insert genes into a wider variety of microorganisms,&rdquo; says Jos&eacute; L. Martinez, who had to give up modifying a type of yeast cell himself before the birth of the CRISPR technology, despite four years of strenuous efforts. With CRISPR, Martinez and his colleague at DTU Bioengineering, Professor Uffe Hasbro Mortensen, succeeded in modifying the cell in two years.<blockquote id="isPasted"><cite>Before CRISPR, genetic modification of a microorganism was a difficult, slow, and boring process, and only possible with a few organisms. -&nbsp;</cite>ASSOCIATE PROFESSOR JOS&Eacute; L. MARTINEZ, DTU BIOENGINEERING</blockquote></section><section><h2>Achilles heel of the technology</h2>Although it is technologically possible to have microorganisms produce anything in a laboratory, the Achilles heel of precision fermentation is scaling up the process. Upscaling is about increasing the production of a given substance from a few milligrams in the laboratory to a yield of several tons in a factory. This means extra work for the researchers.&ldquo;We can make anything in the laboratory, but as soon as we scale up the production up, we encounter difficulties. When the microorganisms go from living in a 1-liter fermentation tank to a larger tank, they often respond to changes of, e.g., temperature, osmotic pressure, and oxygen and salt content, etc., and the production of the given substance may slow down or even stop. Thus, we also work a lot on manipulating the microorganisms, so they can cope with the changes. At worst, we will have to start over and find a new microorganism,&rdquo; says Jos&eacute; L. Martinez, who explains that it is becoming continuously easier to search for nature&#39;s own answer to microorganisms that are robust enough to cope with upscaling.&ldquo;Thanks to the rapid technological development in areas such as genome sequencing, robots, big data handling, and artificial intelligence, we can now screen thousands of microorganisms in a week, as opposed to around one hundred just ten years ago,&rdquo; says Jos&eacute; L. Martinez, adding:&ldquo;The portfolio of potential microorganisms to utilize has grown enormously because we can find them now. Nature has actually already invented all solutions. We just need to find them.&rdquo;<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1679412422490-Pilot-plant.jpg" style="width: 766px;" class="fr-fic fr-dib">At Pilot Plant at DTU Chemical Engineering at Lyngby Campus biotechnological solutions is being upscaled. Photo: J&oslash;rgen True&nbsp;<h2 id="isPasted">Big market growth on the horizon</h2>In order for precision fermentation to replace dairy cows, beef cattle, chickens, oil, gas, or coal, it is crucial to find solutions that enable the microorganisms to produce large amounts of the desired substances. Otherwise, the processes will not be profitable for the companies as the end products end up being far too expensive.Despite the challenges of upscaling, precision fermentation is predicted to reach new heights in the coming years. According to the Wall Street-based research firm Polaris Market Research, the global precision fermentation market was worth $1.3 billion in 2021 and will grow by 48 per cent annually until 2030. The market analysis predicts that alternatives that can lead to substitutes for meat, fish, and eggs will drive growth on the precision fermentation market.A growth, which the research firm attributes to the increasing demand for food, that does not burden the environment or the climate but instead is facilitated with a lower energy consumption, lower CO2 emissions, a lower water consumption, and without the use of huge areas of agricultural land. Last, but not least, production will be able to move geographically closer to consumers, thus also avoiding the energy consumption and CO2&nbsp;emissions associated with transporting products over great distances.<h2 id="isPasted">Important player in the green transition</h2>These perspectives have led to precision fermentation being touted as one of the most important technologies in the green transition. But an even greater potential lies ahead, says Jos&eacute; L. Martinez:&ldquo;In the coming years, there will be a change in the way we feed our microorganisms. They have to feed on something inside their steel tanks, and today we feed them sugar, among other things. But we are developing new feed solutions because we find microorganisms that can live off waste and by-products from businesses, greenhouse gases or even plastic. Enzymes have been found that can biodegrade plastic into compounds that we can use as feed for the microorganisms. This is truly mind-blowing. Just imagine that one day we will be able to produce medicine or food using our plastic waste. It&#39;s revolutionary. It&rsquo;s the essence of green transition.&rdquo;</section>

Egg whites, cheese, yogurt, milk, vitamins, fragrances, colouring agents, flavour additives, vaccines, and cancer and malaria medicine are just some of the things that are manufactured today using components produced with precision fermentation. Photo: Shutterstock

Microorganisms in large steel tanks can help us produce food, chemicals, medicine, and fuel without the use of fossil resources or animals. The technology is called precision fermentation and is predicted to be one of the most important players in the green transition.

"We can produce anything"

Sustainable aviation fuels (SAFs) significantly reduce the climate impact of aviation in terms of both its <a href="https://www.dlr.de/content/en/articles/dossier/electric-flight/climate-impact-air-transport.html" id="isPasted" target="_blank" title="One-third CO2 and two-thirds non-CO2 effects">carbon footprint and other climate impact not related to carbon dioxide</a>. In the future, the targeted use of SAFs in contrail regions can help to rapidly reduce the climate impact of air transport. Flight tests using aircraft powered by 100 percent SAF are to take place again in order to prepare for this transition. In the &#39;VOL avec Carburants Alternatifs Nouveaux&#39; (VOLCAN) and the DLR Neofuels project, an Airbus A321neo will use pure SAF in both engines for the first time. The Falcon 20E research aircraft from the German Aerospace Center (Deutsches Zentrum f&uuml;r Luft- und Raumfahrt; DLR) will chase the A321neo and researchers will analyse the emissions and ice crystals in the aircraft&#39;s exhaust plumes. Safran, Dassault Aviation and ONERA are also participating in the project. The research flights will take place from the end of February to the end of March 2023 in specially reserved airspaces off the coast of France.&nbsp;<h2 id="isPasted">A question of condensation</h2>The Airbus A321neo is a modern commercial aircraft equipped with lean-burn engines that enable it to burn kerosene while producing very little soot. &quot;We are particularly interested in how ice crystals form when several orders of magnitude less soot is emitted by the CFM LEAP-1A engines in lean-burn mode,&quot; explains DLR Project Leader Christiane Voigt of the&nbsp;<a href="https://www.dlr.de/pa/en/desktopdefault.aspx/" target="_blank" title="External link DLR Institute of Atmospheric Physics">DLR Institute of Atmospheric Physics</a>. &quot;To do this, we will use the Falcon to conduct emission measurements both in the near field, approximately 100 metres behind the A321neo, as well as in the contrails in the far field at distances of several kilometres.&quot;The researchers are planning approximately 15 joint flights, during which the Falcon 20E will follow the A321neo. Different variants of the sustainable fuel &#39;Hydro-processed Esters and Fatty Acids&#39; (HEFA) will be tested under various modes of engine operation. HEFA is produced from paraffinic hydrocarbons, which are generally derived from used cooking oil and other waste fats, and is free of cyclic hydrocarbons (aromatics) and sulphur. Pure SAFs with no aromatics have several advantages, such as the reduced generation of soot particles during combustion. This can also lead to a reduction in ice crystals that form on the soot. Reducing ice crystals and contrail formation can significantly reduce climate effects, as&nbsp;<a href="https://www.dlr.de/content/en/articles/news/2021/02/20210617_significantly-lower-climate-impact-when-using-sustainable-fuels.html" target="_blank" title="Significantly lower climate impact of contrails when using sustainable fuels">DLR has demonstrated together with NASA</a>.<h2>Flight test research stages</h2>DLR conducted extensive flight tests to characterise the emissions of synthetic fuels as early as 2015 with the&nbsp;<a href="https://www.dlr.de/content/en/articles/news/2021/04/20211129_100-percent-sustainable-fuels-emissions-study-shows-early-promise.html" target="_blank" title="First in-flight 100 percent sustainable-fuels emissions study of passenger jet shows early promise">ECLIF1 campaign</a>. These flight tests were continued in 2018 with the ECLIF2 campaign in collaboration with NASA. During the ECLIF3 campaign 2021 the first emission measurements were conducted during flight tests using 100 percent SAFs on an A350, in collaboration with Airbus and Rolls-Royce.The&nbsp;<a href="https://www.airbus.com/en/newsroom/stories/2021-10-this-a319neo-is-the-latest-to-test-100-saf" target="_blank" title="External link Airbus Newsroom: This A319neo is the latest to test 100% SAF">first test flights of the VOLCAN project</a> with the use of SAFs from the manufacturer Total Energies in one engine took place in 2021. The emission measurements in the VOLCAN project are complemented by ground measurements in which the&nbsp;<a href="http://www.dlr.de/vt/en/" target="_blank" title="External link DLR Institute of Combustion Technology">DLR Institute of Combustion Technology</a> in&nbsp;<a href="https://www.dlr.de/content/en/sites/stuttgart.html" target="_blank" title="Stuttgart">Stuttgart</a> is participating. The Falcon 20E research aircraft is operated by DLR&#39;s&nbsp;<a href="https://www.dlr.de/fb/en/desktopdefault.aspx/" target="_blank" title="External link To the DLR Websie of the Flight Experiments">Flight Experiments facility</a> in&nbsp;<a href="https://www.dlr.de/content/en/sites/oberpfaffenhofen.html" target="_blank" title="Oberpfaffenhofen">Oberpfaffenhofen</a>. The aim of the new experiments is to measure the emissions of lean-burn combustion and to investigate resulting contrail formation. One question is whether other particles also lead to the formation of contrails when soot emissions from lean-burn combustion have already been reduced by orders of magnitude.<h2>The goal &ndash; climate-compatible air transport</h2>The goal is to achieve a climate-neutral economy and society by the middle of this century. The European Green Deal requires a comprehensive commitment to research and development in air transport. To this end, DLR has developed an&nbsp;<a href="https://www.dlr.de/content/en/articles/news/2021/04/20211215_towards-zero-emission-aviation.html" target="_blank" title="Towards zero-emission aviation">aviation strategy</a> that maps out the research path to achieve climate-neutral flight. The goal is highly efficient, climate-friendly aircraft that utilise various new propulsion concepts and sustainable fuels according to their flight range and size. DLR&#39;s whole-system research expertise enables it to adopt the role of virtual manufacturer (virtual OEM) and facilitate an accelerated energy transition in the air transport sector. New technologies and fuels, as well as climate-friendly flight management, are intended to further reduce emissions of carbon dioxide, nitrogen oxides and particles by air transport and decouple them from the predicted growth. SAFs, in combination with highly efficient turbofan engines, will play a key role here, particularly for long and medium-haul flights.

View of the Air­bus A321neo from the DLR Fal­con 20E. Credit: DLR (CC BY-NC-ND 3.0)

Sustainable aviation fuels (SAFs) significantly reduce the climate impact of aviation in terms of both its carbon footprint and other climate impact not related to carbon dioxide. In the future, the targeted use of SAFs in contrail regions can help to rapidly reduce the climate impact of air transport. Flight tests using aircraft powered by 100 percent SAF are to take place again in order to prepare for this transition.

Emissions and contrail study with 100 percent sustainable aviation fuel

This is because hydrogen gas easily reacts in the atmosphere with the same molecule primarily responsible for breaking down methane, a potent greenhouse gas. If hydrogen emissions exceed a certain threshold, that shared reaction will likely lead to methane accumulating in the atmosphere &mdash; with decades-long climate consequences.&ldquo;Hydrogen is theoretically the fuel of the future,&rdquo; said Matteo Bertagni, a postdoctoral researcher at the&nbsp;<a href="https://environment.princeton.edu/" target="_blank">High Meadows Environmental Institute</a> working on the&nbsp;<a href="https://cmi.princeton.edu/" target="_blank">Carbon Mitigation Initiative</a>. &ldquo;In practice, though, it poses many environmental and technological concerns that still need to be addressed.&rdquo;Bertagni is the first author of a research article <a href="https://www.nature.com/articles/s41467-022-35419-7" target="_blank">published</a> in Nature Communications, in which researchers modeled the effect of hydrogen emissions on atmospheric methane. They found that above a certain threshold, even when replacing fossil fuel usage, a leaky hydrogen economy could cause near-term environmental harm by increasing the amount of methane in the atmosphere. The risk for harm is compounded for hydrogen production methods using methane as an input, highlighting the critical need to manage and minimize emissions from hydrogen production.&ldquo;We have a lot to learn about the consequences of using hydrogen, so the switch to hydrogen, a seemingly clean fuel, doesn&rsquo;t create new environmental challenges,&rdquo; said&nbsp;<a href="https://engineering.princeton.edu/faculty/amilcare-porporato" target="_blank">Amilcare Porporato</a>, Thomas J. Wu &rsquo;94 Professor of&nbsp;<a href="https://cee.princeton.edu/" target="_blank">Civil and Environmental Engineering</a> and the High Meadows Environmental Institute. Porporato is a principal investigator and member of the leadership team for the Carbon Mitigation Initiative and is also associated faculty at the&nbsp;<a href="https://acee.princeton.edu/" target="_blank">Andlinger Center for Energy and the Environment</a>.The problem boils down to one small, difficult-to-measure molecule known as the hydroxyl radical (OH). Often dubbed &ldquo;the detergent of the troposphere,&rdquo; OH plays a critical role in eliminating greenhouse gases such as methane and ozone from the atmosphere.The hydroxyl radical also reacts with hydrogen gas in the atmosphere. And since a limited amount of OH is generated each day, any spike in hydrogen emissions means that more OH would be used to break down hydrogen, leaving less OH available to break down methane. As a consequence, methane would stay longer in the atmosphere, extending its warming impacts.According to Bertagni, the effects of a hydrogen spike that might occur as government incentives for hydrogen production expand could have decades-long climate consequences for the planet.&ldquo;If you emit some hydrogen into the atmosphere now, it will lead to a progressive buildup of methane in the following years,&rdquo; Bertagni said. &ldquo;Even though hydrogen only has a lifespan of around two years in the atmosphere, you&rsquo;ll still have the methane feedback from that hydrogen 30 years from now.&rdquo;In the study, the researchers identified the tipping point at which hydrogen emissions would lead to an increase in atmospheric methane and thereby undermine some of the near-term benefits of hydrogen as a clean fuel. By identifying that threshold, the researchers established targets for managing hydrogen emissions.&ldquo;It&rsquo;s imperative that we are proactive in establishing thresholds for hydrogen emissions, so that they can be used to inform the design and implementation of future hydrogen infrastructure,&rdquo; said Porporato.For hydrogen referred to as green hydrogen, which is produced by splitting water into hydrogen and oxygen using electricity from renewable sources, Bertagni said that the critical threshold for hydrogen emissions sits at around 9%. That means that if more than 9% of the green hydrogen produced leaks into the atmosphere &mdash; whether that be at the point of production, sometime during transport, or anywhere else along the value chain &mdash; atmospheric methane would increase over the next few decades, canceling out some of the climate benefits of switching away from fossil fuels.And for blue hydrogen, which refers to hydrogen produced via methane reforming with subsequent carbon capture and storage, the threshold for emissions is even lower. Because methane itself is the primary input for the process of methane reforming, blue hydrogen producers have to consider direct methane leakage in addition to hydrogen leakage. For example, the researchers found that even with a methane leakage rate as low as 0.5%, hydrogen leakages would have to be kept under around 4.5% to avoid increasing atmospheric methane concentrations.&ldquo;Managing leakage rates of hydrogen and methane will be critical,&rdquo; Bertagni said. &ldquo;If you have just a small amount of methane leakage and a bit of hydrogen leakage, then the blue hydrogen that you produce really might not be much better than using fossil fuels, at least for the next 20 to 30 years.&rdquo;The researchers emphasized the importance of the time scale over which the effect of hydrogen on atmospheric methane is considered. Bertagni said that in the long term (over the course of a century, for instance), the switch to a hydrogen economy would still likely deliver net benefits to the climate, even if methane and hydrogen leakage levels are high enough to cause near-term warming. Eventually, he said, atmospheric gas concentrations would reach a new equilibrium, and the switch to a hydrogen economy would demonstrate its climate benefits. But before that happens, the potential near-term consequences of hydrogen emissions might lead to irreparable environmental and socioeconomic damage.Thus, if institutions hope to meet midcentury climate goals, Bertagni cautioned that hydrogen and methane leakage to the atmosphere must be held in check as hydrogen infrastructure begins to roll out. And because hydrogen is a small molecule that is notoriously difficult to control and measure, he explained that managing emissions will likely require researchers to develop better methods for tracking hydrogen losses across the value chain.&ldquo;If companies and governments are serious about investing money to develop hydrogen as a resource, they have to make sure they are doing it correctly and efficiently,&rdquo; Bertagni said. &ldquo;Ultimately, the hydrogen economy has to be built in a way that won&rsquo;t counteract the efforts in other sectors to mitigate carbon emissions.&rdquo;<hr>The article, &ldquo;<a href="https://www.nature.com/articles/s41467-022-35419-7" target="_blank">Risk of the hydrogen economy for atmospheric methane</a>,&rdquo; was published Dec. 13, 2022, in Nature Communications. In addition to Bertagni and Porporato, coauthors include Stephen Pacala of Princeton University and Fabien Paulot, a scientist at the Geophysical Fluid Dynamics Laboratory of the National Oceanic and Atmospheric Association. The research was supported by the National Science Foundation, BP through the <a href="https://cmi.princeton.edu/" target="_blank">Carbon Mitigation Initiative</a>, and the Moore Foundation.

A rise in hydrogen emissions means that more hydroxyl (OH) would be used to break down hydrogen, leaving less OH available to break down methane (CH4). Illustration by Bumper DeJesus

Hydrogen’s potential as a clean fuel could be limited by a chemical reaction in the lower atmosphere, according to research from Princeton University and the National Oceanic and Atmospheric Association.

Switching to hydrogen fuel could prolong the methane problem

The researchers used experiments and advanced computation to develop a technique using nanotechnology to split hydrogen from liquid ammonia, a process that until now has been expensive and energy-intensive.In an&nbsp;<a href="https://www.science.org/doi/10.1126/science.abn5636" target="_blank">article</a> published online Nov. 24 in the journal Science, the researchers describe how they used light from a standard LED to crack the ammonia without the need for high temperatures or expensive elements typically demanded by such chemistry. The technique overcomes a critical hurdle toward realizing hydrogen&rsquo;s potential as a clean, low-emission fuel that could help meet energy demands without worsening climate change.&ldquo;We hear a lot about hydrogen being the ultimate clean fuel, if only it was less expensive and easy to store and retrieve for use,&rdquo; said&nbsp;<a href="https://halas.rice.edu/halas-bio" target="_blank">Naomi Halas</a>, a professor at Rice University and one of the study&rsquo;s principal authors. &ldquo;This result demonstrates that we are moving rapidly towards that goal, with a new, streamlined way to release hydrogen on-demand from a practical hydrogen storage medium using earth-abundant materials and the technological breakthrough of solid-state lighting.&rdquo;Hydrogen offers many advantages as a green fuel, including high energy density and zero carbon pollution. It is also used ubiquitously in industry; for example, to make fertilizer, food and metals. But pure hydrogen is expensive to compress for transport and is difficult to store for long periods. In recent years, scientists have sought to use intermediate chemicals to transport and store hydrogen. One of the most promising hydrogen carriers is ammonia (NH3), comprised of three hydrogen atoms and one nitrogen atom. Unlike pure hydrogen gas (H2), liquid ammonia, although hazardous, has existing systems for safe transportation and storage.&ldquo;This discovery paves the way for sustainable, low-cost hydrogen that could be produced locally rather than in massive centralized plants,&rdquo; said&nbsp;<a href="https://nordlander.rice.edu/members/nordlander" target="_blank">Peter Nordlander</a>, a professor at Rice and another principal author.One persistent problem for advocates has been that cracking ammonia into hydrogen and nitrogen often requires high temperatures to drive the reaction. Conversion systems&nbsp;<a href="https://www.sciencedirect.com/topics/engineering/ammonia-decomposition#:~:text=At%20400%C2%B0C%2C%20the,atmospheric%20pressure%20circumstances%20%5B11%5D." target="_blank">can require temperatures</a> above 400 degrees Celsius (732 degrees Fahrenheit). That demands a lot of energy to convert the ammonia, as well as special equipment to handle the operation.Researchers led by Halas and Nordlander at Rice University, and&nbsp;<a href="https://engineering.princeton.edu/faculty/emily-carter" target="_blank">Emily Carter</a>, the Gerhard R. Andlinger Professor in Energy and the Environment and a professor of&nbsp;<a href="https://mae.princeton.edu/" target="_blank">mechanical and aerospace engineering</a> and&nbsp;<a href="https://www.pacm.princeton.edu/" target="_blank">applied and computational mathematics</a> at Princeton, wanted to transform the splitting process to make ammonia a more sustainable and economically viable carrier for hydrogen fuels. Using ammonia as a hydrogen carrier has drawn considerable research interest because of its potential to drive a hydrogen economy, as a&nbsp;<a href="https://pubs.acs.org/doi/10.1021/acs.iecr.1c00843" target="_blank">recent review</a> by the American Chemical Society shows.Industrial operations often&nbsp;<a data-lf-fd-inspected-kn9eq4roawkarlvp="true" href="https://www.energy.gov/sites/prod/files/2015/01/f19/fcto_nh3_h2_storage_white_paper_2006.pdf" target="_blank">crack ammonia</a> at high temperatures using a wide variety of materials as catalysts, which are materials that accelerate a chemical reaction without being changed by the reaction. Previous research has demonstrated that it is possible to lower the reaction temperature by using a ruthenium catalyst. But ruthenium, a metal in the platinum group, is expensive. The researchers believed they could use nanotechnology to allow cheaper elements like copper and iron to be used as a catalyst instead.The researchers also wanted to tackle the energy cost of cracking ammonia. Current methods use a lot of heat to break the chemical bonds that hold ammonia molecules together. The researchers believed they could harness light to sever the chemical bonds like a scalpel rather than using heat to shatter them like a hammer. To do so, they turned to nanotechnology, along with a much cheaper catalyst containing iron and copper.The combination of nanotechnology&rsquo;s tiny metal structures and light is a relatively new field called&nbsp;<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6539533/" target="_blank">plasmonics</a>. By shining light into structures smaller than a single wavelength of light, engineers can manipulate the light waves in unusual and specific ways. In this case, the Rice team wanted to use this engineered light to excite electrons in the metal nanoparticles as a way to split the ammonia into its hydrogen and nitrogen components without the need for intense heat. Because plasmonics requires certain types of metals, such as copper, silver or gold, the researchers added the iron to copper before creating the tiny structures. When finished, the copper structures behave as antennas to manipulate the light from the LED to excite the electrons to higher energies, while the iron atoms embedded in the copper act as catalysts to accelerate the reaction carried out by excited electrons.The researchers created the structures and conducted the experiments in laboratories at Rice. They were able to adjust many variables around the reaction such as the pressure, the intensity of the light and the light&rsquo;s wavelength. But calibrating the exact parameters was daunting. To investigate how these variables affected the reaction, the researchers worked with principal author Carter, who specializes in detailed investigations of reactions at the molecular level. Using Princeton&rsquo;s high-performance computing system, the Terascale Infrastructure for Groundbreaking Research in Engineering and Science (TIGRESS), Carter and her postdoctoral fellow, Junwei Lucas Bao, ran the reactions through her specialized quantum mechanics simulator uniquely able to study excited electron catalysis. Molecular interactions of such reactions are incredibly complex, but Carter and her fellow researchers are able to use the simulator to understand which variables should be adjusted to further the reaction.&ldquo;With the quantum mechanics simulations, we can determine the rate-limiting reaction steps,&rdquo; said Carter, who also holds appointments at Princeton&rsquo;s&nbsp;<a href="https://acee.princeton.edu/" target="_blank">Andlinger Center for Energy and the Environment</a>, in applied and computational mathematics, and at the Princeton&nbsp;<a href="https://www.pppl.gov/" target="_blank">Plasma Physics Laboratory</a>. &ldquo;These are the bottlenecks.&rdquo;By fine-tuning the process while utilizing the atomic-scale understanding Carter and her team provided, the Rice team was able to consistently extract hydrogen from ammonia using only light from energy-efficient LEDs at room temperature with no additional heating. The researchers say the process is scalable. In further research, they plan to investigate other possible catalysts, with an eye to increasing the process efficiency and decreasing the cost.Carter, who also currently&nbsp;<a href="https://www.nationalacademies.org/our-work/carbon-utilization-infrastructure-markets-research-and-development#sectionCommittee" target="_blank">chairs</a> the National Academies&rsquo; committee on carbon utilization, said a critical next step will be to decrease the costs and carbon pollution involved with creating the ammonia that begins the transportation cycle. Currently, most ammonia is&nbsp;<a href="https://www.acs.org/content/acs/en/molecule-of-the-week/archive/a/ammonia.html#:~:text=Ammonia%20is%20produced%20commercially%20via,Fritz%20Haber%20and%20Carl%20Bosch." target="_blank">created at high temperatures</a> and pressures using fossil fuels. The process is both energy-intensive and polluting. Carter said many researchers are working to develop green techniques for the production of ammonia as well.&ldquo;Hydrogen is used ubiquitously in industry and will be used increasingly as fuel as the world seeks to decarbonize its energy sources,&rdquo; she said. &ldquo;However, today it is mostly made unsustainably from natural gas &mdash; creating carbon dioxide emissions &mdash; and is difficult to transport and store. Hydrogen needs to be made and transported sustainably where it is needed. If carbon-emission-free ammonia could be produced, for example, by electrolytic reduction of nitrogen using decarbonized electricity, it could be transported, stored, and possibly serve as an on-demand source of green hydrogen using the LED-illuminated iron-copper photocatalysts reported here.&rdquo;The article,&nbsp;Earth-abundant photocatalyst for H2 generation from NH3 with light-emitting diode illumination, was published in the Nov. 25 issue of Science. Besides Carter, Halas and Nordlander, coauthors include Hossein Robatjazi, who received his doctorate at Rice and is now chief scientist of Syzygy Plasmonics; Junwei Lucas Bao, who is now a professor at Boston College; Yigao Yuan, Jingyi Zhou, Aaron Bales, Lin Yuan, Minghe Lou and Minhan Lou of Rice University; Linan Zhou of both Rice and South China University of Technology, and Suman Khatiwada of Syzygy Plasmonics. Halas and Nordlander are co-founders of Syzygy and hold equity in the company.Support for the research was provided in part by the Welch Foundation, the Air Force Office of Scientific Research, Syzygy Plasmonics, and the Department of Defense.Rice University&rsquo;s Office of Public Affairs contributed to this article.

Computation for the project was performed at Princeton's High Performance Computing Research Center. Photo by Denise Applewhite, Princeton University Office of Communications

Researchers at Princeton and Rice universities have combined iron, copper, and a simple LED light to demonstrate a low-cost technique that could be key to distributing hydrogen, a fuel that packs high amounts of energy with no carbon pollution.

Researchers create green fuel with the flip of a light switch

The Federal Ministry of Education and Research (BMBF) is funding the international research project CARE-O-SENE (Catalyst Research for Sustainable Kerosene) with 30 million euros. It aims to improve the production of sustainable kerosene on an industrial scale. For this purpose, the network partners, including the Karlsruhe Institute of Technology (KIT), are developing tailor-made catalysts in order to further develop the Fischer-Tropsch synthesis (FTS) established in fuel production for the use of renewable energy sources.With a share of more than 80 percent, fossil fuels are still by far the most important raw material for fuel, heating and the chemical industry (source: International Energy Agency, IEA).&nbsp;Sustainable fuels are based on green hydrogen and carbon dioxide - and should make a significant contribution to decarbonising sectors such as aviation, where fossil fuels are particularly difficult to replace.&nbsp;In the CARE-O-SENE project, seven South African and German project partners are therefore researching next-generation Fischer-Tropsch catalysts.<h2>Tailor-made catalysts for the Fischer-Tropsch synthesis</h2>The focus of the application-oriented project is the development of resource-saving catalysts for the Fischer-Tropsch synthesis.&nbsp;In this process, hydrogen and carbon monoxide are converted into hydrocarbons and water under high pressure and high temperatures.&nbsp;The slightly further modified hydrocarbons are the basis of kerosene.&nbsp;Sustainable kerosene is obtained in this way by using green hydrogen and carbon dioxide from biogenic sources or by separating it from the air (direct air capture).&quot;The catalysts have to become more efficient, more selective, and more durable,&quot; says Professor Jan-Dierk Grunwaldt from the Institute for Catalysis Research and Technology (IKFT) at KIT and Chairman of the Research Using Synchrotron Radiation Committee.&nbsp;To develop an optimal design, he and his team are investigating the structures and behavior of the cobalt catalysts used in the FTS under real process conditions - at over 200 degrees and a pressure of more than 20 bar.&nbsp;&quot;We want to understand this in detail so that we can then develop tailor-made catalysts,&quot; says Grunwaldt.For the investigations, the team uses synchrotron research methods: They use high-energy photons to examine the chemical state of the individual metal particles using X-ray absorption spectroscopy on the one hand and the structures of the entire catalyst using X-ray diffraction on the other.&nbsp;&quot;This means that for the first time we can watch FTS catalysts at work during operation, right down to the molecular level,&quot; says Dr.&nbsp;Anna Zimina, head of the CATACT measurement line at the KIT Light Source.The measurements not only provide information about disruptive structural changes that can occur during the chemical reaction and reduce the yield of the target product.&nbsp;The resulting data is also incorporated into theoretical models and sustainability calculations.&nbsp;On this basis, the researchers can make predictions about how the catalyst will change and what adjustments are necessary to make the industrial process stable, ecologically sustainable and economical.&nbsp;&ldquo;Nowadays, theoretical calculations allow us to map the molecular processes to catalysts and thus to better understand them.&nbsp;This then helps to make predictions for better catalysts,&rdquo; says Professor Felix Studt, head of the Theoretical Catalysis department at IKFT.The KIT receives about five million euros from the funding of the BMBF.&nbsp;Part of this goes to the University of Cape Town as a subcontractor.<h2>Goal: to produce decentrally and more selectively and on a larger scale</h2>The scientists involved in CARE-O-SENE are convinced that regions such as South Africa, in which solar and wind energy is available reliably and over a long period of time for the production of green hydrogen, offer great potential for producing green kerosene either decentrally in modular systems , but also to produce on a larger scale.&nbsp;&quot;We want to leverage this potential with this project and our strong consortium partners and increase the yield,&quot; says Grunwaldt.<h2>About CARE-O-SENE</h2>The BMBF funds CARE-O-SENE with 30 million euros.&nbsp;In addition, the industrial consortium partners are contributing ten million euros.&nbsp;Seven partners from South Africa and Germany are involved in the research project, which is an important component of the federal government&#39;s national hydrogen strategy.&nbsp;The coordination lies with the integrated chemical and energy company Sasol and the Helmholtz Center Berlin for Materials and Energy.&nbsp;As the third major partner, KIT is involved with the Institute for Catalysis Research and Technology and the Institute for Industrial Management and Production.&nbsp;Other partners are Ineratec GmbH, a KIT spin-off, the University of Cape Town, with which KIT has had close ties for years,Further information:<a href="https://care-o-sene.com/de_de/" target="_blank">https://care-o-sene.com/de_de/</a>

In the international CARE-O-SENE project, researchers are developing tailor-made Fischer-Tropsch catalysts for the production of sustainable kerosene. (Photo: Tiziana Carambia)

Sustainable fuels are based on green hydrogen and carbon dioxide - and should make a significant contribution to decarbonising sectors such as aviation, where fossil fuels are particularly difficult to replace.

Sustainable kerosene: accelerating production on an industrial scale

Synthetic fuels produced from renewable sources, so-called reFuels, are considered a potential game changer in the fight against climate change.&nbsp;Because reFuels not only promise up to 90 percent CO&nbsp;2-Reduction compared to conventional fuels, they also allow the continued use of existing vehicle fleets with combustion engines - and the entire tank infrastructure from production to transport to sales.&nbsp;In a large-scale project with partners from industry, researchers at the Karlsruhe Institute of Technology (KIT) have now demonstrated in extensive application tests in fleets that reFuels can be used in almost all vehicles and can be produced in large quantities in the foreseeable future.&nbsp;They presented the results of the research project &ldquo;reFuels &ndash; rethinking fuels&rdquo; on Monday, September 19, in Karlsruhe.&ldquo;The use of climate-neutral fuels makes sense above all when battery-electric solutions are not yet a real alternative.&nbsp;In this respect, I am very pleased that the KIT has now been able to demonstrate impressively that reFuels are an equally climate-friendly and economical solution for certain areas of application,&quot; says Berthold Frie&szlig;, Ministerial Director in the Ministry of Transport Baden-W&uuml;rttemberg, on the occasion of the presentation of the results of &quot;reFuels - new fuels think&quot;, the first reFuels project within the strategy dialogue automotive industry Baden-W&uuml;rttemberg (SDA).&nbsp;&ldquo;The project also shows that the commitment of the state and other project partners to renewable fuels has paid off.&nbsp;Baden-W&uuml;rttemberg thus remains a pioneer in the mobility revolution.<h2>Existing vehicle fleets can continue to be used in an environmentally friendly manner</h2>&quot;We will not be able to do without liquid fuels in the foreseeable future, for example in the area of heavy goods traffic, shipping and aviation, but also in the existing car fleet,&quot; says Professor Thomas Hirth, Vice President for Transfer and International Affairs at KIT.&nbsp;&quot;In the &#39;reFuels &ndash; rethinking fuels&#39; project, we have now shown that reFuels work in both old and new cars, as well as in commercial vehicles and locomotives,&quot; Hirth continues.&nbsp;&quot;In short, reFuels are now fully suitable for everyday use!&quot;<h2>CO 2 reduction of up to 90 percent</h2>&quot;We were able to produce tons of reFuels that meet the existing fuel standards for petrol and diesel fuels and have not shown any impairment in performance or wear in series use in a wide variety of engines,&quot; explains Dr.&nbsp;Olaf Toedter from the KIT Institute for Piston Engines.&nbsp;KIT researchers produced and tested gasoline and diesel.&nbsp;They have achieved a CO&nbsp;2 reduction of 22 to 81 percent, depending on the mixing ratio between synthesized and fossil fuels, the raw materials used and the energy.<h2>Industrial production plant planned in Karlsruhe</h2>As a next step, the project partners want to set up an industrial production plant for reFuels on the site of the MiRO refinery in Karlsruhe: &quot;In the future, we want to replace fossil raw materials with renewable energy sources,&quot; explains Dr.&nbsp;Andreas Krobjilowski, technical director of MiRO.&nbsp;&ldquo;Many of the technologies and processes required for this are already available in Germany.&nbsp;MiRO has the know-how and experience to set up and operate such new and innovative systems.&rdquo; However, there are currently not enough affordable quantities of green hydrogen available to switch to greenhouse gas-neutral production.&nbsp;The preliminary products for the reFuels fuels such as synthesized Fischer-Tropsch oil or methanol are therefore to be manufactured in countries&nbsp;that have more wind or solar energy than Germany, for example Chile or southern Spain.&nbsp;The actual reFuels such as petrol, diesel or kerosene could then be produced in domestic refineries such as MiRO.&nbsp;&quot;However, for the urgently needed rapid market ramp-up, we need clarity and long-term security for counting renewable, electricity-based fuels against the greenhouse gas reduction quota,&quot; says Krobjilowski.<h2>Pure reFuels within reach</h2>The scientists are also working on increasing the proportion of refuels in fuel mixtures within the existing fuel standards.&nbsp;&quot;Right down to reFuels pure fuel,&quot; says Toedter.&nbsp;Tests already in progress have been promising.&nbsp;However, there is still a lack of a clear regulatory framework for this, because in Germany only up to 33 percent of refuels can be added.<h2>The &ldquo;reFuels &ndash; rethinking fuels&rdquo; project</h2>In the project, researchers have been taking a holistic view of the production and use of renewable fuels since 2018.&nbsp;Such fuels can power existing combustion engines in the future &ndash; in airplanes, commercial and rail vehicles as well as in cars.&nbsp;Six institutes of the KIT work together with numerous partners from the energy, mineral oil, automotive and supplier industries under the umbrella of the Strategic Dialogue Automotive Industry of the State of Baden-W&uuml;rttemberg on the provision and introduction of reFuels.&nbsp;Two pilot and other technical systems of the KIT supplied regenerative fuels that were processed, characterized and tested in test engines and vehicles.&nbsp;In this way, synthesis processes for reFuels and their use could be optimized, for example, in addition to the CO&nbsp;2-Reduction also to reduce raw emissions.

ReFuels can now be used in almost all vehicles and can be produced in large quantities in the foreseeable future. (Photo: Markus Breig and Amadeus Bramsiepe, KIT)