Is It Possible to Create Aviation Fuel Without the Use of Fossil Fuels?
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Creating aviation fuel without the use of fossil fuels is not only possible but also essential for the sustainable future of the aviation industry. Hydrogen, synthetic fuels, and power-to-liquids represent viable alternatives that can help reduce the environmental impact of air transportation. While each alternative has its own set of challenges, continued research and development in these areas are crucial to overcoming these obstacles and achieving a cleaner, more sustainable aviation sector.
The aviation industry is a significant contributor to global greenhouse gas emissions, and the reliance on fossil fuels for jet fuel exacerbates this issue. With the depletion of fossil fuel reserves and increasing environmental concerns, the search for sustainable and renewable alternatives to conventional aviation fuel has intensified. This article explores the feasibility of creating aviation fuel without the use of fossil fuels, examining various alternatives such as hydrogen, synthetic fuels, and power-to-liquids (PtL).
Hydrogen as Aviation Fuel
Hydrogen is considered a promising alternative to conventional hydrocarbon fuels due to its unique attributes, including global availability, safety, minimal pollution, and lightweight properties. Hydrogen can be used as an energy carrier in aviation, offering a clean and renewable solution. Research has shown that hydrogen can effectively replace fossil fuels in air transportation, providing a sustainable energy system for the future1.
Synthetic Fuels
Synthetic fuels, produced from a variety of feedstocks, present another viable alternative to petroleum-based jet fuels. These fuels can be synthesized using different processes, including the Fischer-Tropsch process, which converts carbon monoxide and hydrogen into liquid hydrocarbons. Synthetic fuels offer the potential to reduce dependence on fossil fuels and enhance energy diversity. However, challenges such as the economic cost of production and the availability of feedstocks need to be addressed to make synthetic fuels a feasible option for aviation in the near term2.
Power-to-Liquids (PtL)
The PtL pathway is an innovative approach that uses renewable electricity, carbon dioxide (CO2), and water to produce sustainable aviation fuel. This process synthesizes a fuel that chemically resembles conventional jet fuel, making it compatible with existing aircraft and infrastructure. PtL fuels have the potential to significantly reduce the greenhouse gas intensity of aviation fuels, aligning with the goals of the Paris Climate Agreement. The state-of-the-art technologies for PtL fuel production and their environmental and techno-economic performance have been reviewed, highlighting the promise of this renewable fuel option for aviation3.
Is it possible to create aviation fuel without the use of fossil fuels?
Petr Vozka has answered Likely
An expert from Purdue University in Analytical Chemistry, Chemical Engineering
The simple answer would be YES, but currently, it would not be economically feasible.
There is already five alternative fuel blending components approved by the ASTM International (US) and DEF STAN 91-91 (Europe). We call them “blending components” as they all have to be blended with petroleum-based jet fuel. The reason is the lack of aromatic compounds. However, the process of one of the blending component (Fischer-Tropsch) was upgraded in order to produce aromatics. This attempt was approved: in Europe as a neat fuel and in the US only up to 50 vol. %. However, this process is not economically feasible and thus this fuel is not commercially produced.
There are multiple other pathways that would produce petroleum-like jet fuel. The only problem is the price.
Is it possible to create aviation fuel without the use of fossil fuels?
Christopher J Chuck has answered Near Certain
An expert from University of Bath in Chemical Engineering, Chemistry, Biotechnology
Great question, which is really quite complex and has a lot of aspects to it. So first up, can we make actual Jet fuel, molecule for molecule, from renewable sources of carbon? The answer is pretty much no, but we can make molecules from biomass that mostly fit the Jet fuel specification, and can be blended with Jet fuel to produce a fuel that fully hits the specification. There are a number of routes that have all been demonstrated to produce a suitable fuel. These include fermenting sugar into alcohol and then chemically converting the alcohols into fuel-like molecules, fermenting sugar into more fuel-like hydrocarbons, thermochemically treating biomass to produce small molecules then converting those into a jet fuel type product. One key technology is to break apart biomass (or other carbon sources such as carbon dioxide from the atmosphere) into carbon monoxide and by adding hydrogen building them up again to produce longer carbon chain fuels. Vegetable oils can also be used as a feedstock and be hydrogenated, like in margarine, then converted into Jet fuels.
However, whatever the route, this is hard. Aviation fuels are the toughest fuels to mimic as the fuel must be safe to handle at room temperature (so will not catch fire when exposed to a spark), but still flow at -47 °C. In addition, there are global standards for fuels, which does not lend itself to alternative local production, as planes must refuel all over the world, and the fuels be entirely compatible. One plane crash due to faulty fuel is always one too many, and as such the specification that a Jet fuel must hit is far more stringent than diesel or gasoline (the process is also extremely long and costly to achieve certification).
To address these issues, one novel approach has been to try and place renewable carbon (carbon from bioresources) into a normal refinery with the crude oil, so that we get the exact Jet fuel blends (as well as all the other fuels) out the end, but all will have a certain percentage of renewable carbon in them. We could debate the promise of this approach all day, but it would take a large buy-in and innovative development in the traditional refinery to make it work.
The second big factor is sustainability, just because something is made from biomass doesn’t mean that it is better for the environment than fossil derived feedstocks. Similarly, there are better non-biogenic carbon sources than crude oil (such as CO2 from the atmosphere or natural gas). For example, jet fuels made from non-sustainable palm oils will be worse for GHG emissions and biodiversity impact than fossil derived fuels…. Probably. There is a lot of uncertainty in these analyses. Therefore, rough rule of thumb is to make sure your feedstock does not compete with food production, does not play a vital role in an ecosystem or is being used for something else that will need it to be displaced and of course, is actually renewable with enough that can be produced each year to fulfil the requirements. Generally speaking, municipal food waste or agricultural residues could fit the bill. Palm oil grown on land that previously supported rainforest will not.
Finally, the biggest stumbling block is cost. Whatever your personal views, most people are just not willing to pay a premium for sustainable products. Unfortunately, there are no two ways about it, aviation biofuels are just not going to be able to compete on price with fossil derived feedstocks. One of the reasons is that jet fuel is mainly not taxed and the margins in this industry are wafer thin. Most companies that went into this space, ended up moving to higher value products and almost all modelling shows that whatever the route chosen the biofuels will cost more.
So where does that leave us? Well it looks like there will simply never be enough biomass to be able to cover the planets entire food and transportation needs. There might well be enough for food and aviation alone, but that is another debate altogether. Ultimately though whatever the renewable fuel mix, at some point very soon, we need to realise that if we want to reduce our impact on the planet we will need to pay for it one way or another. In the aviation sector this could be done through carbon taxation, long term government support for renewable alternatives or mandates on sustainable fuels in this area. The technology is pretty much there, it is the individual and collective will to make that choice that needs work.
Is it possible to create aviation fuel without the use of fossil fuels?
C N Hewitt has answered Extremely Unlikely
An expert from Lancaster University in Atmospheric Science
The statement is poorly framed, because carbon neutrality is – or should be – only one consideration in the debate about our future world. Of equal or greater importance related to this specific topic is global food supply and global food security. Currently, globally, about 14% of all human-edible crops grown are directed to ‘non-food uses’, mainly the production of biofuels, particularly liquid hydrocarbons (Berners-Lee et al, 2018). Some of this biofuel could, in theory, be further refined into aviation fuel. However, this 14% of the potential human food supply produces much less than 1% of current global fossil fuel use. The question to ask is: in a world where some people do not have adequate access to sufficient food, should further pressures be placed on the global food supply by diverting food to alternative uses such as aviation fuel. Please see our recent paper on the global food supply for more details – https://www.elementascience.org/articles/10.1525/elementa.310/.
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