ReFuels: game changers in traffic?

ReFLue research

ReFuels can be used in almost all combustion vehicles. © Markus Breig and Amadeus Bramsiepe/ KIT

Synthetic fuels produced from renewable sources, so-called ReFuels, are considered to be a possible help in the fight against climate change. A new study puts the fuels to the test and comes to the conclusion: ReFuels not only reduce up to 80 percent of CO2 emissions compared to conventional fuels, but also allow existing vehicles with combustion engines to be used.

In order to achieve the climate goals and effectively counteract climate change, greenhouse gas emissions must be reduced in many sectors in Germany. A lot has to change, especially in the transport sector, because both passenger and truck transport are still largely powered by fossil fuels. In order to achieve the goal of climate neutrality by 2050, new innovations to save CO2 are constantly being created as part of the traffic turnaround - including the development of so-called reFuels.

From regenerative raw materials instead of crude oil

ReFuels refers to a range of fuels whose production is based on non-fossil carbon sources. Instead, the necessary carbon comes from the environment, for example from biomass or carbon dioxide taken from the air or exhaust gases. With the help of hydrogen, the carbon it contains is converted into long-chain hydrocarbons, which can then be used as fuel. If electricity from renewable energies is also used in production, the process even has the potential to enable virtually CO2-neutral locomotion. Because just as much carbon dioxide is bound from the environment during production as is subsequently emitted again during consumption.

But can ReFuels really completely replace conventional petrol & Co? Researchers at the Karlsruhe Institute of Technology (KIT) have also asked themselves this question and put the potential of ReFuels to the test in extensive application tests. To do this, they produced large quantities of synthetic petrol and diesel from renewable sources and tested them in various combustion engines in cars and diesel locomotives.

No problems when used in normal combustion engines

The evaluations showed that the reFuels can be used in almost all vehicles and can be produced in large quantities in the foreseeable future: "We were able to produce tons of reFuels that meet the existing fuel standards for petrol and diesel fuels and do not cause any impairment in series use in a wide variety of engines performance or wear and tear,” explains Olaf Toedter from KIT. The scientists have achieved a CO2 reduction of 22 to 81 percent, depending on the mixing ratio between synthesized and fossil fuels, the raw materials used and energies.

The results thus highlight an advantage of ReFuels compared to hydrogen or liquid gas, namely the continued use of existing vehicles with normal combustion engines. A complex conversion is not necessary for the use of regenerative fuels. “The use of climate-neutral fuels makes sense above all when battery-electric solutions are not yet a real alternative. In this respect, I am very pleased that KIT has now been able to demonstrate impressively that ReFuels are an equally climate-friendly and economical solution for certain areas of application," says Berthold Frieß from the Baden-Württemberg Ministry of Transport.

Industrial production plant for ReFuels planned

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. However, in order to be able to completely replace fossil raw materials with renewable energy sources and to switch to greenhouse gas-neutral production, there has so far been a lack of sufficient and affordable quantities of green hydrogen. The primary products for the reFuels fuels are therefore to be manufactured in countries that have more wind or solar energy than Germany, such as Chile or southern Spain. The actual reFuels such as petrol, diesel or kerosene could then be produced in domestic refineries such as MiRO.

The scientists are also working on increasing the proportion of ReFuels in fuel mixtures within the existing fuel standards. "Right down to reFuels pure fuel," says Toedter. Tests that are already underway have been promising, but there is still a lack of a clear regulatory framework for this, because in Germany only up to 33 percent of refuels are allowed to be added.

Source: Karlsruhe Institute of Technology

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