E-Fuels: Can cars drive with them?

Potsdam/Riedlingen. Due to the current political debate, e-fuels are currently on everyone’s lips. Electrofuels, as they are called in English, are fuels that are artificially produced using electricity. If all new vehicles in the EU have to be operated emission-free from 2035, the German Minister of Transport is urged to make an exception for new vehicles with combustion engines that are only operated with e-fuels produced in a climate-neutral manner. While some want to save the internal combustion engine in cars into a climate-neutral world with e-fuels, others consider this idea absurd.

E-Fuels: The theory sounds tempting

It sounds tempting in theory: If e-fuels are produced with electricity from renewable energies and the carbon dioxide (CO2) required for production comes from the air or from biomass, internal combustion engines could be operated in a climate-neutral manner. Because during combustion, only as much CO2 is released back into the atmosphere as exhaust gas as was previously removed: a zero-sum game that does not increase the proportion of greenhouse gases in the earth’s atmosphere. The existing engine technology and tank infrastructure could be retained.

However, the production of e-fuels is considerably more complex than the basic principle suggests. Because although hydrogen – an essential component of fuels – is present in large quantities in water, its extraction as a pure gas, for example by electrolysis, is very energy-intensive. Extracting CO2 from the air is even more difficult. There is the so-called direct air capture process for this, but it also requires a lot of electricity and heat. Because CO2 is only present in the air in very low concentrations, despite its noticeable greenhouse effect in climate change.

Energy efficiency decreases

The production of the fuel itself is also expensive, both the so-called Fischer-Tropsch process and the methanol synthesis with subsequent conversion into synthetic gasoline. And with every process step, energy is lost, so that energy efficiency decreases.


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In addition: “The efficiency of combustion engines is much lower, so that an electric vehicle with the same amount of energy can drive five times further than a vehicle filled with e-fuels,” says sustainability expert Michael Koch from the SRH Fernhochschule in Riedlingen. Koch emphasizes that a lot of electricity is wasted if it is used to produce e-fuels instead of charging electric vehicles.

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Researchers at the Fraunhofer Institute for Systems and Innovation Research (ISI) in Karlsruhe write in a contribution to the discussion that while 13 to 15 percent of the electricity used arrives at the drive wheel of the vehicle with e-fuel, it is 70 to 75 percent with electric vehicles.

Pilot project in Chile: Porsche is building a factory for the production of synthetic fuels in Haru Oni.

Pilot project in Chile: Porsche has built a factory for the production of synthetic fuels in Haru Oni.

The operators of pilot plant Haru Oni ​​in Chile, which includes Porsche and Siemens Energy, is just learning how difficult it can be to produce carbon-neutral e-fuels. In the south of the South American country, a strong wind blows around 270 days a year, which can be used to generate large amounts of green electricity. A 325-megawatt wind farm was actually supposed to be built at the site, but the operators withdrew the application last October because the Chilean government’s requirements were too high. The CO2 is currently not extracted from the air, but delivered by tanker truck. After all, according to Porsche, it comes from a brewery and thus from a biogenic process.

Three liters of water are needed for every liter of e-fuel

The water also comes by tanker – three liters of water are required for every liter of e-fuel. In the future, the water will come from a sea desalination plant. The 130,000 liters of synthetic petrol that are produced annually with the help of the only wind turbine to date are by no means climate-neutral. They are also transported 14,000 kilometers across the Atlantic by ship – which is also not very climate-friendly. Because of the setback at the wind farm, it is also questionable whether around 550 million liters of e-fuels will be produced in Haru Oni ​​in 2027 as planned.

Falko Ueckerdt dated the production of e-fuels Potsdam Institute for Climate Impact Research (PIK) in view. According to his calculations, climate-neutral e-fuels will hardly be available for years to come. By 2035, around 60 projects have been announced worldwide that will increasingly produce e-fuels on an industrial scale. But so far there has only been a final investment decision for one percent of the planned production volume.

Even if all planned e-fuel quantities – almost 50 billion kilowatt hours – could be produced, these fuels produced worldwide would only cover 10 percent of today’s potential e-fuel requirements of aviation, shipping and the chemical industry in Germany.

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Petrochemicals also need e-fuels

If one assumes that global e-fuel production grows as fast as solar power generation, the coverage could rise to 50 percent – mind you: only the German demand of aviation, shipping and the chemical industry. In the foreseeable future there will be no electric drives for aircraft and ships for long distances, because the energy density of batteries is considerably lower than that of liquid fuels. And the petrochemical industry needs e-fuels for the production of plastics. “In these areas alone, unimaginable quantities of e-fuels are required for climate-neutral operation,” emphasizes Ueckerdt.

Koch is not generally against e-fuels, which could make the existing fleet of combustion engines more climate-friendly, but only against planning them for newly registered cars and smaller trucks. With the electric motor, there is already a significantly more efficient drive than the combustion engine. The Riedlinger expert would have welcomed it if the EU had decided to ban new cars with internal combustion engines without any ifs or buts.

“The automotive industry’s demand for clear framework conditions is justified,” emphasizes Koch. A backdoor for the internal combustion engine could mean developing two powertrain systems at the same time, leading to higher costs and lower efficiencies in production – and ultimately higher prices for customers.

Practical in the country?

Koch cannot understand the claim that electromobility is not practicable in rural areas. It is precisely there that there are many homeowners with charging options at home, which many city dwellers still lack. “I can charge my electric car overnight at a normal socket so that it has a range of 200 kilometers,” explains Koch. “And with a wall charger, it fully charges overnight.”

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PIK researcher Ueckerdt points out: “Even without massive CO2 taxation, e-cars are already at the limit of being economical.” He assumes further technical improvements in the next few years, and the vehicle markets could soon tilt in favor of electric vehicles .

We shouldn’t discuss which cannon shoots down the biggest climate sparrow, but fire with everything we have to combat climate change.

Michael Sterner,

Expert from the East Bavarian Technical University of Regensburg

Many experts argue that climate-friendly approaches and technologies should not be played off against each other. “We shouldn’t discuss which cannon shoots down the biggest climate sparrow, but “fire” with everything we have against climate change,” writes Michael Sterner from the East Bavarian Technical University of Regensburg in the book “So we save the climate”. Every measure is needed.

In the end, the price decides

In the end, the price will also decide which drive technology and which fuels will prevail. PIK expert Ueckerdt currently estimates the cost of the synthetic fuel from the Haru Oni ​​pilot plant at 50 euros per liter due to the investment costs. By manufacturing on an industrial scale, the price per liter could drop to around two euros – that would still be four times the wholesale price of fossil fuel. In the long term, production costs could be less than one euro, which would still be more expensive than e-mobility.

E-Fuels: Is this the future or can it go away?

The internal combustion engine can remain – as long as it is operated with climate-neutral fuels. How e-fuels work and how sustainable they really are.

“However, there is great uncertainty about the development of these cost reductions over time,” write Ueckerdt and his PIK colleague Adrian Odenweller in one analysis paper. This depends on how the market for e-fuels develops, partly due to state control.

Because e-fuels will be used primarily for climate-friendly shipping, aviation and petrochemicals in the future, Ueckerdt comes to the conclusion: “The fact that e-fuels could be used on a large scale for passenger cars in the future would be a risky promise that probably cannot be kept .” Because this threatens to increase dependence on fossil fuels.


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