Carbon Recycling: Turning CO₂ into Climate-Neutral Fuel
By: Porsche Ag
Tags: Innovation, Mobility, Automotive, Hybrid, Efuel

eFuels are synthetic fuels produced from water and carbon dioxide

What are eFuels and why Porsche will use them?

eFuels are synthetic fuels (i.e. complex hydrocarbons) made from water (or, more precisely, hydrogen) and carbon dioxide (CO₂). They are a promising climate-friendly alternative to conventional fossil fuels such as oil-derived petrol and diesel. While the energy required for their production comes from renewables such as wind and solar, eFuel production itself involves direct air capture of CO₂. Instead of drilling for oil and moving huge amounts of carbon from the geosphere to the atmosphere, the greenhouse gas is sucked out of the air and ultimately recycled into a liquid energy carrier.

Moreover, eFuels are compatible with internal combustion engines (ICE) and can be used in vehicles on the road today, either as an admixture to petrol and diesel or as a complete substitute. In fact, gas-burning cars running on pure eFuels can potentially be powered in a nearly climate-neutral way, as they emit only as much CO₂ as was previously sucked up from the atmosphere in the production process — a closed cycle with no net increase in carbon dioxide levels. Another advantage of eFuels is that they can be easily stored, transported and distributed in the existing infrastructure.

Synthetic fuels are a climate-friendly alternative to fossil fuels

Producing climate-neutral eFuel on an industrial scale

While the technology underlying synthetic fuels is well understood, carbon-neutral eFuels have not been produced on a large scale yet. To be commercially viable and competitive with conventional gasoline, eFuels need to be produced at a low cost. Porsche is currently conducting extensive research into the industrial production and use of eFuels and has recently launched a pilot project with Siemens Energy and other partners in Chile: The “Haru Oni” project is the world’s first integrated, commercial plant for the production of carbon-neutral eFuels on an industrial scale. Its annual production capacity will increase from around 130,000 liters in 2022 to 550 million liters in 2026 — the equivalent of enough fuel to power one million cars for one year.

Fuel from wind, hydrogen, and CO₂

It is important to note that synthetic fuels are not inherently green. Their respective carbon footprint depends greatly on their production process and source of electricity. On this note, it makes sense to produce synthetic fuels in wind- and sun-rich regions where renewable energy potential is high. For example, The “Haru Oni” project takes advantage of the excellent wind conditions in Chile, using zero-carbon electricity from wind.

How is eFuel made? Its production process starts with electrolysis, where H₂O splits into hydrogen and oxygen. By passing a direct electric current through the water in an electric cell, hydrogen splits off and captures at the negative pole (cathode). The energy efficiency of this process is about 70 percent.

Moreover, using a process known as direct air capture, carbon dioxide is extracted directly from the air. Large fans blow ambient air through filters that chemically bind with CO₂. Next, hydrogen and captured CO₂ are combined to produce so-called eMethanol, used for various purposes as a “green substitute” for fossil-based methanol. However, for our purposes, it is further processed into what we call “eFuel”. Through further refinement, our fuel achieves an octane rating comparable to that of premium gasoline, of course still useable for conventional gasoline engines. We will use eFuels in our motorsport fleet, at the Porsche Experience Centers and, at a later stage, in series-production sports cars.

eFuels can complement e-mobilty (Taycan Turbo S: Electricity consumption combined: 28,5 kWh/100 km; CO2 emissions 0 g/km)

Sustainability at Porsche

At Porsche, we are firmly committed to sustainability and the Paris Agreement. As such, a top priority for us is to advance electromobility. As a complement to this endeavour, we advance the large-scale production of a clean and climate-neutral version of gasoline: eFuels will help us to reduce the carbon footprint of combustion engine and plug-in hybrid vehicles continually. They offer a promising possibility to move away from fossil fuels fully, while holding on to existing fleets. The potential benefits of carbon removal and carbon recycling cannot be overstated, of course. Therefore, it is essential to further industrialize these technologies and make them economically viable.