Opinion: E-fuels are a fool's gold for drivers

Imagine electricity transformed into pure petrol... and what you’re seeing is e-fuel. Though it might sound like alchemy, making them involves nothing more than well-proven physics, chemistry and engineering.

It’s likely you’re going to hear a lot more about e-fuels. They’re green, they’re clean and they’re carbon neutral, or very close to it, so they have immense and obvious appeal for anyone who is fond of both the internal-combustion engine and our planet.

There are only two problems: they’re not an efficient way to use precious renewable energy; and they’re not essential, at least when it comes to cars.

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To understand the inefficiency thing, you need to know at least a little about the basics of e-fuel production. So let’s take a look at a specific example, one that’s been getting some attention recently.

Porsche is supporting, as lead customer, a multinational project scheduled to begin producing e-fuel next year. The Haru Oni project in Chile will use power generated by a forest of big Siemens wind turbines. Their electricity will be used to extract hydrogen from water and carbon from carbon dioxide filtered out of the air. The hydrogen and carbon will then be bonded to create methane gas, which will be converted to liquid methanol. Finally, the methanol will be processed to produce petrol.

What’s important to understand is that none of these steps is 100 percent energy efficient. Only around 50 percent of the electrical energy needed to create the e-fuel ends up stored as available chemical energy in the e-fuel. And much of this, around 70 percent, escapes as heat from the exhaust pipe and radiator when the e-fuel is burned in an internal-combustion engine.

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Credible analyses of the overall efficiency of the entire chain of e-fuel production and use that I’ve found estimate that only about 15 percent of the electrical energy needed to make the stuff actually gets to the point where rubber contacts road. If the same amount of electrical energy was instead used to charge an EV, it would be able to drive four to six times farther than a vehicle powered by an internal-combustion engine burning e-fuel.

Despite this, e-fuels do have a future. In a world where there’s an abundant oversupply of renewable energy, it makes sense to do something smart with the surplus.

While e-fuel will never be the most efficient choice, it does offer a bunch of advantages; it’s easy to store and transport using infrastructure that already exists, and it can be used in vehicles that already exist.

Analyses of the overall efficiency of e-fuel production and use estimate that only about 15 percent of the energy needed actually gets to the point where rubber contacts road

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Even assuming the day comes when more renewable energy is being produced than is required to supply immediate daily needs, pouring e-fuel into cars isn’t the most intelligent thing to do with it. Why? There are other important modern transport modes that cannot be made climate-neutral without them. The idea of running international maritime freighters or long-range commercial aircraft on battery or hydrogen fuel cell power is simply absurd. Ask an engineer...

So until some amazing innovation comes along, e-fuels will be essential to making the modern world work in a clean and green way. Everything from shipping a cheap T-shirt from China to jetting overseas for that longed-for holiday or essential business meeting will come to rely on them.

But e-fuels are not essential to keeping our earthbound wheels turning. Porsche may be supporting e-fuel production, but they also happen to have produced perhaps the most persuasive proof that cars can get along just fine without them.

It’s called Taycan.