Could biofuels save the combustion engine?

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The electric revolution is well underway but advancing biofuel technology could see the beloved combustion engine live to fight another day.

Engines themselves are not the enemy, it is their use of fossil fuels that is, as each combustion cycle releases previously ‘bottled up’ carbon into the atmosphere.

Biofuels, however, made from waste that would be left to rot or be ploughed back into fields, still release carbon, but carbon that was already ‘circulating’ and with the sowing of replacement crops and plants that will themselves take up carbon, the overall result is carbon neutrality.

Now Coryton, a British firm specialising in bespoke biofuels for sectors including motorsport, are looking to bring these carbon-neutral fuels to the masses in the not-too-distant future.

Luke Goldsmith, Coryton’s Sales Director, said: “At the moment we don’t have the economies of scale the oil industry does. But we are starting to see further adoption of these types of fuels. As the volume increases, we are starting to offer more competitive pricing.”

Currently biofuels cost two to three times the amount of fossil derived fuels but with the myths surrounding them being debunked, more companies are seeing the biofuel light, including motorcycle manufacturers like BMW.

Tanker at a Coryton fuel depot

The German giant said: “In our opinion, eFuels have great potential to play an important role in decarbonization. We do not see eFuels in competition with e-mobility, but as an important, complementary parallel path. Because eFuels can do something that e-mobility cannot.”

They added: “What is valuable here is that they have a “drop-in ability” and can be refueled in existing infrastructures all over the world.

“The clear focus is to ensure at least functional neutrality for backward compatibility and, if possible, to take advantage of benefits. Priority is given to the return-free use of eFuels in existing engines.”

One such fallacy is they are not as energy rich as fossil fuel, robbing the petrolhead of valuable bhp.

This is not the case, as shown by the BRX Dakar Rally vehicle developed by Prodrive and running Coryton Sustain fuel.

It placed second when competing and Goldsmith feels this increased drive by motorsport, including MotoGP, towards sustainability will only further the widespread adoption and development of biofuel.

How ethanol is turned to gasoline

Goldsmith said: “The technology we use is not less energy dense, it is an identical chemistry to fossil fuel, they are hydrocarbons, so exactly the same mix of aromatics and paraffins that you get from fossil fuel, you just happen to make them from biomass [rather than oil].”

So why, given the benefits, has biofuel been overshadowed by the electric revolution?

Goldsmith has a compelling theory: “A lot of people when they look at electrification look at that sole point of use, that exhaust pipe at the end and they don’t look at the full life cycle.

Coryton fuel warehouse

“If we consider the full life cycle of analysis, looking at a fuel or a vehicle from the moment it is taken out of the ground or a plant, all the way through to when it goes to the grave or is burnt, only if we look at it from that perspective will we understand where the benefits lie.”


Making fuel from fresh air: Sunlight and air create ‘drop-in’ replacement for burning petrol

First published on December 10, 2021, by Ben Purvis

ETH Zurich roof-top reactor

The idea of conjuring petrol from nothing but fresh air and sunlight sounds like alchemy but a pilot project in Switzerland has proved that it’s possible.

On the roof of research university ETH Zurich sits a miniature solar refinery, using a unique set of processes to create hydrocarbon fuels.

Although there are already projects around the world to create synthetic fuels, taking hydrogen from water and carbon from CO2 in the air, they usually require a large amount of electricity. ETH Zurich’s mini refinery, in contrast, uses sunlight as a direct part of the process and doesn’t need a vast amount of electricity.

There are three processes in the mini refinery. First, it has to extract CO2 and water from the air, before both are fed into a reactor where the real magic happens.

A parabolic mirror directs sunlight back onto another reflector, then focuses it onto the solar reactor, heating it to 1500°C. The reactor is made of cerium oxide, and this burst of heat forces it to release oxygen into the atmosphere.

ETH Zurich reactor diagram

Then the CO2 and H2O are added and the reactor strips oxygen from them leaving a mixture of hydrogen and carbon monoxide. This is called syngas and can be used as the basis for a variety of fuels.

Because heat is only needed for the initial step, the prototype has two solar reactors, with a movable mirror to switch the sunlight’s focus back and forth, doubling its efficiency. The prototype makes around 100 litres of syngas per day.

Stage three takes the syngas and runs it through a gas-to-liquid unit, which converts it to methanol. The university say it could be made into gasoline or kerosene using catalysts.

In terms of emissions, it’s carbon neutral, since burning it will only release as much CO2 as was originally used to create it. However, in a combustion engine there are other emissions, NOx, for instance, which comes from the reaction of nitrogen and oxygen in the air during combustion.

How the ETH Zurich reactor works

However, since CO2 is by far the largest proportion of vehicle emissions, neutralising that promises to make a vast difference.

If you’ve got visions of plonking a reactor like this on your own roof and having an endless supply of petrol, think again. The mini refinery can make around a teaspoonful of fuel per day. Filling your tank could take a while.

It’s calculated that to create a solar plant that could completely replace the 414 billion litres of kerosene used in aviation in 2019 (before the pandemic slashed air travel), you’d need 45,000km2 of desert. That’s equivalent to 0.5% of the Sahara.

The cost of the fuel would depend on the industrialisation of the process, but the scientists behind the project reckon that once solar fuels account for 10-15% of the market they’ll be competitive with fossil fuel prices.


Synthetic petrol: How bikes could become carbon-neutral without switching to battery power at all

First published on 3 July 2021 by Ben Purvis

Filling up a petrol powered motorbike

As governments propose firm dates for the end of petrol and diesel powered vehicles you might be forgiven for thinking we’re living in the end days of the internal combustion engine. But the technology that’s literally driven the transport revolution for more than a century isn’t ready to give up just yet and could be thrown a lifeline by the development of synthetic fuels that are nearly as green as going electric.

Synthetic petrol, diesel and aviation fuels are all the subject of heavyweight pilot projects and are gaining interest fast as they eliminate the CO2 emissions from transport without the need for end-users to switch to new tech. Aviation in particular is backing the idea but motorsport is getting in on the action, with the World Rally Championship due to use 100% sustainable fuel as soon as next year.

While biofuels already offset their emissions to an extent, synthetic fuel takes a more direct approach by stripping CO2 from the air and combining it with hydrogen to create a petrol replacement.

By using wind, solar or hydro-electric to generate the electricity for the electrolysis, the process is sustainable, and while engines using the fuel still emit carbon, the same amount is reabsorbed in the fuel-making process.

The idea of using electricity to create synthetic petrol and then to burn that fuel in combustion engines might seem wasteful but the benefits are also significant, reusing existing infrastructures and giving new life to billions of combustion engines rather than reducing them to scrap. With similar power density to normal petrol, synthetic fuels also mean you don’t need to lug vast batteries around.

At the moment, there are several synthetic fuel projects underway. Porsche – part of the VW Group and hence a sister to Ducati – have invested in Siemens Energy’s Haru Oni pilot project, a prototype plant in Chile that uses wind power to make synthetic petrol. It’s due to make 130,000 litres next year, 55 million in 2024 and 550 million litres in 2026.

BMW, meanwhile, have invested in US firm Prometheus Fuels, which uses a different process but again creates petrol from air, water and electricity.

While many governments seem keen on switching from combustion tech to all-electric vehicles, it’s looking likely that a better approach is to adopt multiple technologies to reach carbon neutrality, applying them where they fit best. And perhaps most importantly of all, synthetic fuel should mean that more than 100 years’ worth of bikes have a future.


Synthetic fuel technology explained:

Siemens Energy’s Haru Oni pilot
  • Methanol-to-gasoline The methanol forms the basis of synthetic petrol, created at the Haru Oni plant using an ‘MTG’ (methanol to gasoline) technology provided by Exxon Mobil.
  • Methanol synthesis Once the factory has extracted CO2 from the air and hydrogen from water, the two can be combined into a synthetic methanol fuel.
  • Direct Air Capture unit CO2 is removed from the air using ‘direct air capture’ technology, which involves chemical filters and large fans to draw the ambient air through the system.
  • Tank farm The resulting fuel is intended to be a direct replacement for fossil-derived petrol, eliminating the need for new engines and infrastructures. Estimates range from as little as £1 per litre to more than £3 per litre by 2030, but that may be worth it as a lifeline for existing engines and an alternative in applications where battery power is unsuitable. 
Stuart Prestidge

By Stuart Prestidge