Alternative powertrain progress may have swung inexorably in favour of BEVs, but there's a big wide world out there where liquid fuels are still in demand.

This month, Toyota, BMW and Repsol began a pilot scheme in Spain to demonstrate how existing vehicles can run exclusively on Repsol's fully renewable petrol, Nexa 95. Bosch is also a collaborator in the project, contributing its 'digital fuel tracking solution'.

Liquid fuel is big in China, but rather than petrol or diesel we're talking about methanol, of which China accounts for around 60% of the world's production. The bad news is that, so far, most Chinese methanol has been made from coal, but the country is investing in e-methanol production.

It began supporting the use of M100 (100% methanol) fuel in cars in 2019 and is now the world's largest market for methanol-fuelled vehicles.

It's not surprising, then, that Horse Powertrain's latest creation is the D20 Methanol, a range-extender EV powertrain featuring an M100-burning 2.0-litre turbo engine and an axial-flux motor-generator.

Axial-flux motors are the biscuit-tin type in the sense they are larger in diameter but very short. This one is almost half the length of an equivalent radial-flux motor (of the conventional cylindrical shape), with 63% greater energy density by volume, so it can produce 63% more power in kW per unit of volume it occupies.

The motor is also yokeless, which means the stator doesn't use a large, heavy iron disc (a yoke) on which to mount electrical coils. Lightweight materials and design features do the job instead.

Electrical efficiency is rated at 96.4%, thanks in part to features such as an embedded silicon-carbide power module to minimise electrical losses.

The D20 is claimed to achieve a 47% energy conversion ratio of the fuel, which is extremely efficient.

A high-energy ignition system contributes to that by enabling ultra-lean burning of the M100.

Cold starts can be tricky, one of the intrinsic drawbacks of methanol fuel, but the new ignition system also means the engine can be fired up in temperatures as low as -35deg C.

NOx emissions comply with China's CN6b standard of 35mg/kWh and the EU's Euro 7 limit of 60mg/km.

In 1999, DaimlerChrysler launched the Mercedes A-Class-based Necar 4 hydrogen fuel cell EV, which ran on hydrogen reformed on board from methanol. The company reasoned that existing filling stations could easily be converted to methanol rather than petrol and diesel by installing liners in underground tanks and swapping out pumps.

In 2005, Nobel Prize-winning chemist George Olah wrote an essay promoting an economy based on methanol derived from hydrogen or CO2, both of which can be produced sustainably.

Perhaps that may never happen, but it seems that methanol still has a major role to play in making vehicular transport more sustainable.