The debate about alternative fuels for cars risks coalescing into a them-and-us conversation depending on your thoughts about battery electric power. This is a pity as it’s causing many other alternative fuel options to be marginalised or forgotten about altogether by drivers.
However, while plug-in electric and hybrid cars take centre stage, for the time being, there’s also a great deal of research and development ongoing inside car companies with fuels such as hydrogen, bioethanol, LPG (liquified petroleum gas) and even steam.
Some of these other sources of propulsion for cars have been around a long time, but let’s not forget that electric cars were only beaten to mass market demand in the early 20th century because of cheap, widely available petrol and the greater range it offered.
Now, the internal combustion engine in its current form is facing an environmental and regulatory deadline, such as the UK’s stated intention to outlaw all new car sales of petrol- or diesel-only vehicles by 2040. This has focused attention on alternative fuels and, given concerns about electricity infrastructure being able to cope with an all-electric car park, means the time is ripe for a broader offer of fuels.
Hydrogen is the most commonly touted substitute for fossil fuels as it could be sold from filling stations in the same way petrol is. A big advantage for hydrogen is drivers don’t have to make any significant cultural shift in the way they run their car or fill it with fuel.
Environmentally, hydrogen has the huge appeal of producing nothing more toxic than clean water when used as a fuel. This is because the fuel cell it powers to make electricity combines the hydrogen with oxygen from the atmosphere, so it effectively works as an onboard generator to power the car rather than having to store electricity in large, heavy batteries and draw its energy from a plug-in source. This is what Hyundai is banking on with its Nexo and follows the Honda FCX Clarity and Toyota Mirai’s lead.
There are downsides to hydrogen as a fuel for vehicles. For starters, there is a very small network of filling stations, even in countries like Germany that have experimented and embraced it more than most. The cost of producing hydrogen in commercially sufficient quantities is expensive too unless sustainable, renewable and low-cost electricity is available for its manufacture. Lastly, the poor availability of this fuel means few car makers offer hydrogen-powered models and that makes those out there very expensive, so there’s a chicken-and-egg situation of who will invest first – the fuel provider or vehicle maker?
This isn’t an issue with LPG, often called Autogas in continental Europe where it’s very popular. It’s been around a long time, has a proven record of cutting fuel bills as it’s much less heavily taxed than petrol or diesel, and most internal combustion engines can be converted to run on it. Along with compressed natural gas and propane that are very similar to LPG, it emits around 120 times less fine particulates than diesel, as well as producing less carbon dioxide.
Why, then, has LPG not gained more of a foothold? This is mainly due to LPG having a very ‘lean’ burn compared to petrol, so you have to combust more of it to get the same power. Most LPG-fuelled vehicles use it as an additional fuel alongside petrol, switching to LPG when the car is up to operating temperature. While fuel duty is low for LPG, it’s a worthwhile consideration as a fuel, though there are still tailpipe emissions with it.
The same is true of biodiesel, which is made from crops such as rapeseed by the process of transesterification. It does require some energy to produce biodiesel, but the majority of carbon dioxide it emits when used in cars is offset by the plants grown to produce it. The bigger stumbling block is biodiesel costs more per litre to make than crude oil-derived diesel, which puts off many users.
Like biodiesel, alcohol-based fuels such as methanol, butanol and ethanol are made from sustainable crops. Unlike biodiesel, these fuels consume more greenhouse gasses as the crops grow than are emitted when the fuel is burnt in an engine. A lower energy density does mean you need to burn more alcohol to get the same given power as petrol. At present, only a handful of racing cars use pure alcohol for power, but it is available as E85, where 85% of the mix is ethanol.
Other fuels being worked on include nitrogen, water and solar, such as the One from Dutch firm Lightyear. It’s due on sale in 2020 with a claimed range of 500 miles and the company says it only needs to be charged from a socket once every few months.
Alongside the handful of hydrogen cars currently on sale like the Hyundai Nexo and Toyota Mirai, the Lightyear One is the only car looking for a different path to plug-in battery electric vehicles at present. What is certain, regardless of the fuel powering it, is the car will be with us for a very long time to come.
Writer: Alisdair Suttie