8 roads to fossil fuel freedom
Image credit: Nick Smith
These days there are plenty of alternatives to filling your tank with prehistoric dead organisms. Here we take a look at some of the contenders.
A hydrogen fuel-cell future
Widely forecast as the one of the only serious mainstream technology challengers to electric vehicles (EV), the hydrogen fuel-cell ‘alternative to the alternative’ is steadily gaining traction with manufacturers, with the Toyota Mirai now in car showrooms, albeit sporting a hefty price tag. While consumer media reviewers are distinctly underwhelmed by the performance of hydrogen-powered cars, the attraction to the green motorist is that the simple equation of hydrogen in the tank combining with oxygen from the air to emit nothing but water, places the technology firmly in the zone of a realistic sustainable future for drivers. The technology isn’t new, with virtually every car manufacturer having come up with a prototype hydrogen fuel-cell in the past two decades. Factors that have delayed migration from prototype to production include the cost of the precious metal required (typically platinum) in the fuel-cell itself, and concerns over storing sufficient on-board hydrogen to produce a meaningful range for the motorist. With the Mirai there is capacity for 5kg of compressed hydrogen, with each kilogram yielding a mileage equivalent to a gallon of unleaded petrol, while the cell itself is roughly the same size as a conventional fossil-fuel tank. With a range of 300 miles-plus, hydrogen fuel-cell cars don’t come with the ‘range anxiety’ of EV cars. But on the other hand, you’ll find there are far fewer places to refuel.
The ‘alternative to the alternative’ will give EV a run for its money.
Biofuels: an interim measure?
Whether you are using bioethanol (an alcohol derived from corn and sugarcane) or biodiesel (vegetable oils and animal fats), according to the RAC, biofuels “offer alternatives to crude oil-derived fuels such as petrol and diesel,” and are increasingly being seen as a medium-term solution to fossil fuel usage, “as we move to a world where electric vehicles become the norm.” The reason biofuels aren’t widely accepted as a panacea is that, while undoubtedly an improvement on fossil fuels, both bioethanol and biodiesel come with an environmental cost. Bioethanol, for example, is only classified as ‘carbon neutral’ because the crops that constitute the raw material for the fuel only just remove the carbon-dioxide generated during its production. And while bioethanol could represent as much as an 85 percent improvement on emissions by fossil fuels, a lot depends on how the fuels are produced and used. The more efficient variants are so-called second-generation biofuels that are produced from sustainable resources rather than those grown for food. Changes to the UK’s Renewable Transport Fuel Obligation (RTFO) mean that biofuel targets will double, so that organisations supplying 450,000 litres a year (or more) will have to make sure their mix is at least 12.4 percent biofuel by 2032, up from the current target of 4.75 percent. While the legislation affects suppliers to the haulage and airline sectors, the Department of Transport says the effect will be to deliver “emissions savings equal to taking hundreds of thousands of cars off the road.”
Strong potential but for the moment lacking in mass appeal.
Electricity: current thinking
According to Autocar magazine, 2020 is the year the electric car will ‘hit the big time’. It’s taken a decade for the practical motoring and economic aspects of EV to make it a serious competitor to the petrol car, but the rise to market acceptance (as discussed elsewhere in this issue) has been propped up by consumer willingness to accept price premiums and range limitation as the cost of supporting a green alternative. For Autocar, as we enter the third decade of the century, the EV is a no-brainer: “An electric vehicle lets you travel in silence and produces zero emissions. You don’t have to pay road tax, London dwellers don’t need to worry about the Congestion Charge, and the government will even give you a grant to buy one.” We have driven a long way since the first commercial models came with a range of 80 miles, at a cost of half as much again as a comparable fossil-powered vehicle. “Today, in many cases, real-world range has more than doubled and that price premium has almost disappeared.” With models from brands such as Kia, VW, Peugeot, Hyundai, Mini, Renault and more, the all-time best-selling plug-in hatchback in the UK is the Nissan Leaf with 24,000 units registered as of September 2018. To put this into context, the Ford Fiesta sold three times as many units in 2019 alone. With the Leaf eligible for the government’s PiCG (plug-in car grant) of £3,000, it has become Autocar’s ‘default recommendation’ replacement for the fossil-fuelled family hatchback.
With media and market backing this alternative is the current favourite.
Full steam ahead?
Since its invention in the early 18th century by Thomas Newcomen, and its subsequent development by James Watt, the steam engine has revolutionised the world. It replaced sails in ships, drove the expansion of the railways in the 19th century and literally powered the factories of First Industrial Revolution. What’s perhaps less well known is that until the dawn of the 20th century half of the cars made in America were steam powered, with boiling water established as the predominant automotive technology over the new-fangled internal combustion engine. It was so dominant that in 1906 a steam car called the Stanley Rocket held the land speed record of 127mph. With its constant pressure (no need for gears and clutches) and ease of operation, the future of the steam-powered car seemed set fair. That is until Henry Ford came along with the mass-produced Model T that in 1918 was six times cheaper than the vastly superior Stanley Steamer. Even before Ford came along, the fate of the slow-starting steam engine was sealed by the invention of the electric starter motor that went through early development in the late 19th century and was first installed in production models by Cadillac in 1912. While steam as a concept has never become extinct – VW was working on a steam alternative as recently as the 1990s, and in 2009 a new steam land speed record was set – today it is unlikely to make a dent in either fossil fuel or electric.
After a promising start this technology ran out of steam.
Where’s the compressed air?
Compressed air vehicles (CAVs) have been around since the 19th century when they were used in the mining industry and on the Paris tramways (as well as in torpedo propulsion) and the idea remains popular as an alternative to fossil fuels. As recently as 2007, Tata Motors signed an agreement with Motor Development International (MDI) to roll out a CAV called the AIRPod. Two versions were mooted: compressed air only and a hybrid. Designed as a zero-emission alternative for urban driving, they had a top speed of 110kph (68mph) and a range of 80km (50 miles), with prototypes being tested in airports. Despite appearing on the US reality TV show Shark Tank, the AIRPod has failed to materialise on the road. The principle behind the CAV is one of the simplest of the alternative technologies. Air compressed at a compressed air station is transferred to a storage tank on the CAV and slowly released to drive a pneumatic motor that converts air power to mechanical power. This is then transferred to the wheels, and the vehicle moves. But there are at least three main problems currently preventing the concept getting beyond the prototype stage, despite the hype that repeatedly surfaces in the media about the CAV’s greener, cheaper credentials. First, the compressed air system doesn’t produce sufficient torque, second is the indirect energy cost of compressing the air in the first place, and third is the safety concerns over lightweight vehicles powered by compressed air in collision conditions.
A solid idea but plans for the future have been more hot air than compressed air.
LPG: leaner and greener
If there was an alternative to petrol that was half the price and produced significantly less tailpipe emissions, you’d think that motorists would flock to it. According to the RAC, it is the alternative fuel that’s ‘left out in the cold’. LPG, or liquified petroleum gas – butane, propane or even ‘autogas’ – is actually a by-product of the crude oil refining process that was once discarded, but is now seen as a low-carbon fuel that can be used to power cars. LPG is particularly clean burning, which means that LPG cars have half the nitrogen oxides of petrol and 20 times less than diesel. To use LPG you will need to convert your car, a process that not only uses up your boot space and makes the vehicle heavier, but is also puts you in a significant minority of one per cent of road users. And because the UK government doesn’t incentivise the adoption of LPG in the same way as it does EV (converting your car will set you back £2,000), and because LPG rarely receives any promotion as a low-carbon alternative, many motorists are simply unaware of its existence. It follows that if hardly any motorists use it, hardly any fuel stations will stock it, despite LPG costing half the price of petrol. A few manufacturers such as Ford and Vauxhall have dabbled with the ‘dual-fuel’ production model market, but today Renault’s Romanian-based subsidiary Dacia is the only carmaker selling new vehicles in the UK capable of running on LPG.
Value for money isn’t enough to make LPG the ‘must have’ consumer option.
Liquid nitrogen: abundant resources?
Given that there is plenty of nitrogen around – it is the seventh most abundant element in the Solar System – that would seem incentive enough to exploit it as an alternative to fossil fuelled cars. In fact, the idea of a nitrogen-propelled vehicle has been around since the 19th century, when the Liquid Air Power and Automobile Co set up production in Massachusetts and demonstrated a modified ‘locomobile’ at an exhibition in London, where it was claimed that the vehicle could operate over 40 miles (64 km) at 12 mph (19 km/h), running on liquid air, sold at one shilling (£0.05) per gallon. Today, there isn’t much commercial interest in the technology despite its green credentials: the only exhaust emission from vehicles is nitrogen, and so there is no production of localised pollution in the atmosphere that is 78 percent nitrogen in any case. The issue with nitrogen-fuelled vehicles is that the energy itself isn’t carbon-neutral because of the energy-intensive process that goes into compressing the nitrogen before fuelling the vehicle. While this could theoretically be done with clean energy resources, the process is expensive, and while a zero-emission alternative to fossil fuels is appealing for the motorist, car manufacturers are voting with their feet in favour of hydrogen and EV as mainstream development technologies. Meanwhile scientists continue to experiment with nitrogen technology, with Dr Carlos Ordonez modifying a 1973 Volkswagen to come up with the ungainly ‘CooLN2Car’ that was capable of a top speed of 25mph.
On paper one of the best ideas out there, but not sustainable financially.
Kinetic energy recycling: using what you’ve got
Ever since the first Toyota Prius first put in an appearance two decades ago, the idea of ‘regenerative braking’ has become a standard approach to increasing geographical range in hybrid and electric vehicles. It may not be so when driving a car, but when cycling it is obvious that one of the biggest wastes of energy is braking (as well as the energy required to get going again from a standing start). Don’t do this, but if you were to touch the brake pads on your bike, you might be surprised how hot they become. Never touch the brake pads on a Formula One car because they can heat up to 1000C under braking. In the days before we worried about energy, automobile brakes were friction based, their only job being to convert the vehicle’s kinetic energy into wasted heat in order to stop a car. All of that energy was simply lost to the environment. Today, brake energy regeneration systems are making their way onto a growing number of both EV and fossil cars as a method of harnessing onboard energy loss in order to reduce fuel consumption, whatever fuel you use. Regenerative braking uses an electric vehicle’s motor as a generator to convert much of the kinetic energy lost when decelerating back into stored energy in the vehicle’s battery. And while this might appear to make a vehicle more efficient, in fact it is only making it less inefficient.
A really neat way to put energy back in the system, but only part of the solution.
This article was updated on 15 July 2020, shortly after publication, to clarify that new LPG cars manufactured by Dacia were at that time available to buy new in the UK.
Sign up to the E&T News e-mail to get great stories like this delivered to your inbox every day.