With a rise in numbers of vehicles on the roads, both in the UK and internationally, creativity is going to be needed if the hold of fossil fuels is going to be broken. However, there are some more leftfield fuel options on the way – and indeed already available – for those willing to think well outside the dominant petrol and diesel paradigm. Here are five of them.
An older-model diesel engine can be converted to run on leftover frying oil – your very own greasy biofuel—for a couple of hundred pounds. It's cheaper, performs roughly the same and produces fewer emissions, so you might expect more than the few hundred existing users of this fuel to catch on – but there are down sides. Chippies have realised there's money to be made from their waste, so prices are rising, while producing non-waste oil from agricultural sources poses broader sustainability questions.
The waste products of chocolate production have been cited as another possible biodiesel source. Since optimistic academic reports on a trial with Cadbury's in 2009, not much has since been heard of this delicious route to the roads.
The farming of alligators for food and their skins is on the rise, leaving a lot of reptile blubber with nowhere to go – until now, possibly. A study at the University of Louisiana proposes that the millions of pounds of 'gator fat produced every year - and that from other animals such as pigs and cows - should be turned into fuel. This idea relies on a new technique reacting the fat with methanol at high temperatures to produce biofuel, and researchers say this can be done within minutes – making it a commercial proposition.
Scotland's finest tipples could be the route to developing bio-butanol, described as a “next-generation biofuel”. Whiskey distilleries have been identified as a starting point for a possible fuel revolution, as waste from malt and the residue left after distillation are mixed and fermented to produce acetone, butanol and ethanol. The butanol is the prize here, but while it can be used in unmodified engines, it may be more a fuel for planes rather than cars.
There are broader applications of the processes used, as Mark Simmers, CEO of Celtic Renewables explained: "The future potential for us is hundreds of millions of liters of biofuel, because not only does the process apply to whisky residues, but it works for residues of spirits industries, the beer industry, and a range of agricultural wastes."
The UK's first bus powered by human waste began its route last year. It's not literally a case of poo-to-power, having been turned into biomethane first. There's never going to be a shortage of what's flushed down our toilets, so there's certainly the promise of longevity in this one, especially when used alongside other household waste products.