The UK press has gone mad over a new energy technology in recent days. I’ve been asked whether it is really as exciting as it seems?
“Exclusive: Pioneering scientists turn fresh air into petrol in massive boost in fight against energy crisis” ran the headline in the Independent on 19th October, and the story was picked up by the BBC on various channels. “we have been inundated here at AFS with requests for media interviews and comments from social media forums” says the home page of the company’s website – Air Fuel Synthesis.
So is it real? Well it certainly has a highly credible and solid technology foundation – the company was founded by Professor Tony Marmont, who has worked on aspects of renewable energy for many years.
Is it highly novel? Not really. The basic idea is that petrol, like all fossil fuels, is made of hydrocarbons – that is, long chains of hydrogen and carbon atoms. So if you use the right catalysts and processes, you can combine hydrogen and carbon to make fuel, which is what they do.
The hydrogen comes from the electrolysis of water and the carbon can come from the air – though the company speak about highly concentrated sources of CO2 like breweries, distilleries or aerobic digesters.
The problem is of course the question of how much energy is needed to run the whole process. The energy can come from renewable sources – and needs to, in order to keep it carbon-neutral – but the question is whether that energy is better used elsewhere, and more to the point, how much it costs to use it here.
I have seen statements for similar technology that it would require about 20 kWh to produce a litre of fuel. I very much doubt that this includes the energy which would be required if the carbon dioxide were to come from the air (concentrated sources are not that widespread). But even assuming that it does include this and is therefore extendable on a large scale, the problem is that that 20 kWh from a wind turbine or other clean energy source would power an electric car to travel about 60 km, whereas that litre of fuel (which will contain about 10 kWh) would power an internal combustion engined car only 15 km.
Let’s recap those numbers – they are surprisingly stark: we would get four times more mobility out of the primary energy if we used it in electric cars, than if we produced air fuel – at least four times, given the CO2 extraction energy issue and given the fact electric cars are still early stage technology. The difference expands to seven times if you take the efficiency of a Tesla Roadster.
About 13% of our transport fuel is used in applications which require liquid fuel – aviation and shipping – and this innovation has a great and potentially lucrative market there. But for the largest share of the transport market – private cars – the weight of the numbers strongly suggests that EVs are likely to be more successful.
I hate to splash even a few drops of cold water on new innovators’ work, as I’ve spent many years innovating myself – however I’ve also come to the conclusion that our media’s slightly hysterical obsession with the “new new thing” is destructive to the progress of clean energy. The fact is that the physics is quite simple, we have almost the technology we need already, and the main issue is not innovation, but deployment (and the incremental innovations and cost reductions that will follow from large scale deployment).
* The Numbers
Energy consumption of petrol car: 70 kWh/100 passenger-km (typical family car)
For electric car: 34 kWh/100p-km – Nissan Leaf, according to the US EPA.
For Tesla Roadster (2-seater sports car): 21 kWh/100p-km – EPA.
Image:Scientist via Shutterstock