Graphene-based hydrogen storage
Regular readers of this column will have noted my Jeremy-Clarkson-like, petrol-head enthusiasm for motor-cars, preferably powered by large petrol engines, and producing inordinate amounts of power. As our friends the Americans say, “There’s no substitute for cubic inches”. You may therefore have run away with the idea that I’m opposed to novel or unconventional power sources for cars.
Not so. With cars (as with renewables) I’m in favour of novel technologies provided they’re competitive. And not just competitive in terms of price and performance, but also in terms of convenience, speed of refuelling, and availability of fuel. Even if today’s electric cars were affordable, their limited range (especially if you want add-ons like headlights and air-con) counts against them. Who wants a car that won’t go 300 miles between fill-ups? Especially when it takes eight hours to fill it up.
Of course proponents of electric vehicles are keen on reducing CO2 emissions, and electric cars only reduce emissions if you have low-emission electricity to start with, which adds a whole new dimension to the problem.
But if carbon (in some people’s minds) is the problem, it may also be part of the solution. Carbon is a remarkable element, partly for its ability to form long-chain molecules. It is all around us in the form of hydrocarbons (like oil) and carbohydrates (like bread). It is also in us — in proteins, in our DNA. We hear a lot about the dangers of atmospheric CO2, yet CO2 is merely a trace element in the atmosphere, at around 400 ppm, or 0.04% (if I’ve got my decimal point in the right place). It is also a vital trace gas — without it, life on earth would be impossible.
Carbon, of course, also occurs in a pure form — or rather, several pure forms. We’re accustomed to carbon in the forms of soot and graphite (as in lead pencils). We’re also familiar at least with the idea of diamonds, which are a different pure form of carbon, in a cubic lattice pattern which is extraordinarily hard. In recent years, new structures of pure carbon have been discovered. One is the “Buckyball”, a spherical structure comparable to the pattern on a soccer ball, or a geodesic dome.
Indeed it acquired its name of Buckminsterfullerine, or Buckyball, by reference to Buckminster Fuller, who designed the geodesic dome.
Yet another form of carbon is graphene, which is another structure to which carbon lends itself — a single sheet, one atom thick, of carbon atoms. This material has remarkable properties. It is extraordinarily strong in relation to its weight. And its electrical conductivity is many times that of copper wire.
I am now getting well beyond my technological comfort zone. But I am reliably informed that graphene offers the possibility of very efficient storage of hydrogen. (It also offers the possibility of a breakthrough in battery technology). There seems to be a possibility that a graphene hydrogen tank could power a car, more efficiently than merely compressed hydrogen in a pressurised tank. Graphene storage has a further attraction to the climate alarmist brigade, in that excess electricity produced by intermittent generating technologies like solar PV could be used to make hydrogen by electrolysis of water — in effect, a means of storing excess energy generated by intermittent renewables. Right now, I’m opposed to wind and solar because they are hopelessly expensive and inefficient. But with solar PV (if not wind) there is some prospect that they could become cost-efficient in a few years — perhaps thin film technology applied to the south-facing windows of large buildings. If this were so, then hydrogen could be a suitable storage mechanism for any excess energy generated.
This leaves huge unanswered questions, starting with the economics of the whole process (in turn depending on future developments on solar PV), and going on with the distribution infrastructure for hydrogen. We have a vast chicken-and-egg problem. You can’t sell hydrogen cars without a hydrogen infrastructure, and you can’t fund the infrastructure until you have the demand. The availability of the huge prior investment on petrol/diesel fuel distribution creates a massive barrier-to-entry for new technologies.
That is a barrier not faced by gas, since distribution down to the domestic level is already largely in place. So despite the hydrogen-storage properties of graphene, we may find cars in 2030 powered not by hydrogen, or electricity, but by natural gas piped directly into peoples’ homes and garages. This in turn will be supported by the massive new sources of gas which are currently coming on stream.