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Apr 22, 2014

Renewables changing the nature of power

New technology has dramatically increased the possibilities of renewable energy. But the material revolution challenges those who want to preserve the existing relations of production, consumption and energy.


Halfway through April this year, scientists at Harvard and MIT announced something extraordinary: they had found a way to create solar cells that can store accumulated energy from sunlight, and then — with no more than a burst of a few photons — release that energy in a steady and continuous form. These new types of solar cells — called photoswitches — are made from a form of carbon nanotube called azobenzene, which can exist in two different configurations. One collects energy from the photons that hit it and stores it, another releases it. Because they can be switched from one form to another, the cell is essentially a battery, and this solves many of the problems of storage that arise with a weather-dependent system such as solar.

The great advantage of such a technology is that it would make possible solar cells that were an utterly stable continuous power supply. When you combine it with work being done elsewhere on solar cells that can perform in cloudy conditions, you have the plan for an entirely stable solar delivery system — indeed, one that is more stable than the large-scale privatised power systems that we currently rely on, subject to mass technical failure, Enron-style credit events, and routine under-maintenance.

Such technology is small miracle, yet it’s only one examples of dozens of advances occurring as renewable energy technology comes into contact with new materials and starts to be transformed by them. Thus, in the weeks and months before this recent announcement, news in renewables included: a new nanomaterial that can increase solar fuel cell efficiency by up to 80%, a solar-powered hybrid car that can charge up without needing to dock at a recharge station; and a plane the size of a 747 that will be able to fly around the world without refuelling. On every front, the renewables revolution is gaining pace — not merely gaining pace, but accelerating exponentially — and the overwhelming reason for this is new materials.

Graphene and related forms of carbon have busted open the limits that solar technology hit in the 1990s — limits that made it easy for smug members of the fossil and nuclear lobby to argue that renewables would never be able to supply the energy needs of a modern civilisation. That supposition was based on a crude version of what we might call “molecularism” — a willingness to accept given limits of technology based on the aspects of it that used to be close to us: the limit of the molecule. In that conception, it is easy to see why people could believe that there were limits to the capacities of solar and other renewables. There is no excuse now. The new materials revolution means that anything is possible with regard to renewable energy. The 3D/additive revolution means that we can make machines whereby anyone can print these things out from machines that are themselves powered by this energy. The material revolution makes it first conceivable — and then unavoidable — that these new technologies will converge on an energy revolution, one that will leave existing old-school technologies hopelessly behind.

“These new materials also promise a revolution in the capacity for energy storage.”

In the decade since this new field was opened up, the possibility of cheap, simple and easily reproducible and distributable power and power technologies has opened up afresh. The simplicity and manipulability of new materials such as azobenzene makes possible a re-engineering of solar cells at the molecular level, reaching into the mechanism of the cell at a level not previously accessible. The 80% increase in cell efficiency comes about by coating the cell with a material composed of tungsten and a new ceramic called hafnium that allows the cell to collect much of the heat energy that it would otherwise lose. Graphene itself can also be used directly with solar cells, the conductivity of the material allowing it to act as a super-efficient charge carrier within the cell — retaining its properties even if combined with other materials such as silicon.

Alternatively, the current expense of mass producing such graphene-based cells can be reduced if the silicon is replaced entirely with graphene, combined with titanium oxide and perovskite. Because the cell can be produced at low temperatures, around 150 degrees Celsius, they can be mass-produced at a cost comparable to existing solar cells, and eventually much cheaper — or, indeed, printed out. In wind power, graphene combined with various metals would make possible wind turbines that are significantly lighter with a larger surface area for generation. This would work in conjunction with a plethora of new wind turbine designs that go well beyond the propeller-style turbine that have become a fixture of the landscape.

In Minnesota, a group called Sheer Wind has developed a “funnel”-style wind turbine that channels the wind collected and uses the design of the funnel itself to accelerate the wind (a 15km/h wind can be accelerated to 55km/h) to drive the turbines at the other end). Nor is it only existing forms of power that can be generated by new materials. Whole new modes of energy generation are being discovered. Thus, the superconductive properties of graphene mean that it is possible to generate electricity simply by running saltwater over it. The moving water loses and then reabsorbs electrons as it passes across the graphene, thus creating a current. Graphene can also be used as an insulator, in a form known as aerogel. Aerogels are simply liquid gels with the liquid removed and replaced by air.

Created from various materials — silicon aerogels have been the most common for decades — the creation of a graphene aerogel yields the most strength for the least weight. The most recent form of graphene aerogel, created at China’s Zhejiang University is seven times lighter than air, with a cubic centimetre weighing 0.16 milligrams, which is more or less weightless for common purposes. Its use as an insulator comes from its high melting point, at around 2000 degrees Celsius.

These new materials also promise a revolution in the capacity for energy storage. Even using the existing materials for batteries — principally lithium — the application of 3D printing makes it possible to create small but powerful batteries less than 1mm wide, capable of being recharged, and simply embedded permanently in objects. Using zinc instead of lithium, Norwegian group Thin Film has designed a battery that can be printed out by either a 3D printer or even a plain old 2D printer depositing metal inks onto a  surface such as acetate. Graphene itself can be used to create a new form of supercapacitor, a device that has hitherto been used to deliver quick short bursts of energy, but which can be quickly recharged.

By layering graphene and electrolyte in a process compared to traditional paper-making, a team at Monash University in Melbourne have managed to create a supercapacitor that also has the properties and capacity of a standard battery, but is essentially flat. A simpler version of a graphene supercapacitor can essentially be home-brewed by smearing graphite oxide onto a DVD and putting it through a DVD burner. An even more exotic process in battery design is to use sea bacteria that have adapted to breathing in metal to power batteries.

To combine these new technologies with new sources of energy would be the final part of the “universal constructor” — a machine that can print out a copy of itself, and its own energy supplier, in a perfect circle. This offers the possibility that energy distribution can be radically decentralised and democratised, as the cost of generation is pushed remorselessly in the direction of zero. The major energy companies have already begun a pushback against this. Thus in Oklahoma, the single most Republican state in the United States, people who put solar panels on the roof of their homes and then wish to sell the excess energy back to the grid — a now-common practice, given solar’s increasing yield — are to be subject to a tax and a fee for the privilege of doing so. Why? Ostensibly because of “health and safety” reasons, really because an expanding notion of a reversible grid challenges the proprietorial nature of power. This is not simply an expression of cynical interest politics — it is an expression of a deeply held set of values, which are contradictory at their root.

Thus the new material revolution is particularly challenging for those who would like to preserve the existing relations of production, consumption and energy. The renewed interest in renewable energy sources has been a disturbance to that model — the prospect that it could quite rapidly combine with these other technological forces must count as something of a torment.

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