Archive for November, 2010

If the technology we’ve got isn’t sustainable, doesn’t that mean we need better technology?

Wednesday, November 24th, 2010

Friends of the Earth have published a new report called “Nanotechnology, climate and energy: over-heated promises and hot air?” (here but the website was down when I last looked). As its title suggests, it expresses scepticism about the idea that nanotechnology can make a significant contribution to making our economy more sustainable. It does make some fair points about the distance between rhetoric and reality when it comes to claims that nano-manufacturing can be intrinsically cleaner and more precise than conventional processing (the reality being, of course, that the manufacturing processes used to make nanomaterials are not currently very much different to processes to make existing materials). It also expresses scepticism about ideas such as the hydrogen economy, which I to some extent share. But I think its position betrays one fundamental and very serious error. That is the comforting, but quite wrong, belief that there is any possibility of moving our current economy to a sustainable basis with existing technology in the short term (i.e. in the next ten years).

Take, for example, solar energy. I’m extremely positive about its long term prospects. At the moment, the world uses energy at a rate of about 16 Terawatts (a TW is one thousand Gigawatts; one GW is about the scale of a medium size power station). The total energy arriving at the earth from the sun is 162,000 TW – so there is, in principle, an abundance of solar energy. But the total world amount of installed solar capacity is just over 2 GW (the nominal world installed capacity was, in 2008, 13.8 GW, which represents a real output of around 2 GW, having accounted for the lack of 24 hour sunshine and system losses. These numbers come from NREL’s 2008 Solar Technologies Market Report). This is four orders of magnitude less than the energy we need. It’s true that the solar energy industry is growing very fast – at annual rates of 40-50% at the moment. But even if this rate of increase went on for another 10 years, we would only have achieved a solar contribution of around 200 GW by 2010. Meanwhile, on even the most optimistic assumption, the IEA predicts that our total energy needs would have increased by 1400 GW in this period, so this isn’t enough even to halt the increase in our rate of burning fossil fuels, let alone reverse it. And, without falls in cost from the current values of around $5 per installed Watt, by 2020 we’d need to be spending about $2.5 trillion a year to achieve this rate of growth, at which point solar would still only be supplying around 1 % of world energy demand.

What this tells us is that though our existing technology for harvesting solar energy may be good in many ways – it’s efficient and long-lasting – it’s too expensive and in need of a step-change in the areas in which it can be produced. That’s why new solar cell technology is needed – and why those candidates which use nanotechnologies to enable large scale, roll to roll processing are potentially attractive. We know that currently these technologies aren’t ready for the mass market – their efficiencies and lifetimes aren’t good enough yet. And incremental developments of conventional silicon solar cells may yet surprise us and bring their costs down dramatically, and that would be a very good outcome too. But this is why research is needed. For perspective, look at this helpful graphic to see how the efficiencies of all solar cells have evolved with time. Naturally, the most recently invented technologies – such as the polymer solar cells – have progressed less far than the more mature technologies that are at market.

A similar story could be told about batteries. It’s clear that the use of renewables on a large scale will need large scale energy storage methods to overcome problems of intermittency, and the electrification of transport will need batteries with high specific energy (for a recent review of the requirements for plug-in hybrids see here). Currently available lithium ion batteries have a specific energy of about half a megajoule per kilogram, a fraction of the energy density of petrol (44 MJ/kg). They’re also too expensive and their lifetime is too short – they deteriorate at a rate of about 2% a year. Once again, current technology is simply not good enough, and it’s not getting better fast enough; new technology is needed, and this will almost certainly require better control of nanostructure.

Could we, alternatively, get by using less energy? Improving energy efficiency is certainly worth doing, and new technology can help here too. But substantial reductions in energy use will be associated with drops in living standards which, in rich countries, are going to be a hard sell politically. The politics of persuading poorer countries that they should forgo economic growth will be even trickier, given that, unlike the rich countries, they haven’t accumulated the benefit of centuries of economic growth fueled by cheap fossil-fuel based energy, and they don’t feel responsible for the resulting accumulation of atmospheric carbon dioxide. Above all, we mustn’t underestimate the degree to which, not just our comfort, but our very existence depends on cheap energy – notably in the high energy inputs needed to feed the world’s population. This is the hard fact that we have to face – we are existentially dependent on the fossil-fuel based technology we have now, but we know this technology isn’t sustainable and we don’t yet have viable replacements. In these circumstances we simply don’t have a choice but to try and find better, more sustainable energy technologies.

Yes, of course we have to assess the risks of these new technologies, of course we need to do the life-cycle analyses. And while Friends of the Earth may say they’re shocked (shocked!) that nanotechnology is being used by the oil industry, this seems to me to be either a rather disingenuous piece of rhetoric, or an expression of supreme naiveity about the nature of capitalism. Naturally, the oil industry will be looking at new technology such as nanotechnology to help their business; they’ve got lots of money and some pressing needs. And for all I know, there may be jungle labs in Colombia looking for applications of nanotechnology in the recreational pharmaceuticals sector right now. I can agree with FoE that it was unconvincing to suggest that there was something inherently environmental benign about nanotechnology, but it’s equally foolish to imply that, because the technology can be used in industries that you disapprove of, that makes it intrinsically bad. What’s needed instead is a realistic and hard-headed assessment of the shortcomings of current technologies, and an attempt to steer potentially helpful emerging new technologies in beneficial directions.