By Dave Elliott
In his powerful and eloquent new book, The Burning Answer, which seems to be a response to Mike Berners-Lee’s book on climate change, The Burning Question, Imperial College Professor of Physics Keith Barnham contends that, despite our much higher energy demands now than in earlier periods of human evolution, our sun can provide all our primary energy needs again. Solar technology can save us from the threats of global warming, diminishing oil resources and nuclear disaster, if we take the necessary action.
He touches on all the renewables, but focuses on solar PV, an area in which he has worked over the years. As in the 2013 Energy Policy paper he co-authored (Energy Policy, 54, 385), PV, along with biogas, is seen as a good complement to wind. He makes a strong case for policy change, suggesting that the UK could and should have 37GW of PV soon, and takes exception to some of the views that have shaped the current energy policies, for example challenging some of DECC Chief Scientist Prof David MacKay’s assertions on PV’s land use. He also has a go at the Royal Society.
However all this is done without rancour and, although some of the political actions suggested to back the Solar Manifesto that he offers may seem naïve to seasoned activists, it’s a beautifully and indeed at times lyrically written book. It takes us through a lot of basic physics (maybe a little too much!), from electromagnetism to quantum theory, with a colourful tour of the key contributions of the great physicists, in order to set the scene for PV. He highlights the fact that it was Einstein who laid the basis for both PV and nuclear power, noting that it was the later that was pursued, at least initially, since it had direct military applications.
It’s fascinating stuff, replete with many helpful analogies for the lay reader. Some are quite fun, although some are maybe not so useful. Is it fair to say that, while with hydro power, solar energy lifts water vapor from the sea, via clouds, to fill hydro reservoirs to create potential energy, it is ‘much more straightforward’ to have light photons promoting electrons from the valence band across the band gap to the conduction band in a PV cell? Some of the basic definitions are also a little odd. He defines burning (his book’s title theme) very broadly, as ‘the generation of heat and light energy by consuming a fuel while producing waste’. So that includes what happens in the sun. But he wants us to move away from using the old finite stored solar energy in fossil fuels to using continuous incoming real-time solar energy from the sun- the source of both being the ‘burning’ of hydrogen in the sun. Well maybe it’s burning, even if no oxygen is involved, which is a perhaps more familiar definition of burning. But it’s similarly a bit hard to see nuclear fission (which he strongly opposes) as burning: uranium is the left over from the collapse of some old stars, but that’s hardy ‘burning’, although we do commonly talk of ‘burner reactors’.
Definitional issues aside, his analysis lifts off when, after a side tour around the linked history of nuclear bombs and nuclear power, and a helpful exposition of semiconductor theory, he finally starts looking at PV. He provides an excellent tour through all the technical options, including his own pioneering quantum well work and new ideas about artificial photosynthesis, and then looks at applications. But in the latter, there is another definitional problem. He makes a careful distinction between energy (kWhs etc) and power (kWs etc), but he suggests that at any particular point in time it is the power available that matters to users, not the total energy available. At one point recently, around noon is summer sun, he notes that PV met 50% of the electricity load in Germany, even though, over the year, it only supplies about 5% of German electricity. It is true that at times it is possible for PV arrays to deliver energy at or near their full rated power generation capacity (Germany now has 37 GW of PV), and at that point the marginal cost of supplying energy from PV is low. Indeed, as Barnham says, it can fall below that of fossil plants, or even be effectively zero- briefly. But that doesn’t necessarily make it cheaper/kWh delivered to consumers overall, averaged over the year, than other sources. The low marginal cost of PV at peak has to be set against the need to meet demand at other times by other means- you have to look at the complete system. Clearly PV can deliver power well matched to peak daytime demand in summer e.g. for air-conditioning, and direct to users, without long-distance transmission losses. Moreover, PV, like wind and most of the other renewables, has no direct fuel costs, so making it, and the other renewables, increasingly competitive, as the direct and indirect costs of fossil fuel inevitably rise over time, and as, with high grade uranium ore becoming scarce, nuclear costs (and fuel production emissions) continue to escalate. However, there are grid-balancing costs with variable renewables like PV. But, based on the German Kombikraftwerk ‘combined power plant’ networking experiment, Barnham doesn’t see balancing as a major problem operationally or in cost terms. The Kombikraftwerk test showed that PV, coupled with wind, biogas and hydro in an integrated and balanced network, could meet demand around the year, and wind biogas and hydro are relatively low cost.
Interestingly though, he seems to favor local balancing like this, within one country, and does not support the Desertec plan to use supergrid links from North Africa to the EU to import some of the power from solar arrays in the desert. That seems odd. Unless cheap storage emerges, wider-area grid integration of a range of renewables via supergrid links is likely to be important for effective balancing.
Quibbles like that aside, it’s a remarkable book, covering so much background, from cosmology to climate change, and also surveying all the renewables, including the non-solar ones. It offers some interesting insights, e.g. on tidal current venturi systems and geothermal energy, as well as on CHP, heat pumps, and even electric vehicles, powered ultimately by solar-derived fuel. And it also gives advice on how to sort out your own home! And overall it relays a strong and positive message: a solar and renewables based future is possible and indeed may be our only hope. Much more so than fusion. After all, we already have a working fusion reactor- the sun. Interestingly Barnham says that it was an article, ‘2079: a century of technical and socio-political evolution’ by David Mathison, in the journal Impact of Science on Society (29, 83, 1979), which he read while working as a particle physicist at CERN, that led him to re-focus on solar power. Mathison predicted social collapse without it. Maybe Barnham’s book will have a similar radicalising effect on a new generation of scientists.
The Burning Answer Weidenfeld & Nicolson, with concessions from: www.guardianbookshop.co.uk/BerteShopWeb/viewProduct.do?ISBN=9780297869634