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Newsletter 17th November 2006

- Alternative fuels - Thoughtful comment on climate change - Seeing the wood for the trees - No more wires?

Alternative fuels
With the present focus on climate change policy, alternative energy sources of various sorts have also been much in the news. Nuclear fusion, for one, is the subject of an article in the BBC’s Green Room series (Nuclear fusion: a necessary investment). The author is Kaname Ikeda, nominated as director general of the Iter project (International Thermonuclear Experimental Reactor) to be constructed near Marseille. This represents the next step on the road towards a viable fusion reactor. The JET (Joint European Torus) reactor, in Culham, Oxfordshire, has shown that power generation is possible. The only problem is that the energy needed to create the reaction was greater than the energy output. Iter aims to produce a (small) net energy output.
If all goes well, a prototype reactor could be producing electricity in 30 years, with a fully commercial facility being opened ten years later. A long timescale, but for something which has always been 50 years away in our lifetimes, this represents real progress. This means that, by mid-century, we could begin to see deuterium and lithium as our key fuels for distributed power, and our reliance on fossil fuels could finally wane. In the meantime, nuclear fusion remains the only viable option for baseload generation if we want to cut down on the use of coal, oil and gas.
Of course, that may be the direction for power for homes, offices and factories (if we have any left in 2050). When it comes to transport, however, we need to think differently. Hydrogen is often put forward as the car fuel of the future. On the face of it, this is a perfect fuel: available in vast quantities (although inconveniently chemically bound to other elements) and producing only water vapour from exhaust pipes. However, there are also enormous practical problems. Hydrogen has to be generated and then distributed and stored under high pressure and at low temperature. Car fuel tanks will have to be heavy and bulky to safely retain this low density liquid at high pressure.
Nevertheless, manufacturers are working actively on demonstration projects, and there are already a handful of buses in Reykjavik and a few other places which demonstrate that hydrogen works as a road transport fuel. Most of the attention is focussed on the use of fuel cells to combine the hydrogen with oxygen from the air. However, hydrogen can also be used as a fuel in conventional internal combustion engines. BMW have just taken the interesting step of launching a 6-litre, V12 7-series which can run on either petrol or hydrogen. The only difference from a conventional car is that there are two filler caps and not much luggage space: half the boot is needed for the hydrogen tank.
There are other practical issues. Refuelling with liquid hydrogen at -253°C takes eight minutes to transfer six litres (a tankful) which will power the car for 200 kilometres. In the likely event that the car then runs out of hydrogen some distance from one of the five filling stations in the world which supply it, the driver switches to petrol with the press of a button. Nevertheless, despite the impracticality, these cars demonstrate what is possible, and are likely to be snapped up by celebrities to replace their Prius or Lexus hybrids. BMW will produce 100 and lease them to people in California and Germany.
The other issue with hydrogen at present is that, however cleanly it may burn, it has to be generated using some kind of non-fossil fuel based energy source if it is to have any net benefits, and most of these are currently uneconomic. The obvious one in the longer term is going to be fusion.
Thoughtful comment on climate change
As regular readers will know, our aim is to promote rational debate on contentious issues. Unfortunately, there has been far too much polarisation and name-calling around the issue of climate change, so it’s good to highlight genuinely thoughtful contributions. Simon Castles, writing in Australia for the Melbourne-based Age newspaper, has written an article which I would urge every one of you to read and pass on to your friends.
Called A cool head in hot times, Castles admits his lack of knowledge of the science, but suggests some key ways to look at reports critically. He lists four errors to look out for. These he calls filtering (looking only at the evidence which supports your preconceptions), polarised thinking (seeing things in stark, black and white terms), over-generalisation (making unwarranted leaps of logic from one observation) and catastrophising (not a very elegant word, but you’ll get his meaning). That seems to us to be a pretty good set of principles.
Seeing the wood for the trees
Some good news on the environment: Study hopeful for world’s forests says the BBC, for example. The essence of the story is that researchers think that it is possible that deforestation may be coming to an end. They have used more sophisticated measurement techniques than normal. Rather than measure forested area alone, they have also been able to estimate the density of growth, to give a better measure of the total biomass. Using this more accurate assessment, they find that there has been a net increase in forests in 22 of the 50 most forested countries in the world over the last 15 years.
That should give no reason for complacency, of course, because much of the continuing loss of forest is in poorer countries in the southern hemisphere. But the scientists found that increasing prosperity can have a positive effect on trees as well as people. On average, when GDP per capita reaches $4,600, there is a tendency for forest area to increase again. Much of the current loss is for agriculture, but we should not forget that, for the world’s poorest, wood is their only source of fuel. Change that, change the dependence on subsistence farming, and there is less need to cut down forests.
No more wires?
It sounds far-fetched, but MIT researchers are proposing that we may be able before too long to recharge batteries on mobile devices wirelessly. Already, wireless recharging is possible if the device is in direct contact with an induction charger. But, if you try to extend the distance, the energy is dissipated in all directions. The suggestion is that power could be transmitted by a “non-radiative field”, that is, the magnetic component of an electromagnetic field. By having a simple coil fixed to a ceiling, it seems that the electric field is confined to the area near the ceiling, so causing no harm to anyone, while the magnetic field can be picked up by a resonant receiving loop some metres away. For more, see Cut the cables in the latest edition of the Economist.