Is science sometimes in danger of getting tunnel vision? Recently published ebook author, Ian Miller, looks at other possible theories arising from data that we think we understand. Can looking problems in a different light give scientists a different perspective?

Energy Feedstocks

In my previous blog, I mentioned David MacKay's excellent book, in which he emphasized that we should focus on numbers. The problem with numbers, of course, is that they are easy to generate, but often different sets do not compare easily. Since then, I have seen an Editorial in Angewandte Chemie International Edition by Hartmut Michel, who more strongly suggested abandoning biofuels and going for electrified transport. So what do we make of this? Michel’s case was mainly based on efficiency: plants can only convert about 4% of the light energy, and in practice as little a 1%, and then about half of that is used on fertilizer, pesticides, ploughing, transport and the chemical conversion. On the other hand, photovoltaics can convert 15% of their energy to electricity so the use of biofuels involves an extremely inefficient land use. Note that the argument against biofuels includes externalities (which properly have to be considered) but the argument for electrification omits them. For biofuels, MacKay has calculated power available per unit area, and the figures are, in W/m2:  biodiesel from rape – 0.13, sugar beet to ethanol -  0.4, ethanol from cane sugar – 1.2, ethanol from corn – 0.02, ethanol from switchgrass – 0.2, jatropha on good land – 0.18, jatropha on waste land 0.065, pond algae – 4 (if fed with CO2). He then disposes of algae in the sea by noting the productivity drops 100 fold without adding CO2, then he notes that to use the sea, country-sized areas would be required. Biofuels Digest has listed the following numbers, in t/acre/annum: managed prairie – 2.5, switchgrass – 5-9, Eucalypts – 10, Miscanthus – 12, macrocystis – 50, microalgae – 60. So, what do you make of this raft of numbers?
 
The point of my ebook, Elements of Theory, was to put forward the Aristotelian method of analysing an argument and putting forward a theory. What most people do not appreciate is that Aristotle effectively invented discrete mathematics; unfortunately algebra had not been invented so he had to use awkward sentences instead of simple symbolic statements. However, if we think in his way, we note that transport has one function, to get something from A to B. There is a set of requirements to get from A to B, and the whole set has to be considered, and that includes the convenience. Energy efficiency is not a goal in itself. The provision of fuel is a subset of the set, but not the only one, and these subsets are rather complicated.
 
As an example, MacKay shows how the range problem for electrified cars can be solved with 500 kg of batteries, when a range of 300 km is plausible. That seems plausible until, in the fine print, we see we are driving at 50 km/hr (30 mph). Now that is not a typical speed on, say, the M1. From Michel, the supply of the necessary electricity is from photovoltaics spanning various deserts, with the current being supplied by superconducting cables. Leaving aside the issue of night-time, the demand for an enormous number of batteries and for elements like tellurium, one suspects that he has never seen a desert dust storm.
 
Of course it is also easy to pick holes in such arguments, and by itself that achieves little except that it might identify areas to carry out more research. I suspect that one of the more promising options has been essentially rejected in the above discussion. Everybody believes it would not be worth considering because there are a few seemingly insurmountable problems. My argument is that we need the research carried out now to determine whether they can be overcome, but even more importantly, we need to better think out where we are going to invest. More in due course.
Posted by Ian Miller on Mar 22, 2012 10:51 PM Europe/London

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