Catching up this morning with the Economist's bloggers, I read a Babbage column on wind energy and the Californian dream. As with many other science and technology blogs that I read, the interest comes as much from the discussion as it does with the originating column. This was a case in point where a couple of contributors had a lively interchange about [i] the 2nd law of thermodynamics and the extent to which it applies to wind energy / power given that these do not derive from heat energy (with inevitable commensurate losses), and [ii] the extent to which electric vehicles [EV] can be said to be efficient. It seems (see below) that the USA has followed the EU is deciding not to think about the source of the electricity when considering EV efficiency. This has the advantage that EVs are portrayed as super-efficient compared to almost every other kind of road transport; its disadvantage is that the laws of physics have either been ignored, suspended or repealed in the process. It also means that, in the short-term at least, EVs are more justifiable in carbon terms in a country like France (all that nuclear) or Norway (all that hydro), compared to the UK and Germany (all that oil / gas / coal – and CO2). Do you suppose that this will be reflected in advertising for electric cars? Neither do I.
The most interesting contributions to the column came from No Mist and Jim Bullis (who, like Babbage, writes from the USA). Jim is no stranger to the Economist's blogs, as this link to a recent discussion shows. Here, there is an interchange with Cambridge's David MacKay (whose book Sustainable Energy without the hot air I have already commented on), around the efficiency of EVs – which is also a feature of the Babbage column.
This is a far from arcane dispute about the rate at which electricical and thermal energies equilibrate. Jim Bullis:
Look at the fueleconomy.gov site and go to the electric vehicle tab. You will eventually discover that a gallon of gasoline represents 33.7 kWhr of electric energy. A gallon of gasoline has never produced more than about 11 kWhr of electric energy. Not in the USA or the UK at least, due to that nasty old Lord Kelvin and his stupid law. Under Kelvin's crusty opinion, the only equivalence is the amount of heat that can be produced by these two forms of energy. Seriously, MPGe as thus defined by our EPA is an outrageous lie. And it will trick people into buying electric vehicles that have no special merit in limiting CO2.
Of David MacKay's book, Bullis adds: "Other than the flawed promotion of the electric vehicle, this is a well written and useful book”. In many ways, I think it a masterly book (which I have just finished). I found it especially clearly written but missed this equivalence point.
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