After the recent postings on more general (yet by no means less important) aspects of climate change, we are back with a more transport-orientated topic: the hydrogen vs. the battery-electric vehicle.
Two recent contributions by the BBC UK's TopGear productions lay the ground for this discussion. In a recent episode of the TV programme, a TopGear "correspondant" went to Germany to test GM's new prototype hydrogen car: the Hy-Wire.
The vehicle is powered by a hydrogen fuel cell and operated via a drive-by-wire system. The prototype actually drives and apparently cost around £5M to build. Prototype costs and "driveability" aside, the program gives very incomplete information on the requirements of fuel cell technology, let alone associated costs and impact on the environment. For instance, it is stated that this car "runs on seawater", and that the technology will be available in 10-20 years.
Regarding the former, yes, seawater can be used to form hydrogen (namely through a process called electrolysis), albeit at very high energy costs. Hydrogen can also be obtained from regular air, or even better, methanol. However, in any case a high energy input is required to obtain hydrogen, since it is not widely available in natural form. This means that even though only water comes out of the vehicle's exhaust pipe, the energy which has gone into the entire process is actually superior to that required for today's standard combustion engines. Also, since we already need to employ significant amounts of energy to create hydrogen, why don't we just use the energy directly to power vehicles, e.g. battery-electric ones?
Regarding the availability of the vehicle itself, the 10-20 year timeframe is very optimistic. The problem are costs of the fuel cell technology and, more importantly, the required infrastructure to fill the car up with hydrogen. It is highly unlikely that this will exist in a meaningful coverage in the stated timeframe, considering the massive investment required. Again, one could fuel the car with methanol and gain hydrogen on the go (through a process called reforming), but once again, it would be more efficient to use the energy directly to propel the vehicle.
To conlcude, it is very sad to see the makers of such a popular and influential program like TopGear repeat exactly the one-sided mantra used by many major vehicle manufacturers. The solution is clearly elsewhere, and it is sad to see that after the last 10-20 years, Jeremy Clarkson and his colleagues are not one inch closer to it.
ON the OTHER hand, a recent publication of the TopGear MAGAZINE (which I was told has a somewhat greener view of things with respect to the power-is-everything TV programme), featured a 50-odd page section on green vehicles, from battery-electric to biofuel powered ones (fuel cells are mentioned in a 1/8th page insert, and are presented in a well-balanced way). At last, there seems to be hope that one day some of this attitude might transpire into the TV programme and even Jeremy Clarkson will eventually get it!
