The BMW Group Forschung and Technik has announced that, in co-operation with researchers from Austria they have developed a hydrogen combustion engine that achieves an efficiency level of up to 42 percent, which is equivalent to the best modern diesel engines.(source: greencarwebsite). Several remarks are in order here. First of all we must clearly distinguish hydrogen combustion engines, where hydrogen is burnt in a more-or-less conventional combustion engine, from fuel-cell driven vehicles. Here hydrogen is used in a fuel-cell to generate electricity which powers the car. While the efficiency of a fuel cell is often reported to be 50% and above, there is only limited data on real world tests and the efficiency is likely to be less high. Secondly, for a true comparison one should look at the whole loop, including the production efficiency of hydrogen. This will then depend on the purity of the hydrogen needed, which is much higher for a fuel cell than for a combustion engine. Personally, I believe that in the long run the fuel cell might be the right bet, but for the short term, the BMW development is promising. But the biggest issues still remains open: how do we distribute the hydrogen, how do we store it and how do we produce it.
