Hydrogen and fuel cells for transport: energy storage problem
Professor Kevin Kendall, FRS
Chemical Engineering, University of Birmingham, UK
Using hydrogen and fuel cells (HFCs) for transport should double the efficiency and reduce emissions to zero, except for water vapour exhaust. The most famous application is the NASA moon missions, where auxiliary power and drinking water were provided by a 10kW alkali stack. Now that aircraft are going more electric, fuel cells are being investigated but compressed hydrogen is shown to be poor in terms of weight and volume. For large planes, liquid hydrogen is good, but for small unmanned air vehicles (UAVs) propane is difficult to beat.
Ground transport includes forklifts, bikes, buses and cars. Here the polymer electrolyte membrane fuel cell (PEMFC) is being tested and progress is being made in performance, lifetime and cost. Lithium ion batteries and supercapacitors are beneficial in hybrids. Compressed hydrogen at 350 and 700 bar is the standard fuel at present. At Birmingham, five HFC cars have been tested on campus since the first UK hydrogen filling station was installed there by Professor Kendall in 2008. The results show that the prototypes beat all combustion cars in fuel economy, largely because of lightweight construction. Surprisingly, the results fitted a Coulomb friction law line. Further improvement of the drive train showed that these cars were ultimately better than all other HFC cars. The race to market in 2015 is now taking place between the major manufacturers.