The only thing slowing the progress down is the fact that it is not economically worth the investment. Don't throw rocks at the oil companies. If there is enough money in it they will do it! ****, if there is enough money in it I will do it! Fuel cell technology has many issues but the biggest is that it is only an energy storage system. You still need to make hydrogen and deal with all the issues of containing and storing the smallest molecule on the periodic table. If you think it is clean just realize you cannot make hydrogen with solar energy in anything near the volume that will be required to run an industry. No, don't say wind.