Time is crucial sometimes – regarding the passenger car, discussing decarbonization, in multiple ways: While the electric engine has reached highest efficiency and certain vehicle categories equipped with traction battery are being produced at reasonable prices, this is not the case in regard to hydrogen and synthetic fuels. Technologies such as fuel cells and the necessary infrastructure are developed indeed , but not ready for the market.
Because of its high volatility, hydrogen is likely to leak from the tank. After periods of over a week, half a vehicles tank capacity may have escaped due to leakage.
Unfortunately, it is hardly mentioned in the discussion, that solutions theoretically available must always be considered in conjunction with the fact that renewable electricity generation is spatially limited in densely populated areas. If the traction battery is used in a car, eight out of ten windmills turn for propulsion. If we use the fuel cell, only the energy from two to three windmills reaches the tire on the road. This is partly due to the electrolysis' conversion losses. However, the now common refueling with hydrogen at 250 to 700 bar and with a pre-cooling of −40 ° C must also be taken into account.
To power 33 million fuel cell cars (75 percent of today's car fleet in Germany), an additional electric total output of 28 gigawatt – next to 42.000 Kilometers of new pipelines – an additional total electrical output of 28 gigawatts is required, so the Jülich Research Center. That roughly corresponds to the output of 50 coal-fired power plants. For comparison: A total of 148 large coal-fired power plants are currently in operation in Germany. As long as regenerative power generation potential is scarce – In 2019, 60 percent of German electricity will not yet come from green electricity sources – but significant decarbonization has soon to be achieved, the now technically and economically feasable, solutions should be implemented, to assure that consumer demand can accelerate the development of the renewables.
For a number of transport solutions the electric drive, exclusively with traction battery, does not make sense. Although Elon Musk (Tesla) speaks of the battery-operated passenger jet, this, taking physicochemical reality into account, remains fiction. Long distance cargo shipping or transport by truck, require battery capacity to an extend, that, due to the resulting weight and required space, is of disadvantage. In those cases the question of technology is justified, however.
Comprehensively considering the cars', the vans' and the bussses' drive technique, this question is answered, though: If we include the future energy system, its supply side fluctuations, into our considerations, if we seek to economically introduce storage capacity at the same time, and as a systemic component of the energy transition, an automated battery exchange, millions of traction batteries, pooled to local grid storages, are the realistic solution at present.