Hydrogen can be used to produce either combustion for ordinary gasoline engines or electricity for electric vehicles. Both have many advantages and a few drawbacks.

Hydrogen Combustion Engine (HCE)

BMW, Ford, Mazda, and Mitsubishi have proved that an ordinary (slightly modified) engine can run on either gasoline or hydrogen. This option has the huge advantage that existing vehicles don't have to be dumped in favor of electric ones. This will save people billions of dollars―there are more than 800 million vehicles on roads world-wide.

When using hydrogen as fuel, those who love their SUV's, trucks, minivans, or sports cars can proceed as usual without feeling guilty and without being exploited at the pump.

Manufacturers don't have to close factories producing these popular vehicles. All they have to do is to change the propulsion of these vehicles from gasoline to hydrogen. The problem is not the vehicle but its fuel. One major advantage of HCE is that it starts easily in below zero temperatures, making it more viable in cold countries where electric vehicles falter.

There are many car-lovers who will never be happy with electric cars, because they will miss the satisfying purr of the internal combustion engine. It sounds like a mere psychological preference, but don't under-estimate human nature.

Don't forget the huge number of suppliers (and their employees) who all contribute to the manufacturing of engines. If the internal combustion engine will disappear overnight it will have a devastating ripple effect throughout the economy--hurting workers in manufacturing and maintenance, as well as the millions of car owners.

Drawbacks of HCE are the same as for HFC: storage, transport, and safety.

Hydrogen Fuel Cell (HFC)

This technology combines hydrogen and oxygen via a catalyst to produce electricity to propel a car via an electric motor. The only byproduct in the fuel cell is water. That is also its weak spot in extremely cold weather -- when not operated, the water may freeze up the unit. Yet, most automobile manufacturers experiment with this option.

Batteries

A legitimate question is: If the path from windmill to battery is three times more efficient than from windmill to hydrogen (Bossel), why not store the clean electricity (from wind, water, and sun) in rechargeable batteries? 

Answers:

1. The amount of clean electricity fluctuates according to the availability of wind, water, and sun. Batteries can't absorb all surplus clean electricity, and most battery-powered cars will be recharged at night when sunlight is not available. On the other hand, hydrogen provides a handy additional option for storing surplus clean energy.

2. The drawbacks of battery-powered cars are:

However, the fuel-cell is a long term plan. It can help to eliminate some of the weaknesses of batteries mentioned above. Cars with ordinary engines have to be gradually replaced by these fuel-cell models. It may take well over thirty years to complete the process. Climate change will not wait that long. We have to act now to prevent the collapse of the environment and the world economy. Hydrogen-propelled combustion engines provides immediate relief for ecology and economy.

HCE and HFC have to be applied simultaneously, the first giving immediate relief, the second providing future options.

Like HCE, HFC also has to deal with problems regarding storage, transport, and safety.

CONCLUSIONS

1. BMW, Ford, Mazda, and Mitsubishi experiment with gasoline/hydrogen combustion engines. This option will work well for the medium term when hydrogen infrastructure is still lacking, and while millions of existing gasoline cars are still on the road. These engines are more reliable in sub-zero temperatures than the battery/fuel-cell option.
2. Other car makers experiment with battery/fuel-cell combinations or battery/engine hybrids. Because batteries and fuel-cells do not work well in temperatures below minus 10 C, these options are not for countries that experience low temperatures often. Then the hybrid option is more realistic.
3. Public use and preference are the ultimate tests for any device. It may be the best policy for vehicle manufacturers to offer both options (combustion and electricity) to the public and let them determine what works best in different situations.

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