What about hydrogen cars?

A:

It's possible they are the future, but they're not yet the present. Hydrogen Fuel Cell Vehicles (FCVs) have many difficult and expensive engineering challenges to solve before they will ever be widely available, and even then, the energy required per km will probably continue to be substantially higher than for EVs.

We asked NZ scientist Thomas Everth, for his evaluation.

"Hydrogen is not the "most abundant resource" in the universe from the perspective of humanity. In fact, if you tried to find free hydrogen anywhere on the planet, you would struggle. Free Hydrogen is highly reactive. Therefore almost all of it is already oxidized H2O here on planet Earth, and no electro-chemical energy can be extracted from it.

"Hydrogen from the perspective of being a resource for energy is useless unless it's free, reduced to its atomic or molecular H2 form. And doing so requires energy. At least as much as one gets back when oxidizing it back to H2O again, and, in fact, significantly more so, because the processes to reduce H2O to H2 and O2 are inefficient.

"Chemically bound Hydrogen is like a spent battery. It has no use unless it's charged again. Charging a BEV battery is highly efficient. Well over 90% efficiency. Charging - read reducing - H2O back to H2 and O2 is significantly less efficient. And it doesn't end there. The energy in your EV battery is ready to let rip... The H2 produced at some electrolysis plant must be compressed, shipped, stored, dispensed, stored again, and finally while being oxidized again, electricity must be extracted to drive your car."


Overall the efficiency will struggle to get far beyond 20%...only slightly more efficient than a fossil fuelled internal combustion engine. Compared to a BEV with over 70% efficiency, FCV cannot compete with green electricity from the grid.

What this means is that if you have a limited amount of renewable electricity, you are much better putting it into directly charging via battery, just based purely on what you get out of it, compared to hydrogen. Hydrogen produced with renewable electricity is extremely expensive and in limited supply world-wide, meaning it cannot compete with fossil fuel (petrol/diesel) pricing at the pump either. Currently the majority of H2 is produced from natural-gas/methane CH4 which is also a fossil fuel.

The cost and footprint of a hydrogen recharging station is much greater than a battery electric vehicle charging station. In fact at today's prices you could install 40 EV charging stations for the same price as 1 FCV station, and that doesn't include the infrastructure required to get the H2 to the FCV station. Electricity infrastructure is already in place at most locations.

The main promoters of FCV are Toyota, Hyundai and Honda. Yet they have made very little progress towards bringing a product to the world-wide market. Meanwhile, BEVs are now being produced that can recharge at a public station at a comparable time rate to filling with petrol, and this technology is promised for NZ in 2020 with a gradual rollout.

The Better NZ Trust does not endorse Fuel Cell technology, as we feel that given the above points, limited R&D resources are better spent improving EVs than wasted on FCV.

 

Graphic courtesy of European Federation for Transport and Environment

Original text (before the graphic) courtesy of Thomas Everth, MSc (Physics), researcher "climate education"


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