Opinions26 May 2021 15:52
I read this on a Facebook review of a plug in Mercedes and wondered what people’s thoughts were on some of the comments
Hydrogen fuel myth
There is a lot of talk about the hydrogen economy. It is at best naïve, and at worst it is dishonest. A hydrogen economy would be a pitiful, impoverished thing indeed.
There are a number of problems with hydrogen fuel cells. Many of these are engineering problems which could probably be worked out in time. But there is one basic flaw which will never be overcome. Free hydrogen is not an energy source; it is rather an energy carrier. Free hydrogen does not exist on this planet, so to derive free hydrogen we must break the hydrogen bond in molecules. Basic chemistry tells us that it requires more energy to break a hydrogen bond than to form one. This is due to the Second Law of Thermodynamics, and there is no getting around it. We are working on catalysts which will help to lower the energy necessary to generate free hydrogen, but there will always be an energy loss, and the catalysts themselves will become terribly expensive if manufactured on a scale to match current transportation energy requirements.
All free hydrogen generated today is derived from natural gas. So right off the bat we have not managed to escape our dependency on nonrenewable hydrocarbons. This feedstock is steam-treated to strip the hydrogen from the methane molecules. And the steam is produced by boiling water with natural gas. Overall, there is about a 60% energy loss in this process. And, as it is dependent on the availability of natural gas, the price of hydrogen generated in this method will always be a multiple of the price of natural gas.
Ah, but there is an inexhaustible supply of water from which we could derive our hydrogen. However, splitting hydrogen from water requires an even higher energy investment per unit of water (286kJ per mole). All processes of splitting water molecules, including foremost electrolysis and thermal decomposition, require major energy investments, rendering them unprofitable.
Hydrogen advocates like to point out that the development of solar cells or wind farms would provide renewable energy that could be used to derive hydrogen. The energy required to produce 1 billion kWh (kilowatt hours) of hydrogen is 1.3 billion kWh of electricity. Even with recent advances in photovoltaic technology, the solar cell arrays would be enormous, and would have to be placed in areas with adequate sunlight.
We must also consider the water from which we derive this hydrogen. To meet our present transportation needs, we would have to divert 5% of the flow of the Mississippi River. This would require yet more energy, further reducing the profits of hydrogen. This water would then have to be delivered to a photovoltaic array the size of the Great Plains. So much for agriculture.
The only way that hydrogen production even approaches practicality is through the use of nuclear plants. To generate the amount
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