By Orson Sutherland

, Fuel Cells, Plasma Technology

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Filed under : Scitizen >> Technology >> Future Energies >> To Be or Not to Be: a Hydrogen Economy?

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To Be or Not to Be: a Hydrogen Economy?

4 Apr, 2006 12:05 am

There is much talk about the hydrogen economy taking the baton from the carbon incumbent in the coming decades, but to what degree does this correspond to reality? There are no terrestrial sources of pure hydrogen, so where will hydrogen for future transportation and energy needs come from?

Water is the most abundant source of hydrogen on earth and has potential as a hydrogen store. However, it is energetically expensive to "crack" into hydrogen and oxygen and requires substantial external energy. Another popular method of producing hydrogen is by steam reforming natural gas or bio-fuels such as ethanol (from sugar cane for example), but again the process requires an external energy source. This sheds light on an immutable reality: hydrogen is abundant in nature as part of more complex molecules but it is energetically expensive to extract in a pure form.

With respect to "clean" energy this leads to a bit of a problem, because burning hydrogen in an internal combustion engine (ICE) or extracting electrical energy from it using a fuel cell (FC) may well be clean, but the process that provides the hydrogen itself is not (for the moment). But even this is a negligible problem when compared to the need for an alternative, hydrogen-free energy source to produce the hydrogen in the first place. There is of course the nuclear option, which solves the dual issues of atmospheric pollution and long-term supply of energy, but which has not, for the moment, solved the largely political problem of long-term storage of nuclear waste. Wind and solar are not reliable enough and geothermal has not been proven experimentally to work on a large scale.

This all seems to be implying, unwittingly, a debate on how base energy should be produced in the future and in particularly whether nuclear power is the only sustainable solution in the medium-to-long-term and the only pollution-free option from an atmospheric perspective. Actually, in a world without oil, coal and gas, it is not clear how economies would provide electricity at all without nuclear fission. Nuclear fusion is several decades away from providing a potential solution (if at all) and no other viable energy source or energy system appears to have been discovered or developed.

But do we really need to burn hydrogen in pure form? To run a Proton Exchange Membrane FC you do, but a Direct-Methanol FC runs on methanol. An ICE can be run on hydrogen, but it can also run on carbon-based bio-fuel. If the carbon loop is closed, i.e. the carbon that is burned is directly reabsorbed from the atmosphere by the process of growing the fuel, then producing bio-fuel from biomass minimises the impact of burning hydrocarbons and a long-term, sustainable and nuclear-free energy source is a reality. Importantly, this does not preclude the use of pure hydrogen as an energy store nor does it necessarily obviate the need for a hydrogen economy for transport and localised electricity production, but it does imply a hybrid hydrogen/carbon energy mix for a realistic future closed energy system.

It may appear to be a simple question of semantics, but it is important to make clear that the future of energy (as it stands today) may comprise a hydrogen economy but it is unlikely to be a hydrogen economy.

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