Hydrogen production limitations

 Even though hydrogen is the third most abundant chemical element in the Earth's crust, almost all of this hydrogen is bound up in chemical compounds with other elements. It must, therefore, be produced from other hydrogen-containing sources using the input of primary energy such as electricity or heat.

At present, most of the world's hydrogen (so-called 'merchant hydrogen') is ironically produced from fossil fuels by steam reforming of natural gas and partial oxidation of coal or heavy hydrocarbons. These methods can take advantage of economies of scale and are currently the cheapest and most established techniques of producing hydrogen. That the hydrogen economy is driven by the carbon economy is clearly unsustainable.

Most of the world's hydrogen is currently produced for ammonia/fertilizer synthesis and not easily committed to any new major market (e.g. for hydrogen/fuel cell activities).

Also, the production of hydrogen from fossil fuels using reforming and gasification processes always leads to the emission of CO2, the principal cause of global climate change. To achieve the benefits of a truly sustainable hydrogen energy economy, we must begin to produce hydrogen by electrolysis or splitting of non-fossil resources, such as water, using (ideally) electricity derived from renewable energy sources. The holy grail of hydrogen production is therefore the efficient, direct conversion of sunlight through a photochemical process that utilizes solar energy to split water directly to its constituents, hydrogen and oxygen, without the use of electricity.

Current nuclear (fission) technology generates electricity that can be used to produce hydrogen by the electrolysis of water. Advanced nuclear reactorsa re also being developed that will enable high-temperature water electrolysis (with less electrical energy needed) or thermochemical cycles that will use heat and a chemical process to dissociate water. Fusion power, if successfully developed, could be a clean, abundant, and carbon-free resource for hydrogen production.

Until 2020, hydrogen production from fossil fuels and by electrolysis of water using grid electricity is expected to be the most important sources of hydrogen. During this transition period, advanced and clean reformation/ gasification processes, carbon dioxide capture and sequestration, and new efficient and low cost electrolysers will have to be developed.

However, in the long term, sustainable hydrogen production technologies based on renewable energy resources should become commercially competitive and gradually replace the fossil fuel reformation/gasification. Hydrogen, produced by solar photodecomposition of water or by electrolysis of water using electricity generated from renewable resources, has the potential to be the clean, sustainable and, therefore, climate-neutral energy carrier of the future, eventually eliminating greenhouse gas emissions from the energy sector.

  Hydrogen production limitations copyright 2011 Digtheheat.com