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DESERTEC and INDUSTRIAL PROCESSES

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Given the enormous quantities of energy available in deserts, it is natural to consider whether it might be used to support energy-intensive industrial processes such as the production of aluminium, iron, steel, cement, or glass:

  • The large quantities of heat and electricity that are needed to convert bauxite into aluminium could, in principle, be provided by CSP plants in the Australian desert, close to where the bauxite is mined.
  • The production of iron from iron ore requires a combination of large amounts of heat and a chemical reducing agent such as carbon. In conventional smelting, coke provides the heat and serves as the reducing agent—and large amounts of CO2 are released into the atmosphere. In principle, large reductions in CO2 emissions may be achieved by using solar concentrators or solar electricity instead of coke as the source of heat.
  • It is possible that hydrogen produced by the electrolysis of water (using electricity from CSP plants) might be used as the reducing agent in the production of iron, thus avoiding the use of coke.
  • In processing iron to make steel, the main requirement is heat. In principle, this could be provided by solar concentrators or solar electricity thus eliminating the emissions of CO2 that might otherwise result from burning coal.
  • The production of ordinary 'Portland' cement requires large amounts of heat combined with chemical processing of limestone. Some CO2 comes from the limestone itself but if the heat is provided by burning something like coal, this may be an additional large source of CO2. In principle, that second source of CO2 can be eliminated by using heat from solar concentrators or solar electricity instead of coal. And if geopolymeric cement is produced instead of Portland cement, this would eliminate most of the first source of CO2 as well.
  • Steam generated by CSP could become widely used for industrial processes in the future (see, for example, A solar-powered oil field?).
  • Given that:
    • The mirrors of CSP plants are often made from glass,
    • Glass is made from sand,
    • Sand is often plentiful in the desert regions where CSP plants work best,
    • And the production of glass from sand requires quite a lot of heat.
    it is natural to consider whether the glass that is needed for CSP plants (and other purposes) might, with advantage, be made using the heat from CSP plants.

Social and political dimensions

Although, from a technical perspective, it may make sense to move some energy-intensive industries to desert regions, social and political aspects are clearly relevant too. A good balance needs to be found amongst the several aspects, and that balance may vary, depending on specific industries, specific technologies, and the interests of relevant stakeholders.

Links:

CSP and the synthesis of fuels

Electricity is a very versatile form of energy and can be transported very efficiently over long distances using HVDC transmission lines. But, despite lower efficiencies, energy in chemical forms such as hydrogen, alcohol or hydrocarbons may be better for particular purposes:

  • They can be stored and this can be useful for ironing out variations in supply or demand or as strategic reserves of energy.
  • They provide an alternative vehicle for transporting energy and this may be useful as a means of increasing the security of energy supplies.
  • Although railways and road vehicles (electric and hybrid) can be powered by electricity, aircraft need chemical fuels and the same is true of ships that have an engine and do not rely exclusively on the power of the wind.

So although there will be losses of energy, there may be good reasons to convert CSP energy into chemical form. Here are the main options:

  • Solar electricity may be used to generate hydrogen by the electrolysis of water. It is also possible split water into hydrogen and oxygen using heat from a CSP plant (see Clean Hydrogen Producers Ltd. (CHP)).
  • Another possibility, somewhat more speculative, is to capture solar energy as finely powdered metal (iron, aluminium etc) or boron (see an article from the New Scientist and letters in the New Scientist). Surprising as it may seem, powdered metal or boron may be used as fuel in a Diesel engine, Stirling engine, or gas turbine engine. The oxide of metal or boron that results from combustion may be collected and recycled (at solar power plants) back into powdered metal or boron. Instead of ‘the hydrogen economy’ we should, perhaps, be aiming for ‘the powdered boron economy’!
  • It appears to be feasible to use solar heat or solar electricity (or both) to synthesise hydrocarbons or alcohol from CO2 (extracted from the air) and water. Some of the possibilities are outlined in the following sources:

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Last updated: 2015-01-29 (ISO 8601)