CSP 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.

For example, the large quantities of heat and electricity that are needed to convert bauxite into aluminium could 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 CSP instead of coke to provide the necessary heat.

In processing iron to make steel, the main requirement is heat. In principle, this could be provided by CSP 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 CSP heat 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.

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.

Link: Solar Heat for Industrial Processes (SHIP)

CSP and the synthesis of fuels

Electricity is a very versatile form of energy but, for particular purposes, energy in chemical forms such as hydrogen, alcohol or hydrocarbons may be better:

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:
- A report from Eindhoven University of Technology suggests the use of nuclear power to synthesise hydrocarbons or alcohol. Of course, it would make much more sense to use the enormous quantities of solar power that is available in deserts.
- Converting CO₂ back to fuel. This describes an EU-funded project ("ELCAT") to use solar energy to power the conversion of CO₂ back to hydrocarbon fuels.
- A related technology is the Fischer-Tropsch process for synthesising hydrocarbons from carbon monoxide and hydrogen.