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Thursday, July 16, 2015

Wind turbines complement coal, natural gas and liquid fuels

New German technology converts 2 gigawatt-hours of off-peak electricity from wind turbines into hydrogen in its first year of operation. (See E.ON Wind Energy Gas Storage GmbH)

For private households the “Wind-to-Hydrogen” product can be obtained as a mix of 90 % natural gas and 10 % regenerative hydrogen.

This technology competes with battery energy storage. The commercial value of hydrogen and oxygen from off-peak wind energy has to be weighed up by investors against the cost of storing this off-peak energy in batteries for resale at a higher price during peak periods.
Wind farm energy to hydrogen and oxygen
Wind energy to hydrogen and oxygen

There are opportunities to expand the market for hydrogen and oxygen from low-cost off-peak electricity generated by wind farms:
  • Oil refineries consume a vast amount of hydrogen to produce transport fuels. At present refineries use natural gas to make hydrogen.
  • Oxygen from wind turbine electrolysis units can cut the reliance on air separation plants making oxygen for use in coal gasification. (The process of gasifying coal and municipal or crop waste with pure oxygen also lowers the cost of separating carbon dioxide - itself a valuable product in the emerging algae-oil industry and traditional markets such as fertiliser manufacture.)

The Purox process was developed by Union Carbide in the early 1970's

Air may be cheap but from a thermal-efficiency perspective it's expensive because only one fifth of air is oxygen with nitrogen forming the remaining four fifths. Gasifiers that use air as the oxidizing gas have to heat up five times as much air than one using pure oxygen as the oxidizer and separating carbon dioxide from large volumes of nitrogen is an expensive process.

In the mid-1970's pure oxygen was produced by the fractional distillation of liquid air, a process which is energy intensive and technologically challenging.