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Friday, June 26, 2015

Better concentrated solar power (CSP) stations

Concentrating solar thermal power stations convert as little as 25 to 30 percent of collected solar energy into electrical energy and need large thermal energy storage systems that add to the cost of construction.

Existing technology allows solar thermal energy to be converted into electrical energy with an effective efficiency of 90 percent and eliminates the need for thermal energy storage systems.

Burning hydrocarbons and carbohydrates - energy used and released

What the diagram represents is that 1 kilogram (2.2 lbs) of brown coal is decomposed into carbon monoxide and hydrogen by absorbing 5.54 megajoules of heat energy. 

The resulting carbon monoxide and hydrogen then releases 14.14 megajoules of heat energy when it combines with oxygen to produce carbon dioxide and water vapour.

The net heat energy available from burning this kilogram of brown coal is the difference between these two energy flows: 14.14 - 5.54 = 8.60 megajoules of heat energy.

Burning a kilogram of brown coal in a coal-fired power station allows a proportion of this 8.60 megajoules of heat energy to be converted to electricity.  Typically only about 40 percent is delivered as electricity: around 0.96 kilowatt-hours.

A different way of converting brown coal to electricity enables a far greater amount of electricity to be produced from each kilogram:
  • First each kilogram of brown coal is decomposed into carbon monoxide and hydrogen by absorbing 5.54 megajoules of concentrated solar thermal energy.  
  • Second, the resulting carbon monoxide and hydrogen releases 14.14 megajoules of heat energy when it combines with oxygen to produce carbon dioxide and water vapour in a gas power plant. Typically about 60 percent is delivered as electricity: around 2.36 kilowatt-hours.

The coal needed to produce 0.96 kilowatt-hours of electricity is reduced from 1 kilogram (2.2 lbs) to just 405 grams (14.3 ozs).

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