Friday, 12 February 2010

Co-Generation and Tri-generation

Co-Generation and Tri-Generation processes aim to maximise fuel energy conversion efficiencies.

Normally in electricity generation with fossil fuels or bio-fuels only 25-30% of the fuel energy is transformed into electricity. This is because of the heat produced from combustion to turn a steam turbine or such-like can only utilise part of this energy.

Now it would seem very sensible to utilise all of the heat produced to increase energy efficiency. This is the primary reasoning behind CHP and CHCP. That's "Combined Heat and Power" [Co-Generation] and "Combined Heat Cooling and Power" [Tri-Generation]

The image here uses a Stirling Engine (Green) to turn heat into mechanical energy which in turn can produce electrical energy. Here 4 sets of 35kWe Stirling Engines being run from wood chip gasification (grey tower with yellow wood-gas pipelines). Each boiler (light blue) also produces 160kW of heat energy, which can provide heating water or a combination of heating water and chilled water for air conditioning. By use of an absorption chiller, heat can generate cold!

So in this 4 set arrangement 140 kWe per hour is generated and some 560 kW of heat energy (to be split between heating and absorption chillers for air conditioning plant. This would be sufficient for a hotel, commercial office and suchlike. The system would need around 400 kg per hour of wood-chips with a maximum moisture content at around 50%. Using automated feeders and wood chip quality control a CHP/CHCP plant can provide secure base-load electrical output

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