Monday, July 30, 2012

Introducing Tri-generation

Tri-generation is an extension of cogeneration, adding cooling to electricity generation and heat production. Tri-generation involves therefore the simultaneous production of heat, cooling and electricity. 

Tri-generation is specifically beneficial in a variable climate, such as Victoria’s (Australia), with strong heating demand in winter alternating with high cooling demand in summer.

Also, tri-gen has its greatest benefits when scaled to fit buildings or complexes of buildings where electricity, heating and cooling are perpetually needed. Such installations include but are not limited to: data centers, manufacturing facilities, universities, hospitals, military complexes, colleges, hotels and resorts.

Fuel is burnt in an engine which drives a generator to produce electricity. The waste heat from the engine is used for space, water or process heating, or can be converted to cold water for cooling through the application of an absorption chiller.

The trigeneration concept can also be used with solar photovoltaic cells. By removing and storing the heat from behind the PV panels, the heat can be used with an absorption chiller, cooling down the home.

An absorption chiller is basically an air conditioner driven by a heat source rather than electricity, utilizing excess heat and converting it into cold water or cold air. This is the same process as used in gas camping fridges.

Trigeneration brings significant economic, social and environmental benefits.
  • Greenhouse gas emission reductions of around 60% 
  • Overall energy efficiency typically 80% (compared to 30%): Additional efficiency is gained from reducing electricity transmission losses which are great when heat, cooling and electricity are produced individually. 
  • More affordable energy costs (CPRS mitigation) 
  • Improved energy security and reliability of plant 
  • Less electrical infrastructure to new sites (thermal chiller) 
  • Reduced daytime peak electricity demand: with tri-generation, electricity supply and demand are linked better, peak load demand can be reduced and security of supply is enhanced due to an increased number of diverse electricity generation alternatives. 
  • Building Rating improvement (NABERS) 
  • Network upgrade savings (plants run during daytime peak hours) 
  • Create new jobs

In addition, in some places such as the UK, trigeneration operators also benefit from the following:
  • Exemption from the Climate Change Levy (CCL) for self supply or supply over private wire networks 
  • CCL benefit (equivalent to the financial value of CCL Exemption) over public wires 
  • 100% Enhanced Capital Allowances 
  • 100% Exemption from Business Rates

Source: Moreland Energy Foundation
              UTS - Institute of Sustainable Future
              City of Sydney
              Clean Energy Council Australia

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