Co/Trigeneration:  The Technology

Also known as ‘combined heat and power’ (CHP) and ‘total energy’, Cogeneration is the simultaneous generation of heat and power, both of which are used.

Encompassing a range of technologies, Cogeneration will always include an electricity generator and a heat recovery system.

Cogeneration offers energy savings of between 25-45 per cent compared to conventional electricity and heat supply from power stations and boilers.

In conventional electricity generation, losses of around 20-35 per cent are associated with the transmission and distribution of electricity from relatively remote power stations, via the electricity grid.

These losses are greatest when electricity is delivered to the smallest consumers. By using waste heat, the efficiency of a Cogeneration plant can reach 90 per cent or more. Because electricity generated by a Cogeneration plant is normally used locally, transmission and distribution losses are negligible.

The fundamental principle of Cogeneration is that systems are designed in close proximity to their place of use and are matched to the required capacity. Because transporting electricity over long distances is easier and cheaper than transporting heat, Cogeneration installations are usually sited as near as possible to the place where the heat is consumed and ideally are sized to meet the demand.

When less electricity than required is generated from Cogeneration, it is necessary to buy extra power from the grid. However, when more electricity than needed is generated, the surplus can be sold to the grid or supplied to another customer via a distribution system.