Answer by Dale Blundell (Atkins)
The best applications are those where there is a good all year round heat demand and sufficient electrical demand to minimise electrical export to the network. For example, hospitals, hotels, large airports, swimming pools offer good thermal (hot water, heating and cooling) and power loads for extended daily periods and 7 days per weeks. Community housing may also offer good applications particularly, when a thermal store is employed, as there is often a high hot water and space heating demand for an extended period each day. Where there is insufficient demand for all the heat produced, cooling by the use of trigeneration can enhance the value of the CHP system.
Industrial applications with 24hr operation frequently offer a high electrical and thermal load throughout the day. For example, large chemicals or Food and Drink sector plant might have a large heat demand for processing.
District heating schemes are a good application for CHP, however, it is important to understand the thermal demand profile, and thermal storage to allow longer running of the CHP system and to flatten out the peaks and troughs of demand.
Applications to be avoided include those where there is an intermittent or peaky load profile, or where the demand is only seasonal.
Tariffs play an important element in the viability of CHP, since the higher the cost of energy provided by conventional means (imported electricity and heat from boilers), the greater the cost savings from CHP. A key factor here is the ‘Spark’ spread – this is the difference between the fuel price e.g. natural gas, and the cost per unit of electricity displaced.