For many organisations, combined heat and power offers the most significant chance to reduce their total fossil fuel consumption from on-site boilers and the power stations they import electricity from.

CHP is the simultaneous generation of useable heat and power in a single process. In the case of CHP the heat produced is used in the building and not released wastefully into the atmosphere.

CHP offers energy and environmental benefits over electric- only and thermal-only systems and can deliver substantial financial savings as well as a significant reduction in carbon emissions.

How CHP works:

For CHP to be effective a Combined Heat and Power unit only generates economic and environmental savings when it is running, so it will only be viable if you have a high and constant demand for heat.

This system suits factories and businesses where there is a constant working environment, where the offices or factory is being used and so heated almost constantly.

In a heat engine, which is a device that converts heat energy into mechanical energy, heat from a hot fluid (hot water) is used to do mechanical work.

This means that once this mechanical work has been carried out, heat remains in the fluid which either disperses into the surroundings or can be recovered and used. If the heat is allowed to simply disperse, then it is wasted, a combined heat and power system uses this heat, reducing waste.

There are three stages to CHP which must occur in sequence for it to work effectively:

1. Power generation – the generation of power to do the mechanical work

2. Heat recovery – taking the hot water and using the heat rather than letting the energy be wasted.

3. Heat use – using the hot water to, for example heat the back office.

Heat from a CHP plant can also be used to generate cooling by using something called an absorption chiller unit. An absorption chiller uses waste heat generated from CHP systems, flue gases and steam, to produce chilled water.

CHP that produces heat, electricity and cooling is called ‘tri-generation’.

A site with a large and continuous cooling demand, and maybe a declining demand for heat, may consider replacing a conventional electrical cooling system with absorption cooling.

Converting an electrical load into a heat load in this way has a number of advantages;

• it reduces the site’s demand for electricity

• it increases the options for heat use

• it ‘irons out’ some of the seasonal peaks and troughs in the requirement for heat.

CHP is very flexible; this means it can be tailored to the requirements of each site. It can be used across a wide range of sectors and can provide cost-effective energy solutions for large and small energy users.

Where CHP can be implemented:

Combined Heat and Power Systems can be considered at any site where there is sufficient and constant heat (or cooling) demand, particularly if that demand is for extended periods. It’s particularly suitable for the industrial, public and commercial sectors.

It makes more efficient use of primary fuel for producing heat and power than separate conventional methods; for example, on-site boilers and power stations. This means it can deliver significant environmental benefits and cost savings, given the right balance of technical and financial conditions.

Benefits of combined heat and power

CHP can cut costs, reduce carbon emissions, ensure a more secure energy supply and improve overall energy efficiency.

CHP improves a site’s environmental performance because:

• the primary fuel consumption per unit of energy generated is lower

• fuels with high emissions can be replaced with cleaner fuels

• electrical losses are reduced because the electricity is generated at, or close to, the point of use and is not transmitted over large distances.

By installing CHP, you can demonstrate your commitment to reducing energy consumption, improving sustainability and your awareness of environmental issues, all of which are of increasing interest to shareholders, customers and other stakeholders.