High efficiency generation
July 04th 2007

The potential for CHP in the UK ranges from 18GW to 40GW – huge amounts of energy (and the associated reduction in costs, carbon emissions and primary fuel use.) The technology is proven, it is available at all scales, it uses varying primary fuels,there seems very few reasons not to start installing CHP at every opportunity argues Peter Smith, researcher at the CHPA

Combined Heat and Power (CHP) has long been recognised as a highly efficient, energy saving, and carbon reducing solution.

From 1990 to 2006 the UK’s use of CHP has grown from 2000MWe to 5500MWe. Individually, each MW of CHP provides carbon savings in the range of 250 tonnes per year on average and 5200MWh per year. CHP has a wide range of applications, in that systems can be installed in a wide range of sizes, fuels and technologies.This ensures that CHP can be employed in many different projects ranging from domestic use to industrial production of electricity.

This highly efficient method of using both fossil and renewable fuels can therefore make a significant contribution to the UK’s sustainable energy goals. It is a proven technology with the potential to aid the UK in meeting emission and energy goals, both nationally and within the EU. This in itself will provide environmental, economic, social and energy security benefits to the UK community. If we followed the same path as Denmark and implement widespread use of district heating and decentralised generation (supported by strict legislation) there would be huge savings in fuel and carbon.

In its simplest form, it employs a gas turbine, an engine or a steam turbine to drive an alternator, and the resulting electricity can be used either wholly or partially on-site.The heat produced during power generation is then recovered, and can be used for a variety of functions. For example:

• To raise steam for a number of industrial processes

• Provide hot water for space heating

• With appropriate equipment installed, even cooling

Another major attraction to the use of CHP is decentralised generation. This reduces the amount of energy lost through transmission in the grid. It also provides increased security of supply in localised areas. CHP is most efficient when the heat can be used on site or very close to it (electricity transportation is more efficient than heat over longer distances.)

CHP systems make extensive use of the heat produced during the electricity generation process, achieving overall efficiencies in excess of 70% at the point of use. In contrast, the efficiency of conventional coal-fired and gasfired power stations, which discard this heat, is typically around 38% and 48% respectively, at the power station. CHP delivers a range of economic and environmental benefits – some of these accrue to its users, some to operators of the electricity grid and yet others to the wider community:

• CHP’s high efficiency leads to a reduction in the use of primary fuels. This is a huge factor in reducing cost of generation – which can be passed onto the consumer

• Reduced primary fuel requirements

• Reduction of carbon emissions and other products of combustion. Indeed CHP could provide the largest single contribution to reducing carbon dioxide emissions. Host organisations gain a ‘green’ business image – and the environment reaps the rewards

• Another benefit of using a CHP system is that they can be designed to continue to operate and serve essential loads during an interruption to mains power supplies.This ensures security of energy supplies

• It can meet the needs of industry that requires high quality power such as computer data centres

• Installing an on-site CHP unit within the electricity grid can strengthen the network and remove the need for network operators to upgrade the system

CHP has the support of government to such an extent that there are funding mechanisms in place as an incentive for its use. The Climate Change Levy is the strongest support mechanism in that all Good Quality CHP fuel inputs and electricity outputs companies are exempt. There are also a variety of programmes to stimulate investment such as; Eligibility for Enhanced Capital Allowances (ECAs) and Grant Support.