Striving for CHP Design Excellence
Despite the design best practice promoted by the CHPA amongst other organisations, we’re now seeing evidence of many schemes where it was decided upon to make the system purely electrically led, based on financial reasons alone, rather than from the point of view of maximising efficiency. In these cases, heat is routinely rejected or dumped through dry air coolers to the atmosphere, which is a design philosophy I’d argue stems from the lease hire kW orientated contracts. It is high time that the rejection of heat is seen as a last resort.
A worrying number of CHP systems are being designed to routinely reject large proportions of the heat generated, via dry air coolers. In the vast majority of cases, this is poor practice as it not only reduces efficiency levels, but also hampers CO2 and financial saving potential. Fundamentally, more thought needs to go into the ways heat can be used rather than wasted.
What stakeholders must remember is that CHP modules have been developed to cater for the provision of both heat and electrical demand within a building. If the product of one of these functions is wasted, it is impossible for the system to perform to its full design specification.
Although voluntary, the Department of Energy and Climate Change’s Quality Assurance scheme offers a significant number of additional benefits for CHP investors. Those with small scale schemes where heat is not rejected can benefit from further savings through the Climate Change Levy (CCL) exemption, access to Enhanced Capital Allowances, and metering arrangements to monitor the quality of the scheme. These are all opportunities which should be taken advantage of.
The UK industry has learnt a number of lessons since the adoption of CHP technology, but what we need to remember is that the technology has the potential to offer hugely effective CO2 savings, as well as a secure electricity supply. As with any low carbon technology however, these benefits are subject to responsible design, installation and operation practices.