Energy efficiency
The pros and cons of combining heat and power
Bill Sinclair, technical director, Adveco, discusses the operational costs and the environmental impact of onsite energy co-generation and highlights the increasing performance gap between ‘dirty CHP’ and the latest generation of highly efficient micro-CHP
Whether building a new care home or refurbishing an older property, the importance of energy provision has risen up the agenda, resulting in a proliferation of onsite power generation. According to a report by Centrica Business Solutions, more than 80 per cent of commercial operations are expected to invest in onsite power production to generate up to one-quarter of their electricity requirements by 2025.1
One popular choice has been combined heat and power (CHP), which is also known as co-generation. CHP is the simultaneous production of usable heat and electricity using a single process and source of fuel (typically gas) and is one of the most effective ways to significantly increase the energy efficiency of a building. With an engine directly linked to a generator, similar efficiency levels to those of a
conventional source of power can be achieved and by locating the installation at the point of consumption, the energy losses often associated with power transmission via the grid are eliminated. In addition, thermal energy is extracted from the CHP process by recovering the waste heat produced during the power generation process. This drastically reduces the amount of fuel energy lost to the environment as exhaust, instead using it to contribute towards local heat demand. With significant continuous demand, such as that typically seen in a residential care facility, a CHP unit can run for long periods of time, thus drastically reducing reliance on conventional boiler technology and improving the overall efficiency of a building, reducing emissions and resulting in financial savings.
The advantages
For operators and managers of care facilities, there are two basic questions to ask. If you have CHP, what should you do with it? If you don’t, should you upgrade your plant room to include CHP? CHP has a number of benefits, which include environmental benefits and cost savings, but it only provides a payback case on capital expenditure in the right type of building. If your building already has CHP, it is likely to be because someone chose it for financial or environmental reasons. For example, designers have typically chosen CHP to show carbon savings in order to get planning permission for a project. If you have inherited a building that was completed during the past five years that has CHP, then it was probably chosen to meet these requirements. However, the most important things to a facilities management team are likely to be the functioning of the building followed by the reliability of the heating and hot water supply, operating costs and finally, environmental concerns. CHP is a support technology rather than a critical technology. Water heaters and boilers are critical equipment; if they break down this affects the heating and hot water supply to the building and therefore the comfort and safety of residents. CHP, like many renewables, makes no difference to the reliability of the supply. Whether it is on or off, the building will still have heating and hot water, so if you have inherited CHP, you need to decide what you want to do with it.
CHP can provide up to 90 per cent of the hot water needed by a care home 26
Shutting it down is an option. You could turn it off and forget about it. If you do that then you will not pay for maintenance or energy consumption by the unit and there will be no loss of heat or hot water supply, although there will not be any carbon savings either. Alternatively, you can pay for
www.thecarehomeenvironment.com • March 2020
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