Adding CHP to the boiler mix

Bosch Commercial & Industrial Heating, CHP, boiler, space heating
Exploiting CHP — Pete Mills.

With a number of stakeholders looking at ways to enhance energy-efficiency levels, a systems alliance can often prove to be the most effective option. Pete Mills of Bosch Commercial & Industrial Heating, explains this concept and how adding a combined heat and power module to the ‘boiler mix’ can boost performance.

One of the most widely debated topics in the commercial and industrial facilities industry is the impact of fuel costs, which are undoubtedly on the rise and stretching budgets to extremes. In light of this, we are regularly seeing instances whereby stakeholders are actively seeking alternative solutions to meet their energy requirements.

When it comes to the provision of heating and hot water in a commercial environment, one of the growing trends is the installation of a systems alliance, whereby a secondary or accompanying technology is installed alongside a boiler, to utilise the strengths of each appliance in order to mitigate the impact of rising energy costs and increasingly stringent emissions targets.

One such arrangement for applications with sufficient demand for both electricity and heat is the incorporation of a combined heat and power (CHP) module. As heat is produced as a by-product of the power generated and by distributing via a thermal store, the technology lends itself to operation alongside any other heating source — a high-efficiency boiler being one of the most common examples.

The key to a successful systems alliance comprising CHP is that the system is designed to utilise 100% of the heat generated. With premium efficiency levels and cost savings the ultimate objective for such an arrangement, it is vital that no heat is rejected, which would have the potential to jeopardise the system’s effectiveness and compromise the cost saving benefit. To avoid dumping or wasting of heat, it is absolutely essential that the CHP module is correctly sized. Failure to do is likely to result in the production of too much heat for a building, which will nullify any potential performance enhancements.

In most cases, CHP units are installed in tandem with boilers. However, it is also possible to utilise the benefits of an alternative appliance. Whatever the arrangement, the key to reaping the benefits of a CHP system is to ensure it is sized either to the thermal base load of a project, or 20% of the peak load, to allow for maximum efficiency. Whilst CHP will meet a building’s base-load heating requirements most of the time, a secondary source will generally be required to satisfy a building’s peak heating load. In some instances this may only equate to a few months a year, but during these times, CHP alone would not be the most efficient solution.

A well thought out system design will increase the likelihood of a favourable return on investment, which will in turn lead to quicker payback on the initial financial outlay.

Further benefits can be taken advantage of through Government incentives, with the CRC Energy Efficiency scheme standing as a mandatory requirement for larger organisations to reduce their emissions — a goal the integration of a suitably-sized CHP module is likely to help them to achieve.

Bosch Commercial & Industrial Heating, CHP, boiler, space heating
Mix and match — CHP working alongside high-efficiency boilers can make an impact on rising energy costs and increasingly stringent emissions targets.

Provided the appliance meets the registration criteria, CHP can also enable non-domestic stakeholders to take advantage of the Enhanced Capital Allowance (ECA) scheme, which provides tax relief and improves cashflow for the year that the new equipment is purchased.

Although new installations generally lend themselves to a more effective system design, CHP can also be integrated as part of an existing system, in a retrofit arrangement. With access to an extensive history of energy data, a manufacturer will be able to co-operate with the project consultant to ensure the CHP module is correctly sized and that the arrangement best meets the application’s requirements.

Whilst correct sizing will go some way to maximising performance, as with a boiler, once the CHP is installed it is vital to take care of the long-term health of the system. Investing in a maintenance agreement should be considered an essential commitment. This is not purely down to manufacturers wanting customers to spend more money on their installation, but because investing in CHP without being prepared to invest in the long-term running of the system is a huge false economy for investors.

If CHP units are not correctly maintained post installation there is a risk of the engine breaking down. And when that happens, rebuilding the engine comes with a large cost attached.

It is not surprising that many owners who purchased modules without a maintenance agreement decide to switch them off rather than go the expense of rectifying the problem. Investing in a maintenance contract will help any new project overcome initial teething problems, and then allow the module to operate in harmony within a systems alliance. Whilst it may be tempting for investors not to budget for a maintenance agreement after spending money on the CHP installation itself, it is likely to prove a costly decision over the longer term as it is impossible for CHP to deliver what it has been designed to contribute without operating.

Pete Mills is commercial technical operations manager with Bosch Commercial & Industrial Heating.

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