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Optimisation checklist: How to generate efficiencies

The ultimate checklist for CHP energy users.

Combined Heat and Power (CHP) is the simultaneous on-site generation of low carbon heat and electricity. It provides building owners and developers with a significant opportunity to:

  • Improve their building’s energy efficiency.
  • Reduce the associated energy costs and emissions.
  • Receive important financial and environmental benefits.

As CHP is reliant on its ability to achieve successful long-term operation at high efficiencies, the optimisation of deployment and utilisation of CHP becomes a priority. By making informed considerations around the initial design of the system, you can improve lifetime operation.

There are two main stages to consider:

1. Design and integration: Confirming the economic feasibility of CHP and obtaining the best solution for the building project.

2. Operational performance: Getting the most out of the CHP system’s operation throughout its lifetime by using the insights gained from monitoring performance.

1. Design and integration

Undertake a thorough economic feasibility study

The right application will provide a positive ROI. This will act as a benchmark for performance optimisation to be monitored against throughout the CHP’s lifetime, to ensure that these benefits continue to be realised.

To achieve the best indication of energy cost savings from CHP, you should analyse the site’s existing electricity and thermal load profiles. This will help to ensure the output is matched exactly to requirements. With an initial CHP selection made, carrying out an economic assessment will also highlight the best available return on investment (ROI).

Look at the following lifecycle costs of the CHP system and the expected life cycle financial benefits:

  • Equipment
  • Installation
  • Operation and maintenance costs
  • Savings on energy costs
  • Savings from tax incentives

Make sure a CHP is correctly sized

A CHP unit achieves its highest annual efficiency by operating at full load; utilising both the heat and energy produced, for a specified minimum number of operating hours. Generally, for continuous operation, the CHP unit should be sized to meet the site’s electrical baseload (the minimum demand throughout the agreed period of operation).

Obtaining accurate site load data is the key to successfully sizing the CHP system. Where access and accuracy are questionable, monitoring the system will help to obtain trustworthy information. Accurate data will help you to correctly size CHOP systems so they meet the required performance levels. High availability and performance will lead to greater ROI and the system’s ability to qualify as Good Quality CHP under the CHPQA programme.

Once qualified, the CHP system will do much more than achieve maximum reductions in energy costs and CO2 emissions. Certified CHP systems will benefit from tax incentives, such as the Climate Change Levy (CCL) and Enhanced Capital Allowances (ECAs), creating a significant impact on expected ROI.

Fully integrate the CHP in the system design

It’s essential that the CHP system is well integrated on-site to optimise the use of the electrical and thermal energy generated.

The CHP should always be operated as the lead heat source, with priority over the site’s heating boilers. This will help maximise the use of heat recovered, rather than waste this valuable energy. If heat can’t be used immediately, the provision of a thermal store could be appraised so that heat can be used when it is required. Controlling the system’s return temperature setpoint, so that the return temperature doesn’t creep up too high, will also help.

Position the CHP as close as possible to the site’s service connections. Locate it near to the gas, hot water, and electrical distribution board connections to keep pipework and cabling to a minimum. Short service runs can help the CHP system design and its subsequent operation to be optimised, keeping installation costs down.

The design must allow safe and easy access for regular maintenance and servicing, as this improves uptime and reduces related costs.

2. Operational performance

Protect the CHP with monitoring and periodic system maintenance

The CHP system will have an expected lifetime operation of between 10 and 15 years. Periodic system maintenance is critical to the wellbeing of the CHP operation during this time – ensuring that expected wear and tear doesn't become and issue, allowing for continued operation. If system maintenance is not carried out, the anticipated output from the CHP system operation will be reduced and lower operating efficiencies will occur.

Remote monitoring of the complete CHP system performance is essential for guaranteed operational success. Monitoring alerts the maintenance team to potential faults so issues can be diagnosed early, then rectified quickly and remotely.

Schedule regular performance health checks
Regular performance health checks will help keep an eye on whether the CHP system is meeting the expectations of the building system’s end user, and also the CHP supplier or operator. It is essential that the CHP system’s operating performance is continuously measured and analysed. This will highlight any deviations in operating performance which could inadvertently affect overall CHP optimisation.

This also includes economic and environmental performance requirements, which will need to be watched closely to ensure the system operation provides the expected ROI.

Key takeaways:

The best long-term benefits of CHP units - reduced energy costs and reduced emissions - are the result of an optimised CHP operating running at high efficiency.

  • Optimisation of CHP starts with good design.
  • An economic feasibility study will show how effective CHP can be.
  • The CHP unit needs to be sized correctly.
  • Monitoring and maintenance will keep a check on the CHP system performance.
  • Regular performance health checks will help measure if the CHP operation is being optimised.