Step by Step CHP: the Pitfalls to Avoid Between Planning and Design

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Courtesy of Courtesy of ENER-G

There are many pitfalls in between planning and designing a cogeneration project. Find out how to avoid them.

Cogeneration can save money, conserve energy, and reduce emissions - but specifying the right combined heat and power (CHP) unit for the site in question has its pitfalls.  There are a number of potential pitfalls involved in specifying CHP. What are these  common mistakes? How can you avoid them when taking your CHP project from planning through to design?

The key risks to the viability of a CHP project

    • Poor site energy efficiency

    • Mis-sizing plant

    • Site-specific issues

    • The wrong choice of fuel

    • The finance model

None of these problems, however, are insurmountable.

1.  Poor site energy efficiency

Greater and longer term benefits are available if energy saving measures are implemented and poor performing plant are improved before sizing a CHP system. Remember, every 1°C of site overheating adds 8% to heating costs

So check:

  • Building insulation
  • Lighting
  • Power factor
  • Existing boiler efficiency

2.  Mis-sizing plants

  • Detail is vital when sizing CHP.

  • Calculate hourly consumption of power and gas during the working day, the week and season to season.

  •  Economical viability typically requires a heat demand all year of at least 17 hours a day, 5 days a week.

  • The ratio of heat to power should govern the choice of CHP technology and size. Mismatch could dramatically reduce potential CHP gains.

3.  Future-proofing

    • What are the prospects of fuel and electricity cost changes?

    • Are energy efficiency measures in place?

    • Does the business have plans to expand?

    • Will the site’s heat and power demands change?

5.  Site-specific issues

  • Overlooking the detail in the crucial connections of the CHP system can lead to costs over running during installation.

  •  Check the exact siting of:  the gas network and  power network connections;  a connection to local heat network, where available; a heat rejection outlet, where needed.

  •  Are there planning requirements or noise abatement issues to be considered?

  •  Can the gas pipework accommodate the increased volume of gas?

  •  Will the power network support your connection?

6.  Fuel Selection and Procurement

  • Check the duration and volumes in your gas and electricity supply contract - there could be exit fees.

  • Do you have biogas available? Some biogases can contain corrosive components, so the choice of CHP plant is crucial as is the choice of lubricant.

7.  Finance

  • Consider the best cost model. Do you invest your own money to get all the cost benefits but take on all the risk, or utilise third party financing to share the benefits and minimise the risks.

  •  Check out the incentives, for example, CHP can attract tax and other benefits that can boost the economy - especially when specified to meet the requirements of ‘good quality’ CHP under the CHPQA scheme.


To avoid the pitfalls in cogeneration, detailed design is the only design. Remember to:

    • Audit energy efficiency measures

    • Correctly size the plant based on heat and power demands

    • Mitigate any site specific issues that might affect installation

    • Manage your fuel selection and cost

    • Select a finance model that suits the project

Discover how to cover every aspect of CHP installation in your project specification. Download  the free guide to 'Selecting CHP the ultimate checklist'


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