What is a CHP unit?
CHP is an acronym for the word ‘Combined Heat and Power systems. CHP systems were
originally introduced to the UK as an energy efficiency solution in the late 1990’s. CHPS
units are growing in popularity as organisations and industries look to reduce their carbon
footprint and reduce their energy bills. There are many variants of how the plant can be
used, however they predominantly incorporate heat generation with electricity.
How do they work?
A CHP unit is essentially a heavy commercial diesel engine converted to run off a gas fuel
supply. With all combustion engines, the primary outcome is that significant heat is
generated through the heat of combustion and the friction of mechanical motion. In a car this
would be reduced via oil, air- and water-cooling radiators. In a CHP system, this heat energy
is captured via a heat exchanger and can be used to supplement heating, steam or hot
water systems. Essentially the energy provided reduces the loading on plant item such as
LTHW boilers, domestic hot water systems and steam systems. The secondary outcome of
the engine is to drive a crank shaft which turns a generator to create electricity locally on the
site, with the physics of electricity, the local electricity will be used before any electricity grid
CHP units can come in various sizes servicing large domestic buildings up to 2mw
generation plants for buildings such as factories or warehouses.
Please see the image below for further information:
What are the benefits of a CHP system?
If designed correctly and maintained efficiently, CHP systems can reduce the combined cost
of heating and electricity bills significantly meaning they can have a long-term return on
investment (ROI) and can save significant carbon emissions to the atmosphere as the
energy fuel efficiency produced can be up to 85%.
If commercial businesses who have a CHP can prove they meet the design criteria
(CHPQA), they will become eligible to offset their savings against the Climate Change Levy
(CCL), introduced in 2001. This is known as CCL relief.
Please see the table below:
What are the potential drawbacks of a CHP system?
In Karsons experience, many CHP systems installed are incorrectly designed and specified.
Some CHP systems do not meet the meet the energy saving criteria required for economic
viability. In turn this means that the claimed ROI’s are not met. CHP equipment is advanced
and in-depth feasibility studies should be undertaken to analyse the cost/energy benefits.
CHP systems are still relatively new in concept, typically they are costly to install and are
intrinsically design sensitive. Subsequently, there are many misconceptions about their
operation and how to maintain them. This creates a ‘fear’ from the site managing agents,
maintenance contractors and landlords who inherit them and are worried about how to
approach the operation and maintenance of this equipment. If designed and maintained
properly, CHPs should be cost effective.
It is also well documented that many sites also install CHP to prove their green credentials
and pass planning consent. After this many sites leave their CHP equipment offline and
resort back to conventional grid electricity and gas and electricity supplied heating and hot
water services. This is not what the equipment was designed for and the wasted benefits are
In what capacity are Karsons involved with CHP systems?
Karsons Consulting manage and consult on maintenance management on the maintenance
management of CHP systems on prestigious sites such as Chelsea Barracks.
Karsons also have a team of design engineers who have experience in the design and
maintenance process of this equipment. Karsons have produced detailed feasibility studies
reviewing heat and power demands, operational requirements, running time requirements,
gas pressures, acoustic environments and we can incorporate these into ESOS and
Can Karsons help your with your CHP systems?
Karsons can help from a maintenance, design or diagnostic perspective with your CHP
If you have any further questions regarding the installation or maintenance of your CHP,
please do not hesitate to contact us on the below:
020 3282 7605