HVAC – HEAT EXTRACTION
Tapping into nature
A Queen’s Quay regeneration project in Clydebank is set to be the site of one of the UK’s most exciting energy projects,
creating Scotland’s H rst large-scale water source heat pump scheme to connect to a district heating network
By Toby Clark
T he potential for extracting
heat from natural sources is
enormous, and a substantial
development in Scotland
should be an impressive
demonstration. The £250m Queen’s
Quay regeneration project in Clydebank
will incorporate a large-scale water
source heat pump scheme, using heat
extracted from the River Clyde to supply
hot water and heating to a district
heating network that covers 1,200
homes, as well as businesses and public
buildings.
The project, the largest of its
kind in Scotland, will cost around
£15m. It has been developed by West
Dunbartonshire Council and is being
delivered in partnership with renewable
energy company Vital Energi. West
Dunbartonshire Council is covering
60% of the cost, while the Scottish
government will contribute £6m through
the European Regional Development
Fund, via the Low Carbon Infrastructure
Transition Programme. “The project will
build out over the next 10 years,” explains
Vital Energi operations manager Scott
Lutton. “Initially, we’ll pick up existing
buildings that the council owns, and then,
through the lifetime of the project, we
will pick up the new developments.”
The two 2.5MW heat pumps are being
supplied by Star Renewable Energy
(pictured, below left) and will be installed,
he says, “at the initial stage – as soon as
we produce heat, the heat pumps will be
producing that heat,” but they have the
capacity to support future expansion.
They are supplemented by two gas
boilers supplying up to 7MW each – the
‘energy centre’ (pictured, p25) has an
overall capacity put at 20MW.
The gas boilers, says Lutton, are
not for routine use but “for resilience –
there’s spare capacity and there’s always
redundancy. The heat pumps are the
lead heat source for the site – the gas
boilers will just run to top it up as and
when”. Both the heat pumps and the
boilers can operate in parallel, through
a fully-automated control system. The
heat pumps themselves are electrically
driven: the motors “are big electrical
consumers,” says Lutton, “driven through
large-scale variable speed drives and
they ebb and fl ow with the requirements
of the heat pumps”.
If the heat pumps are off -line for
maintenance, there is also a 130,000-
litre thermal store (“basically a big hot
water tank”) that can be topped up by
the heat pumps or the gas boilers. The
thermal store is integral to the system
design and is utilised to maximise the
system effi ciency. “We’ve got capacity
for another 130,000-litre thermal store
besides”, adds Lutton. There is also the
future provision to add further heat
pumps and another gas boiler, for a total
output of around 30MW.
RIVER EXTRACTION
The heat pumps do not directly take
the water from the river. “We have an
extraction system,” says Lutton. “We put
fi lter heads into the water, the water is
pumped through two stages of fi ltration
and then feeds the heat pumps in the
energy centre.
“Filtration is a massive consideration
– making sure that water is taken out at
an appropriate rate and put back in an
appropriate condition – and also to give
the heat pumps the level of fi ltered and
safe water that they require. Taking the
water out can be done a number of ways,
but making sure it’s in a condition to be
used is probably more challenging.”
But of course, ensuring that the
site is appropriate is vital: “There’s the
survey, detailed analysis and there’s also
24 www.operationsengineer.org.uk May 2019
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