Solar Powered District Heating Project

CHOICES Consortium wins Heat Network Innovation contract

Clean Energy Prospector, Eunomia, ICAX and the University of Bath were awarded feasibility assessment funding from DECC followed by a full grant. The consortium’s CHOICES project demonstrates a small-scale, modular heat and power Energy Centre in Easton, Bristol, using surplus solar PV in summer to charge an interseasonal borehole thermal energy store using air source heat pumps: in winter heat is provided to a district energy network by ground source heat pumps which transfer heat from the warm thermal store.

The CHOICES Energy Centre:

• shifts electric consumption from times of peak winter demand to times of surplus summer solar generation
• exploits Borehole Thermal Energy Storage to store heat from summer to winter
• packages existing commercially ready technologies in a novel use combination
• provides new opportunities for Energy Service Companies to package and sell renewable heat
• and has the potential to scale up rapidly.

Decarbonising heat

The problem to be answered is how to decarbonise heat – currently 80% of UK buildings are heated by gas. One approach is to use CHP (combined heat and power), but when fuelled by gas the carbon reduction potential is limited to around 30% and the long term supply issues remain unsolved. When fueled with biomass then CHP is associated with supply chain complexity, high operational costs and environmental impact from transport and smoke emissions.

All forms of combustion in city centres contribute to air pollution. CHOICES will not emit any carbon dioxide – or any other gas or particulates – on site.

CHOICES: Community Heat Optimisation with Intelligent Control of Energy Storage

The aim of the CHOICES project is to demonstrate decarbonisation of heating by employing an innovative solar district heating network with seasonal thermal storage in the heart of a suburban neighbourhood. The project combines pioneering interseasonal heat storage technology from ICAX, energy-vector research from the University of Bath, CEPRO’s experience in energy metering, monitoring, engagement and billing at the local community level and full life cycle assessment by energy consultancy, Eunomia. The team is working closely with Easton Community Centre and Easton Energy Group at the Owen Square site in Bristol.

Damon Rand, Managing Director of Clean Energy Prospector, says "We are delighted that the CHOICES concept, a simple yet innovative combination of renewable technologies, has the won this contract from DECC. The project will show how much more can be done with solar at the local level, giving people and organisations true choice over how and when they heat their homes and buildings and how they can optimise energy use. There are thousands of similar sites across the UK and projects like this could make the country less reliant on gas in the long run and allow communities to manage their own heating networks."

Heat networks demonstration on site

The CHOICES project integrates a number of renewable technologies with a control system that makes choices between alternative sources of heat generation, storage and supply. These choices will depend on the energy options available at different times of day and different seasons of the year and the heat demand from different buildings at different times.

The CHOICES proposal exploits commercially ready technologies in a novel combination and integrates them with a low temperature heat network. In particular, the use of excess summertime PV electricity to power an air source energy transfer to the thermal store for recovery in winter provides for multiple system efficiencies: PV output is optimised. Heat pump efficiencies are optimised (by charging the borehole field with heat in summer). Heat transfer runs on green electricity which may otherwise cause power quality issues on the local feeder or even reverse flows onto the Medium Voltage network.

Life Cycle Analysis

A full Life Cycle Analysis has been conducted by Eunomia in Phase 1 to quantify the cost and benefits of the CHOICES implementation at Owen Square. The CHOICES Energy Centre is expected to achieve energy savings of up to 64% and annual carbon savings of 38%, increasing to 51% carbon savings against gas by year 10 and 66% by year 20.

CHOICES is adopting a commercially driven, customer focused approach to the delivery of decarbonised heat. The focus of the technology development is to make metered heat financially attractive while facilitating ease of adoption and minimising disruption to customers.

 

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