A simple model for District Heating feasibility

District heating accounts for only 2% of the total UK heat demand, which is partially due to the need for local authorities to employ costly engineering consultancies in the design process. A simple model that a non-technical user at a local authority could operate, to assess the feasibility of any district heating network would allow for future networks to be assessed.
The aim of this work was to build a simple model for district heating feasibility, that could be operated by a non-technical user for multiple locations in the UK. The model was split into six stages, which were represented by the six experimental chapters in this thesis. The six stages were initial heat mapping; a quantification of both the waste heat available before and after recovery; modelling of the heat demand in the local area; optimisation of the network using thermal energy storage; and economic and environmental assessments of the network. To evaluate the success of the model each stage needed to be assessed. The assessment considered the accuracy of the methodology, the ability of a non technical user to operate the model, and the applicability of using the same model in different locations. The model was used to assess the feasibility of a possible new district heating network based in Darley Dale, England, using HJ Enthoven as a case study.
The heat mapping, heat demand modelling, and optimisation stages of the overall feasibility model were shown to be both accurate and simple enough for a non-technical individual to use. A heat mapping methodology was generated that showed a 14% correlation to the UK combined heat and power development map. A heat demand model was created based on industrial regression-based archetype techniques. Monte Carlo simulations were used to assess the sensitivity of the heat demand model. Based on the results of the simulations, the data collection process was modified to manually measure building sizes. A district heating optimisation model was generated based on mixed integer linear programming models for optimisation, that were found in a variety of journal papers. The optimisation process was used to develop standard rules that could be applied to multiple district heating networks. It was shown that the generic models for the quantification of the waste heat available from the industrial source and the waste heat recovery were more complicated than a non-technical user would be capable of using. The quantification model was changed to be based on an assessment from the involved industrial partners and the waste heat recovery model was changed to be based around an assumption of 60% efficient recovery.
It was shown that only minor modifications of a variable maximum distance between the heat source and customers were needed to be made to the feasibility model to allow the same methodology to be used in different locations. The heat demand model was changed by not counting domestic buildings in the data collection stage of the model in rural locations.
The case study district heating network was shown to be profitable, with a net present value of £3.13 million after a 40 year lifespan. The network was shown to be environmentally better than natural gas heating, saving 19,300 tonnes CO2e per annum. The heat demand variation of the network was 2.63 – 8.99 MW, which was supplied by 0.228 – 3.29 MW of industrial waste heat. The heat supply and demand were balanced using the thermal inertia of the pipe network of the network as thermal energy storage and a gas burner.