Guardbridge geothermal technology demonstrator project: feasibility report

5. Heat Demand Analysis

Ramboll Energy have assessed the heat demand at Guardbridge (site and town) and the nearby towns of Leuchars and Balmullo using the Scotland Heat Map and future development data provided by the University of St Andrews. This analysis leads to a preliminary network design ( Section 6) and an economic model of the potential scheme ( Section 7).

The aim of this part of the study was to prepare preliminary district heating network layouts at different scales, based on the demand analysis. These various options provide an indication of the potential annual and peak heating demands that can then be compared against the geothermal heating potential found in Section 4.

5.1 Identifying Potential Demand

The Scotland Heat Map (individual building data) was used to identify areas of heat demand in Guardbridge and the surrounding area (Table. 5.1) and the Fife Development Plan was used to predict future heat demand). From an early stage, it was seen that the only locations within an accessible distance were Guardbridge village, Balmullo and Leuchars. For this study, the town of St Andrews itself was not considered as a potential demand for the system as the closest buildings of large demand, still approximately 6 km away, are University-owned buildings that are currently undergoing connection to a large biomass district heating network. The available heat demand for the towns discussed was extracted and is summarised in Table 5.1.

Table 5.1: Heat Demands in Guardbridge and the nearby towns.

1. Guardbridge

The town of Guardbridge itself is relatively small in comparison with the other nearby areas (Table 5.1). It does, however, have the added bonus of being directly beside the proposed energy centre site and so would not need a long section of transmission pipe to be reached. There are also future commercial and residential developments planned around the town and on the former paper mill site where the University of St Andrews Guardbridge Energy Centre is situated.

2. Leuchars

Leuchars is a primarily residential area, with some local shops but no large commercial customers. There is a primary school to the north near an area of ex-council style homes that would offer an area of high heat demand density. One of the most promising aspects of the demand at Leuchars is the military base and its accommodation. This could potentially be treated as a single customer in regards to a heat supply agreement; streamlining connection negotiations and potentially providing a long term, secure source of demand in the network.

3. Balmullo

Balmullo is comprised almost entirely of residential properties in a relatively dense format which is typically good for a district heating network as it can provide high heat demand density which lowers the relative network costs. It is however, a lot further away from the proposed energy centre location, meaning a large amount of distribution pipe would be required for connection. This connection has the added hurdle of having to cross the Edinburgh to Aberdeen railway line, which can be a very expensive procedure as Network Rail have been known to charge in the region of £20,000 - £30,000 p.a. at an interest rate of RPI + 5% for permission to build across one of their lines. Despite their being a small stream and therefore bridge in place already, the works required to install DH pipe here would likely still incur these fees.

Table 5.2: Future development demand estimates.

Table 5.3: Guardbridge paper mill development proposals and estimated heat demands (provided by the University of St Andrews).

5.2 Future Developments

To maximise the heat demand included in this study and ensure that the network was not just designed for the existing demands, future residential and commercial developments were included in the analysis. There are several areas of land set aside for residential developments around both Guardbridge and Leuchars; details of these were obtained from the Fife Council website and were accurate at the date of initial analysis (August 2015). There is additional development at Guardbridge on the local development plan and this could potentially be connected in the future. The demand estimates for the residential areas were done on the assumption that an average household's heat demand would be 10,000 kWh per year (Table 5.2). The commercial and leisure space at the site of the old Paper Mill (see Fig. 5.1) was based on data obtained from the University of St Andrews (Table 5.3).

The Guardbridge site heat demands, based on the development strategies of the University of St Andrews, were estimated based on floor area and benchmarks, and more detailed analysis regarding the annual heat demand is recommended. The phasing of this demand was estimated based on the development timescale outlined in Table 5.3.

Table 5.4: Projected development of district heating customers and network expansion

Fig. 5.1: Areas of future development in Guardbridge.