Hill of Banchory geothermal energy project: feasibility report

3. The Hill of Banchory Biomass Heat Network

Background

Banchory is a small rural town of approximately 8,000 people, located in Deeside, Aberdeenshire (Figure 4). Popular with Aberdeen commuters, the town has seen considerable expansion in recent years. Hill of Banchory is a development by North Banchory Company on the north east edge of the town, which includes residential commercial and community buildings. ^[1]

Sustainable Development

North Banchory Company ( NBC) set sustainability at the heart of Hill of Banchory. In seeking a low carbon energy solution, NBC conducted a technical options appraisal and decided to build a Biomass Energy Centre and Heat Network.

Given the abundant local forest resources, and a long tradition of forestry in Deeside, biomass was a natural choice for providing a renewable heat resource. A capacity study concluded that sufficient timber could be sourced locally without impacting supply of established industries. Woodfuel could be produced at affordable prices, and local businesses would receive a new income stream.

Figure 4: Local Wood Chips Production near Banchory

Photo: Guy Milligan

Whilst Heat Networks are not yet widely used in Scotland, particularly incorporating biomass, they are commonplace in continental Europe and are a cost-effective and energy efficient way of providing distributed energy. A Heat Network comprises a network of pre-insulated pipes which deliver heat, in the form of hot water, from the point of generation to the final customer. Networks vary in size and length, from small schemes supplying heat to 2 or 3 houses, to city-wide schemes with tens of kilometres of pipes supplying heat to entire communities and industrial areas. They are flexible in design, allowing new customers to be added simply by extending the pipework and adding new heat sources as necessary. These heat sources are diverse and can include renewable energy such as biomass, energy from waste facilities and geothermal sources.

Project Development

In order to drive forward its sustainable vision for Hill of Banchory, North Banchory Company created a new subsidiary company, Hill of Banchory ESCo (HOBESCO), tasked to design, build, own and operate the Biomass Energy Centre and Heat Network. Its primary objective was to provide the new development with affordable green heat.

The Hill of Banchory Biomass Heat Network was designed to be built to support the development as it progresses, which has required a flexible solution. The phases of project development to date are shown in Figure 5.

Figure 5: Hill of Banchory Biomass Heat Network Development to Date

The first buildings to be connected to the Heat Network in 2008 were residential properties. Heat demand from these is relatively low, particularly during the day and summer months, and could be provided from a temporary 1.1MW containerised gas boiler. As the Network was expanded to Banchory Business Park, the increased heat demand from offices and commercial enterprises and improved load balancing (day/night usage), enabled the Biomass Energy Centre to become the heat generation source. The Biomass Energy Centre was commissioned in 2012 and the temporary gas boiler was removed from service.

The Energy Centre has the capacity to provide heat to current and future development at Hill of Banchory, as shown in Figure 6. The Energy Centre is centrally located to provide heat to the development areas as detailed. In 2016 residential properties are planned to be built at the Neighbourhood Centre and at Lochside of Leys, resulting in a further 400 homes over the next 10 years. The Neighbourhood Centre will also include a leisure centre including swimming pool to be built by Aberdeenshire Council in 2016, which could be a large and important heat user, and discussions are being had about potential connection. Other potential buildings include retail and a care village for elderly people.

Figure 6: Heat Network Plan

Image: Jigsaw Energy

Biomass Energy Centre

The Biomass Energy Centre (Figure 7) comprises a primary 900kW biomass boiler and two gas back-up boilers. A second 700kW biomass boiler will be commissioned as more connections are made and heat demand increases. The biomass boilers are integrated with two 50,000 litre thermal stores (hot water tanks) to ensure efficient operation.

Biomass supplies the base load heating requirement, and will account for 70% of total heat generated when the Network is fully built out. Gas will supply the remaining 30% of total heat generated, providing a top-up to the biomass boilers in meeting peak loads, which can be more cost-effectively achieved than biomass.

By incorporating multiple boilers and fuels, the Energy Centre provides resilience in being able to continuously supply heat should plant failure occur. The Energy Centre also has space for additional boilers, or CHP, providing flexibility to allow for the evolving nature of the development.

Figure 7: Hill of Banchory Energy Centre Plant Room

Photo: Guy Milligan

The Energy Centre has generated 11,000MWh heat to date, with 90% from biomass. As a very low carbon fuel, biomass has saved 1,800 tCO ₂e compared with natural gas, making an important contribution in reducing greenhouse gas emissions to the atmosphere.

Customer Satisfaction

HOBESCO is committed to delivering excellent levels of customer service, and The Hill of Banchory Biomass Heat Network is very well supported by its existing customers.

HOBESCO recently conducted its biennial Customer Survey ^[2] in which 89% of customers stated that they were either satisfied or very satisfied with their heat supply. The majority of customers (74%) supported being part of a communal heating system, and 66% considered receiving their heat from a renewable source as being either important or very important. 54% of customers felt that the cost of their heating represented value for money. Whilst this is lower than desirable, customers' opinions are likely influenced by currently low oil and gas prices. Despite expressing some concerns on current price competitiveness, no customers have chosen to disconnect from the Heat Network.

The housebuilder, Bancon Homes, has supported the Heat Network since the first connections were made in 2008, which as a long-term investment in renewable energy has been vital. Bancon's Planning Director, Harry McNab said;

' We are very satisfied with the biomass heating system which has enabled us to provide our customers with more sustainable homes in Banchory, and with the satisfaction that their heating is produced from a local renewable energy resource. District heating integrates very easily with our homes and is simple for our customers to use. We are fully supportive of HOBESCO's Hill of Banchory Biomass Heat Network and it is our intention to connect additional new homes as part of our rolling build programme over the next 10 years. It is very interesting that geothermal energy might be added to the energy mix, which we welcome as another locally produced renewable resource.'