Agri-renewables strategy for Scotland

Chapter 4

Opportunities and Technologies

4.1 The installation of renewable technologies offers land-based industries an opportunity to cut energy costs and generate new income whilst contributing to Scotland's low carbon future. Scotland has established itself as a net exporter of electricity for the past decade and has the potential to export even more clean, green energy.

4.2 Energy is a high value product and its generation may help to smooth the financial volatility of the traditional farming business cycle. Reducing the dependency of farms on fossil fuel derived inputs by investing in energy saving and generating systems can make businesses more resilient to changes in external factors.

4.3 As well as improving the resource efficiency of the farming industry, it can also provide supply chain and marketing opportunities and contribute to delivering the aims of Scotland's Food and Drink Policy. Many produce buyers are now asking farmers and growers to demonstrate their green credentials. There are environmental and reputational advantages to reducing energy consumption and using renewables to reduce carbon footprints.

4.4 The uptake of renewables within farming and rural businesses should not stop at the farm gate. Collaboration between agri-businesses and communities makes economic as well as social sense. It can give the whole community a stake in the success of a renewable project and can help to build community wide resilience which will support long term sustainability of our rural and island communities.

4.5 Agri-renewables covers a range of technologies which can be used to fit the specific energy needs and availability of resources on farms, crofts and estates. Scotland is the windiest country in Europe and onshore wind turbines now generate a significant proportion of Scotland's electricity needs. However, there are substantial opportunities offered by other energy generation sources which are suitable at both farm and community level.

Renewable Electricity

• Solar photovoltaic ( PV) systems use silicon semi-conductors to convert energy from the sun into electricity. Solar PV panels can make good use of existing farm roofs, so no additional space is needed to site equipment.
• Hydropower schemes harness the energy from flowing water using a turbine or generator. Key factors affecting viability are the fall distance of the water, the head, and the flow rate of the water course.
• Wind power can be harnessed by the installation of a wind turbine or turbines that will generate a clean and renewable source of electricity to be used either on-farm or sold to the Grid.

Renewable Heat

• Solar panels for heating and hot water use different technology to solar PV. These systems rely on the heat in sunlight to warm water in special panels or tubes. The system consists of a roof mounted collector plate, a hot water storage tank and a pumped circulation system. The most common type of collector units are either a flat plate or evacuated tube design.
• Biomass boilers use either woodfuel or straw to generate heat, which can be used for almost any heating need on the farm. Available systems include domestic log burning stoves and stoves with back-boilers to much larger pellet or woodchip burners that can provide space and water heating for larger farm buildings.
• Heat pumps are heating mechanisms that can acquire low temperature heat and upgrade it to a higher, more useful, temperature by using a simple refrigeration process. The low temperature heat can come from many sources including soil, water or outside air.

District Heating

• District heating is the supply of heat by hot water to a number of buildings through a heat network of underground pipes. It is an effective way of reducing the carbon intensity of heat and reducing fuel costs.
• A heat network can use heat from a range of renewable sources including biomass, heat pumps and solar thermal. A growing number of farms and estates have woodfuelled heat networks supplying steadings, offices, cottages and agricultural buildings.

Biogas

• Anaerobic digestion produces biogas which can be burned to create electricity and heat or can be processed to produce bio-methane which can be injected directly into the gas network. Anaerobic digestion also produces a rich bio-fertiliser known as digestate, which is high in valuable nutrients such as nitrogen and phosphorus which are beneficial for healthy plant growth and fertile soil.

Fuel Cells

• Fuel cells offer the potential to be used in conjunction with many energy technologies to deliver additional efficiency and power recovery.

Skills and Advice: Woodfuel Scotland

The use of woodfuel to produce energy is growing rapidly across Scotland, as people realise the financial and environmental benefits of this natural fuel source. Woodfuel is most cost effective and low carbon when sourced and supplied locally, it is particularly beneficial in off-gas grid areas and where end users have access to their own supply of wood.

Forestry Commission Scotland provides advice and guidance on woodfuel via the Use Woodfuel website. This includes information for those who are interested in using wood as a source of energy, as well as for those who are interested in becoming woodfuel suppliers.

Specific guidance aimed at farmers and estate owners thinking of utilising their own woodlands for woodfuel is available, as well as case studies on farm woodlands.
A Business Guide for Cooperative Working in the Woodfuel Supply Chain provides step by step information on collaboration for mutual benefit.

Regional woodfuel forums also exist across Scotland, providing a valuable opportunity for networking between local woodfuel users and suppliers. Groups are active in the Borders, Dumfries and Galloway, Grampian, East of Scotland, Ayrshire, Central Scotland, Highlands and Islands and Argyll.

Informative wood fuel events designed to encourage the expansion of the woodfuel industry, organised by both Forestry Commission Scotland and other external agencies are held at national and international levels.

Biomass Case Study: Henderston Farms

Farm: Henderston Farms is a 600 acre mixed arable, sheep and cattle farm with around 500 acres of forestry, located near Dundee.

Installation: The 50 kW woodchip ETA boiler was installed in July 2012. The boiler heats a five bedroom farmhouse and also provides hot water, at 60°C, to the barn. The system includes a 1000 litre Akvaterm accumulator tank to assist with efficient running of the boiler and heating system, as well as a 300 litre pressured water store for the barn.

Fuel source: Around 31 tonnes of sub-30% moisture woodchip are required per year. For the first year, chip has been bought in from various local suppliers, at around £110 per tonne. As the farm has its own woodlands, the intention is to self-supply in the future. It is expected that the self-supplied chip will be approximately half the cost of bought in chip.

Costs and savings: The total installed cost of the boiler, including the building work needed, was around £50,000. It is expected that annual Renewable Heat Incentive ( RHI) payments will be in the region of £5,000. The farmhouse was previously not heated to a comfortable level due to the cost of running the oil and electric storage heating systems that were in place. It is therefore difficult to assess the exact fuel bill savings the boiler will deliver at Henderston Farms, but it is thought to be around £2,000 a year. There is a small labour cost associated with the management and maintenance of the system, for filling the hopper and emptying the ash, plus the cost of the annual service.

With thanks to Andrew McCall, Henderston Farms.