On Your Farm

“Harvesting renewable energy – by capturing it from the sun through plants, harnessing wind and water, or digesting waste and agricultural by-products to produce biogas, are all viable economic opportunities for farmers and landowners”.
Nick Cooper - Rural Development Service 2007

Farming and rural land management have huge potential for adopting new practices to help tackle climate change in the UK by reducing green house gas emissions, and by using sustainable energy technology. These new practices will also help maintain, and in many cases, improve the rural economy by stimulating and diversifying local industry, developing a marketable green image for rural services, whilst lowering energy bills and boosting rural employment.

This section aims to provide links to easily digestible, up to date, practical information to help farmers and landowners identify the scope for energy savings as well as the use of renewables in their operations, or as a possible means of diversifying.

Farming and climate change

Farming contributes 7% of the UK’s Green House Gas (GHG) emissions, that contribute to global climate change. This includes around 39% of methane emissions, 67% of nitrous oxide emissions and 1% of carbon dioxide emissions. Although they are much smaller in absolute quantity, the methane and nitrous oxide emissions are important as they are more potent greenhouse gases:

Methane has around 20 times the greenhouse effect of carbon dioxide and is released by natural livestock emissions and manure.
Nitrous oxide has around 310 times the greenhouse effect of carbon dioxide and is released from the production and use of fertiliser (including from muck-spreading) and soil disturbance.
Carbon dioxide is released by burning fossil fuels (e.g. fuel in tractors, farm vehicles, machinery and the production of agricultural chemicals), changes in land use and land management.The Carbon Trust estimates that energy savings of up to 20% across the sector are possible totalling over £40 million each year.

Energy Efficiency – the first step towards sustainable energy use

Saving energy:

Is the simplest way to increase profits without having to increase sales
Results in more accurate control of environmental conditions for production which in turn helps to improve the quality of the produce.
Helps reduce your carbon footprint, which is now a key marketing tool for any business.

For help and advice on all aspects of energy saving for your business, visit the Carbon Trust website or NFU members can contact the NFU Energy Service

How will climate change affect you?

As its name suggests, climate change will affect growing seasons and the range of crops suitable for cultivation in the UK. Although some scientists suggest that there might be a small net benefit to UK farmers by expanding the range of crops that can be grown, there are also likely to be increased losses due to storm damage (especially of cereals), flooding – as occurred in the Severn Valley in summer 2007 – and periodic droughts. Although it may seem counter-intuitive to be threatened by both drought and flood, changing weather patterns are leading to more intense depressions and prolonged periods of high pressure, while warming seas are causing rainfall associated with the depressions to be more intense. This will require careful crop selection, as well as additional infrastructure in terms of drainage (and the occasional loss of water meadows to flooding).

Farming Futures is a collaboration project between the National Farmers Union, Country Land and Business Association and the Applied Research Forum (representing the agricultural and horticultural levy boards). The project is coordinated by Forum for the Future and funded by Defra's Climate Challenge Fund. Its website aims to provide information on the challenges and opportunities of climate change, as well as suggested adaptations and mitigation measures which farmers could start considering. The site includes latest news; sector specific fact sheets about climate change and its impacts; events; case studies and other useful links. Visit www.farmingfutures.org.uk

Renewable Energy Technologies

There are a variety of renewable energy technologies that can be suitable for farming and rural land management situations. Click on the following links for detailed information about each technology.

Wind

Many farms have the potential to install a small wind turbine that can help meet the immediate demand and occasionally export surplus electricity to the national grid. Small scale wind turbines, typically up to around 6kW peak, can often be located close to farm buildings, and should be relatively straightforward in terms of connections and gaining planning permission. Careful positioning is important, to ensure the best use of prevailing winds and to avoid losses due to turbulence created by buildings or trees. Tenant farmers may be able to install their own turbine with the permission of the landowner.

Larger turbines are generally not owned by farmers themselves, but placed on land for which the landowner collects a rent; this may be related to the output of the turbine or a fixed annual payment for use of the land and associated access. Planning constraints tend to limit the selection of sites more than the availability of an adequate wind resource; the process can be slow and kit is recommended that bodies such as the British Wind Energy Association (BWEA) are consulted at an early stage.

Useful links:

Solar water heating

Many farms have a significant demand for hot water, typically for uses such as a milking parlour or in an associated bed and breakfast operation. Solar hot water can be cost effective where there is a regular demand for warm water, and can be used to preheat water in conjunction with a more conventional border.

Useful links:

Solar Photovoltaics (PV)

The most common use for solar electricity is to keep batteries charged for small applications such as electric fencing. A small solar panel will reduce the need for frequent swapping of batteries for recharging, and is an ideal application where low voltage supplies are needed away from existing electrical connections.

Larger scale photovoltaic arrays can also be mounted on the roofs of farm buildings, provided they are aligned between SE and SW. These are not currently cost-effective where the buildings are already connected (or near) to the mains electric supply.

Useful links:

Small Hydro

Small-scale hydro, generally of up to 25kW output, is often one of the most cost-effective measures for consideration on farms. Usually constructed as a run of river scheme, or through the refurbishment of an old mill stream, no significant water storage is required. A low head (height from which the water will drop) – as little as 2m – is sufficient, and there are a variety of technologies available based on the flow rate and head.

Useful links:

Biomass

Biomass is the term used for any crop grown for use as a solid fuel (biofuel is used for liquid fuels). The crop can be specifically grown for energy, or it can be a by-product of other crops, such as straw. The biomass itself can be subject to relatively little processing (such as logs which will simply need chopping to a consistent size), or processed on or offsite through baling or chipping. Waste wood can also be included as biomass.

Wood chips can be produced from a range of clean wood sources, including waste wood, forestry thinnings and biomass crops such as willow or poplar, which may be grown in coppices on a short rotation cycle. Wood chips can then usually be fed automatically into a boiler from a hopper, making them suitable for use with modern central heating systems.

Low grade grain can also be used in automated boiler systems, although there is also a potential demand for the grain to be sold for conversion into bioethanol for use as a road fuel.

Special boilers can be purchased that can handle straw bales. This is an economical and readily available fuel source, and some boiler models are suitable for use in smoke control areas.

Finally, biomass combined heat and power (CHP) units are a particularly efficient way of providing electricity when there is also a long season demand for heat. These can be especially cost-effective where there are intensive poultry or pig units, or heated greenhouses.

Useful links:

Heat pumps

Heat pumps work by using a typical refrigeration cycle to absorb solar heat captured by the ground or a water source, and then raising the refrigerant temperature to a level suitable for heating purposes. A heat exchanger extracts the heat from the refrigerant for use in room or water heating. Heat pumps supply more energy than they consume because they can extract up to 75% of the heating energy they produce from the environment. The only running cost is the electrical energy needed to drive the compressor. Typically, heat pump systems achieve overall efficiencies of between 200-400 per cent depending on operating conditions.

Ground source heat pumps (GSHP) – a pipe is buried underground in a trench or in a vertical well and water is pumped through it and heated by the underground energy. In the UK, solar radiation keeps the ground at a stable temperature of 11-12ºC.

Water source heat pumps (WSHP) – a pipe is sunk below surface water level and water is pumped through it and heated by the solar energy stored in the water source. A typical water source might be a lake, flowing water or a deep well.

In rural environments, ground source or water source heat pumps are most cost-effective where high levels of building insulation have been achieved and where mains gas is unavailable, or costly to supply.

Useful links:

Biogas

“Using anaerobic digestion from manure, slurry and food waste to create methane as a source of bio-energy. The potential role of anaerobic digestion in agriculture is vast, and includes the production of biogas for fuelling vehicles and producing heat and electricity, and the production of a more stable digestate ideal for sustainable use as an organic fertilizer or compost”.
John Gilliand CoChair of the Rural Climate Change Forum RCCF

Slurry, green waste or waste food can all be used to create biogas in an anaerobic digester. These are typically a large sealed vat that contains bacteria that digest the materials in the absence of air (ie without oxygen) to create biogas, which is a mix of methane and carbon dioxide. The methane can then be used to heat water or generate electricity, ideally through a small combined heat and power (CHP) unit. Pioneered in countries such as Denmark, anaerobic digesters are now increasingly being used in the UK as they also reduce the risk of environmental problems from the runoff from slurry, especially in pig farming. The solid matter remaining after digestion than then be used on farms as a fertiliser, creating a beneficial closed loop.

Useful links:

Other bio energy opportunities

A key contribution from agriculture to tackling climate change will be through bio energy to replace fossil fuels and growing crops to replace fossil fuel feedstocks in other products. Crops currently being grown commercially in the UK for subsequent conversion to liquid biofuels include oilseed rape, sugar beet and wheat. Other crops potentially include potatoes, a number of other roots and grasses. Further information and contacts are available for farmers on non-food and energy crops from the following links. Defra supports the growing of these crops through the Energy Crops Scheme.

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