Renewable energy on off-grid farms

In the autumn 2011 edition (number 116) of the Yorkshire Dales Society's publication, Yorkshire Dales Review, Dr Dorian Speakman wrote about a visit to upland farms in the Yorkshire Dales National Park to learn about how they generate renewable energy. The article is reproduced below with the permission of the Yorkshire Dales Society:

HIGH POWER

Renewable energy on off-grid farms...

Dr Dorian Speakman, formerly of the Tyndall Centre, University of Manchester, reports on a fascinating visit to some innovative green energy schemes in the Dales.

Running a farm at altitudes of over 400m (1,300ft) above sea level has its challenges - not least because of the climate. At these heights it is considerably more cloudy, cold, windy and wetter than in the dale down below. But some of these elements of the weather can be turned into an advantage. On a day hosted by the National Park and the National Trust, a tour round some upland farms above Malham demonstrated just how this can be achieved. Up at Middle House Farm, on the limestone plateau above Malham Tarn, a third new wind turbine has been installed, which has a 6kW peak capacity. Our first visit was to see this turbine in action, but actually seeing it was, interestingly enough, quite tricky, as the blades of the turbine were well blended into the scenery. Only when we got within a few hundred metres could we make out the wind turbine on a hillside below a limestone scar - on an open, treeless plateau.

The day we visited it was a breezy showery day, and the turbine was turning rapidly and producing a useful 4.5kW. This model was reportedly much quieter than its predecessor which managed a much less impressive 800 watts. From the turbine platform, the electricity wires are buried underground and lead from the exposed shelf of hillside a couple of hundred metres down to the farm. With 8000 kilo watt hours kWh (units) produced last year, it provided a saving of £2,000 for the farm. The power is fed into a bank of 48 batteries which then feed the electricity into an inverter to provide mains voltage. Much of the usage is for domestic uses such as the washing machine, and with the batteries full, there was plenty of power available when we visited. Nevertheless, with many quiet calm days these last two winters, the diesel generator has had to be brought into use to keep the house supplied. So while the wind turbine has reduced the need for the diesel generator, it has by no means eliminated its use. To reduce use of a generator further a solution might be to increase energy storage, involving a bigger bank of batteries and a control system, or another, second source of renewable energy.

Two miles away, just over the watershed at Tennant Gill, a twin renewable power solution was our next port of call. Despite the heavy rain, the solar panels installed on the roof of a barn were still producing power. Because the barn was not classed as a heritage building, there was no problem with the aesthetics and planning permission. The heavy rain encouraged us back to the farm buildings, where we could inspect a micro-hydro scheme. This runs through four pipes which force water through two turbines: with a 90m (300ft) drop from the stream, there is plenty of energy in the water. The turbines provide a 'trickle' charge of 2kW which feed into a battery bank and inverter allowing for an output of 6kW. This was demonstrated as the 18 strong party was treated to hydro-powered tea - a large tea urn was heated using power generated on the farm, that and the cakes were most welcome in an afternoon beset by squally showers.

Installing the system is not just a technical issue of a site's potential, as hurdles over planning permission and environmental impact need to be overcome as well as assessing the economic benefit from the government's feed-in tariff. The feed-in tariff is a payment made to owners of renewable power installations if they have an approved installer. The generator is paid per unit of electricity irrespective of their own usage; even off-grid installations can receive (slightly lower) payments. This year, the government is holding a review on the feed-in tariff, in which the generous allowance for solar power generation is likely to be reduced to allow for other renewable energy sources to be supported.

Incredibly, with power from both hydro-turbine and the solar panels, the diesel generator had only to be used for half an hour in total during the previous year. With these resources, serious financial and carbon savings can be made, as well as a high degree of independence for power supplies.

Thanks are extended to Adrian Shepherd of YDNPA and Richard Humpidge of the National Trust for organising this event, and to the forms for their hospitality.

About the Yorkshire Dales Society

The Yorkshire Dales Society is an independent Dales-based charity, and a not-for-profit limited company, with around 1,400 members, which was established in 1981 (registered charity No 515384).

The Society is an educational charity with its prime object being 'To advance the public knowledge and appreciation of the social history and the physical and cultural heritage of the Yorkshire Dales and to preserve its condition, landscape and natural beauty'.

For more information about the Society and to join, see their website at www.yds.org.uk.