Farming for energy – do solar and geothermal power have a place in a modern farming landscape?

On Friday I attended the Devon County Show, at Clyst St Mary outside Exeter. Now I love the Show, and try and attend as often as possible. I love the crafts, the gardening, the livestock (I have a special place in my heart for the heavy horses and the Dartmoor Grey-faced sheep), but this year I was looking for something else – I was looking for energy.


In the last 6 months I have begun to notice just how many onshore wind and solar farms there are near me and having an interest in geothermal power I wanted to see if this move into farming energy was represented at the county’s biggest exhibition of farming and rural life. What I found was pretty interesting. Energy farming was present at the show, but the largest contribution was for solar.


I spoke to one of the companies – Faltser Energy – about the use of solar by consumers in Devon. The sales representative, Greg Hockin, told me that it was a pretty mixed portfolio, especially for their company. A lot of products were for individual installations, but they also supplied to farms, most often as a supplement to activities (i.e. on a barn roof) than as a revenue generator. He also mentioned that they had developed a technique to colour the panels – something I had never seen! I understood the green or the blue, but pink solar panels?!? Seems a bit like an extreme choice for me!!


Another thing that Mr Hockin mentioned is that all the panels were made in the UK. When I questioned him further, he did clarify that by saying that many of the components would be made overseas, for instance in China, then assembled in the UK and that got me to thinking about what a solar panel is actually made from….


I’ve never really had a close look at a solar panel, but when you get near you can really see the crystalline structure of the panel itself. Solar panels are usually made with silicon crystals which provide the pretty crystalline pattern. They usually have another mineral added into the mix to make them more efficient, such as gallium arsenide, cadmium telluride or copper indium diselenide. One tricky thing with these compounds is that the source elements are all listed as under moderate to high risk on the British Geological Survey’s ‘Risk List‘, a list that calculates the risk to the supply of economically important elements. For four of the elements used, the main producer and reserve holder is China. So with China having the monopoly on these mineral’s supply and on production of many of the component parts, how much can you really say is made in Britain? And if we had to, could we make solar panels entirely from British products? Well the simple answer is probably not. Although you can find many of these elements in their mineral forms in the UK either as an ore or a byproduct of processing that ore – none of them exist in quantities large enough to mine commercially anymore – our reserves are depleted.

An ore rock of Gallium.

Gallite – an ore rock of Gallium.

So do we have another option? Well, although solar power is great, I have great faith in the future of geothermal, and at the Clean Earth stand, I met a young man, whose parents have adopted geothermal power on their farm in an interesting way. At Clean Earth, they are involved in leasing land from farmers to create energy farms – be it solar, wind or biomass. They have a number of success stories around the south west (anyone from down here may know about Crealy Adventure Park? They now have 2020 solar panels to supplement the Park’s use of energy from the National Grid), but I was most interested to hear about Mesmear Farm in Cornwall.


At Mesmear, the Roses have combined a geothermal powered heat pump with solar panels to provide heat and electricity to the farm and the rental cottages they maintain. The geothermal heat pump makes use of the farms proximity to the massive granite batholith nearby and heats water to around 50°C for space heating and hot water from a ground temperature of about 11°C.

To me this was an innovative use of combining a tried and tested (but limited) method of electricity production – the solar panels – with a new and innovative, but untested method of heat and energy production – the geothermal. The farm still draws from the National Grid, but only at times of peak requirement and it’s carbon footprint is much smaller. It makes me wonder how many farms, business and households across the South West (and in other areas where geothermal is an option) are using this low key, combined method of incorporating geothermal into their energy mix. I’d love to hear from you if you do!!

So there you have it, it’s easy to dismiss the Devon County Show as all mud and cows, but there are important things for geologists there too…. and the odd dinosaur!