On the Farm
Energy Independence and Feed-In Tariffs
  
Over last weekend we installed a 10kw solar PV system on the roof of our dairy.

I have been thinking about moving the farm towards energy self-sufficiency for several years, but until now the only progress we had made was to install a ground source heat pump, as the main source of heat for our farm-house.

When a neighbour of mine, Peter Segger, installed a solar PV unit about a year ago, I started investigating options for the farm more seriously. I met with Howard Johns, founder of Southern Solar, to assess our requirements.

Unfortunately, the farm is at the end of a rather spindly single-phase supply line, limiting the amount of power we can put back into the grid. We were advised that 10 KW would be the absolute maximum we could install. This is a shame, since our roof is south facing and could have accommodated at least 20KW of panels, and next door the livestock building has an enormous roof, so the potential would have been even greater.

We didn't have any cash, so in order to go ahead we have had to borrow all the money for these units, which we should be able to pay off in around 7 years.

The fact that all this had to happen in the last two weeks was, of course triggered by the Government announcement that the feed-in tariff rates for renewable energy will be halved after 12 December. I was on the farm when I heard and called Southern Solar to ask if they could install our unit before the deadline. Thankfully they could, so we count ourselves lucky, since if I understand it correctly, we will receive a guaranteed payment of 37.5 pence per kilowatt of electricity generated. Plus any electricity that we use, up to the total amount generated by the unit, will be free.

Considering the recent controversy around tariff rates, it occurs to me that by introducing attractive feed-in tariffs for small-scale producers the government created an unusual situation where early adopters are receiving a higher financial reward for their efforts than the big guys.

As far as I can calculate, even at the new rates, which I think have dropped to just over 20p a kilowatt, there will still be a strong financial and environmental incentive for continuing to invest in renewable energy at a farm and household level.

Nevertheless it seems a huge shame that the government is acting in this way, since psychologically many people who would have installed PV now won’t, causing huge collateral damage to the emergent UK renewables industry.

My sights are now focused on retrofitting our slurry system with an anaerobic digester (AD), to convert the methane, bubbling away on the surface of our lagoon, into electricity and hot water. If we get this organised, plus install a wind turbine, then the farm should be carbon neutral - i.e. largely self sufficient in renewable energy and conceivably a net exporter of electricity into the grid.  

As I have said before, if we think of the farm as a 'cell' in the larger body of sustainable food and energy systems, then by testing the right solutions at a micro level, we find potentially scalable answers.  Thinking like this also brings the additional benefit of perspective. If we can relate to what we are doing at home then it becomes much easier to understand what is needed in the wider world.

Albert Strauss' slurry pits

I recently visited Albert Strauss of Straus Family Creamery in California. One of his most impressive achievements was that he has succeeded in harvesting the methane from his slurry pits, by covering them with a weighted tarpaulin, trapping the gas, and piping it into a stationary engine with a generator to produce electricity and hot water. As you can see from my picture, the unit was generating 61 kilowatts when I was there, and this, combined with the output from a solar pv unit, is moving him well on the way towards energy self sufficiency. 

Generator Readout

As far as I can see, there is no reason why we shouldn't do this at our farm. We will have to work out the logistics of emptying our slurry lagoon when it has a tarpaulin stretched across it, plus we will have to decide whether we need to put our slurry through a separator to screen out the dry matter. Oh yes, then there is also the small matter of the capital cost, but according to Albert, the investment can pay off quite quickly and I'm hoping there may still be grants available to contribute!


Patrick