Saturday, 21 May 2011

Photovoltaic Energy Neutral Grass Based Dairy Farms

Two grass based dairy farmers in the Pasture to Profit Network(one in Herefordshire & the other in Brittany, France) have or are about to achieve “Energy Neutral” status (with regard to electricity use on farm). Both have installed solar panels on their farm shed roofs.
Energy neutral status is where 100% of the energy that is consumed is actually generated by the farmer user. To become self sufficient or completely clear of the National Grid should be the goal of every farmer. Ideally the dairy industry should be able to produce its own electricity. Now the goal changes to “Energy Neutral chain of production with 100% of the energy that is consumed by the different links in the chain must be generated within the chain itself.” Dairy farmers will become the key players as they have the ability to generate energy from solar & wind turbines. In the Netherlands there is a National goal of 20% of the energy use being sustainable energy by 2020. Currently it is approx 3.5%. The farmers in the Netherlands are at about 8% sustainable energy.
Matthew in Herefordshire & his landlord have recently installed (2nd May) Photovoltaic panels capable of 48Kw peak system. There are 230 panels each of 212w. These are on south facing roofs. The photovoltaic system has an expected 25 yr life with a small reduction in efficiency over that time. To date he has generated more electricity than he has consumed at the milking parlour. (2534kwh produced & 2304kwh consumed).There is a long term guaranteed contract for the feed in tariff currently approx 32p/kwh which is inflation indexed. His current cost of National grid electricity is 10.86/day & 6.22/night. There is an approx 10 year payback on current prices but rapid inflation of energy prices should substantially reduce the payback period.
However I think the key component of Matthew’s system is the Smart Meter which measures & allows monitoring of power consumption. This was installed 3 yrs ago by his power provider.
By checking his electricity consumption online he can view his daily, weekly, monthly use patterns. “Merely measuring something has an uncanny tendency to improve it” Paul Graham. What Matthew has discovered is that although he is generating more than he is consuming he is NOT completely clear of the grid. The reason is that dairy farms have two peak consumption periods each day. These peaks are currently beyond the generating capacity of the solar panels. The next obvious step is to look at reducing peak demand.

Alain & Odile, pasture based dairy farmers in Brittany have also installed a photovoltaic system. Their system is calculated to annually generate approx 56,010kwh whereas the annual consumption is approx 30,000kwh. Current charges are 8.4cEuro/day & 5.45cEuro/night with a Feed in Tariff of 60cEuro for 20 years. In France interest is chargeable on the loans for these systems whereas in the UK there are interest free options. The calculations for Alain & Odile’s installation suggest that during the summer months the photovoltaics will generate far more electricity than is consumed but that could be reversed during winter. The payback period is calculated at 12 years on current prices not counting the saved National grid costs. It looks a very good investment for a dairy farmer to make.
The challenge on both farms will be to reduce peak daily demand during each milking.

I urge every dairy farmer to install a Smart Meter so that you can come to grips with your energy useage patterns.
The onfarm initiatives & innovation of both these farmers is very exciting & I congratulate you both.

Current UK Pasture Measurements
The Welcome Rain of last week now seems a distant memory as this week has seen no rain but drying winds. Most grass based dairy farms are drying out at an alarming rate. However the current pasture covers remain under control with longer than normal grazing rotations. There is serious concern about crops sown for outwintering & spring sown pastures.
Average Pasture Cover (kgsDM/ha) & Pasture Growth (kgsDM/ha/day)

South Ayrshire, AFC 2347, pasture growth rate 88kgs/ha/day

Derbyshire, 2220, growth 65, demand 64

Shropshire, 2269, growth 44, slowed this week cold winds no rain

Shropshire, 2300, 44, 26 day grazing comfortable despite dryness

Herefordshire, Growth 52, demand 47, Farm very dry again

Dorset, 2321, growth 56, demand 36

Devon, 2200, growth 40, 30day rotation feeding silage

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