Rainwater harvesting and energy efficiency on Cheshire dairy farmTuesday 31 July 2012
An erroneous water bill from a leak in a pipe led to Cheshire dairy farmer John Allwood deciding to invest in rainwater harvesting.
In 2001 host farmer John received a water meter reading and bill of £3.5K for a water trough that had been shut off. It transpired after much investigation that there had been a leak in the pipe work. After discussion the issue had been resolved, however after the reality of how much could be spent on water, John thought seriously about ways to harvest water and cut costs.
350 herd size
Indoor housed with only in-calf cows out to grass
Three times a day milking; 5am/1.30am/8.30pm
Three full-time staff, one part time, night milkers
3.6 million litres per year
In 2002 an 18,000 gallon tank was installed and buried under a shed that was being built; the shed was built for stables as a livery diversification project. The roof space of this shed and others, with a total of over 1,500 square metres, collects the rainwater through a network of pipe work.
One of the biggest cost in the rainwater harvesting investment was the piping and down pipes. In heavy rain the tank will take four hours to fill and has a 48-hour through put of water. It takes 8p of electric per hour to pump water out of this tank through the farm’s 50mm main which supplies all fields and cow buildings.
In 2005 the purchased water bill was rising to around £12,000, which is when John decided on investing in a bore hole. The investment took one year to pay back. It is 62 metres deep, of which 30 meters is into sandstone. There is a pipe from the bore hole to the underground rain water tank, which the bore hole supplies the tank when there are lower levels of rainwater.
There is a float valve which will shut when the tank is full. The bore hole fills the tank which is topped up with rainwater. There is cost of 10p per hour to extract borehole water, usually working about 75% of the day. However in the last 11 months the herd size and a management change to a three-times-a-day milking there is a further increase in demand for water. The farm spend on water is now £3,500 per year.
Management of the rainwater harvesting system is minimal, however regular cleaning of gutters is required. At Huntington Hall there aren't any trees close to the cattle buildings so less clogging of gutters, no leaves in guttering, but birds can be a problem.
As a back-up system to the rainwater harvesting and bore hole, mains water is still plumbed into the farm
Resourceful use of water
The water is used three times; two reserve tanks (5,000 litres) fed by the large water tank feed water to the plate cooling system, fed back to a 10,000 litre tank which then is used for volume washing, this water is then used in the flood wash system.
The ice builder compressors are used between 12am-8am on off peak electricity to build the ice as cheaply as possible
The Ice cooler is 150Kw in size, and is only capable of making enough ice for one milking. This is used for cooling the milk in the afternoon as it would use peak rate electricity if no ice was available.
The Heat exchanger system recovers enough heat out of the milk tank’s compressors to heat water (1000L) to 46 degrees which is then used to supply the boiler for the parlour wash cycle.
Around 185,000KW used per year for the farm. That equates to an electricity cost, on average, to around 0.58ppl
The event, organised by Lesley Innes at Reaseheath College for the Livestock Programme, also saw ADAS water specialist Martyn Silgram give a talk on alternative water sources, the saem talk he gave in Cumbria and Lancashire earlier in the year, talking about ram pumps, solar pv pumps, rainwater harvesting and other alternative sources of natural water and the cheaper costs involved compared to mains.