How does green farming work on a modern productive dairy farm and what does it really mean?
Being green can mean many things but to me it is about using resourses efficiently and not wasting anything. This can be seen in many places on many farms. Take for example feeding the cows.
There are many ways to feed cows but I have choosen the grazing system for the cows as it suits how I like to farm and is a cheap and efficient way of producing milk.
For much of the year the cows are outdoors grazing grass. During this time we do not have to feed silage, clean them out or bed them down. This has large savings in labour, materials, electricity, diesel and machinery. The longer the cows are outside grazing the less resourses they use. Conversely when the cows are indoors they have to be fed silage which is harvested in the summer, ensiled then fed out during the winter and they also need to be cleaned out and bedded down. This all requires labour, power and machinery.
The rotational grazing system has allowed me to keep the cows outside for longer periods and make large savings in both cash and carbon terms.
The compressor is an electrical pump which uses the air, to both heat the water for washing the plant and create ice for cooling the milk. It has three main jobs.
It takes the heat from the milk and allows it to cool down.
It uses the heat from the milk to warm water which we use for washing the plant with. It can warm the water to over 55c.
The compressor also runs at night using cheap, surplus electricity from the grid creating ice. This is stored in an insulated tank called an ice bank.
This compressor is only designed to do part of the cooling of the milk. Just using compressors to cool the milk during milking would requires a huge amount of power and cost.
The ice bank
This is simply a huge insulated store that holds ice that is produced by the compressor at night. During milking, well water is run through pipes in this tank and pumped to the plate cooler where it helps to pre cool the milk.
The plate cooler
This is effectively a double skinned radiator.
During milking the milk is pumped from the parlour through this unit to the bulk tank. At the same time ice cold water is pumped from the well, through the ice bank and through the plate cooler to cool the milk.
The double skin allows the ice water to take the heat from the milk without mixing with the milk.
The combined effect of the ice bank and well water is to reduce the temperature of the milk from above 30c from the cow to below 9c when it goes into the tank.
The cows produce over 6000 litres of milk daily which has to be cooled and stored below 4.5 c.
By using the ice bank and plate cooler we are able to reduce our electrity consumtion and cost considerably.
The Bulk Tank
The final part of the cooling process finishes here with the milk arriving at around 9c. The compressor finishes the cooling, pushing refrigerant around the skin of the tank taking the temperature of the milk down to 4.5c. The milk is stored here until the tanker collects the milk every morning and takes it to be pasturised and bottled.
This old bulk milk tank came from a friend who gave up dairy farming a few years ago. We have used the tank to store the water that runs through the plate cooler. By the end of each milking there is enough water in the tank to wash the floors of the parlour with.
A 50KW system was installed at the farm in 2012. It produces roughly half of the 90,000 Kilowatt electricty requirement of the farm.
As we can produce power in the day time it makes sense to use as much of of it as possible during daylight hours. So for much of the year we run the compresoor and water heater during the daytime to match the power that it produces with our consumption. Any electric that we do not use is exported to the national grid.
During the dark months of the winter the production of power from the panels falls dramatically. At this point it is more economic to run the water heater and ice bank at night using cheaper electricity from the grid.
Green farming does not mean that a radical organic approach needs to be taken. I try and employ a common sense approach to reducing waste and combining knowledge with technology can reduce our carbon footprint and the cost of producing milk. Whether you believe in global warming or not, reducing energy costs and consumption makes good business sense and reduces our exposure to energy prices.