Farm Diversification

Game Farm, located at Singleton, Poulton-le Fylde, extends to 120 ha of lowland grass and is home to the 300 cow Avenham Holstein herd. James Rogerson has been milking the pedigree herd three times a day since 1982 and average yield is an impressive 11,500 litres. With a large volume of milk to cool and the hot water required for plant and tank washing, calf feeding and steam cleaning electricity costs were considerable.

Why install renewable energy?
Milk from Game farm is sold to Arla Foods. When Arla raised the issue of improving its green strategy and that of its suppliers James was keen to participate. A desire to help his customer achieve their objective of reducing consumption of energy and water across their supply chain was the initial driving force that led James to investigate heat recovery in the dairy.

How did you identify the type and scale of renewables project?
The layout of the dairy equipment at Game Farm could easily accommodate a heat recovery system so James did some calculations and estimated that the installation would pay for itself in three to four years. This rate of return seemed like a worthwhile investment so James decided to go ahead.

Researching the idea
Heat removed from milk during the cooling process is normally expelled from the condenser of the refrigeration plant. This heat is discharged to atmosphere or effectively wasted. At the same time a source of heat, normally electricity is used to heat water for use in the dairy. Heat recovery units work by utilising some of the heat discharged by the refrigeration plant to pre-heat water. Two types of heat recovery unit (HRU) are available. Flow based HRUs work very much as a plate cooler works. A flow of water passing over the hot refrigerant pipes recovers heat. This type only works if the water is flowing at the same time as the compressor unit is running. In a storage based HRU a heat exchanger is incorporated into an insulated water storage tank. Heat from the refrigeration gases passes to the water within the tank. Remaining heat in the gases is discharged to atmosphere in the normal way. Pre-heated water from the tank passes to the water heater reducing the amount of energy required to bring it to the required temperature.
 
James opted for a storage HRU and chose a “Fre-Heater” manufactured by Mueller. It consists of a heavy duty glass lined inner vessel surrounded by a stainless steel heat transfer surface covered with two inches of foam insulation and housed in a stainless steel outer vessel.

System Establishment
The system at Game Farm was installed by G.D. & M. Dunglinson and cost less than £4000. It has 450 litres of storage capacity and it can reclaim up to 60% of the heat which otherwise would be lost.

Problems encountered
The installation has been problem free to date. Efficiency of the heat transfer is best when the tank is replenished with cold water at the start of milking. When demand for hot water has been low sometimes some of the hot water is drained off.

Critical Success Factors
Critical success factors for the Game Farm project include:

• Water temperature similar to domestic hot water is achieved in tank and boost heating is only required when above average amounts of pressure washing has been carried out.
• An additional hot wash of the dairy plant is now carried out because of the plentiful supply of hot water. The plant is much easier to keep clean.
• Water heating costs are greatly reduced.
• Milk cooling times have fallen by an hour a day leading to a further energy saving.
• A plentiful supply of hot water is available for calf feeding.
• James now anticipates a shorter payback time than originally estimated. In the order of two years.