Broom House Farm Furnace, Oakerthorpe, DE55 7LL
To reclaim the excess heat from the Anaerobic Digester Engine, heat blown to atmosphere as waste from the engine exhaust and engine cooling system.
With consultation with the client, Mr Easom and Digester Technical Manager, the brief was to reclaim the energy which was predicted as up to 170 kilowatts per hour, to be captured into a 27000 litre buffer vessel.
The early idea was to create a space heating system for the farm workshop & calf nursery.
This involved capturing the energy from the engine header of the bio digester, which allowed collection of the engine heat from the digester bacteria beds and biogas boilers for system back up, should the engine fail or too much bio gas is produced from the digesters for the engine to cope with. The surplus heat is blown out to atmosphere as waste.
The heat reclaimed from the header via hydraulic separation via a plate heat exchanger and heat meter, (for reclaimed energy measurement) is collected into a 2700 litre buffer vessel, then distributed to the workshop and nursery via unit heaters. The success of the energy capture proved to improve the development of the calves and the workshop became warm. However it was clear that the energy harnessed for reuse on the dairy process was in fact only a fraction of the energy available. Further discussions with the client, concluded that further energy capture could be made and more processes on the farm would benefit from the energy surplus.
To create a constant temperature drinking water system for the dairy herd, using the energy from the 2700 litre buffer vessel and via a plate heat exchanger, the incoming mains cold water passes through the heat exchanger and via an electronic mixer delivers 26 degrees of drinking water to the dairy herd drinking troughs.
This in itself delivered the most interesting results, Increased Milk Yield and Healthier Cows in both physical appearance and general health.
The measured daily consumption of water showed the consistency of the cow’s water consumption.
At this stage the energy available approached double that was previously assumed by the engine provider, this was increased by modifying the prevention of reverse circulation in the bio gas boilers when static and the electronic mixing of the heating to the digester beds. This allowed for further adaptions –
- Heating to the milking parlour, via unit heaters
- Replacement of the diesel heater for milking parlour wash down system (displacing the diesel fuel and carbon value).
- Heating and hot water to site toilet and wash room (displacing the electric heating and hot water system).
- Farm vehicle washing facility.
The system has been in operation for 12 months and with this testing period the findings have been
- A capture of energy of 1.2 million kilowatt hours which would have been pushed to atmosphere.
- A Dynamic change to the health and welfare of both the dairy herd and the staff of this busy diary.
- A rise in milk production from the same number of cows has been recorded by the milk marketing board.
The impact of this process and modern farming instincts of the Easom family have created a truly sustainable cycle.
- The slurry is harvested for the digesters
- The biogas via the engine produces energy as electricity to the main grid
- The heat energy from the engine is reclaimed and recycled into the farm process
This is sustainable renewable energy in reality, given that the average 100 metre square house in the UK will use 24000 kilowatt hours for heating and hot water, this capture of otherwise lost energy asks the question of what are the potential possibilities for reclaimed energy sources in the UK commercial sector.