Energy efficiency top priority for dairy sheds

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Robin McNeil of Venture Southland

By Peter Owens

According to Robin McNeil of Venture Southland, the annual energy use in a typical Southland dairy farm milking shed is around 100,000kWh, or 160kWh for each cow and peak electrical load for a typical dairy shed is currently around 50 kW (plus 2,000kWh per hectare per year for land that is irrigated).

This works out that with a 50 bale rotary shed and milking 700 cows, electricity costs about $15,000 per year. The size of southern herds is increasing but energy costs are escalating rapidly. This is causing considerable concern and at the recent Southland Energy Conference in Invercargill, Mr McNeill facilitated a session on efficient use of energy in the dairy shed.

The conference was attended by more than 150 people, including architects, engineers, builders, property developers, home owners, dairy farmers, council staff and councillors.

It became clear from the session that there were many limitations to retrofitting an existing dairy shed for energy efficiency that would not be present in the building of a new shed.

The session was asked to offer ways in which the most energy efficient dairy shed could be established. Suitable supply and quantity of water with provision for the catchment and storage of rain water were considered to be very important matters to be decided before siting a dairy shed.

It should also have easy access to electricity and be reasonably accessible for heavy vehicles. However, proximity to a dwelling was not considered to be a major matter. The session was in general agreement that the shed should be designed to be functional and there should be consideration of staff needs such as shower, staff room, toilet and kitchen.

There was also substantial agreement that there should be serious consideration of effluent solutions when designing the shed and that value should be added to the effluent with bio-digesters or irrigation options.

On the actual heavy energy uses in a shed, the session was strong on serious consideration of integrated heating and cooling mechanisms before purchase and installation. At the same time it is essential to assess and quantify the actual requirements for hot water.

The session was united in insisting that in the most energy efficient dairy shed there must be open standards of technology with compatible equipment. There must also be communications between equipment and protocols must be simplified as well as the means of operating equipment.

Other matters the session suggested as being important for energy efficiency included reasonable regulation of water use and an efficient system for recycling water.

Overall, there was general agreement that there must always be an ability and willingness to monitor sheds and systems at all times. There was also widespread agreement that if the shed is to be energy efficient, the staff must know what they are doing. At the same time people who design dairy sheds must be made aware of the real problems affecting the efficient energy operation of such dairy sheds.

The session was also very strong in insisting that energy efficiency in the dairy shed is often blighted by poor power supply. This means before building a new dairy shed or installing new and expensive systems, it is essential to ensure a good source of power without fluctuations of supply and surges.

Because of the uncertainty of the quality of supply in some areas it is also essential to have a backup supply that is regularly tested.

At the same conference Mike Bourke of EECA Business said the authority was aware of the plight of the dairy farmer and in its move to make New Zealand more energy efficient under the terms of its mission statement it makes the following funding available.

EECA Business will fund up to a third of the cost of buying and installing a heat recovery system:

  • In existing sheds, EECA will cover up to 33 percent of the cost of buying and retrofitting a system
  • In new dairy sheds, EECA will cover 25 percent of the cost of buying and installing heat recovery technology
  • Upgrading to more energy efficient equipment (such as drive control systems and lighting) may also qualify for EECA funding
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