Farmer turns a nasty odour into the sweet smell of success

Casestudytile SteveLepperSmellofSuccess 001 SL B 201508 Open

Managing and reducing costs is obviously a big focus for any successful business. Energy is one area where savings can often be found – and many Kiwi businesses are finding that improving their energy efficiency through fresh thinking can also provide some valuable, and unusual, extra benefits.

Farmer turns a nasty odour into the sweet smell of success [pdf 133 KB]


For Taranaki pig farmer Steve Lepper, it was all about the smell. Manure from his 400 sows and about 9,500 piglets each year, was processed in large effluent ponds and created quite a stink for the neighbours downwind.

In 2008 Steve invested in a state-of-the art biogas-producing anaerobic digester pond which converts pig poo to power, saving about $65,000 a year in energy bills and solving the problem of smells from his piggery.

Steve recouped the cost of the system within three years as well as reaping other benefits.

“The initial aim was to alleviate smells but it’s ended up producing a lot of electricity and hot water for us,” said Steve.

The project was masterminded by National Institute of Water and Atmospheric Research (NIWA) research scientist Stephan Heubeck, who had previously designed covered anaerobic piggery ponds simply to control odour.

Stephan designed a purpose-built 7,200 cubic metre digester pond with a heavy duty plastic cover to trap both the offending odour and the high energy biogas given off by the waste.

Every day the cover traps around 300 cubic metres of biogas, containing about 200 cubic metres of methane which is drawn off through a network of collecting pipes.

The gas is compressed, pumped through a scrubber to neutralise bad smells and then used to power a petrol engine which spins a 40 kilowatt electricity generator. This supplies roughly half the piggery’s daily electricity needs

“It also has heat exchangers which take the heat from the engine and use it to heat water to 80°C, sufficient to warm part of the piggery via underfloor heat pipes and reducing reliance on radiant heat lamps to keep the piglets warm.”

“But as well as that, energy efficiency investments usually come with a host of other benefits, from increased productivity, better working environment, increased customer satisfaction – or in this case, a more fragrant neighbourhood!”

All in all, an odorous problem which came up smelling of roses.

Big Numbers

  • 400 sows and about 9,500 piglets
  • 300 cubic metres of biogas
  • $65,000 savings per year in energy bills

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