Solar PV delivers a 10-20% reduction in energy costs to Northern Rivers piggery
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The Drews are investigating a solar PV system for their homestead and their piggery to deliver power for lighting, feed augers and heat lamps for the piglets. “We are keen to reduce our dependency on the grid and save on running costs so that we have a prosperous future,” says Nick Drew, a fourth-generation pig farmer.
Other energy-saving initiatives Nick is implementing or considering include installing more efficient heat lamps in the nursery and switching the mill over from a PTO off the back of an old 30hp Massey Ferguson tractor, to 21 and 6hp electric motors for the hammer mill and the mixer. The current set-up incurs significant losses, with a five-metre belt drive and limited capacity to vary motor speed to suit the load.
Nick and Jacqueline Drew run a mixed piggery and macadamia business on land just north of Lismore, New South Wales. The facility breeds about 2,500 pigs a year from a breeding stock of around 150 sows. There is also a herd of around 90 cattle, which feed on pastures that benefit from the treated waste from the piggery. With energy costs of roughly $8 per pig born and bred per year, there is significant incentive for the Drews to invest in reducing that cost to $5-6 per pig and thereby improve margins and the viability of this small business.
Energy needs and planning for the future
The Drews are interested in installing one or multiple solar PV systems to help meet the energy needs of their home and piggery. They are aware that feed-in tariffs in NSW are now a modest 6c/kWh, so they are working to properly size a system that will maximise the savings from self-consumed generated electricity for the lowest capital cost.
They are also looking at the viability of installing an integrated solar PV and battery storage system on-farm, but expect this to be more cost-effective in two years, by which time the cost of batteries, it is predicted, will have halved (driven primarily by the expected increase in demand for electric vehicles and the end of the NSW Solar Bonus Scheme feed-in tariff in December 2016).
In addition to breeding pigs, the Drews mill grains and mix their own feed for the pigs on site. If the Drews decide to expand their operations, they will have look at generating electricity from waste and at converting their mill, which currently runs on diesel power, to an electric system.
The piggery’s energy profile
Table 1: NS & JA Drew’s Piggery’s energy breakdown
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The farm’s largest energy expenses are found in the mill, followed by the piggery. Electricity use is primarily derived from pumping and treating waste, lighting and heat lamps.
Table 2: NS & JA Drew piggery’s energy breakdown by end-use purpose
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Figure 1: NS & JA Drew’s Piggery’s energy use ‘baseline’ by type and purpose
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Cost reduction opportunities
Four energy savings opportunities were identified by the team, with the potential to save the Drews more than $2,000 (18%) in energy costs. All four are being considered by the Drews,with assistance from the NSW Farmers' Energy Innovation Team. These are highlighted in Table 3.
Table 3: Full list of opportunities. Note: ‘UI’ indicates ‘Under Investigation’.
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During a two-hour discussion with NSW Farmers’ Energy Team in the backyard of the homestead, Nick and Joanne discussed their business plans and decided on their energy innovation priorities.
The business priorities that will impact on any future investments in energy management include the following:
- No immediate plans to expand operations.
- Securing the farm’s energy supply and reducing its exposure to any future significant energy price rises that mightmake the business unviable.
- Considering potential alternative energy sources and their relative impacts on the environment.
Solar PV installed in the Drews’ piggery shed and house to deliver 20-40% savings – more if the mill is converted to electricity
In order to improve energy reliability and reduce existing electricity costs on the farm, the Drews have been considering adding solar PV, including utilising battery storage as either a backup (for blackouts) or as a way of replacing electricity from the grid. At this point, the financial case for purchasing sufficient battery storage to go ‘off-grid’ is still a difficult one to make, but when you factor in the reliability and security of knowing you can control your own energy supply, this option looks more attractive.
The case for solar PV was investigated by the Energy Team using the solar sizing tool, with results favouring a 1.5kW solar PV system for the house and an 8.6kW system for the shed powering the lights, lamps, mill and mixer. Using this tool, estimated savings of around $4,000 year on year are possible, with potential to add more PV panels and battery storage at a later stage so as to get fully off the grid.
Figure 2: System savings and costs for a PV system for piggery operation
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Figure 3: System savings and costs for a PV system for homestead
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Conversion of diesel-powered mill and mixer to electric power reduces energy costs, but solar power brings bigger savings
As the team wandered around the piggery sheds, they discovered an old but reliable diesel Massey Ferguson powering the mill via a series of gearboxes and five-metre-long rubber drive belts. Immediately, the team considered the potential for switching from a PTO off the back of the 30hp tractor to employing more efficient 21 and 6hp electric motors for the hammer mill and mixer.
There are significant losses in the current set-up, with a five-metre belt drive and limited ability to slow the motor down to suit the load.
Figure 4: The mill is powered by a PTO from a 30hp Massey Ferguson tractor “retired to the shed”. The hammer in the mill is belt-driven, raising questions around efficiency and maintenance costs/effort. The NSW Farmers Energy Innovation Team has quantified the cost savings for converting to electric motors for the mill and the mixer combined with solar-generated power.
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Such a set-up is not uncommon, given the ingenuity of most farmers and their interest in re-using equipment that may otherwise lie rusting away in paddocks. A conversion to electric motors will facilitate the business case for solar PV, providing long-term cost savings for the Drews’ business.
Nick and NSW Farmers’ Energy Innovation Team discussed the preferred configuration. “I hadn’t considered electric motors for the mill,” says Nick. “It certainly makes sense if we invest in solar to use the sun as our power source for the mill, especially during peak periods of the day when we are paying 30 cents or more per kilowatt. In fact, we can limit our use of the mill and the mixer to these times of the day – mainly in the afternoon.”
High-efficiency heat lamps for piglets: marginal heat recovery may be the answer
Infrared bulbs are 100 watts each and are used to provide heat and red light for the young pigs. This application of energy is critical to the Drews’ core business, as the value of the piglets is dependent partially on the ambient temperature in the sheds and subsequent weight gains as well as on the pigs’ general wellbeing.
Apart from electricity use, maintenance is a key factor, as Nick highlighted. “We replace failed bulbs around 290 times a year. It’s a real issue for us … we simply need to find alternatives!” At $9 per bulb, that equates to $2,592 a year just for replacing bulbs. Together with electricity costs of $5,000 a year, the combined cost is around $7,500 p.a., so alternative heating solutions are well worth investigating.
“There are three key themes here,” says Gerry Flores, Energy Team Leader from NSW Farmers. “First, we are researching what is available in more reliable and energy-efficient bulbs and second, with support from Energetics, we are looking at alternative sources of heat that might be recovered via a heat exchanger to provide hot water that could be used to heat the nursery.” Existing sources of heat on the Drews’ pig farm include the tractor exhaust or radiator (but times of use, physical location and noise have eliminated this option for waste heat recovery).
The third theme is to size the solar PV array for the shed to accommodate battery storage, which could be utilised at night and on cold days when there is little or no sun.
“Our advice to the Drews was to wait a year or two for batteries to come down in price,” says Gerry.
Outcomes for piggery
A solar-powered piggery and homestead, an upgraded mill and more efficient heating could deliver savings of almost $4,000 p.a. or around 20% of the farm’s total energy costs, improving energy productivity, dropping the cost of breeding and rearing the pigs from $80 per pig to around $64, and delivering substantial bottom-line benefits to the Drews’ business.
Figure 5: Expected energy savings from continuing implementation of projects at NS & JA Drew’s piggery
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Solar PV is fast becoming cost-competitive with lower system costs and high on-grid electricity prices
The Drews will continue to explore energy-generation and energy-efficiency options that secure the future of their northern NSW piggery, especially if they decide to expand production.
In the short term, Nick will be installing one or multiple solar PV systems, and will continue to investigate heating options with a view to reducing the current load before he purchases the solar PV panels or any batteries.
In the medium term, the business case for upgrading the mill will be developed and a decision will be made to invest in the upgrades that have the best likelihood of lowering the piggery’s operating costs and optimising the solar PV systems planned for implementation in 2015-16.
Long-term opportunities for the Drews include large savings from electrifying all or most of their diesel-operated farm vehicles, potentially reducing energy costs by 40% or more. The cost savings could be as much as 100% if the investment in storing energy for use after dark and on cloudy days can be justified. NSW Farmers will be monitoring innovation in battery storage and releasing information as we get closer to the shutdown of the NSW feed-in tariff in December 2016.