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Blueberry Fields

Sunshine delivers energy productivity for blueberry farm in Northern Rivers NSW

[Click here to download a PDF version of this information paper]

Water, sunlight and clever farm practices will strip out 10% of the energy costs for this small farm just south of Byron Bay.

Otto and Lynette Saeck have been improving their business continually over the past 10 years. Their next opportunity is to optimise water application and pumping schedules and exploit the sunshine available using solar PV-generated power to reduce their grid-delivered electricity use dramatically. Other initiatives they’re considering include installing high-efficiency motors (HEMs) and variable speed drives (VSDs).

Pilot site: “Blueberry Fields” – Byron Bay, NSW 2481 Date of visit: 21 May 2014 Authors: Gerry Flores, David Hoffmann, Leigh Rostron & Phil Shorten
 

Otto and Lynette Saeck have been running their property on the north coast of NSW since 1995, growing a number of blueberry varieties and harvesting the crop year-round. Different types of blueberries grow better in warmer or cooler climates, and the time from flowering to fruit harvest is normally around three months.

Blueberry Fields covers an area of around 100 acres and is an irrigated farm. The property includes a large coolroom in which fruit, during harvest, is stored overnight, then shipped out to local markets and retail locations the following morning. The coolroom is kept at between one and three degrees Celsius, as temperatures close to zero prolong fruit shelf life.

Reducing energy costs supports competitive pricing for Blueberry Fields

Not all blueberries are created equal. The Saecks aim to use their land on a consistent basis, as this allows them to take advantage of the existing infrastructure and maintain a steady income stream. The land at Blueberry Fields is devoted to a variety of blueberry types, many of which are harvested between April and November, as well as some that are harvested in the warmer months around December. Blueberries grown in the southern States (Victoria and South Australia) typically ripen in the summer months, meaning that competition within Australia drives blueberry prices down between December and February.

The main energy use at Blueberry Fields, like that of most horticultural operations, is electricity for coolroom storage, diesel fuel for tractors, and electricity for pumping water to maintain adequate soil moisture levels to grow healthy plants.

For Otto and Lynette, savings opportunities identified include using solar PV-generated power to offset both pumping for irrigation on their blueberry bushes and electricity used for cool storage. Both systems operate for the majority of the year (the coolroom runs all year) and provide good opportunities for reducing costs. Using solar PV would enable the Saecks to offer competitive pricing while maintaining a reasonable margin.

Other cost-saving opportunities include examining tractor tyre pressures and conducting regular fuel monitoring in order to ascertain when and how much fuel is being used.

The Saecks are also looking at improving their already high-tech pumping infrastructure with a more efficient VSD for the farm’s existing pump. This could yield electricity savings of more than 30%. Finally, the farm is investigating the purchase of a new tractor, with particular interest in fuel-efficient tractors, as well as electric-battery-powered vehicles that, potentially, could be charged through solar PV.

Blueberry Fields’ energy profile

Table 1: Blueberry Fields’ energy breakdown
Table 1: Blueberry Fields’ energy breakdown

The farm’s largest energy expenses are firstly, diesel-fuelled tractors and secondly, electricity use for pumping.

Table 2: Blueberry Fields’ energy breakdown by end-use purpose
Table 2: Blueberry Fields’ energy breakdown by end-use purpose

Figure 1: Blueberry Field’s energy use ‘baseline’ by type and purpose
Figure 1: Blueberry Field’s energy use ‘baseline’ by type and purpose

Cost reduction opportunities

A total of six energy savings opportunities were identified by the team, with the potential to save the Saecks more than $6,000 or around 12% of the farm’s current energy costs. All six opportunities have been prioritised for investigation by the Saecks with assistance from NSW Farmers. These are highlighted in Table 3 .

Table 3: Full list of opportunities. Note: ‘UI’ indicates ‘Under Investigation’.
Table 3: Full list of opportunities. Note: ‘UI’ indicates ‘Under Investigation’.

In a two-hour discussion with the Energy Team on the Saecks’ back verandah overlooking the blueberry fields, Lynette and Otto outlined their business plans and energy innovation priorities. To ascertain priority opportunities, they pinpointed key drivers for investing in energy management that included:

  1. community responsibility – supporting and bolstering the Blueberry Fields’ ‘green’ credentials;
  2. maintaining year-round production for market advantage; and
  3. improving the asset value of the farm.

Using a simple matrix to compare the relative value of each identified opportunity, the Saecks came up with the following key priorities:

  1. installing a 1-3kW solar PV system to supply electricity to the coolroom during the day;
  2. installing a 5-10kW solar PV system to supply electricity to the main pump for irrigating the blueberry bushes;
  3. investigate the financial case for installing a high-efficiency motor (HEM) and/or a variable speed drive(VSD) on the main irrigation pump; and
  4. improving tractor efficiency by investigating optimal ballast and tyre-pressure points.
Figure 2: The farm management team decide on their priority energy cost-saving opportunities after considering their business plans and goals for the farm.
Figure 2: The farm management team decide on their priority energy cost-saving opportunities after considering their business plans and goals for the farm.

Solar PV power for pumping could save the Saecks $25,000 over 10 years

It was ascertained that the main pump at Blueberry Fields could be powered by a 7kW solar PV system to provide electricity to the pumps that supply water to the farm’s fields. The size of the system proposed is based on the current electricity load of the pumps to ensure that it has sufficient capacity to service all the farm’s pumping requirements, saving the Saecks around $2,500 year on year.

More information on solar PV pumping is available online and in NSW Farmers and OEH’s solar PV pumping guide . Pumping calculators are also available from most major pump suppliers.

Figure 3: Solar-powered pumping applications are accommodating larger loads, and reduce maintenance and ‘attendance’ costs significantly. The farm can virtually run itself!
Figure 3: Solar-powered pumping applications are accommodating larger loads, and reduce maintenance and ‘attendance’ costs significantly. The farm can virtually run itself!

Such a set-up for pumping from dams is becoming more common when loads are frequent and reasonably consistent, therefore justifying a solar-powered solution ,” says Phuong, energy consultant from Energetics.

She adds, “The more common set-up is small bore pumps powered by solar systems, but the manufacturers are now making a wider range of solar solutions accommodating both small and medium size applications, as much as 10-15ML a day in some cases.”

Coolroom temperature set points

The coolroom is a vital link in the chain at Blueberry Fields, as fruit arrives from the fields and is transferred to the delivery truck (another coolroom) within 24 hours of picking.

Otto and Lynette have assessed the limitations related to product quality carefully and have determined that a coolroom set point of 0.5°C is suitable for guaranteeing fruit quality and maximising energy savings.

Figure 4: Striking a balance between energy savings and fruit longevity –the Saecks have reviewed the technical literature on blueberries and have adjusted their coolroom temperature set point so as to maximise energy savings without jeopardising the quality of the fruit.
Figure 4: Striking a balance between energy savings and fruit longevity –the Saecks have reviewed the technical literature on blueberries and have adjusted their coolroom temperature set point so as to maximise energy savings without jeopardising the qual

In general, every 1 °C increase in a coolroom’s set point can decrease its energy usage by up to 3% (Gabor, 2013).

Refer to the NSW Farmers’ factsheet ‘Energy-efficient coolrooms and refrigeration’ for more information.

Variable speed drives (VSDs) for Blueberry Fields’ coolroom compressor

With the wide range of blueberry varieties grown at Blueberry Fields, the farm’s coolroom is in demand year-round. The coolroom compressor runs constantly, even with the varying load brought about by the changing volume of stored fruit, air temperatures and door openings.

Given this variation, savings of 15-20% are possible from the 10kW, 13hp compressor motors.

Visit NSW Farmers’ information paper on energy efficient cool rooms and refrigeration for a more detailed, technical explanation and a breakdown of the anticipated savings.

Beyond VSDs, the Saecks are considering upgrading to:

  • high-efficiency compressors, offering up to 7% in energy savings;
  • an electronically commutated (EC) motor for evaporative fans, with expected savings of 2-5%; and
  • screens, or rooms with staged compressors, achieving 5-15% savings depending on occupancy rates and subsequent cooling loads.

High-efficiency variable speed drive (HE VSD) on the farm’s main irrigation pump

The irrigation system at Blueberry Fields includes sophisticated pumping infrastructure worth upwards of $1 million AUD. The system is managed from a central irrigation pump, which can be set to deliver water to the different lots around the farm.

Figure 5: Blueberry Fields' irrigation infrastructure delivers water and nutrients from a central point using a a single-speed pump and remotely controlled valves that direct the flow to specific lots. A high-efficiency VSD could improve the efficiency of this system and deliver substantial savings.
Figure 5: Blueberry FIelds' irrigation infrastructure delivers water and nutrients from a central point using a a single-speed pump and remotely controlled valves that direct the flow to specific lots. A high-efficiency VSD could improve the efficiency of

Although the current set-up is highly automated, the farm’s control strategy has not been updated to reflect changes in the fields, land moisture and crop species over the years. Moreover, the existing single-speed pump does not always deliver the correct water flow and pressure to the various lots being irrigated.

Currently, Otto and Lynette are in discussions with their irrigation engineers about options for upgrading their control strategy and will also be investigating the installation of a high-efficiency VSD for the main pump. These changes will enable them to:

  • have better control over their irrigation strategy;
  • reduce their pumping electricity costs;
  • reduce fertilisation costs; and
  • ensure that crops have the correct level of water.

Part of this work will involve conducting trials to determine the appropriate pump speed to ensure water is delivered at the required flow and discharge pressure for each of the different lots. While this balancing of flows could be achieved via the introduction of throttling valves on the delivery side of line, this would result in energy wastage. Installing a VSD would allow the flow to be adjusted in a far more cost-effective manner, and any reduction in motor speed results in exponentially larger reductions in energy use and cost. For a more detailed technical explanation of the relationship between changes in speed and energy use, refer to NSW Farmers’ fact sheet on VSDs .

If they find that a new motor is required as part of the set-up, the Saecks will investigate options for a high-efficiency motor (HEM). While HEMs may cost a little more, they can provide long-term savings through lower energy consumption and operating costs. Generally, however, upgrading to an HEM is considered cost-effective only if a new motor has to be purchased anyway (rather than as a retrofit/replace).

For more information, download NSW Farmers’ information page ‘Energy savings from high-efficiency motors’ .

Solar PV system to cool the berries and maintain their freshness

Year-round use of the coolroom at Blueberry Fields makes solar PV feasible for this part of the operation.

“It’s not often you see a coolroom in horticulture being used every day. The electricity generated can be utilised, saving 20 or more cents per kilowatt hour, rather than the power going back to the grid periodically, receiving at best six cents a kilowatt hour,” says Gerry Flores, manager of the Energy Innovation Program for NSW Farmers.

Figure 6: Solar PV solutions work best for farms that have consistent and continuous loads during daylight hours.
Figure 6: Solar PV solutions work best for farms that have consistent and continuous loads during daylight hours.

Outcomes for the berry farm

Solar pumping, tweaking the coolroom set-up and supplying solar power to the coolroom – which is running every day, all year round – will save Blueberry Fields more than $6,000 a year, every year.

This combination of having a control strategy and deploying energy-efficient technologies and renewable energy projects with an average payback period of four years will help the Saecks reduce their electricity and diesel costs and improve their blueberry business’s bottom line.

Figure 7: Expected energy savings from continuing implementation of projects at Blueberry Fields
Figure 7: Expected energy savings from continuing implementation of projects at Blueberry Fields

Blueberries with green credentials

Otto and Lynette will continue to explore options for energy generation and energy efficiency that secure the future of their berry farm just south of Byron Bay, with information on off-grid solutions supporting their goals for boosting the business’s green credentials. If they choose to export their product down the track, the Saecks’ story could be well received in European markets, in which produce with ‘clean, green’ credentials is highly valued.

In the short term , in addition to implementing solar-powered pumping and using the on-site solar PV array to provide power to the farm’s coolrooms by day, the Saecks will discuss the option of upgrading their existing irrigation pump motor to a high-efficiency variable speed drive (HE VSD) motor with their irrigation engineers.

In the medium term , a sound business case could be made for expanding the coolroom refrigeration area at Blueberry Fields to provide storage for neighbouring farms’ produce and create additional revenue for the Saecks.

Long-term opportunities include large savings from electrifying all or most of the farm vehicles, thereby reducing Blueberry Fields’ energy costs by 40% or more. Otto and Lynette will keep up on the latest developments in battery and other energy storage devices that could help their operation to achieve carbon-neutral status as well as future-proofing their profit margins. Some forecasters contend that by 2017, batteries could be half the cost that they are now.

The cost savings could be as much as 100% if the investment enables Blueberry Fields to store solar-generated energy for use after dark and on no-sun days.

NSW Farmers will be monitoring innovation in battery storage and releasing information in support of these decisions as we get closer to December 2016, when the feed-in tariff will disappear for farmers in NSW.

Figure 8: A 1.5kW mobile solar pumping array on a trailer.
Figure 8: A 1.5kW mobile solar pumping array on a trailer (Sustainable Technologies, 2014).

MORE INFORMATION ON ELECTRIC TRACTORS

www.engagingnature.com/tritonev.html

 

MORE INFORMATION ON MOBILE SOLAR PUMPS

sustech.cc/email/solarpumps2

 
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