Boosting coolroom efficiency with VSDs, electrifying spraying operations and investing in solar could bring energy savings of 40% to Northern Rivers fruit farm
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Fruits of Byron is an early-to-market fruit grower for the Brisbane and Melbourne markets that may also be an early adopter of energy storage technology. “I am weighing up tried and proven solar PV to charge an electric ute,” says Mark Napper, CEO of Fruits of Byron, a boutique grower of custard apples and peaches.
Other initiatives Mark’s taking include reviewing pumping options to reduce his irrigation energy costs, and energy-efficient design options for a new coolroom as part of his business expansion plans.
Mark Napper owns Fruits of Byron, a boutique fruit farm near Byron Bay in north-eastern New South Wales. Shaun, the farm manager, operates the farm, which produces custard apples, peaches and other fruits and is located south of Bangalow in Byron Bay Shire. The property consists of undulating country, with a regular water supply via two spring-fed dams and a creek. Its produce ripens early compared with fruit grown further south, giving Mark a strategic advantage as he is able to go to markets earlier than producers down south. To optimise this advantage, Mark is looking at ways of lowering the farm’s production costs. This includes exploring options for lowering the cost of running coolrooms, which provide capacity that is sometimes offered to other local farms (mainly potato producers) under a toll or contract arrangement.
Energy needs and planning for the future
In addition to reducing energy use on the farm, Mark is exploring options for generating power on site using solar PV cells, and at the feasibility of switching some of his diesel-fuelled equipment over to electrical power. While he explores these cost-cutting measures he is embarking on a new venture involving the use of his two coolrooms. The neighbours are growing potatoes and looking for storage space so Mark has decided to offer his coolroom storage to this these neighbours and others at a modest fee. There is a risk, however, that the cost of operating the coolrooms for this purpose will exceed the modest fee being charged.
Fruits of Byron energy profile
Table 1: Fruits of Byron’s energy breakdown
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The farm’s largest energy expenses are the electricity used by one of its cool rooms, and diesel, as used for tractors, pumping, and other vehicles.
Table 2: Fruits of Byron’s energy breakdown by end-use purpose
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Figure 1: Fruits of Byron’s energy use ‘baseline’ by type and purpose
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Cost reduction opportunities
A total of nine energy savings opportunities were identified by the team, with the potential to save Mark more than $7,800, or 40%, in energy costs. Five opportunities have been prioritised for investigation by Mark and his team, with assistance from NSW Farmers. These are highlighted in Table 3 in blue shading.
Table 3: Full list of opportunities for Fruits of Byron
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Figure 2: One of the two cool stores available on the farm for toll storage. Solar PV can de-risk losses that may otherwise be incurred from escalating electricity costs.
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The journey to clean-energy fruit production
Mark and Shaun discussed their business plans and energy innovation priorities with the Energy team. These entail:
- optimising the existing refrigeration system;
- ensuring the tractor is set up and operated efficiently
- if possible, replacing the diesel-powered tractor with an electric ATV and spray rig;
- installing solar PV to provide energy use during the day;
- upgrading existing pumping infrastructure; and
- using a larger solar PV system and energy storage (batteries or hydrogen cells) if the business case for this stacks up by 2016.
The following sections expand on each of these priorities and opportunities.
VSDs to lower coolroom load
Currently, the coolroom evaporator fan runs constantly 24 hours a day, although the load varies with harvest and potato storage. Varying the fan speed in line with the room’s varying loads will reduce overall power consumption.
To ensure the most energy-efficient coolroom set-up, Mark intends to install variable speed fans (VSDs), reseal the doors, optimise the set points for cool and hot weather, and install a VSD on the compressor motor. These upgrades have the potential to reduce the farm’s electricity load by 20-30%. They will also help reduce the size of the solar PV system required to service this equipment and reduce costs.
Figure 3: Main refrigerated coolroom uses 63GJ of energy at a cost of around $5,600, which is 45% of the total electricity used on the farm. If the new storage business takes off, this cost will triple, with an additional, larger coolroom coming on line.
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More information on the energy savings from variable evaporator fan speeds is available through the following links:
- Refrigeration – variable evaporator fan speed (AgInnovators)
- Variable Evaporator Fan Speeds (Minus 40)
Improve spraying tractor efficiency or move to electric alternatives (tractors/ATVs)
The largest energy use on Fruits of Byron comes from diesel used by the 80 hp Kubota M8030DT to trail and power a John Shearer airblast sprayer (Figure 4).
Figure 4: The biggest energy consumption at Fruits of Byron comes from diesel used for the 80hp Kubota tractor, which hauls and operates an airblast sprayer.
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Along with Shaun, the machine’s operator, Mark is exploring two main opportunities for improving the efficiency of his spraying operations on-farm:
Optimising tractor maintenance, set-up and operation
A 15% improvement in fuel efficiency could add up to $750 in yearly cost savings for Fruits of Byron.
A first step that could improve efficiency immediately would be ensuring that the machine undergoes any maintenance and repair work that may be required.
The next step is analysing tyre pressures, ballast points and wheel slippage to assess whether any optimisations can be made. Research by NSW Farmers and groups such as Efficient20 suggests that the fuel use of non-optimised machines can be reduced by 20% through these optimisations. More information on these options is available in the following information papers:
- Energy efficiency and farm vehicles
- Tractor ballasting
- Monitoring wheel slip to achieve fuel efficiency
- Tyre pressure and fuel efficiency
- Efficient20 Advisor’s brochure
Figure 5: Possible fuel savings from tractor efficiency measures
Efficient20, UK, 2013
Additional measures include ensuring that the correct gear is being selected for each operation. The ‘Gear-Up-Throttle-Down’ (GUTD) practice can result in significant fuel savings if employed when a machine is significantly underloaded. More information is available in the following paper:
Swap the farm’s diesel-powered tractor for a smaller electric ute or ATV
A longer-term plan to address the energy used for spraying relates to Mark’s interest in newer electric tractors/vehicles.
Mark is considering an electric-powered utility vehicle (like the one shown in Figure 6 ) to replace the farm’s Kubota. Potentially, this could save him around $5,000 in diesel costs per year, and would enable Fruits of Byron to claim additional ‘green’ credentials for its products in niche markets in Sydney, Brisbane and Melbourne.
Figure 6: 30hp 2015 Polaris Ranger EV (electric)
Randall Reilly, 2015
The vehicle could be fitted with a spraying rig (run on a 5.5hp petrol engine), an orchard volute and a 100-litre tank in the front (safety and weight restrictions prevent Mark from using anything larger) to achieve a set-up similar to that shown in Figure 7 , below.
Figure 7: ATV engine-driven mist sprayer and 2-way orchard/vineyard volute
mistsprayers.com, 2015
Website: www.mistsprayers.com
Although this solution will save on diesel fuel and enhance the property’s carbon balance, the limited range of the machine (around 16-18km, according to Equipment World, 2015 ) and the limited capacity of its spray tank suggest that some changes to the farm’s spraying regime would be required.
The battery range of the machine will suffice to spray only abount 40% of the farm’s crop, and the spray-tank capacity will be enough to spray only around five hectares. This means each spraying of Fruits of Byron’s approximately 16 hectares of planted trees would require at least three recharges of the battery and three top-ups of the sprayer tank.
“If we have sufficient tank storage to cover one paddock, that will work for us. Given the undulating land and the sheds’ central location, refilling after each of our five paddocks may not be a burden... These are options I will explore over the next couple of months, assuming we can access a test vehicle,” Mark says.
Fruits of Byron will look at ATVs as well as other electric vehicle options; however, these types of vehicles are still new and are relatively rare and difficult to obtain in the Australian marketplace. Additionally, some owners of electric vehicles have commented about having problems with maintenance, and with the performance of the battery and the machine.
These limitations and potential faults need to be investigated further before Mark makes a final investment decision.
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The benefits of electric vehicles include less noise pollution, less maintenance, fewer emissions and, in some cases, soil compaction, as well as cost savings. |
With additional development, it is expected that battery-powered or even hydrogen-powered electric tractors may become stronger contenders with respect to performance and affordability.
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A hydrogen-fuelled future for tractors? In addition to smaller electric ATVs, Mark is interested in the viability of using hydrogen fuel cells to provide electric power for larger tractor machines. Some manufacturers have produced experimental prototypes, such as the NH 2 from New Holland.
Figure 8: NH2 hydrogen fuel cell tractor New Holland, 2009 Unfortunately, these tractors are not yet available in the Australian marketplace; they have some limitations; and their components are still prohibitively expensive – the fuel cell alone is estimated to cost more than $350,000 ( Tractor Data, 2009 ). |
Installing a solar PV system
The business case for installing solar PV is attractive for Fruits of Byron, since the farm’s coolroom and shed meters currently use electricity at a rate of 27c/kWh – more when you account for connection and service charges. Other electricity uses on the farm are controlled loads, charged at off-peak rates of approximately 16c/kWh, with less potential for savings from implementing solar PV power-generation technology.
“We don’t expect electricity prices to come down more than 25% even with a discount, so it’s worthwhile exploring a solar solution,” says Mark.
Electricity use on the Fruits of Byron farm is predominantly tied to the energy needs of the coolroom, which stores produce from neighbouring farms as well as Mark’s own production. The consistency of this load during daylight hours means that energy is needed by day that a solar PV system could help provide. As seen in the figure below, electricity use increased substantially after Fruits of Byron’s coolroom began operating in the spring of 2013.
Figure 9: Average electricity used per day on meters connected to Fruits of Byron’s coolroom and other shed loads.
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The shed at Fruits of Byron registers around 70kWh of energy used per day. Assuming four peak sunshine hours and that approximately 30%of energy is used during sunlight hours, a
5-6kW solar PV system could maximise the amount of energy generated that is consumed on site, saving Mark 27c/kWh and enabling savings of around $2,200 per year. A system of this size would have a simple payback period of four years.
A larger solar PV system (8.5kW or greater) could also prove practical and cost-effective in certain circumstances, such as:
- if Mark decides to move ahead with obtaining an electric ATV for spraying;
- if the system will also be generating energy to meet electricity needs from other meters (that is, if combining several accounts and meters is possible);
- if the electricity actually used during daylight hours represents a larger portion than the estimated 30-40% Mark could expect to save if he added solar PV (which could be determined by on-site logging/monitoring); and/or
- if Mark decides to store some of the solar power generated on site in batteries, for price arbitration or to enable the farm to go ‘off grid’.
Improving irrigation equipment
The irrigation equipment used to water Fruits of Byron’s trees is, potentially, more than 30 years old. The performance and efficiency of the system is not great and recently, it has been experiencing consistent pressure drops.
Figure 10: Some of the irrigation equipment at Fruits of Byron is likely past its prime and resulting in increased energy use.
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As can be seen in Figure 11 , the energy used by irrigation equipment can vary widely and is difficult to predict. Irrigation requirements have also decreased in the past two years as there has been ample rain to sustain the farm’s crop.
This means that only around 4,000kWh of electricity was used to pump water for the farm in the past year. The irrigation pumps are also on a low controlled-load tariff rate of approximately 16c/kWh.
Upgrading to high-efficiency motors could save Mark 15% on the electricity used to irrigate the crop. But with cheap off-peak electricity rates, this would result in savings of only $100 to $130 in a year with ample rainfall.
Mark is therefore concentrating his efforts on improving other types of energy use around the farm.
Figure 11: Fruits of Byron’s average electricity use, per season (90 days), for irrigation pumping.
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Install a large solar PV system to be used in conjunction with storage batteries
Mark is also interested in enabling Fruits of Byron to operate ‘off grid’, using solar-generated energy with a battery bank to store and provide power for times when solar resources are limited (say, on cloudy days and at night-time). He intends to explore various scenarios using solar PV and batteries.
Electricity price arbitration
Going entirely ‘off grid’ may be an expensive proposition for Mark. Initially, therefore, he should look at the case for maximising savings by price arbitration using batteries and solar PV. This would entail:
- moving all electricity use on-farm to a time-of-use tariff;
- installing a large solar PV system and a battery bank;
- at times when electricity is expensive (peak), draining energy from the battery bank or using solar-PV-generated power to meet requirements (meaning no consumption of grid power);
- if solar PV generation exceeds the farm’s electricity needs, using excess ‘solar electricity’ to charge the battery bank;
- at times when energy is cheaper (off-peak hours at night and over weekends), using grid electricity to meet loads and charge the battery if solar PV generation is insufficient; and
- employing control systems to moderate switching between power supplies automatically, so that power can be used on the farm at any time with no discernible limitations in delivery.
Figure 12: Possible daily electricity use at Fruits of Byron if a 20kWh battery is installed and combined with a 30kW solar PV system. During off-peak times (midnight to 7am on workdays and all day on weekends), the battery will replenish its charge using low-cost electricity. Additionally, when the solar PV system generates in excess of the electricity needs of the farm, the surplus energy can be used to charge the battery. The battery can then help supply power at times when electricity from the grid is expensive.
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With no interval data on electricity consumption available,
a preliminary analysis looked at the average electricity consumed, aggregated from all loads on a given day. Currently, this is an average of 120kWh, which has been modelled as a consistent 5kW load, as shown in Figure 12 .
This simplified model is illustrative only, but its results suggest that a 30kW solar PV system, combined with a 20kWh-capacity battery bank, would allow price arbitration that could save Mark approximately $5,000 to $6,000 per year. It is estimated that this set-up would cost approximately $70,000 to install.
- Estimated cost: $70,000
- Expected yearly savings:$5,000-$6,000
- Simple payback period: 12 years
This solution would require Mark to undertake additional investigation; most importantly, he needs to identify the actual day-to-day energy use profile of the property, including the extra demand on days requiring substantial irrigation and/or electric-vehicle charging, or that might come from further expansion of the farm. Mark must also determine whether the various circuits around the farm can be joined so that all of them source their power from a single central location.
Going off the grid
While for Mark’s business, the cost of going fully off the grid is much higher than other options he’s considering, it may provide additional benefits, including those that arise from having a more secure energy supply, and stronger innovation and ‘green’ credentials.
“A solar system with batteries will help us hedge against energy prices increasing, as well as periods of low storage levels,” notes Mark.
Some preliminary analyses conducted by NSW Farmers suggest that the following set-up would provide a potential best financial case for going ‘off grid’:
- a 100kW PV system;
- a 115kWh battery-capacity system; and
- a 5kW-capacity diesel generator to help provide power and for recharging the batteries during prolonged times of little solar resource.
The system would have ongoing maintenance and fuel requirements (600 litres of diesel, amounting to about $1,250 per year) but would also eliminate the cost of grid-provided electricity (currently about $10,500).
Unfortunately, however, a system like this would likely have a hefty outlay cost of around $220,000 AUD. This would mean that the simple payback of the system may extend past 20 years. Since the batteries are unlikely to sustain their life past 10 years, a system of this sort may not make Mark his money back at all.
Nonetheless, the price points of solar PV and battery systems are continuing to decrease, as evidenced by the recent launch of products such as Tesla Motors’ PowerWall . And with possible price escalation in the cost of grid-provided electricity, the financial case for going off-grid may well improve, making Mark’s desire to own an energy-independent farm a financially viable goal.
Outcomes for Fruits of Byron
If implemented, solar-powered cooling and lighting, an upgraded refrigeration system and electric spraying could save Fruits of Byron around $9,000 per year, or 40% of its annual energy costs. Just as importantly for Mark, this would reduce some of the risks in the farm’s new storage business.
Figure 13: Expected energy savings from continuing implementation of projects at Fruits of Byron
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Planning for the new world of energy storage
Mark will continue to explore energy-generation and energy-efficiency options that secure the future of his fruit farm, with increasing storage potential, especially if costs can be kept low enough to maintain the business case for his neighbours’ use of Fruits of Byron’s large coolroom. Moreover, sun-powered fruit production could further enhance the branding for this boutique fruit producer.
Over the short term , Mark will begin monitoring electricity and diesel use more closely with a view to refining the business case for implementing a solar PV unit and electric vehicles.
In the medium term , the business case for upgrading the farm’s coolroom refrigeration will be developed and Mark will make the decision whether to invest in equipment that will lower his operating costs and de-risk his new fruit and vegetable storage venture.
Long-term opportunities for Fruits of Byron include large savings from electrifying all or most of its farm vehicles, expected to reduce the farm’s energy costs by 50% or more. NSW Farmers will be monitoring innovation in battery storage and releasing information to support these decisions as we get closer to December 2016, when the Solar Bonus Scheme will cease to pay any sizeable feed-in tariff for such systems
More Information
On electric/hydrogen farm vehicles:
- http://www.equipmentworld.com/the-2015-polaris-ranger-ev-is-a-powerful-electric-utv-that-moves-around-the-jobsite-in-stealth/
- http://www.polarisindustries.com.au/specials/ranger-electric-vehicle/
- http://www.titanutv.com/catalog/titan-utv-models_1/titan-scout-e2_6
- http://www.tractordata.com/news/2009/02/new_holland_nh2_hydrogen_tractor.html
- http://agriculture.newholland.com/us/en/About-New-Holland/Innovation/Pages/NH2-Tractor.aspx
- http://www.engagingnature.com/tritonev.html
- https://www.ev-power.com.au/-PROJECTS-.html
- https://www.wsaa.asn.au/NewsAndMedia/WSAAUpdate/Pages/Floating-solar-array-captures-energy,-conserves-water.aspx
- http://www.pluginncw.com/news/2014/6/20/polaris-ranger-ev-conversion