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Sizing up solar - is it right for you?
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There's been a growing interest in renewable energy options in recent years in response to escalating energy prices.
Like any investment on the farm, looking at renewable energy requires careful consideration of factors such as the up-front-cost, the payback period, and the lifespan of the investment.
Diesel is still the primary energy source for irrigated growers, but grid-connected irrigators also have an opportunity to consider solar in the context of government incentives subsidising renewables; low cost solar; and feed-in-tariff (FIT) prices.
Given cotton’s requirement for high solar exposure, it means that solar Photo Voltaic (PV) energy is one of the primary considerations when it comes to incorporating renewable energy into irrigation.
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In the energy use and efficiency chapter within the Australian Cotton Production Manual published by CRDC and CottonInfo, Jon Welsh (CottonInfo / AgEcon), Janine Powell (AgEcon) and Phil Szabo (Taylored Engineering Solutions and Research) provide the following tips when it comes to considering alternative energy sources:
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- Satisfactory commercial payback occurs on solar only irrigation projects where water extraction rates are high and an earthen water storage dam is nearby to maximise available solar pumping hours through the year. These generally occur in shallow to medium depth groundwater irrigation bores.
- Matching solar powered irrigation pumping with sporadic or seasonal demand (e.g. capturing overland flow) of surface water has proven challenging with analysis showing standalone PV investments are on the low-end of commercially acceptable returns.
- Hybrid systems allow a pricing hedge of different energy sources and can reduce the reliance on fossil fuels and grid power. At dawn and dusk, DC current from PV is mixed with AC current from the generator to ensure consistent voltage supply to the irrigation pump.
- A new pumping system can offer considerable labour savings through remote monitoring and precise measurement of water resources, pump performance and pumping inputs.
- Installation returns of PV hybrid systems have shown acceptable project payback where an earthen storage can be used or year-round or out- of-season generation can be used. This may occur through pumping into storage in cooler months, operating grain drying equipment or (potentially) charging electric vehicles/machinery and replacing fossil fuels.
- For grid connected pumps, a feed-in-tariff generates revenue during periods of no pumping, which can greatly assist project returns. Negotiating a competitive feed-in-tariff forms part of project feasibility for grid-connected irrigators.
- With the cost of PV continuing to fall, domestic and industrial users have a rare opportunity to achieve commercially acceptable returns and payback periods in the current environment of rising energy prices and PV subsidies.
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A range of resources for growers are available on the CottonInfo website, including a case study with the Gill family at Narromine, who implemented a solar and diesel hybrid system at one of their pump sites. An analysis conducted in 2018 showed a reduction in pumping costs from $76/megalitre to $41/ML and slashed diesel use by between 45,000 and 55,000 litres a year. Over 25 years, that equated to a saving of more than 1 million litres of fuel and a reduction of over 3000 tonnes in carbon emissions. Andrew Gill explains more in the video above.
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