Developing Wind and/or Solar Powered Crop Irrigation Systems for the Great Plains

Some small scale, off-grid irrigation systems (< 2.5 ha) that are powered by wind or solar energy are cost effective, but this article discusses ways to achieve an economical renewable energy powered center pivot irrigation system for crops in the Great Plains. It was found that partitioning the center pivot irrigation system between a winter crop and a summer crop improved the match of wind turbine power generation to irrigation energy required. It was also found that a solar-photovoltaic (PV) array was a better match to the irrigation energy requirement of a winter and summer crop than using only a wind turbine, but a wind/solar hybrid was a better match than wind alone. Although solar PV systems were shown to be a better match than wind turbines for irrigation power requirements, solar PV systems are more expensive than small wind turbine systems for large-scale irrigation water requirements in the Great Plains. Including on-farm uses for the excess wind and solar electricity instead of selling the electricity back to a utility company at usually low prices, improves the profitability of a renewable energy powered irrigation system significantly. For a utility electrical price of $0.10/kWh, a wind turbine installed price of $3000/kW, no loan required (e.g. no loan costs), and the excess renewable energy generated electricity used for on-farm use only, a payback period of seven to eight years was possible with no state or federal incentives. With 55% federal incentives and the same assumptions, a payback period of four to five years was possible. Also, if the assumed operations and maintenance costs doubled, the payback period increased about two years. However, cost reductions are still required for both wind and solar energy systems in order that renewable energy systems can be competitive without the need for state or federal incentives when loans at 90% of installed cost with a 6% interest rate are required.