Variable speed drives — an energy-saving option for irrigated horticulture
Summary
A variable speed drive (VSD) is used to adjust a pump’s flow or pressure to the field requirements (actual demand).
Adopting VSDs in irrigation was historically for operational reasons such as providing constant pressure outputs, ‘soft starts’, or reducing pump wear.
More recently, as energy prices continue to rise, the opportunity to save energy has emerged as a more important objective.
Irrigation pumping costs can be higher than they should be for three reasons:
- More water than necessary is pumped and applied to a crop.
- The pump has a low operating efficiency, and operating away from its best efficiency point (BEP).
- The pumping pressure, or operating head produced, is greater than necessary.
This Primefact discusses using VSDs (variable speed drives) as a method to potentially reduce a pumping plant’s required operating head to achieve reduced energy usage.
Two case studies describing the reasons why and issues related to the adopted VSDs are also presented.
