Proficient Pumping

Sometimes going full bore is not the right solution.

Case in point: A 50-horsepower irrigation pump at Hans Nelson & Sons Nursery only ran at top speed, delivering too much water at times. The nursery needed to adjust the flow as watering needs varied. To solve the problem, the grower installed a variable frequency drive (VFD) on the pump, providing the watering flexibility it needed. The VFD also significantly trimmed water and electricity costs.

The Boring, Ore.-based nursery grows shade, ornamental and flowering trees in the field. The grower also must get water to its greenhouses.

Several years ago, the nursery installed a 50-horsepower submersible turbine irrigation pump. It delivered water, but always at maximum flow — 300 gallons per minute — even when just light watering was needed.

“It went from nothing to wide open, often pumping out way more water than we needed,” said Dan Nelson, president of the nursery. “It’s not very often that we need to pump that much water.”

The wholesale nursery needed a way to use the pump at a reduced flow.

VFD adjusts speed
Once the VFD was installed, it adjusted the pump speed, which regulates water flow and cuts operating costs.

“The VFD lets you dial down the pressure. We can pump at 150 gallons per minute when we need to,” Nelson said.

The nursery received help from Portland General Electric (PGE) and the Energy Trust of Oregon. PGE and the Energy Trust provided technical expertise in identifying the solution and verifying that the new VFD was properly installed and adjusted to maximize savings.

The nursery earned a cash incentive through the Energy Trust’s production efficiency program. The incentive helped offset project costs and sped up payback on the nursery’s investment.
 

The VFD computer control adjusts irrigation as needed, saving water and energy.

“Several other nurseries in the area have installed them. It’s an easy solution,” Nelson said.

The nursery is saving water and saving approximately 19,000 kilowatt-hours of electricity annually, accoording to PGE. That represents a 52 percent reduction in energy use for the pump.

The nursery uses drip irrigation in all of its fields, Nelson said.

“With drip, we don’t lose any water from wind or high temperatures,” he said. “And we can water huge blocks at a time.”

The grower also fertilizes trees through the drip system.

“We have a Dosatron injector system that we pull along the nursery with a trailer to fertilize the trees,” he said.