”They’ve been overtaken by developments!” With this brief statement, sales engineer Poul Bøgelund from Grundfos sums up the reasons why many Danish waterworks now face very high electricity bills for powering their old systems.

”Many systems date back to the days where consumers and businesses simply used water without any thought to water conservation. And the waterworks were built and sized in the firm expectation that consumption rates would only go up. Now, we can take pleasure in the fact that common sense has prevailed throughout the community, but at the same time many waterworks wince every time their electricity bill falls due.” explains Poul Bøgelund.

Much more widespread common sense among consumers and rapid advances in technology means that many Danish waterworks use 20 to 25% more energy than they need to.

New pumps showed the way

The waterworks of the city of Vejen, Denmark, was one of the sites where the opportunity for energy savings helped prompt a decision to replace the entire stock of old pumps.

”In Vejen we recommended installing four Grundfos CRE90-3 pumps with frequency converters for speed regulation. We saw that these multi-stage centrifugal pumps would yield greater energy savings than pumps fitted with just a single impeller.” says Poul Bøgelund, who promised the staff at Vejen that a pump replacement would save them approximately 46,000 kW/h a year.

So how did it go? ”The savings came to 46,800 kW/h,” states department manager Tage Hansen, Vejen Waterworks. ”Being able to predict savings with that sort of accuracy is very impressive.”

Pump controllers can also be energy guzzlers

”Few people realise that the pump controller itself can guzzle up quite a lot of energy,” says Poul Bøgelund. The fact is that energy consumption can be reduced by up to 12% compared to other pump controllers – and those controllers are not ancient, but simply belong to the previous generation.