Cas d’application

Eurawasser, Lübzin Waterworks

Lübzin Waterworks: optimum value for  specific energy expenditure

EURAWASSER Nord GmbH’s partner  is EURAWASSER Aufbereitungs- und  Entsorgungs GmbH Berlin, a subsidiary  of SUEZ ENVIRONNEMENT, France, active  nationally since 1990. EURAWASSER’s contracting  companies are local authorities  and public utility companies. EURAWASSER  offers local authorities comprehensive  long term collaborations for water and  wastewater in the context of various models  adapted to the specfic context.

These  models range from management contracts  to operational management, co-operation  and operator models including holdings.  The collaboration model includes commissioning  operations, maintenance, modernisation  and the development of drinking  water and wastewater facilities as well  as other services. EURAWASSER implements  new water resource management  measures for efficiency, service and cost  transparency. The 900 employees of the  group are responsible for the drinking water  supply and sewage disposal for around  750,000 people in cities, communities and  rural areas and have an annual turnover of  around 120 million Euros. SUEZ ENVIRONNEMENT  is a market leader offering over  120 years of experience and know-how.

SUEZ ENVIRONNEMENT ensures the water  supply for 68 million people and sewage  disposal for over 44 million people as well  as waste disposal for 46 million people.  The company has 62,000 employees in  over 100 countries and an annual turnover  of around 12 billion Euros.

The situation

“Water supply facilities have exceptionally  high energy demands. In a time of ever increasing  energy prices we have to optimise  constantly and come up with new processes”,  this is Eurawasser’s corporate philosophy as  acknowledged by Ulf Lorenz from the technology  department and groundwater development  and detection specialist. Michael Belosa  the waterworks foreman agrees. However, this  is not merely a formality on paper: “our management  gives us specific annual goals, and  energy savings are always a top priority”.

As a result the Grundfos service team was  commissioned to perform the life cycle cost  analysis at the Lübzin Waterworks. The purpose  of this service is to identify the pump  systems in the waterworks that could benefit  from cost-effective energy reductions.

The solution

In May 2007, the Grundfos service specialist at  the Lübzin Waterworks investigated the situation  and recorded the existing performance  data for the well and clean water pumps, their  efficiency factors and their energy consumption. 

Using specially developed evaluation software,  they compared the values obtained with those  of the potential new pump. The actual savings  potential for identical operating points  was under investigation. The investigating  team soon reached a conclusion: the actual  performance data of the old pump no longer  corresponded to the parameters of the tool  identification plate. Possible causes included  wear and tear on the parts resulting in, for example,  an increase in the impeller clearance,  compromising overall efficiency.

The service team suggested three clean water  high pressure pumps from the CR range and  two well pumps from the SP range as replacements.

The outcome

After installing the new Grundfos pumps, the  annual electrical energy saving for the same  performance was 11,376 kWh. With electricity  at 0.14 €/kWh, this corresponds to annual  operating savings of €1,593/year and 60% for  the CR pump and 56% for the SP pump.

The investment will be paid off after 4 and 2.6  years respectively. Diagrams 1 and 2 show the  proportion of energy costs for the old pumps  compared to the new ones and the savings  potential (in green) for the next 10 years allowing  for a 2.5% inflation rate, as well as the  investment costs (in blue).

Ulf Lorenz: “Basically, we knew that the Lübzin  Waterworks was in need of refurbishment: if  the pumps are only operational for two hours  a day, then the installation is obviously oversized.  Ideally, the pump run time should be  from 10 to 12 hours a day”, says Lorenz. This  also optimises the treatment process by reducing  the load on the filter (a lower filter  rate), better enabling the filter to reduce iron  and manganese levels. The higher the filter  rate caused by oversized pumps, the more  iron and manganese remains in the clean water  and the more residue collects in the pipes.  “Properly designed pumps don’t just save energy,  they also reduce flushing and cleaning  work in the mains. The situation is similar for  the well pump: if a lot of water is pumped in  a short time, this will have a harmful effect on  the well.”

Optimisation result: the overall energy consumption  of the Lübzin Waterworks dropped  considerably, with the specific energy expenditure  reduced from 0.57 to 0.38 kWh/m³.

A survey by the TUHH DVGW research centre  at the Hamburg-Harburg Technical University  produced interesting results on the project’s  energy efficiency/savings in water treatment  [1]. For the 422 participating utility companies,  the average value of the specific energy  expenditure (electricity consumption) per cubic  metre of clean water is 0.58 kWh/m³ (diagram  3)

With a value of 0.38 kWh/m³, the newly installed  pumps at Lübzin are much more energy  efficient. “For two-tier waterworks, energy expenditure  must be our main priority” opines  Michael Belosa. 

“Eurawasser and Grundfos have agreed that  Grundfos will perform a post-analysis after the  proposed changes have been implemented. The  measurements performed in July of this year  showed almost exactly the predicted values”,  said Ulf Lorenz.

Summary: the Lübzin Waterworks example  shows that even when the specific energy  expenditure already presents a good average,  there is still room for potentially huge savings.

Eurawasser Nord now aims to perform LCC  analyses on more and more waterworks and  rectify any problems.