Idea

Denmark’s water supply and sewage services have an annual power consumption of approximately 800 GWh. Studies show that there is great potential to make savings, approximately 200 GWh, equivalent to approximately 25% of consumption.

There are a great number of water supply and sewage services and they share many problems. The majority are currently owned by the municipality but under the water reform they will become independent legal entities in the course of a few years.

In this connection, a campaign supported by the Danish Electricity Saving Trust has been initiated. The campaign target is to realise power savings of 25% over 5 years, equivalent to an efficiency enhancement of ‘production’ of 33%. As an absolute minimum target, it should be possible to achieve a total reduction in power consumption of 10% over 5 years, equivalent to an increase in efficiency of at least 11%. The saving is calculated as the reduction in relevant key figures for power consumption.

As part of the campaign, existing experience will be used to develop a user-friendly catalogue showing a number of solutions and measures that can be used to advantage in the various processes in the water cycle and their power saving potential.

This website represents this information gathering and thus the current best practice in the field. We realise that not all good examples are necessarily included because documentation is often lacking and because it has quite simply not been possible to contact everyone. We would therefore encourage you to report good examples that can be included in subsequent versions of the catalogue, which has just been created as a website that can be continuously updated.

The optimum supply

In connection with the present project, we have focused on minimising energy consumption in connection with the establishment and operation of water supplies. In this connection, it is interesting to consider the ‘optimum, energy-wise supply’. However, this is a rather abstract exercise because there are a wide range of factors that impact on the ability to minimise energy consumption, while remaining within the limits set by sound operating practice and the requirements for water quality.

The incentive to make energy savings may, of course, be financial and/or political. Ideally, there should be a connection between these stimuli.
In banal terms, an energy-optimised supply can be defined as a supply that produces one m³ water with the lowest possible energy consumption, defined on the basis of a standard calculation.

That said, however, it should also be mentioned that location, source, supply area, water treatment, consumer patterns, taxes, requirements for conversion as a result of new technology, repayment times, etc. affect whether it is financially viable to change the production equipment or make special considerations in connection with the engineering of a new waterworks. It is rare for the energy-wise approach to be the sole deciding factor. It is necessary to see the whole picture.

When modifying existing plants, the proposals on the present website can be used as a starting point. They can also be used when engineering and constructing new works. In the latter case, it can be of advantage to introduce energy-wise engineering.