Innovative Energy Concepts in the Water Supply Sector - Implementing Environmental and Resource Management - page 27

generative water pumping station via the construction of an underground dam in a
karst system was initiated ( Figure 4.1 ). Within a karst cave, water is dammed up
to a height of 10-15 m. The main part of the captured water is used to run an in-
verse operating pump (PAT, pump-as-turbine), which is coupled via a mechanic
drive directly to the pumps that are lifting the water (Nestmann et al. 2008). Under
full load conditions about 65 litres/second can be pumped over a 220 m distance to
an elevated tank. This amount of water is sufficient to supply a population of
80,000 people with 70 litres/day. The innovative character of this approach is that
the pumping station becomes independent from external energy sources, using
100% 'renewable' energy. Additionally, the use of a PAT instead of a turbine
leads to reduced costs, an increased robustness and easier maintenance of the
equipment.
Fig. 4.1. Schematic overview of the planned retention and lifting of the cave water (left),
underground water sources of the karst cave Bribin (right) (source: IWG)
Since it is not sufficient to pump the water to the surface, the project also takes
care of the distribution of the drinking water within the supply area. The Water
Supply Network Section is involved in this part of the project. Within the project
area a distribution system already exists. The objective of the sub-project is to per-
form a rehabilitation planning for the existing system. The decisive factor in
achieving a positive energy balance is the development of an optimised opera-
tional strategy. Pump manufacturers predict an energy saving potential for pump-
ing systems of between 20-40% worldwide by means of optimised operational
strategies (Broderson 2006). Therefore attention has to be drawn to the selection
of the 'right' pumps in terms of appropriate pumping head and quantity of water.
Additionally, the pumping schedules have to be well designed. To develop an op-
timised operational strategy, the use of a numeric model of the water supply net-
work is of advantage. The setup of the numeric model is therefore one of the first
steps during the work of the Water Supply Network Section. Further, it is planned
to implement a SCADA system (Supervisory Control And Data Acquisition sys-
tem) in combination with the control technology of an industrial partner. The final
goal will be to develop an operational management tool, which will be able to ana-
lyze the data of the control system and the calculation results of the numeric
model. The tool will provide the operator with recommendations on operational
strategies, adapted to the real-time state of the system.