Green Win, the system set up at the University of Liège, has made it possible to test the operation of large pumps, which can weigh up to one tonne, and pump 300 litres per second in waterways.
Even though river freight is much less polluting than road transport, the high energy consumption of the pumps that control the water level of rivers and canals in north-west Europe can be further reduced, while also reducing their greenhouse gas emissions.
In the midst of the climate crisis, water is a major challenge. The Belgian city of Liège is crossed by the River Meuse. The river, like other waterways, is managed by an operator; each European country has one or more management bodies. Europe has 35,000 km of waterways.
Hydraulic researchers at the University of Liège are working on ways to save energy in the management of these river routes, in collaboration with the thermodynamic laboratory. The Green Win project funded by the European Union has tackled excessive consumption during water pumping for five years. Water pumping has a significant carbon impact in north-west Europe, accounting for 25-33% of the annual electricity consumption of waterway management organisations and around 20% of total emissions.
Benjamin Dewals, professor at the university, explains that “a test bench has been installed which enables submersible pumps to be tested in almost real conditions. These are pumps capable of pumping water up several tens of metres. The system makes it possible to estimate the quantities of energy consumed for a very wide operating range in terms of flow rate and height where the water is pumped up.”
Simulating all possible situations
The University of Liège is a benchmark in Europe in terms of hydraulic research. The researchers have installed a hydraulic loop, which simulates all kinds of situations that can be found in the field. The tests were carried out with four pumps sent from Ireland and Great Britain, in a tank three metres wide and 4.50 metres high.
Jorys Hardy, a postdoctoral researcher, explains that “in this tank there was water and the pump sucked the water in, the water went through pipes inside the laboratory, and we had certain sensors along the water's course in order to measure the flow rate and the pressure generated by the pump... as well as a regulating valve to reduce the flow rate.”
“By reducing the frequency of the pumps’ rotational speed we increase the efficiency of the pump,” emphasises Benjamin Dewals, before adding “we go further than the manufacturers’ recommendations for use.”
Green Win’s budget amounts to 2.67 million euros, including 1.6 million subsidised by the European Union cohesion policy.
Eleven pilot sites in Europe
Five countries associated with the project (Ireland, UK, Netherlands, Belgium and France) are verifying operation under real conditions in 11 test locations. These include the Etang du Stock lake, in Moselle, which has been modernised thanks to technical advice from the University of Liège. Managed by Voies Navigables de France (VNF - the French Waterways Office), it is one of their largest pumping stations. The lake is precious as it represents a useful water reserve of 33 million m3 of water over an area of 1,500 hectares.
Jérôme Pfeiffer, deputy district head in Moselle for the VNF, details the modernisation of the station which “made it possible to install five submerged pumps which today can be managed remotely. We observed a 30% increase in energy savings,” he adds.
The lake filling speed capability has been improved.
When boats pass through the locks, thousands of litres of water flow downstream. The pumping station pumps water from the lake to the canal around a hundred times a year.
Olivier Christophe, engineer and project management manager in Strasbourg for the VNF, confirms that “initially the station is used to fill the reservoir lake in wet periods, and in dry periods, the canal which is six metres higher. We need to supply it with water, so for that we need a pumping station.”
France, the European country with longest length of waterways
With its 8,500 km of waterways, France has the largest network in Europe. The VNF’s main mission is to closely regulate water resources in the public interest and with respect for the environment. This also enables navigation and ensures the safety of hydraulic structures. To modernise, the VNF has also received 200,000 euros in European subsidies as part of the Green Win project. The total investment in modernising the Etang du Stock site amounts to 1.2 million euros.
The economic and environmental benefits are already clearly visible: the researchers hoped to reduce CO2 emissions by 65 tonnes per year on the 11 pilot sites of the Green Win project, but in fact the reduction amounts to 200 tonnes.