How to Downsize Diesel Generators on Microtunneling and Pipe Jacking Operations Using Flywheel Storage

Customer Requirements

The territory of French utility company Atlantic’eau is 70% dependent on the Loire for its drinking water supply. To secure the region’s water supply, Atlantic’eau decided to interconnect the drinking water network located north of the Loire, linking Nantes to Saint-Nazaire, with the one serving the south of the Loire from Basse-Goulaine. This required new pipeline to be laid between Vigneux-de-Bretagne and Rouans. This 600mm diameter and 17km long pipeline crosses the Loire between Le Pellerin and Couëron inside a larger 1.8 meter concrete tunnel. It transports up to 18,000m³ of drinking water per day by gravity.

Results

The technique used, known as microtunneling, uses a tunnel boring machine which is advanced by a process known as “pipe jacking”. In this process, hydraulic rams are used to push the machine through the earth. Bentonite is used a lubricant to ensure the pipe passes smoothly through the earth. Generating hydraulic pressure to perform tunnelling operations requires large hydraulic pumps, which in turn require large amounts of electric power to run. In common with many pump types, hydraulic pumps have a large power requirement during start-up. As the pumps are started many times per day, a Peak Power 200 flywheel system was deployed. By providing a boost of 85kW and improving the power factor by providing reactive power, the diesel generator could be reduced in size.

In many ways this was a straightforward application, but it’s notable for several reasons:

Firstly, this application required large amounts of power – in this case provided by a pair of synchronised 500kVA generators.

Secondly, due to the remoteness of the site no mobile phone data connection was available. Normally this would mean no telematic connection, but in this case Dumarey Green Power fitted the unit with an external Wi-Fi antenna, so the unit could connect through Wi-Fi. This allowed remote monitoring to ensure the performance of the system was maintained.

Finally, this is the first reported use of the Peak Power 200 on a tunnelling application. Dumarey Green Power would like to thanks all the teams involved, including those from tunnelling company Denys, and power providers Power Solutions and Locquet Power and Light.