While Europe acts to reduce carbon emissions and meet its goal of 20% renewable share by 2020, it has also committed to improving the aquatic quality of all water bodies including riverbeds downstream hydropower dams through the less known Water Framework Directive (WFD).

In many cases this imposes a substantial increase of the so called ecological flow (eco-flow) released from hydropower dams to their downstream riverbeds. Increased eco-flows means lost production, as the eco-flow water will not pass through the main plant turbine. Estimated consequences of full imple­mentation of the WFD is a 3-5% loss of European hydropower production, amounting to 10-15TWh per year, equivalent to 1000 – 1500 modern wind turbines.

On the positive side, these increased eco-flows become sufficiently large to financially be exploitable for adapted turbine solutions in the 100 – 2000 kW range. This is why European hydropower producers seek new solutions to turbinate these increased eco-flows.

CleanPower Turbinator

Norwegian company CleanPower has over the last decade developed the Turbinator, a small hydro turbine with an integrated generator and capabilities that make it particularly well-suited for turbinating eco-flows.

Each unit is configured for site head, flow and suction head need. It is compact, has a fully sealed generator cooled by the water flow, and can in some cases be installed outdoors, without a power house – minimszing civil works cost and footprint.

The first pilot installation on the Statkraft Hegset dam in Norway in 2010 confirmed the conceptual design (see November 2010 article in IWPDC), and through subsequent installations in Norway, details in the construction have been improved and refined up to the present commercial product.

Technical description

The Turbinator is a low head axial flow Kaplan turbine with fixed runner wheel pitch and adjustable guide vane, with an integrated direct drive permanent magnetised synchronous generator (PMG). The PMG rotor sits on the perimeter of the runner wheel, making a unit with one single rotating assembly. It connects to up- and downstream piping with standard flanges, making installation particularly easy.

The control panel features fully autonomous operation under remote surveillance, adaptable to customer requirements, SCADA integration etc.

CleanPower can configure Turbinators for heads ranging from 10 to 50m, with power ranging from 100 to 1500 kW by selecting among a pallet of runner wheel geometries and size models.

In the development phase CleanPower collaborated closely with the Swedish Kaplan turbine expert Evald Holmèn. The axial Kaplan runner wheel designs are based on model tested Kaplan configuration developed in Swedish turbine laboratories.

EDF Raviège dam

The 40m high Raviège hollow gravity dam on the Agout river in the Tarn region of South-West France was built in the late 1950s and is operated by EDF. It was upgraded in 2015 with a Piano Key weir for improved flood management.

The Raviège lake is the annual storage reservoir of the Agout valley and the power station directly adjacent to the dam delivers power and flow during peak hours.

As the eco-flow release was been increased in 2014, for the periods where the main power station is not running, EDF sought a compact turbine solution that would fit the narrow space available between the existing bottom outlet and other existing civil works. Following technical evaluations and site visits to existing installations in Norway, EDF selected the Turbinator. In addition to the advantageous small footprint, it was also considered reliable due to its simple and robust design.

EDF Project Manager Yann Marcilloux explains: "We have chosen the innovative solution from CleanPower because it reduces the footprint of the installation by a factor of two or three compared to a conventional solution, simplifying the installation on the downstream side of the dam. The installation will give a production of around 2000MWh covering the annual consumption of a village with 1000 inhabitants."

Simplistic installation

The Turbinator is conceived to achieve a compact and robust yet simplistic installation. Using this approach the Turbinator has the potential to open up hydropower installations on sites previously not financially viable. Its main features are:

Minimal footprint – Turbinator can be used on sites where traditional solutions would not fit, opening up previously unexploitable hydropower resources.

  • Easy flange in / flange out installation
  • Generator efficiently cooled by the water stream
  • Reliability through a simple and robust design with only one rotating part
  • Low noise

With its small footprint, EDF is studying other possibilities for similar eco-flow installations where the footprint of the power station is a problem. There are possibly several sites in France where the eco-flow is delivered without creating any energy because of the site configuration.

Market potential

Commenting on the market outlook CleanPower CEO Egil Opsahl said they have received significant interest for their solution both from Europe and elsewhere, and are in dialogue with Norwegian, Italian, Spanish, North- and South-American, Caribbean companies.