Introduction

Compared with a classic hydroelectric plant, the energy generation upon potable water conveyance offers numerous advantages. The environmental impacts, related to this system and integrated in a project with multiple choices, are very slight. The forced pipe is not specific to the system because it also feeds the potable water network of Megève. Moreover, pipes are buried, and catchments are on the hill. There are no visual impacts because the system is located in the basements of the Sports Centre and is invisible. In the same way, no additional disruption of the aquatic ecosystem is endangered by the energy promotion of an existing water network. The sound impacts are probably the most important, and are simply felt in a limited area inside the Sports Centre. They do not disrupt in any way to the normal functioning of the Centre, except in case of concerts in the Conference room, where, most of the time, turbines are stopped. At the level of the potable water quality, there is no problem because water that has already passed through  the turbines is not supplied back into the water network, but drained off in the stream of the Arly. The re-introduction of the water into the network that has already gone through the turbines, is possible, but not really economically interesting in the case of Megève because it requires the functioning of pumps to bring water back to the working pressure, which is approximately 7 bars. Generally, there is no reason for not supplying the water that has gone through the turbines in the potable water network. In other plants, there is no major problem to report, except an increase of ventilation following the fact that water has gone through the turbines. The hydroelectric system does not bring any chemical water pollution. Nevertheless, it is possible to take additional precautions by using food fat in bearings and/or by putting in waterproof bearings on the turbines.

Objectives and target audience

To reduce the use of the non renewal resources and to innovate the production processes (technologies alternative).

Financial Resources and Partners involved

The investment relative to the putting back of the turbine into service, and to its automation is to 234 000 euros between 1981 and 1985, representing an investment of about 830 Euro/kW. The maintenance of the system is cheap, and carried out  by the maintenance shifts of the sports centre. Now, the turbine works at approximately 4 800 hours a year. Annual savings linked to the micro plant are about 38 100 euros/year in the field of the electricity self-consumed (pumps, turbo compressor, light…), and 7 620 euros coming from the sales of the energy produced to the French Electricity Company.
Partners involved:  MEGEVE City Municipality.

Process

The hydroelectric micro plant is located in the Sports and Conference Centre of Megève, which is a multifunctional and covered complex of 9 320 square metres (sports, pool, ice rink, shows, conferences). Built at the same time as the Sports Centre, it dates back to 1968, and belongs, just like the latter, to the town of Megève. In 1978, the annual consumption of fuel oil reached 540 000 litres. That is why the Municipality of Megève decided to undertake an important programme, in the long term, of energy economy to reduce this consumption and for a better use of the hydraulic energy available: Replacement of the 2 boilers of 1 850 kW by 2 boilers of 464 kW.

• Installation of a heat pump water-water of 70 kW driven by the turbine.

• Improvement of the recovery of calories from the turbo compressor producing ice for the ice rink and heating water for pools.

• In 84-85, there was an increase of the capacity of the reservoir of the Livraz from    1 000 to 5 000 square metres, optimization and automation of the working turbine, generator, heat pump, home consumption of the energy produced, sale of the surplus, and purchase of water if there is a lack of it, priority always being obviously given to public consumption.

Results

The results are considerable because the annual consumption of fuel oil has thus, on average, gone from 540 000 to 180 000 litres a year since 1983. And this despite important expansions such as an outside Olympic pool (50 m) in 1981, a gymnasium and covered tennis court of 2 500 square metres in 1984, heated by circulation in the ground of the water of pools (27°C), the latter being heated by the turbo compressor of the ice rink, etc. The electric consumption of the Centre is approximately 1 200 MWh/a. The volume of water going through the turbine is, in average, of 1 500,000 sq.m./y.
Company and especially to the electricity self-consume on the site, Megève can ensure the annual running of the Sports and Conference Centre at a competitive price, and offer its inhabitants and tourists great cultural and sports facilities.
The people in charge of the system of the hydropower micro plant of Megève are unanimous as for the quality of facilities : their profitability (due to the low cost of investment compared with a classic system) and their slight impacts on the environment are just so many elements which should, in the future, win over more and more other local authorities. All these are significant assets which add to the satisfaction of producing and using a clean and renewable energy, in prospect of a sustainable development and of an harmonious town and country planning.
The short and medium-term prospects of the persons in charge are, in this field:

• to replace, over approximately 600 metres, the pipe of a diameter of 300 m by a pipe of a diameter of 350 m, to reduce the losses of charge, and then increase the efficiency of the turbine (made and in operation since May 2002).

• to use, on another site, an already existing pipe for potable water conveyance of a diameter of 250 m and of a length of 1 000 metres, to settle a Pelton turbine of 100 kW on it.

• to study, between May and October, the action of the turbines over important supplies of stand by water, recently created for the production of artificial snow (snow-blowers), and only used between November and April.

Critical Success Factors / Challenges