Les défis de remettre à neuf des centrales hydroélectriques

Bien que de nouvelles centrales hydroélectriques soient construites encore de nos jours à l’échelle mondiale, et que plusieurs projets de centrales soient à l’étude, il n’en demeure pas moins que la grande majorité des centrales actuellement en opération ont été construites il y a plus de 20 ans, certaines datant même de plus de 50 ans. Divers facteurs rendent la réfection de ces centrales inévitable, les plus évidents étant l’usure des équipements, l’encrassement de la tuyauterie et les besoins accrus en entretien.

Not only are these refurbishments associated with repairing or replacing equipment and piping, they are also often linked to an increase in turbine-generator unit capacity. In fact, new technologies offer operators the option of increasing the power produced by turbine-generator units (additional capacity), most specifically by improving the turbine wheel blade or penstock wall profiles. For example, 50% additional capacity for a 50 MW unit translates into an increase in annual power output of 219 GWh, considering a 50% utilization factor. If we consider a production cost of 2.5 ¢/kWh and a sales price of 7 ¢/kWh, this results in a gross annual profit increase of $9.9 million. Even for a project costing only a few tens of millions of dollars, the return on investment is recovered within just a few years. In order to proceed with increasing a generating station’s capacity, the mechanical and electrical auxiliary systems connected to the turbine-generator units often require refurbishment due to the increased requirements associated with the higher turbine-generator unit capacity, such as a greater need for cooling water and for air to the air brakes and to the regulation system.

Years ago, medium and large generating stations (with capacities varying from several hundred to several thousand megawatts) were on the receiving end of many refurbishment projects, since even a slight increase in capacity resulted in significant production increases. However, with the price of electricity rising continuously, it has also become profitable to refurbish smaller generating stations, those with capacities of a few tens of megawatts. This is true for both private generating stations and those run by larger government agencies.

This white paper covers the major mechanical challenges associated with refurbishing hydroelectric power plants.