Les petites installations hydroélectriques dans les pays industrialisés

Small hydroelectric installations in the industrialized countries

Ingénieur en Chef des Ponts et Chaussées, Chargé de Mission auprès du Directeur du Gaz, de l'Électricité et du Charbon

Abstract

Since 1973, the potential benefit of hydraulic power has evolved in varied ways in different regions of the world. It has increased considerably in those zones that otherwise must have recourse to small thermal stations burning oil (diesel sets). It has increased much less in an industrial country like France, which, in an initial phase, quickly replaced much of the heavy fuel oil burnt in thermal power stations by coal, and then, in a second phase, has very significantly boosted its production of nuclear electricity. Between 1973 and 1979 (i.e. before the nuclear programme committed since 1974 began to come into service) the average sales price of electricity, expressed in constant francs, fell slightly in low voltage and did not even rise by 20 % in high voltage. The situation may vary from one industrial country to another, but in general, electricity prices have risen much less than those of oil products. However, the potential benefit of stations that can be used for peakload consumption (stations associated with large reservoirs, and those that transfer energy by pumping) has become much greater, since these make it possible to avoid the use of gas turbines that burn fuel oil. On the other hand, run-of-river plants, which produce a large proportion of their energy in summer, have become less cost-effective in the last ten years, especially if account is taken of the greater attention that is now paid to environment problems. In France, alongside a number of small installations operated by EDF there are plants owned by private persons or companies whose production is consumed by them or sold to the electricity distributors. In 1979, production from this private sector totalled 2.0 billions kWh out of an overall hydroelectric production of 62.6 billions and total consumption of 236 billions kWh. For more than 20 years, this private sector has been very active: small out-of-date installations have been closed down, larger ones have been modernized or newly built... but so far there has been no change in the corresponding rate of increase in production that can be attributed to the energy crisis. It may however be estimated that the production of electricity from plants with powers of less than 5,000 kW could rise further by 1 to 2 billions kWh in forthcoming decades. The prices at which electricity distributors - and EDF in particular - are required to buy in electricity from the private sector have risen on average by 20 % in constant franc terms in the last ten years; this rise may vary considerably from one rate bracket to another (summer/winter, peak/off-peak times). This increase, which may be less in the future, is considered to be a sufficient incentive for the building of new plants. But it is to be feared that if there is a proliferation of small plants in certain mountainous zones the distribution networks to which they are connected may have to be significantly reinforced; the costs of this reinforcement will obviously have to be taken into account with the cost of these plants. For, the lines and the transformers are designed to keep variations in the voltage delivered to subscribers within a range fixed by regulation. The presence of a small plant modifies the voltage variations in the system and in particular can cause sudden variations if there are abnormal incidents at the plant. In certain very special cases it may even be necessary to build separate mediumvoltage networks, on the one hand to bring in energy from small hydraulic power stations and on the other to supply current to subscribers. In conclusion, while small hydroelectric stations can certainly make an important contribution in developing countries in damp or mountainous regions, industrialists thinking of building new 10w-fall stations in France should carry out careful and serious studies before committing themselves. Since 1973, the potential benefit of hydraulic power has evolved in varied ways in different regions of the world. It has increased considerably in those zones that otherwise must have recourse to small thermal stations burning oil (diesel sets). It has increased much less in an industrial country like France, which, in an initial phase, quickly replaced much of the heavy fuel oil burnt in thermal power stations by coal, and then, in a second phase, has very significantly boosted its production of nuclear electricity. Between 1973 and 1979 (i.e. before the nuclear programme committed since 1974 began to come into service) the average sales price of electricity, expressed in constant francs, fell slightly in low voltage and did not even rise by 20 % in high voltage. The situation may vary from one industrial country to another, but in general, electricity prices have risen much less than those of oil products. However, the potential benefit of stations that can be used for peakload consumption (stations associated with large reservoirs, and those that transfer energy by pumping) has become much greater, since these make it possible to avoid the use of gas turbines that burn fuel oil. On the other hand, run-of-river plants, which produce a large proportion of their energy in summer, have become less cost-effective in the last ten years, especially if account is taken of the greater attention that is now paid to environment problems. In France, alongside a number of small installations operated by EDF there are plants owned by private persons or companies whose production is consumed by them or sold to the electricity distributors. In 1979, production from this private sector totalled 2.0 billions kWh out of an overall hydroelectric production of 62.6 billions and total consumption of 236 billions kWh. For more than 20 years, this private sector has been very active: small out-of-date installations have been closed down, larger ones have been modernized or newly built... but so far there has been no change in the corresponding rate of increase in production that can be attributed to the energy crisis. It may however be estimated that the production of electricity from plants with powers of less than 5,000 kW could rise further by 1 to 2 billions kWh in forthcoming decades. The prices at which electricity distributors - and EDF in particular - are required to buy in electricity from the private sector have risen on average by 20 % in constant franc terms in the last ten years; this rise may vary considerably from one rate bracket to another (summer/winter, peak/off-peak times). This increase, which may be less in the future, is considered to be a sufficient incentive for the building of new plants. But it is to be feared that if there is a proliferation of small plants in certain mountainous zones the distribution networks to which they are connected may have to be significantly reinforced; the costs of this reinforcement will obviously have to be taken into account with the cost of these plants. For, the lines and the transformers are designed to keep variations in the voltage delivered to subscribers within a range fixed by regulation. The presence of a small plant modifies the voltage variations in the system and in particular can cause sudden variations if there are abnormal incidents at the plant. In certain very special cases it may even be necessary to build separate mediumvoltage networks, on the one hand to bring in energy from small hydraulic power stations and on the other to supply current to subscribers. In conclusion, while small hydroelectric stations can certainly make an important contribution in developing countries in damp or mountainous regions, industrialists thinking of building new 10w-fall stations in France should carry out careful and serious studies before committing themselves.