Can small-scale hydropower contribute significantly to the energy transition?

The potential for additional development of small hydropower in Switzerland is around 1.5 TWh per year, or around 3% of our current electricity consumption.

In Switzerland, small hydropower plants (or “small hydropower”) are defined as hydropower plants with a capacity of less than 10 MW. These facilities usually harness the power of waterfalls ranging in height from 1 m to more than 1,000 m.

Because of the seasonal variability of river flows, the power output of small hydroelectric facilities, like that of large run-of-river facilities, varies throughout the year. While installations in the Alps have their maximum production between spring and summer (due to snowmelt), lowland or Jura Arc structures tend to have maximum production between autumn and spring. The latter structures are of particular interest to Switzerland, which has a shortage of domestic electricity supply in winter [→ Q11].

Small hydropower plants are available in yet another configuration: “accessory” or “multi-purpose” power plants. This term refers to works “grafted” onto existing water pipes, such as drinking water or waste water networks, irrigation networks, tunnel drainage networks, etc. These mini-power plants are particularly interesting because they require a minimum investment, take advantage of existing infrastructures, and do not generate any additional negative environmental impact while offering a relatively constant production of electricity from renewable sources throughout the year.

Although small hydro has been in operation for decades, it is considered “new renewable energy” [→ Q46] and as such benefits from the federal government’s feed-in tariff remuneration system (RPC) support programme [→ Q79]. In 2004, before the introduction of RPC, Switzerland already had more than 1,000 small hydropower plants with a combined output of approximately 3.4 TWh, or 10% of our hydropower production at that time. The implementation of the RPC in 2006 accelerated the development of small hydropower, with almost 800 new small hydropower plants having received a positive decision between 2006 and June 2014, and more than 400 other projects currently on a waiting list. To date, more than 1,000 small hydropower plants have been installed, with a total cumulative capacity of 0.76 GW. They have produced more than 3.4 TWh of electricity, which represents a significant fraction of the production of new subsidised renewable energies (wind, photovoltaic, biomass, geothermal).

It is estimated that the total generating capacity of small hydropower could increase by a further 2.5 TWh per year. This increase would mainly result from the modernisation of existing facilities, the rehabilitation of abandoned sites and the construction of new facilities. In all, small hydropower plants could then supply around 5 TWh of electricity annually. How much of this potential will actually be exploited will depend on the federal government’s support for small-scale hydropower, which cannot be developed without a contribution from the RPC [→ Q58].