Hydraulic power: what is the future for white coal?

With 69.8 TWh in 2024, renewable hydroelectricity reached its record level of production since 2013. Second source of electricity in France, it is also the first source of renewable energy.

At the end of 2024, theHydraulic power represented 14% of national electricity production, far behind nuclear power with 67.4%, but ahead of other renewable energies (wind, solar, bioenergies, etc.). In 2024, its production covered 15.8% of French electricity consumption.

Derived from the power of water, hydraulic power is a renewable energy with low greenhouse gas emissions and reduced production costs. These advantages seem to make it an indispensable energy to achieve the carbon neutrality in 2050.

However, despite the record increase in production in 2024, the last few years have shown the limits of the potential of “white coal”.

Is it energy from the future or from the past? What are its strengths and challenges? How can it be part of the energy transition?

Lighting.

How does hydraulic power work?

Run-of-river power plant, lake power plant, small hydroelectric power plant, STEP (pumped energy transfer station)...: these different types of hydroelectric installations are distinguished by Their power and their production potential.

But they all share one thing in common: use the force of water to produce electrical energy.

Source: Run-of-river power plant - Encyclopedia of Energy

Basic principles of hydraulic power

Hydraulic power uses thekinetic energy created by the movements of water to produce energy. It operates natural movements like currents or waterfalls, or artificial elevations created by man. The greater the height difference between the downstream and the upstream of the power plant, the higher the water pressure and the more the production capacity increases.

Unlike wind and solar, hydroelectricity offers energy storage capacities can be immediately transformed into electricity without loss of efficiency. It thus plays a major role in the regulation of electricity production and distribution.

The key components of a hydraulic power system

Hydraulic turbines

The hydraulic power system is based on turbines. These are activated by the movements of the water. The greater the pressure and the speed of the water, the faster the hydraulic turbines rotate.

Kinetic energy is transformed into so-called mechanical energy. It can be used directly, as in the case of the watermills of our ancestors, or transformed into electrical energy.

Alternator or generator

It is the alternator or generator that transforms mechanical energy in electrical energy. The electric current then passes through a transformer to adapt the voltage to domestic uses and allow the transport of electricity in the network.

Tank and pipes

Some hydroelectric power plants are equipped with a weir.

Its role: to retain water. This is released on demand via a system of valves, and directed to the turbines via pipes.

Powerful installations with strong differences in altitude, lake power plants make it possible to quickly regulate electricity production according to consumption needs.

Conversely, run-of-river power plants and small hydropower plants do not have storage tanks. Water flows naturally for continuous electricity production.

What are the advantages of using hydraulic power?

A renewable and clean energy, hydraulic electricity has numerous environmental advantages. Produced locally, it contributes to the economic development of territories.

Environmental benefits: renewable green energy

Hydraulic power emits very few greenhouse gases, a considerable advantage for carbon neutrality. Its emissions are estimated at 6 g of CO₂ per kWh, identical to those ofnuclear electricity.

To compare with other renewable energies, photovoltaic electricity emits an average of 44 g eq. CO₂/kWh and onshore wind 14 g eq. CO₂/kWh. These greenhouse gas emissions are much lower than those of fossil fuels: 243 g eq. CO₂/kWh for natural gas or 1,060 g eq. CO₂/kWh for a coal power plant.

Water is also a natural and sustainable resource. During the hydraulic power production cycle, it does not undergo any transformation. It follows its path and reintegrates the water life cycle downstream.

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Economic advantages: an accessible production cost

As the Commission de Régulation de l'Énergie (CRE) observes, the cost of hydroelectric production varies greatly from one installation to another. It varies from 37 to more than 200 €/MWh depending on investment and operating costs, the capacity of the structure and its age. In comparison, in a 2023 report, CRE estimated the full cost of nuclear power at €60.7/MWh over the period 2026-2030.

But while the most powerful power plants may require large investments, operating and maintenance costs are reduced. And these very long-lasting installations allow certain amortization of costs over time.

Social benefits: jobs that cannot be relocated

Very localized, the hydroelectric sector contributes to the economic development of territories. According to a study by the Syndicat des Énergies Renouvelables, hydroelectricity represents more than 30,000 direct, indirect and induced jobs in France, which cannot be relocated.

Large dams are also attractive tourist sites, rooted in local history. Hiking, industrial tourism, sports activities can be organized safely around the reservoirs, in partnership with operators.

Hydraulic energy: the challenges

No power generation solution is perfect. While hydraulic power offers many advantages, it raises environmental and safety questions.

Environmental issues: protecting ecosystems

The construction of hydroelectric dams and their artificial water reservoirs is shaking up the surrounding ecosystems.

As early as 2006, France took up this issue in order to reduce the environmental impact of hydroelectricity. The law on water and aquatic environments imposes a framework for the deployment of hydroelectric power plants.

It requires operators to take measures to preserve the fauna and flora upstream and downstream of the power plants: maintain watercourses at a reserved minimum flow, set up fish passes, respect stream beds, etc. The legislation also protects certain watercourses, etc. The legislation also protects certain watercourses, which are identified as natural reserves for certain aquatic species.

Safety of hydraulic structures: constant surveillance

In 1959, the collapse of the Malpasset dam in Fréjus, Var, caused the death of 423 people. This accident is the only one recorded in France over a century.

While dam failures are rare, France has put in place a reinforced security system. Under the aegis of the State Hydraulic Works Safety Control Service (SCSOH), operators are required to constantly monitor hydroelectric power plants and to carry out regular checks and periodic hazard studies.

Hydraulic energy: what are the future prospects in France and in the world?

A pioneer energy, hydroelectricity is one of the oldest energies in the world. If it had its heyday in the 20th^E century, can it find its place in the 21st^E century?

The main production sites in France and around the world

France has more than 2,500 hydroelectric installations. With 25.7 GW installed, the power potential has remained stable for several years. The greatest potential for hydraulic production is located in the mountainous regions of the South.

In 2024, the podium is occupied by:

• The Auvergne-Rhône-Alpes region, which represents more than 44% of the hydroelectric power connected in France (11,422 MW) with a production of 29,835 GWh.
• The Occitanie region, which represents nearly 21% of French hydroelectric power (5,347 MW) with a production of 11,242 GWh.
• The Provence-Alpes-Côte d'Azur region, which represents 12% of the installed capacity in France (3,230 MW) with a production of 12,041 GWh.

The second largest producer of hydroelectricity in Europe after Norway, France remains far from the main producers of hydroelectricity in the world: China, Brazil, Canada and the United States.

Globally, hydroelectricity represented 14.3% of global electricity production in 2024. It is the third source of electricity behind the coal (34.3%) and the natural gas (22%).

The Three Gorges Dam in China is the largest hydroelectric power plant in the world. With 22.5 GW installed, it represents the power of 16 nuclear reactors.

What is the future for hydroelectricity in France and around the world?

In France

With 25.7 GW of installed capacity, hydroelectricity represents 17.4% of the French electrical production and storage fleet, but only 14% of the electricity produced.

While 2024 was a record production year due to abundant rainfall, hydropower suffered several years of drought, especially between 2020 and 2022, with a drop in production of 28%. Hydroelectricity is therefore highly dependent on hydrological conditions.

Second limit to the development of hydraulic energy in France: the achievement of the production capacities of the French hydroelectric park, deployed since the end of the 19th century^E century.

However, there is still room for improvement. The project of multiannual energy programming under discussion (PPE3) plans to increase the capacity of hydroelectric power plants by 2.8 GW in 2035. France is focusing in particular on WWTPs, with 1.7 GW of additional power.

In the world

Globally, hydroelectric potential is far from reaching its peak. According to Pierre-Louis Viollet, director of the EDF R&D department, annual production now reaches a third of its capacity.

The African, South American and Asian continents contain unexploited resources. Investments coupled with strong political will could increase global hydroelectric production to 14,600 TWh and cover 75% of global electricity consumption.

Among the flagship hydroelectric projects, China announced in early 2025 the construction of the world's largest dam: with a capacity of 60 GW, the Motuo dam should produce around 300 TWh each year, almost the equivalent of France's annual nuclear production!

Other gigantic dams are under construction or studies, including the Australian “Snowy” 2.0 project.

Following construction delays, the commissioning of this 2,000 MW wastewater treatment plant with a capacity of 350 GWh and a storage capacity of 350 GWh is expected in 2028.

To conclude...

Renewable, economical and low CO emitting₂, hydraulic power is emerging as an essential energy source in the energy transition. It forms the basis of tomorrow's energy mix, alongside solar and wind energy.

Although its development prospects seem limited in France, existing hydroelectric power plants constitute a real energy treasure to be preserved and optimized in order to continue to transform blue gold into electricity. What if the future of hydropower also came from small hydroelectricity and from the sea with tidal energy.