Hydro Power Development

Deep rocky canyons, such as those along the Colorado River in Arizona, can provide suitable locations for hydroelectric dams.

Hydropower is one of the oldest renewable energy sources used by humankind and remains a major source of renewable electricity. Further development is expected particularly in emerging and developing economies, where substantial hydropower potential remains untapped. The construction of new plants will nevertheless depend on economic feasibility, environmental conditions and the availability of suitable locations.

Hydropower remains the world’s largest individual source of renewable electricity. In 2024, it supplied approximately 14% of global electricity generation. Although solar and wind power are expanding rapidly, hydropower continues to play an important role in electricity production and provides valuable flexibility in power systems.

Further hydropower development is expected particularly in countries with substantial untapped potential, including Brazil, China and India. New projects may include both medium-sized plants and large reservoirs, whose construction can have significant environmental and social impacts. Small hydropower plants can contribute to local electricity supplies, while the refurbishment and modernisation of existing facilities can extend their operating lives and improve their performance.

Hydropower will play an increasingly important role in energy storage. Pumped-storage hydroelectric power plants provide a proven and efficient solution for storing large amounts of energy and balancing electricity supply and demand. By the end of 2025, their total installed capacity worldwide had exceeded 200 GW, with further projects under construction and development.

4 pictures

4 pictures

Ocean Power Development

Experimental and early commercial technologies are being developed to harness energy from ocean waves.

The use of ocean energy is developing through several different technologies. Tidal range power plants are an established form of electricity generation, while tidal stream turbines and wave-energy converters are progressing through demonstration and early commercial deployment. Their future contribution will depend on technological reliability, installation costs and the availability of suitable marine locations.

Tidal energy can be harnessed by constructing barrages across bays or estuaries, where the difference between high and low tide is used to generate electricity. Such projects may significantly affect local ecosystems and water circulation. An alternative is the construction of artificial tidal lagoons, which use a similar operating principle but offer greater flexibility in selecting the location and layout. Their feasibility depends on construction costs, tidal conditions and environmental impacts.

Tidal stream generators (TSGs) extract energy from moving tidal currents without requiring the construction of a barrage. Their environmental and visual impacts are generally different from those of tidal range projects, although suitable site selection and assessment of potential effects on marine life remain necessary. Most designs use horizontal-axis turbines resembling underwater wind turbines, while vertical-axis configurations are also being developed.

Tidal stream turbines must withstand strong currents, cyclic mechanical loads and the corrosive marine environment. Their structures and materials therefore require robust design and effective protection. Individual turbines can have rated outputs of several megawatts, while arrays of multiple turbines may be developed into larger installations as the technology matures.

The predictable pattern of tides makes tidal electricity generation easier to forecast.

Tidal power generation is highly predictable, although its varying output must be taken into account when integrating it into the electricity grid.

Ocean waves contain substantial energy that could contribute to future electricity generation. A variety of wave-energy converters are being developed, using different mechanical and hydraulic principles to transform wave motion into electricity. Although several technologies have been demonstrated at sea, their wider deployment still depends on improving reliability, reducing installation and maintenance costs and limiting environmental impacts.

The Pelamis wave-energy converter was one of the pioneering technologies developed to generate electricity from ocean waves. Its full-scale devices underwent sea trials in Scotland, providing valuable operating experience. However, the developer, Pelamis Wave Power, entered administration in 2014, and the technology did not achieve widespread commercial deployment.

Ocean thermal energy conversion (OTEC) uses the temperature difference between warm surface water and cold deep ocean water to generate electricity. In suitable tropical locations, a temperature difference of around 20 °C or more can provide relatively continuous power generation. Wider deployment remains limited by high costs and low conversion efficiency.

3 pictures

3 pictures