Small hydro is the development of hydroelectric power on a scale suitable for local community and industry, or to contribute to distributed generation in a regional electricity grid. Exact definitions vary, but a "small hydro" project is less than 50 megawatts (MW), and can be further subdivide by scale into "mini" (<1MW), "micro" (<100 kW), "pico" (<10 kW). In contrast many hydroelectric projects are of enormous size, such as the generating plant at the Three Gorges Dam at 22,500 megawatts or the vast multiple projects of the Tennessee Valley Authority.
Hydroelectricity, or hydroelectric power, is electricity generated from hydropower. Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and also more than nuclear power. Hydropower can provide large amounts of low-carbon electricity on demand, making it a key element for creating secure and clean electricity supply systems. A hydroelectric power station that has a dam and reservoir is a flexible source, since the amount of electricity produced can be increased or decreased in seconds or minutes in response to varying electricity demand. Once a hydroelectric complex is constructed, it produces no direct waste, and almost always emits considerably less greenhouse gas than fossil fuel-powered energy plants. However, when constructed in lowland rainforest areas, where part of the forest is inundated, substantial amounts of greenhouse gases may be emitted.
Micro hydro is a type of hydroelectric power that typically produces from 5 kW to 100 kW of electricity using the natural flow of water. Installations below 5 kW are called pico hydro. These installations can provide power to an isolated home or small community, or are sometimes connected to electric power networks, particularly where net metering is offered. There are many of these installations around the world, particularly in developing nations as they can provide an economical source of energy without the purchase of fuel. Micro hydro systems complement solar PV power systems because in many areas water flow, and thus available hydro power, is highest in the winter when solar energy is at a minimum. Micro hydro is frequently accomplished with a pelton wheel for high head, low flow water supply. The installation is often just a small dammed pool, at the top of a waterfall, with several hundred feet of pipe leading to a small generator housing. In low head sites, generally water wheels and Archimedes' screws are used.
The Conowingo Dam is a large hydroelectric dam in the lower Susquehanna River near the town of Conowingo, Maryland. The medium-height, masonry gravity dam is one of the largest non-federal hydroelectric dams in the U.S., and the largest dam in the state of Maryland.
Holtwood Dam is the oldest of three major dams built across the lower Susquehanna River, and the middle location of the three. It was constructed as the McCalls Ferry Dam between 1905 and 1910 by the Pennsylvania Water & Power (PW&P) Company. The dam was renamed Holtwood in honor of two company executives. PW&P merged with Pennsylvania Power & Light (PPL) in 1955. In 2015 Talen Energy took over PPL's generation and immediately sold the Holtwood plant to Brookfield Renewable Energy Partners to comply with federal antitrust requirements.
The Safe Harbor Dam is a concrete gravity dam, with an associated hydroelectric power station, on the lower Susquehanna River. It is the most northerly and last of three Great Depression-era public electrification projects' hydroelectric dams, and was constructed between April 1, 1930 and December 7, 1931. It created a long and relatively shallow lake, known as Lake Clarke, along the upper stretch of the Conejohela Valley. The creation of the lake shrank the upper Conejohela Flats in size.
The Cluny Power Station is a conventional hydroelectric power station located in the Central Highlands region of Tasmania, Australia. The power station is situated on the Lower River Derwent catchment and is owned and operated by Hydro Tasmania.
The Meadowbank Power Station is a run-of-the-river hydroelectric power station located in the Central Highlands region of Tasmania, Australia. The power station is situated on the Lower River Derwent catchment and is owned and operated by Hydro Tasmania.
The Caruachi Dam is a concrete gravity dam on the Caroní River in Bolivar state, Venezuela. It supports a hydroelectric power facility with a 2,160 megawatts (2,900,000 hp) capacity. It is about 59 kilometres (37 mi) downstream from the Guri Dam belonging to the Central Hidroeléctrica Simón Bolívar, and about 35 kilometres (22 mi) from where the Caroni and Orinoco rivers meet at Ciudad Guayana.
Hydroelectricity is, as of 2019, the second-largest renewable source of energy in both generation and nominal capacity in the United States. In 2021, hydroelectric power produced 31.5% of the total renewable electricity, and 6.3% of the total U.S. electricity.
The Manuel Piar Hydroelectric Power Plant is a stalled hydroelectric development project in the Lower Caroní River Basin of Venezuela. The project, started in 2006, includes the installation of 2,320 megawatts (3,110,000 hp) MW to generate annual average energy of 12,100 gigawatt-hours (44,000 TJ). As of 2019, the project is unfinished.
Mechanicville Hydroelectric Plant is a 18.3-acre (7.4 ha) national historic district located at Mechanicville in Saratoga County, New York. The listing included one contributing building and three contributing structures. The district dates to 1897 and includes notable Queen Anne architecture.
Stave Falls Dam is a dual-dam power complex on the Stave River in Stave Falls, British Columbia, Canada. The dam was completed in 1912 for the primary purpose of hydroelectric power production. To increase the capacity of Stave Lake, the dam was raised in 1925 and the Blind Slough Dam constructed in an adjacent watercourse 500 m (1,600 ft) to the north, which was the site of the eponymous Stave Falls. In 2000, the dam's powerhouse was replaced after a four-year upgrade. The original Stave Falls powerhouse was once British Columbia's largest hydroelectric power source, and is a National Historic Site of Canada.
The Duber Khwar Hydropower Plant is located near the town of Pattan in Kohistan, Khyber Pakhtunkhwa, Pakistan on the Duber Khwar River, a right bank tributary of the Indus River. It is approximately 340 km NW from Islamabad, the federal capital of Pakistan.
The Nadarivatu Dam, also known as the Korolevu Dam, is a concrete gravity dam on the upper reaches of the Sigatoka River in Nadarivatu District of Nadroga-Navosa Province, Fiji. The primary purpose of the dam is to generate hydroelectric power in a 41.7 megawatts (55,900 hp) run-of-the-river scheme. The Nadarivatu Hydropower Scheme was first identified in 1977 during a hydropower study. Detailed plans for the project were developed in 2002 and major construction began in 2009. The power station was commissioned on 7 September 2012 but an inauguration ceremony led by Prime Minister Frank Bainimarama was held a week later on 14 September. Funding and loans for the project was provided by several organizations to include the China Development Bank, Fiji Electricity Authority bonds, ADZ Bank. The 40 m (130 ft) tall dam diverts water from the Sigatoka River through a 3,225 metres (10,581 ft) long headrace/penstock tunnel to a power station along the Ba River to the southwest. The power station contains two 20.85 megawatts (27,960 hp) Pelton turbine-generators. The drop in elevation between the reservoir and the power station affords a gross hydraulic head of 335.7 metres (1,101 ft).
The Snoqualmie Falls Hydroelectric Plant is located just north of Snoqualmie in King County, Washington state, US. It is situated about 22 mi (35 km) east of Seattle. Located just below the Snoqualmie Falls, the power plant consists of two power houses, Plant 1 and Plant 2. Plant 1 was completed in 1899 and is located underground. It is the first completely underground hydroelectric power plant ever built in the world. Plant 2 was built in 1910 and is located along the right bank of the Snoqualmie River. Both plants receive water from a small reservoir created by a weir atop the falls. Plant 1 has an installed capacity of 13.7 MW and Plant 2 a capacity of 40.2 MW for a total installed capacity of 53.9 MW, enough to power 40,000 homes.
The John Butters Power Station is a conventional hydroelectric power station located in Western Tasmania, Australia. The power station forms part of the King – Yolande River Power Scheme and is owned and operated by Hydro Tasmania.
The Ottenbach Small Hydro is a 1920 electrified small hydroelectric power station of the former Silk Weaving Mill A. F. Haas & Co. in the Swiss village of Ottenbach. It is preserved in its original condition of 1920, still able to operate, aimed to be an historical witness of the industrial archaeology. The ensemble of factory, power plant and hydraulic structures is a cultural asset under preservation order.
St. Anthony Falls in Minneapolis, Minnesota, is the only natural falls on the Mississippi River. Since almost the beginning of settlement in the area by European descendants, the St. Anthony Falls have been used for waterpower. The first allowed settlers were at Ft. Snelling, where construction began in 1820. A sawmill was operating 1821 and a flour mill in 1823. As soon as the land at the sides of the falls became available it was purchased with the intent of using the waterpower of the falls. First lumber mills covered the falls, cutting lumber floated down the Mississippi. After 1870 flour mills started to dominate the area. From 1880 to 1930 the area was the number one flour producer in the US. In later years, some of the power came from steam, but in 1923 half of the waterpower used was for flour milling. Other industries have also used the waterpower.
Kabeli B1 Hydropower Station is a 25 MW run-of-river hydro-electric plant located in Panchthar District of Nepal. The promoter and operator, with a 20% share, is Arun Kabeli Power Limited (AKPL), a subsidiary of Arun Valley Group.
