User:Funkymonk3y489/Small hydro

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Small hydro is the development of hydroelectric power on a smaller scale as compared to traditional large-scale hydro. Exact definitions are arbitrary and vary by country, but a "small hydro" project is typically less than 50 megawatts (MW) and can be further subdivided by scale into "mini" (<500kW), "micro" (<100 kW), and "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.

Small Hydro Power (SHP) projects have grown rapidly in the past two decades. They are easier to integrate into local environments, producing hydroelectric power on a scale suitable for local community and industry, or contributing to distributed generation in a regional electricity grid. In isolated areas that are uneconomic to serve from a national electricity grid, they provide a renewable energy solution to energy injustices.

Small hydro developments have received support from investors and renewable energy activists alike, though the exact environmental effects of smaller scale hydro are not yet fully understood.

Description

The use of the term "small hydro" varies considerably around the world. The maximum limit is usually somewhere between 10 and 30 MW and is stretched up to 50 MW in the United States, Canada and China. In India, hydro projects with up to 25 MW station capacities have been categorized as Small Hydro Power (SHP) projects.

Small hydro can be further subdivided into mini hydro, usually defined as 100 to 1,000 kilowatts (kW), and micro hydro which is 5 to 100 kW. Micro hydro is usually the application of hydroelectric power sized for smaller communities, single families or small enterprise. The smallest installations are pico hydro, below 5 kW.

Most Small Hydro projects utilize a run-of-river system instead of a conventional impoundment system and the the disadvantages associated with reservoirs. Since small hydro projects usually have correspondingly small civil construction work and a smaller or no storage reservoir, they are seen as having a low environmental impact compared to large-hydro. Many countries do not require reports or environmental impact assessments for small hydro installations, making the exact environmental impacts unknown.^{[citation needed]}

In California, hydroelectric generating stations with a maximum capacity of less than 30 MW are classified as small, and are eligible for inclusion in the state's renewable portfolio standard, while hydroelectric generating stations with a higher capacity are classified as large and are not considered renewable.

Generation

Main article: hydroelectricity

Hydroelectric power is the generation of electric power from the movement of water. A hydroelectric facility requires a dependable flow of water and a reasonable height for the water to fall, called the head. In a typical installation, water is fed from a reservoir through a pipe into a turbine. The water flowing through the turbine causes an electrical generator to rotate, converting the motion into electrical energy.

Small hydro may be developed by constructing new facilities or through re-development of existing dams whose primary purpose is flood control, or irrigation. Old hydro sites may be re-developed, sometimes salvaging substantial investment in the installation such as penstock pipe and turbines, or just re-using the water rights associated with an abandoned site. Either of these cost-saving advantages can make the return on investment for a small hydro site well worth the use of existing sites.

Brazil is another country which is investing heavily in small hydro. Brazil itself is a leader in hydroelectric generation, the world's third most hydropower installed capacity country at 79 GW, behind the United States at 100 GW, and China in first place with 171 GW.^{[citation needed]}  Fifty one new small hydro projects are, as of 2024, being constructed in Brazil.

Environmental Regulations for SHPs

Maximum energy generation capacity is the primary factor of small hydro project classification. Factors like dam height, reservoir area, outlet structures and operating procedures are not standardized under this metric, leaving little consideration and regulation of potential ecological impacts.

Because of considerable discrepancies in SHP classification, environmental licensing processes also vary significantly. Around two-thirds of countries do not require a formal environmental licensing process to construct and operate small hydropower projects. In India, SHPs under 25mW do not require an EIA and instead have a Detailed Project Report with evaluations that often only provide basic information to policy and decision makers. Most SHP licensing processes involve a simplified Environmental Impact Assessment (EIA).

Advantages and Disadvantages

The primary advantages of small hydro development include low costs to build, expansion towards energy justice environmental justice and the ability to remain disconnected from centralized power grids. Disadvantages include social injustices within permitting processes and a current lack of knowledge surrounding environmental effects.

Cost to Build

Small hydro projects may be created from the re-development of existing dams whose primary purpose is flood control or irrigation. Old hydro sites may also be re-developed, salvaging substantial investment in the installation such as penstock pie and turbines or through the re-use of water rights. ^{[citation needed]}

Many companies offer standardized turbine generator packages in the approximate size range of 200 kW to 10 MW. These "water to wire" packages simplify the planning and development of the site and minimize non-recurring engineering costs. While synchronous generators capable of isolated plant operation are often used in disconnected areas, small hydro plants connected to an electrical grid system can use economical induction generators to further reduce installation cost and simplify control and operation.

Although the cost of small hydro projects are generally far lower than large-scale hydroelectric systems, there is a cost to construction. Considering this, if a small hydro project proves to be uneconomical it will have an outsized budget expenditure relative to large projects which run over-budget.

Energy Justice

Many small hydro developments are made in rural or isolated areas where it is expensive to connect to national power grids. For instance, rural areas in India or other countries that have flowing water regimes utilize small hydro to provide a renewable source of energy without connection to the national grid. In communities which are geographically isolated from national power grids, small hydro projects provide the greatest reduction in greenhouse gas emissions.

In a number of communities which lack essential electricity access, small hydro offers a reliable and clean source of electricity. Small hydro projects do not normally require significant government assistance. Gaps in governance allow small hydro projects to be built and which provide local power to local communities. For investors, environmentalists, and policy makers, small hydro projects are considered most viable when there is little ecological impact and projected profit after construction. It is shown to be relatively easy for stakeholders to green-light small hydro developments if these conditions are met, even to a slight degree.

Alternatively, some montane villages in India assert that small hydro projects on river tributaries can harm the community more than large dams on the main river. Small tributaries play an essential role in the water supply of villages in mountainous regions, irrigating agriculture and supplying water to the community. Diversion of these streams for small hydropower generation may threaten local livelihoods when not considered adequately.

-include info about ability to connect rural communities to source of renewable power... supporting development on renewable energy and bridging transition away from fossil fuels

-include info about regulation weaknesses and shortcomings of impact assessments in justice of utilization and placement of small hydro projects (quick reference to indigenous Chilean communities promised of no more hydroelectric projects on certain river, but company flew under the radar through gov. loopholes to get SHPs built)

Environmental Effects

Environmental effects of small hydro projects are understudied.

Disadvantages of small hydro exist primarily in habitat alteration and species disturbance. and potential cost increase. Some of the disadvantages of small hydro come in the form of how the running water system is disturbed. Within run-of-river design projects, flow regime alteration leads to loss of river cohesion and connectivity, contributing to habitat degradation for fish and macroinvertebrates.^{[citation needed]} Small dams and ensuing water diversion may hinder the movement of fishes as well

Multiple small hydropower projects are occasionally placed segmentally on rivers, but little research has been done on the effects of multiple installations in a collective area. In China, researchers found the cumulative effects of reduced connectivity for rivers with 31 small hydro projects to outweigh the connectivity impacts associated with four larger scale projects.

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Questions for editor:

1. Is the "Generation" section necessary for this article? The lead section already links to hydropower, making me feel as though an insight into the generation of hydropower is not needed. What do you feel?
2. "Project Design" is another section I feel unsure about, though I do not have a mechanical background so I am biased in my "to include, or not to include" perspective. In terms of keeping that section, where is a good organization for it within the article?
3. Within "Generation" and "Project Design," there are sentences describing economic advantages / incentives to an adoption/ transition of small hydro projects. Could I include this within the "Advantages and Disadvantages" section and omit the need for the information in the two prior sections? Or do you think its better to keep it where is and not highlight it in advantages/disadvantages section
4. Are additions written in a neutral voice? Its hard for me to tell given my own biases and knowledge over the subject matter, so I would love a second opinion not hat or areas where it could be better.

Added References for personal additions:

Anderson, Elizabeth P.; Freeman, Mary C.; Pringle, Catherine M. (2006-05). "Ecological consequences of hydropower development in Central America: impacts of small dams and water diversion on neotropical stream fish assemblages". River Research and Applications. 22 (4): 397–411. doi:10.1002/rra.899. ISSN 1535-1459.

Couto, Thiago BA; Olden, Julian D (2018). "Global proliferation of small hydropower plants – science and policy". Frontiers in Ecology and the Environment. 16(2): 91–100.

Erlewein, Alexander (2013-11-01). "Disappearing rivers — The limits of environmental assessment for hydropower in India". Environmental Impact Assessment Review. 43: 135–143. doi:10.1016/j.eiar.2013.07.002. ISSN 0195-9255.

Kibler, Kelly M.; Tullos, Desiree D. (2013). "Cumulative biophysical impact of small and large hydropower development in Nu River, China". Water Resources Research. 49 (6): 3104–3118. doi:10.1002/wrcr.20243. ISSN 1944-7973.

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References added for previously missing citations:

"What is small hydro?". IEA Hydropower. Retrieved 2025-02-19.

Commission, California Energy (current-date). "Hydroelectric Power". www.energy.ca.gov. Retrieved 2025-02-19.