Small means different things to different people. In the hydroelectric domain small, for the IEC, means installations of up to 15 MW, but in some countries it may cover systems of up to 30 MW.
The concept covers a wide range as it includes micro-hydro schemes, which can be as large as 500 kW and are generally run-of–the-river developments for villages, and pico-hydro systems that have a capacity of 50 W to 5 kW and are generally used for individuals or clusters of households.
IEC pioneering role
International Standards for hydroelectric installations are prepared by IEC TC 4: Hydraulic turbines. This is one of the IEC's oldest TCs and it celebrates its 100th anniversary this year. The TC covers river and dam installations as well as tidal barrage.
TC 4 prepared IEC 61116, Electromechanical equipment guide for small hydroelectric installations, in 1992. The Standard describes the installation and operating conditions of power station, equipment specifications, as well as specifications concerning the inspection, delivery, operation and maintenance of installations.
In October 2010 TC 4 also published IEC 62006, Hydraulic machines – Acceptance tests of small hydroelectric installations, which "applies to installations containing impulse or reaction turbines with unit power up to about 15 MW and reference diameter of about 3 m".
New IEC entrant
The scope of the recently created IEC TC 114: Marine energy – Wave, tidal and other water current converters, is being extended to cover aspects of river currents as the technology deployed for certain marine tidal and current installations is also relevant for specific river applications. TC 114 AHG (ad hoc Group) 2, is tasked with assessing the "power performance (…) of electricity producing river current energy converters".
Some tidal turbines are now being installed in marine and river environments.
Huge needs, significant potential
Many small communities, in certain developing countries in particular, are not connected to a grid and may be entirely cut off from electricity. Small hydro schemes, including pico-hydro installations may be the solution to bring power to these communities.
Small hydro can also be an attractive solution for large countries. In the US, for instance, 85% of the 2 500 operating dams are categorized as small scale as they have a rated capacity of less than 30 MW. However, an estimated 97% of the country's 79 000 dams are not generating any power, many having been built to control water levels or for other purposes. Equipping these dams to produce electricity could provide an additional 7,3 GW of capacity by 2025. The environmental impact would be minimal as these dams are already built.
In July 2013 the US Senate unanimously adopted two bipartisan hydroelectric power bills, previously passed by a large majority in the House of Representatives. These bills will, among other things, favour the development of small hydro projects by streamlining the Federal Energy Regulatory Commission’s permissions process for low-impact small hydro and close-loop pumped-storage projects. President Obama signed into law the two bills on 09 August 2013.
China has the largest small hydropower market in the world in terms of installed capacity (representing 59% of the world's total in 2009), driven by programmes for providing rural electrification.
Under the national medium and long-term development plan for renewable energy, China is planning to have 75 GW of small hydro cumulative installed capacity by 2020 (out of a total estimated capacity of 128 GW).
Small hydro could also benefit from rural electrification programmes being set up in many other countries. Chile, for instance, has embarked on various small hydro-programmes, such as the 16,2 MW scheme one in the Bio Bio region that is near completion. The same can be observed in Brazil.
India's Ministry of New and Renewable Energy estimates the potential for power generation from small hydro to be more than 15 GW.
Countries throughout the world, including in Europe are investing in small hydro projects to bring power to rural communities, meet their overall energy requirements and reduce their dependence on imports of oil and gas.
Small hydro is also seen as offering the possibility of bridging the "power divide" in Africa with "new initiatives being launched in Central Africa (Rwanda), East Africa (Kenya, Tanzania and Uganda) and Southern Africa (Malawi, Mozambique and Zimbabwe)."
Not so spectacular, but very effective
Small hydropower schemes are not as spectacular as large hydro projects which often benefit from extensive media coverage, however, they have the potential to add significantly to the power capacities of many countries. Just as important, if not more, to bring electricity and economic prospects to hundreds of millions living in regions and communities that have been deprived of these for too long.