As a renewable energy source, hydropower plays an important role in the energy transition to reduce global emissions. In mountainous European countries like Switzerland, Austria and Norway, hydro provides 60-90 % of domestic electricity generation.
Hydropower may also play an important role in helping to balance the grid, by compensating for fluctuations in solar photovoltaic (PV) and wind energy generation, through pumped storage when electricity is used to pump water into reservoirs at a higher altitude during periods of low energy demand.
Large hydro projects are, however, expensive to build with massive capital costs and also have significant environmental impacts. Most of the world’s hydroelectric capacity comes from big reservoir- based dams which require vastly more land per unit of energy produced than any other major electricity source. It affects marine life too. Dams built on rivers stop fish from migrating and hinders salmon from moving upstream to spawn in freshwater. Dams can also affect water temperatures and water flow, both of which affect marine life.
In recent years, there is increasing interest in small “run-of-the-river” hydro systems which generally do not involve a lot of energy storage. They use turbines that can operate on wide flow ranges, generating energy on high or low river flows, whatever is in the watercourse at the time. The systems are generally classified according to the amount of power they can generate at any given moment, i.e. micro systems up to 100 kW, mini systems up to 1 MW and small hydro systems up to 50 MW.
Micro systems can cost as little as USD 1000 - 20 000 to install, depending on the size, the location and the energy required. They can power individual homes and small communities and have negligible impact on the environment. The only prerequisite is to have a river flowing nearby and ideally combined with other renewable sources such as solar and/or wind, to cope with seasonal variations in the river flow during dry weather periods.
Market researchers predict that the global small hydropower market will grow fast during the coming years.
Micro hydro systems have, besides solar (PV) systems, huge potential, especially in developing countries with off-grid electrical systems for rural communities. But there is significant potential also in developed countries, f.ex. in France is now the major proportion of the hydro projects installed small installations.
Within IEC is there a working group to standardize small hydraulic turbines. The group is also working on the
maintenance of the standard IEC 62006 which specifies acceptance tests of small hydroelectric installations.
More information may be seen here.
(This article is based on an article in IEC’s etech newsletter; edited by T.Sollie)