Mini hydro power plants have been generating renewable electricity for over a century, although many have now fallen into disuse. In Spain there are barely more than a thousand plants in operation, which have been reduced by almost half since the 1960s, when they were at their peak. However, despite being a specific type of power plant, it is included in the category of hydroelectric power .
How electricity is generated
Mini-hydroelectric power is obtained by channelling water through pipes where the waterfall is located, taking it to the power station or making it fall to the turbine. In this way, the pressure exerted on the turbine will convert it into electricity. In other words, the water, when falling, exerts pressure on it and transforms it into electrical energy.
Therefore, electrical energy is obtained from the kinetic energy of the water itself, caused by gravity, which means that the natural or artificial gradient will largely determine the power. Dams with an installed power of no more than 10 MW and dimensions of less than 15 metres are usually considered mini-hydraulic dams.
Advantages of mini hydraulics
Aside from the potential environmental problems and the significant installation required, although flow-water power requires minimal construction work, mini-hydro power has numerous advantages. One of them is that it is not intermittent, as is the case with wind or solar power, or that it has no end, since no matter how much it is used, the river continues to flow and does not run out.
It is also non-polluting, as it does not emit greenhouse gases, which is a great advantage over other sources such as those from fossil fuels. In turn, the proximity of the place where it is produced not only promotes energy independence but also avoids the use of large high-voltage networks, thus saving us their high environmental and economic cost, as well as electricity losses in transport.
In addition to being used in public electrical systems , mini-hydro can be used to generate electricity for self-consumption or, in the event of surpluses, even to sell the electricity to the grid.
Possibilities for self-consumption
If in a given location we have a waterfall capable of ensuring a minimum electricity supply, we will obtain a regular supply that can be an interesting alternative to other renewable energy sources such as solar or wind.
And, of course, mini hydro can be combined with other energy sources, such as solar, wind or geothermal, the choice of which will depend on our budget and the climate of the place. However, doing so will be unnecessary if we do not need to increase electricity production.
Conclusions
The specificity of hydroelectric power is that there are no dams, or if there are any, they are very small. Basically, mini – hydroelectric power stations do not consume water from the river, they simply collect it and then return it further down the riverbed. Specifically, electricity is generated by waterfalls, without following the system of large hydraulic dams, which are not very ecological because they threaten the ecosystem and the global hydrological cycle.
In this way, there would be two types of mini hydroelectric power stations : those at the foot of the dam, which retain the water in a small reservoir, and those with run-of-river water, which involve building a diversion of the river to feed a channel that, by means of pipes, carries the water to the turbine and finally returns it to the riverbed. In both cases, although their impact is much less than in the case of large dams, they can be harmful to the environment, so the environmental recommendations of the World Commission on Dams must be followed for their planning and execution.
