THE’hydroelectric energy it is one of the oldest and cleanest forms of electricity production: it exploits the force of water to generate renewable, constant and emission-free energy. But how does a hydroelectric plant really work?
To find out and understand step by step how water becomes electricity, we entered inside a real mini hydroelectric power plant in Piedmont, along the Dora Baltea. In this journey through canals and turbines, we show you how even the smallest plants can have a huge impact on the production of clean energy.
What is a mini hydroelectric plant and how does it work
There mini hydroelectric power station it is different from the classic hydroelectric power plant, which draws from a large dam or an artificial basin: this type of power plant, in fact, exploits the natural course of a river – in this case the Dora Baltea – and through a jump in the water, which is equivalent to a difference in altitude, it produces electricity. The facilities are small and perfectly integrated In the landscape.
As seen in the video, the river water is conveyed, through a canal, inside the Quassolo plant, which can exploit up to 75,000 liters of water per second to generate electricity. The flow (which after energy production is completely returned to the river) first passes through metal grids, which retain leaves, branches and debris. Then the cleaner comes into operation, a large mechanical comb that collects and disposes of them. The clean water then enters the plant.
Inside, there is a large inclined tube: it is the penstock, which in this case creates a jump of 3.75 metres: This jump increases the potential energy of the water, allowing it to generate more force when it spins the turbineand in doing so transforms the kinetic energy into mechanical energy. The crankshaft then transmits the mechanical energy to the generator, which in turn converts it into electricity. Finally, the energy passes through the transformerswhich increase the voltage to be able to insert it into the national electricity grid.
The gems of the power station: the inflatable barrier and the fish ladder
As seen in the video, one of the most interesting aspects is the inflatable barrier: a sort of flexible dam that rises or falls in about 40 minutes, depending on the water level. When the river is in flood, the head is lowered to avoid excessive rises in the water; when there is little water flow, the system is adjusted so that the flow can optimize production. If, however, the water level is too low, the control unit deactivates to ensure the minimum vital flow of the river.
To safeguard the ichthyofauna, there is also the climbing ladder for fish: a real corridor that allows them to swim from downstream to upstream for reproduction. As seen in the video, the scale is monitored by cameras that check the presence and health of the fish.
The importance of mini power plants in Italy
On the Dora Baltea there are dozens of mini hydroelectric power plants, of which seven belong to Edison. A mini power plant like the one in Quassolo produces around 8 GWh per year, while the largest hydroelectric power plant in Italy reaches 430 GWh. The difference is enormous, of course, but the strength of the mini power plants lies in their capillary diffusionIn the low environmental impact (as can be seen in the video, many of these structures are perfectly integrated into the landscape or built on existing works, such as irrigation canals or historic crossroads) and in the possibility of exploit hydraulically the river even in flat areas.
In short, often we don’t realize we have a mini power plant near our housebut together these small structures represent a fundamental part of Italian renewable energy: let us consider that, overall, all Italian hydroelectric power plants – large and small – provide approximately 20% of the energy produced at a national level.
