Hydropower – a Local, Renewable, and Reliable Energy Source
Water is the driving force of all nature – Leonardo da Vinci.
Hydropower is energy harnessed from falling or flowing water. It is among the oldest of energy sources. Hydropower was used extensively in the Roman Empire to mill grain, and powered watermills in Persia as far back as the 5th century BC.
Any location where water falls or flows from a higher to a lower point can be used for hydropower. Today hydroelectricity is used to supply a considerable percentage of some countries’ power: for example, 99% of Norway’s electricity is generated by hydropower alone.
Hydroelectric plants work by using the movement of water to drive turbines, which then power a generator to create electricity. Water is more than 800 times denser than air and its movement provides a powerful driving force.
Converting electricity hydroelectrically is among the simplest and most efficient energy conversion types. Unlike in thermal systems — such as fossil fuels and nuclear power — turbines and generators are powered directly by falling or flowing water, which is driven by gravity. This means no energy is lost through energy conversion, such as the conversion of chemical energy (like coal) into kinetic energy (moving steam) needed in coal generators.
Hydropower stations can be built with or without dams and reservoirs. Those hydropower plants that use reservoirs can store water at higher altitudes for any length of time. This potential energy is then used to meet peak, seasonal, or emergency energy demands.
As well as being among the greenest of energy sources, hydropower offers considerable scalability. ‘Pico’ hydroelectricity generators (< 5 kW) are used to power individual households in developing nations. On the other hand, the three largest active power plants in the world are all hydropower plants: the largest, The Three Gorges Dam in China, has a capacity of 22.5 GW, providing power to 80 million homes.
Despite their significant potential energy, the main problem with large-scale hydroelectric power plants is the environmental destruction and social disruption caused by the creation of reservoirs. Mini-hydroelectric power plants do not demand the construction of dams or reservoirs because they only require low capacities of moving water.
These capacities are provided by local streams and rivers with the installation of a filter (water intake), which can be installed according to the size and demand of local energy needs. The pipes used to carry the water in mini-hydroelectric plants are small, meaning that their environmental impact is minimal. Accordingly, there is no need to build penstocks — waterways below dams that are used to power turbines in large hydroelectric plants.
Even naturally occurring lakes and pools can be used for mini-hydroelectric plants, assuming there a difference in elevation.
Perhaps the greatest benefit of small-scale hydropower plants is that they do not require energy to be transported long distances from the energy source to where the energy is consumed. This results in minimal energy losses due to transportation, benefiting both the economy and the planet. Energy can even be stored for periods of peak demand using pump and reservoir systems.
Recent advancements regarding the construction of high capacity inverters mean that output power can be conditioned to suit both the power grid and the electricity consumer.
Furthermore, because the basic conditioning of hydroelectric generators can be controlled by basic circuitry, no complicated controls — and therefore no in-depth training or expertise — is needed to keep small hydropower plants running reliably. Due to the small scale of their components, mini-hydropower plants also require less maintenance and engineering to install and run.
Mini-hydroelectric plants also offer easy modular installation. After their installation, further adjustments can be made according to changing local demands. The electricity production of a single plant can therefore be scaled up accordingly, with the installation of further heads in series (i.e. more generators downstream or below the line of falling water).
This increases both the reliability and ‘redundancy’ of mini-hydroelectric plants — the duplication of necessary components to prevent possible failure. Accordingly, even remote off-grid populations and areas are guaranteed a reliable source of electricity.
In remote and developing regions in particular, mini-hydroelectric plants can be the only means of generating a stable and local supply of power. Surplus energy can even be sold back to the national grid, especially during rainy seasons, providing remote communities with revenue and increasing renewable energy use.
The European hydropower industry is, technologically speaking, both well-developed and mature. However, there remains massive unused potential for small hydroelectric plants across almost every European nation. Indeed, barely half of all small-hydropower capacity in Europe has yet been tapped.
Europe has many high-altitude, and low or medium population density areas. These areas are relatively difficult and costly to supply with electricity generated by centralized power plants.
Many of these areas are also best suited to mini-hydro electricity production. This has two significant benefits. First, local renewable power resources are used to power local communities and businesses. Second, money, electricity, and the environment are all being saved, as electricity does not have to be transported from large centralized power plants, many of which are powered by fossil fuels or nuclear power.
This advantages national governments as well as local communities. Meeting carbon footprint demands, such as EU emissions’ targets, is a key motivator for significantly increasing the percentage of power generated by small hydroelectricity plants in Europe.
Accordingly, it is in the interest of governments to aid and subsidize increased mini-hydroelectric power plants and services for both environmental and economic benefit.
The power produced by mini-hydroelectricity plants is among the cheapest of all types of energy. A good illustration of this is the cost of each kilowatt produced over the lifespan of a plant: for mini-hydroelectric plants, this cost can be reduced to merely 0.02 USD per kWh.
Furthermore, the payback time for mini-hydroelectricity plants is less than half that of battery-storage solar panels. Unlike solar panels, which are costly to manufacture and whose power output is dependent on seasonally variable sunlight, mini-hydroelectric plants offer more consistent electricity production. They can be installed in any location with flowing water, providing on-site and reliable renewable energy with considerable scalability.