Hydroelectric energy or the power of the water, is another form of renewable energy that is very well developed on the planet compared to the others sources of alternative energy.
Hydroelectric Energy Definition
Hydropower represents the energy of the falling water or the fast running water that is turned into mechanical energy to spin a turbine and generate clean electricity using generators.
Hydroelectric energy accounts today for more than 16% in the world’s electricity generation from all energy sources, and along with the other renewable energy sources available on the planet will slowly replace fossil fuels such as coal, oil and natural gas in terms of energy generation.
Being part of the renewables, hydroelectric power is today a cheap and old source of clean power that can be classified into several categories:
Types of Hydroelectric Power Plants
1. Conventional hydroelectric or storage hydropower (dams)
Hydroelectric dams use large reservoirs to store the water, and clean energy is produced by releasing the water from the reservoir.
Storage hydropower provides the base load and can be shut down or started when needed and according to the demand in the system.
It can operate for weeks or even months without using the hydrological inflow.
2. Pumped-storage hydropower
When energy demand is low, water is stored and moved uphill into reservoirs to be later released and used to generated clean electricity when demand for energy in the system is high again.
3. Run-of-the-river hydropower
Uses the kinetic energy of the rivers and streams to generate clean electricity without relying on water reservoirs.
4. Conduit hydroelectricity
Uses the water that has been diverted for use in a system to generate clean electricity.
5. Tidal (offshore marine)
Uses the kinetic energy of the tides to spin underwater turbines that will generate clean electricity using reversible generators.
Knowing how this clean energy source is generated today, we can move forward to see what are the pros and cons of hydroelectric energy.
Pros of Hydroelectric Energy
Being a renewable energy source, hydroelectric power has today many advantages over fossil fuels.
1. Is a Renewable Energy Source
Hydroelectric energy is produced today using the earth’s water and the force of gravity (falling water), which both represent renewable resources because they were here long before us and will be here for a very long period of time in the future.
Water can never run out of supply because the natural water cycle is sending the water that evaporates from the oceans (recycled water) back to the planet under the form of rain.
Hydroelectric power can be affected seasonally by drought and low water levels, but this is only temporary.
2. Is a Clean and Alternative Source of Electricity
Besides being part of the renewable energy sources, hydroelectric energy is also a clean and alternative energy source because releases no harmful emissions into water or the atmosphere and because is clean, it will successfully replace the dirty fossil fuels in a not so far future.
3. Is a Cost Competitive Source of Electricity
Today, hydroelectric power is considered a cost-competitive energy source because it is cheaper than other sources of electricity.
A hydroelectric power plant will have low maintenance costs because it has a small number of parts in the system and are designed to work for decades.
Any minimal replacements will not affect the activity of the power plant and the price of the clean electricity produced by the plant.
4. Is a Flexible Source of Clean Power
A hydroelectric power plant represents today a very practical and flexible source of clean electricity because the power plant can be started or halted in a pretty short time if needed.
By adjusting the water flow from the reservoirs, the power plant can also increase or decrease its energy output.
This might be reason why hydroelectric power plants are often used to backup other source of energy (even conventional).
5. Brings Economic Growth in Remote Areas
The presence of a hydroelectric power plant will generate new constructions, infrastructure, industry and commerce even if the area is remote.
Residents that decide to live in the remote area will have access to clean electricity, but also to qualified education and health care.
6. Hydroelectric Power is Suitable for Industrial Applications
The clean energy produced by hydroelectric power plant is usually sent to the grid, but in some cases, smaller units can generate electricity for specific industrial enterprises.
Large industrial plants could rely on smaller hydroelectric power plants that are built to supply them with clean electricity.
Cons of Hydroelectric Energy
There are also some downsides related to hydroelectric power because the underwater turbines and the water reservoirs are affecting the environment.
1. High Upfront Costs
Building a new hydroelectric power plant is very expensive especially if the location is remote.
There are several environmental and logistical challenges related to any new hydroelectric project, and this is might be the reason why the entire process is very long and expensive.
When the power plant finally enters into service, will need to generate clean electricity for several years to cover its initial investment.
2. Greenhouse Gas Emissions
Hydroelectric dams rely on water reservoirs to be able to operate for weeks or even months without using a natural water flow.
The environmental problem related to air pollution appears when the water reservoirs are used to flood an area, and the plants living there are dying and starting to rot, which releases methane and carbon emissions into the atmosphere.
3. Risk of Dangerous Failure
Hydroelectric power plants are keeping huge volumes of water behind a man-made thick concrete wall.
In certain conditions (earthquakes), such man-made constructions could suffer a fatal failure and if the concrete wall is affected, the water flow could escape and flood a pretty large area (a small village), which can lead to hundreds of human casualties.
Besides people, in such catastrophic failures, the water flow will also kill animals, plants, trees and several other forms of life who live on land not underwater.
4. Risk of Drought
Building a hydroelectric power plant may create local drought and this will affect both the local agriculture and also the energy output of the power plant.
Another problem could be created by the high price of electricity generated by the low volume of water during the season when the drought occurs.
5. Can Damage Ecosystems
The huge reservoirs of water used by the hydroelectric power plants can produce the submersion of extensive areas upstream the dam, can destroy lowlands and riverine valley forests, marshlands and also grasslands.
The same hydroelectric power plants can destroy underwater ecosystems, both upstream and downstream of the dam.
Keeping the gates of the turbines often open for a long period of time can affect the natural flow of water, which will affect the river ecosystem and the environment surrounding the river.
Animals, birds and different plant species living in marshy habitats could be destroyed by the hydroelectric power plant.
6. Relocating people and entire villages
People living downstream the hydroelectric power plant could be heavily affected by floods produced by the strong water currents released while opening the dams.
The construction of dams could relocate people and entire villages just because the area is suited for a hydroelectric power plant.
Conclusion
Hydroelectric power keeps increasing its share in the world’s energy mix along with the other sources of renewable energy while fossil fuels like coal are decreasing their presence.
The shift towards low-carbon energy sources and renewable energy has been already started and this guarantees us that the era of fossil fuels that polluted the environment is slowly fading out and makes room for the new and green sources of power representing the future.
