As part of assessing the best energy sources for the future, we are looking at the pros and cons of these different energy sources.
This is our guide on the pros and cons of hydro energy (also referred to as hydroelectric or hydropower energy).
Hydro energy appears to not only be a key part of our immediate energy future, but also of our long term energy future worldwide as renewable and clean energy becomes more important.
Summary – Hydroelectric & Hydropower (Hydro Energy) Pros & Cons
Some of the main pros and cons of hydro energy might be:
- Is Currently The Leading Renewable Energy Source Of Electricity Supply & Consumption Worldwide
- Is Currently The Leading Energy Storage Source Worldwide
- Pumped Hydro Energy Storage Can Start Up Quickly
- Pumped Hydro Energy Storage has a good lifetime
- Pumped hydro energy storage has potential to power the world
- Renewable, unlike fossil fuels which are finite
- Green energy – zero emissions while in operation (however, pumped hydro can use fossil fuels for pumping)
- Reliable – there’s little inconsistency and fluctuation in water energy compared to sun or wind energy
- Flexible and adjustable when in use
- No fuel required (like coal or nuclear for example)
- Running costs are usually pretty low
- Can be a cheap way to source renewable electricity
- Hydropower built with dams provide multiple benefits
- Can be made on both small and large scales
- Can be a portable source of energy on a small scale
- Can give individuals energy independence
- Can supply energy off grid
- Can be used rurally or remotely where there are running water sources
- Pumped hydro be used as a renewable source of energy storage
- Damming of water can be environmentally damaging
- Large scale hydroelectric plants can be very costly to construct
- The largest scale and highest producing hydroelectricity plants can be limited in terms of growth – there’s only a limited number of places in the world that are suitable
- Can be sensitive to natural events
Hydropower is already well developed and is the leading renewable energy source worldwide (makes up about 50% of renewable energy at the moment).
It can be used on large scales like dams and major water diversion projects, or on smaller scales in rivers and streams with water wheels and portable water turbine energy generators.
Although it still has long term use because it is renewable and green energy, and it still has potential for expansion left, there are questions over the practical expansion of hydro power because of feasibility questions involved in locating and building new hydro sites (some places like the Grand Inga Dam in Africa for example have huge potential, but face feasibility challenges like being overpriced, funding issues, planning issues and corruption).
It could be used in the future as a complimentary energy source to solar and wind in a renewable energy future.
*Note – the above pros and cons are broad generalisations. Obviously there are different variables to each specific energy project that impact the final pros and cons (like new technology that reduces emissions for coal power plants just as one of many examples). Each energy project and situation (in different countries and cities) should be analysed individually. Having said that, some broad principles and patterns about the pros and cons of different energy sources tend to stay consistent too.
What Are Hydroelectricity, Hydro Power & Hydro Energy?
Hydro energy is the creation of energy with the use of water.
You can read about the three types of commercial/large scale hydro energy (run-of-river, storage and pumped) in this guide (note that each can often be combines – which is why you get pumped storage hydro power for example).
In reality, they could be separated into hydroelectric dams (that funnel water from a river into big tunnels), and pumped storage hydro projects (that have higher and lower water reservoirs where the water is pumped up and released down between the reservoirs).
However, there is also small scale hydro power and hydro energy systems that use water wheels for example to generate energy on small streams and rivers near farms and in remote areas.
Hydro Energy Pros
- Is Currently The Leading Renewable Energy Source Of Electricity Supply & Consumption Worldwide – producing and having a consumption share of about 50% compared to other renewable sources (bettermeetsreality.com)
- Is Currently The Leading Energy Storage Source Worldwide – Pumped hydro accounts for 97 percent of energy storage worldwide (sciencealert.com)
- Pumped Hydro Energy Storage Can Start Up Quickly – Pumped-hydro energy storage can go from zero to full power extremely quickly – it takes only a few minutes (sciencealert.com)
- Pumped Hydro Energy Storage Has A Good Lifetime – has a typical lifetime of 50 years and is the lowest cost large-scale energy-storage technology available (sciencealert.com)
- Pumped Hydro Energy Storage Has Potential To Power The World – new studies indicate that thousands of new pumped hydro energy storage sites have been located worldwide, and only a small % (around 1%) of these sites need to pass final approval factors in order to provide enough stored energy to power the world. Sites were assessed by the algorithm for space, suitable terrain, and the right variations in elevation. They can operate at maximum power for between 5 and 25 hours (sciencealert.com)
- Renewable – unlike fossil fuels, hydroelectricity is renewable because of water used from the natural water cycle.
- Green Energy – hydro electricity does not produce greenhouse gases or pollution whilst in operation. However, the exception to this is pumped hydro which can use fossil fuels for energy for the pump.
- Reliable – there’s very little fluctuation in terms of the output of hydro electric power plants. All they need is water and they can generate energy as a base load energy source running continuously. This is unlike wind power for example which can be intermittent.
- Flexible & Adjustable When In Use – adjusting water flow and output of electricity is easy for hydro electric plants. At times where power consumption is low, water flow is reduced and the magazine levels are being conserved for times when the power consumption is high. Likewise with pumped hydro water storage, pumped-hydro energy storage, it can be adapted as electricity demands change.
- No Fuel Required – unlike a coal power plant which needs to be refuelled with coal, water power plants don’t need to be fuelled. They have access to continuous water flow.
- Running Costs Are Usually Quite Low – plants do not require a lot of workers and maintenance costs are usually low.
- Can Be A Cheap Way To Source Renewable Electricity – Historically, hydropower has been the cheapest way to source renewable electricity (cnet.com)
- Dams Provide Dual Benefits – for hydropower plants built on dams, the dams provide flood control and irrigation techniques, in addition to hydropower.
- Micro/Small Hydropower Is Available – can be installed in small rivers or streams with little or no discernible environmental effect or disruption to fish migration. These are 10 megawatts, or projects of 30 megawatts in North America. A small hydro plant may be connected to a network or may only provide energy to an isolated community or a single house.
- Pumped & Storage Hydro Can Store Energy – pumped hydropower has the ability to store energy when water is stored in the lower level, and pumped up to the higher level when needed for energy generation. In the future, pumped hydropower could run with renewable energy like solar and wind power for the pumping – making it cleaner and more sustainable. This also provides another alternative to having to store energy from solar and wind energy in huge and costly storage batteries (sciencealert.com)
– energyinformative.org, efficientgreenpower.com, bettermeetsreality.com, sciencealert.com
Hydro Energy Cons
- Newly Discovered Pumped Storage Hydro Energy Sites Still Need To Pass On-Site Research & Final Approval Tests – at the moment, potential new sites have only been identified by an algorithm, so further on-the-ground research needs to be done. Factors that need to be considered are the ownership of the land, any specific engineering or environmental challenges they might present, availability of upper and lower reservoir locations, potential route for a connecting tunnel, whether the land is located in a national park or urban area, and potential capacity to store energy (which is usually in the 2-150 GWh of energy range) (sciencealert.com).
- Can Be Environmentally Damaging – damming of water, changed water flow and the construction of roads and power lines can all affect water environments and wildlife, such as fish. Dams or major water diversions with manipulation of water around the generator can negatively impact ecosystems for fish species who rely on certain water levels and other water environment characteristics.
- Large Scale Hydroelectric Plants Can Be Very Costly To Construct – hydroelectric power plants can be expensive to construct and install.
- The Largest Hydro Energy Plants Can Be Limited Physically In Terms Of Growth Potential – there’s only a limited number of suitable reservoirs where hydroelectric power plants can be built and even less places where such projects are profitable. As of 2014, there are currently about 30 major power plants that are expected to generate more than 2.000 MW under construction. Only one of these projects was started between 2012 and 2014 (energyinformative.org)
- Can Be Sensitive To Natural Events – Electricity generation and energy prices are directly related to how much water is available. A drought could potentially affect this (energyinformative.org)
Example Of Hydroelectric Energy Being Used In The World
China is home to one of the largest hydroelectric projects in the world:
- Hydroelectric power has become China’s main source of renewable energy production.
- The … Three Gorges Dam [was] completed in 2012 at a cost of over $37 billion [and] is the largest hydroelectric dam in the world and boasts a generation capacity of 22,500 MW.
- The dam generates 60 percent more electricity than the second-largest hydropower dam, the Itaipu dam in Brazil and Paraguay.
- Including the Three Gorges Dam, China has constructed 4 of the top 10 largest energy-producing hydroelectric dams in the world.
- From 2000 to 2015, China increased its hydroelectric energy-generation capacity by an impressive 408 percent. As a result of the Three Gorges Dam and other projects, China became the world leader in hydropower in 2014.
The Potential Future Of Hydropower & Hydro Energy
Recent studies suggest hydro energy could be one of the keys for a 100% renewable energy future.
Sciencealert.com provides a summary of how thousands of new potential hydro energy sites have been located world wide (and how their potential for energy production and storage could power the world).
Also, various studies that investigate what a 100% renewable energy future might look like for various countries and worldwide, identify pumped storage hydro energy as one of the three main renewable energy sources to potentially make this happen in an energy mix, along with solar and wind energy.
Pumped and stored hydro energy in particular has the ability to compliment the often variable nature of solar and wind energy (whereby energy can be intermittent between times of more and less sunshine and wind).