Pros & Cons Of Hydro Energy (Hydroelectric & Hydropower)

In this guide, we list the pros and cons of hydro energy (also referred to as hydroelectric or hydropower energy).

This guide forms part of a series of guides we have put together outlining the benefits and disadvantages of different energy sources and energy generation methods

 

Summary – Pros & Cons Of Hydro Energy (Hydroelectric & Hydropower)

Some of the main pros and cons of hydro energy might be:

 

Pros

Is currently the leading renewable energy source of electricity supply and consumption worldwide 

Is currently the leading energy storage source worldwide

Is The Leading Renewable Energy Source In Some Countries

Some countries have increased their hydro power capacity in the last few decades

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

Is renewable, unlike fossil fuels which are finite

Green energy – zero emissions while in operation (however, pumped hydro can use fossil fuels for pumping), and produces no waste

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 provides 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 can be used for energy storage

Pumped/stored hydro can compliment variable solar and wind energy sources

Doesn’t use up land space like a solar farm or wind farm might

 

Cons

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 (like droughts, precipitation, or a changing climate), and this can impact other things like prices

Some hydro plants use fossil fuels for pumps to pump water

 

General Summary

Hydropower is already well developed/established, 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 has utility to 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 Is Hydro Energy? And What Is Hydroelectricity & Hydro Power?

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 they can be combined with each other sometimes – 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 

 

Is Currently The Leading Energy Storage Source Worldwide

Pumped hydro accounts for 97 percent of energy storage worldwide (sciencealert.com)

 

Is The Leading Renewable Energy Source In Some Countries

Hydroelectric power has become China’s main source of renewable energy production

As a result of the Three Gorges Dam and other projects, China became the world leader in hydropower in 2014

– (chinapower.csis.org)

 

Some countries have increased their hydro power capacity in the last few decades

From 2000 to 2015, China increased its hydroelectric energy-generation capacity by an impressive 408 percent (chinapower.csis.org)

 

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)

This makes hydro energy valuable in a power grid with different energy sources, and especially variable energy sources

 

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)

A longer lifetime might mean better potential for returns from the initial investment sum

 

Pumped Hydro Energy Storage Might Have Potential To Grow

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)

 

What this means is that pumped hydro energy storage may have the potential to expand/grow if these sites can be used.

 

Renewable

Hydroelectricity is renewable because of water used from the natural water cycle.

As long as the natural water cycle stays consistent in any one area, that water can always be used, unlike fossil fuels for example which are finite.

 

Green Energy

Hydro electricity does not produce greenhouse gases or waste whilst in operation.

However, the exception to this is pumped hydro which can use fossil fuels for energy for the pump, and in this case there may be emissions.

Hydro energy also doesn’t produce a waste by-product directly, unlike coal for example which might produce fly ash.

 

Reliable

The output of hydro electric power plants tends not to fluctuate.

They only need water to provide a base load energy source running continuously.

This is unlike wind power for example which can be intermittent/variable.

 

Flexible & Adjustable When In Use

Hydro can adjust water flow and output of electricity relatively easily.

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 refuelled.

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.

This increases their utility.

 

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 to 30 megawatts hydro set ups.

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.

This ability to store energy means that hydro doesn’t need battery storage like for example solar might.

 

Stored Hydro Is Complementary To Solar & Wind Power

Stored hydro provides a good compliment to solar and wind energy, as huge and costly storage batteries may not have to be used (sciencealert.com), and the variable nature of solar and wind can be offset by hydro 

This is in comparison to having to use fossil fuel energy as a backup power source for fossil fuel energy.

 

Run Of River Hydro Doesn’t Use Up Land Space

Hydro set ups installed in rivers don’t use land real estate like a solar farm or wind farm might have to.

This could be useful for cities and towns that are land scarce.

 

(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).

Without further confirmation of suitable sites, hydro energy is capped in it’s future capacity to generate electricity

 

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 both 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 [and] Only one of these projects was started between 2012 and 2014

– (energyinformative.org)

 

Can Be Sensitive To Natural Events … Which Can Also Affect Pricing

Electricity generation and energy prices from hydro energy are directly related to how much water is available to generate power.

A drought could potentially affect this (energyinformative.org), as well as rainfall, a changing climate, a water scarce environment, and so on.

 

Some Hydro Plants Use Fossil Fuels

For pumping water uphill for example.

Although, pumped hydropower could run with renewable energy like solar and wind power in the future – making it cleaner and more sustainable.

– energyinformative.org

Having said this, there’s still an environmental and resource footprint to making and disposing of solar panels.

 

Example Of Hydroelectric Energy Being Used In The World 

In China:

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.

– chinapower.csis.org

 

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).

 

Sources

1. https://en.wikipedia.org/wiki/Hydroelectricity

2. http://energyinformative.org/hydroelectric-energy-pros-and-cons/

3. http://efficientgreenpower.com/hydroelectric-energy

4. https://www.renewableresourcescoalition.org/alternative-energy-sources/

5. https://water.usgs.gov/edu/hydroadvantages.html

6. https://chinapower.csis.org/energy-footprint/

7. https://www.bettermeetsreality.com/the-different-types-of-renewable-energy-sources-with-examples/

8. https://www.bettermeetsreality.com/installed-capacity-production-consumption-of-renewable-energy-worldwide-by-country-by-source/

9. https://www.sciencealert.com/scientists-spot-530-000-potential-pumped-hydro-sites-to-meet-all-our-renewable-energy-needs

10. https://www.cnet.com/news/if-renewable-energy-can-power-entire-countries-why-isnt-everyone-doing-it/

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