Hydroelectric power how it works

Hydroelectric energy, also called hydroelectric power or hydroelectricity, is a form of energy that harnesses the power of water in motion—such as water flowing over a waterfall—to generate electricity. People have used this force for millennia. Over two thousand years ago, people in Greece used flowing water to turn the wheel of their mill to ground wheat into flour.

How Does Hydroelectric Energy Work?

Most hydroelectric power plants have a reservoir of water, a gate or valve to control how much water flows out of the reservoir, and an outlet or place where the water ends up after flowing downward. Water gains potential energy just before it spills over the top of a dam or flows down a hill. The potential energy is converted into kinetic energy as water flows downhill. The water can be used to turn the blades of a turbine to generate electricity, which is distributed to the power plant’s customers.

Types of Hydroelectric Energy Plants

There are three different types of hydroelectric energy plants, the most common being an impoundment facility. In an impoundment facility, a dam is used to control the flow of water stored in a pool or reservoir. When more energy is needed, water is released from the dam. Once water is released, gravity takes over and the water flows downward through a turbine. As the blades of the turbine spin, they power a generator.

Another type of hydroelectric energy plant is a diversion facility. This type of plant is unique because it does not use a dam. Instead, it uses a series of canals to channel flowing river water toward the generator-powering turbines.

The third type of plant is called a pumped-storage facility. This plant collects the energy produced from solar, wind, and nuclear power and stores it for future use. The plant stores energy by pumping water uphill from a pool at a lower elevation to a reservoir located at a higher elevation. When there is high demand for electricity, water located in the higher pool is released. As this water flows back down to the lower reservoir, it turns a turbine to generate more electricity.

How Widely Is Hydroelectric Energy Used Around the World?

Hydroelectric energy is the most commonly-used renewable source of electricity. China is the largest producer of hydroelectricity. Other top producers of hydropower around the world include the United States, Brazil, Canada, India, and Russia. Approximately 71 percent of all of the renewable electricity generated on Earth is from hydropower.

What Is the Largest Hydroelectric Power Plant in the World?

The Three Gorges Dam in China, which holds back the Yangtze River, is the largest hydroelectric dam in the world, in terms of electricity production. The dam is 2,335 meters (7,660 feet) long and 185 meters (607 feet) tall, and has enough generators to produce 22,500 megawatts of power.

Hydroelectricity has been providing around 5-7 per cent of Australia’s total electricity supply for decades.

There are over 120 operating hydroelectric power stations in Australia, large and small, mostly located in south eastern Australia. The most well known of these is the Snowy Mountains Hydro-Electric Scheme. There are also three major PHES systems connected to the national electricity grid.

The Australian Government’s first Low Emissions Technology Statement identified the importance of large-scale energy storage solutions, such as PHES, to ensure the security and reliability of Australia’s electricity grid.

In 2021, we announced funding for Australia’s first PHES system in 37 years. Located at the former Kidston Gold Mine in north Queensland, the project will be the first to support the integration of variable renewable energy generation from solar and wind.

In 2020, construction began on the Snowy 2.0 project, which will link two existing dams in the Snowy Mountains and provide 2000 MW of capacity and 350,000 MWh of storage. We supported the feasibility study for this project, which, once built, is forecast to be able to power approximately 3 million homes over a week.

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• Low Emissions Technology Statement

How are we supporting PHES projects?

Our purpose is to support the global transition to net zero emissions by accelerating the pace of pre-commercial innovation, to the benefit of Australian consumers, businesses and workers. By connecting investment, knowledge and people to deliver energy innovation, we are helping to build the foundation of a renewable energy ecosystem in Australia.

We have identified that PHES will play a significant role in helping Australia transition to renewable energy, and will continue to provide funding support and guidance to assist with development and financing.

Hydroelectricity (also known as hydro) is a well-developed renewable energy technology that has been around for more than a century.

Hydro uses flowing water to spin a turbine connected to a generator that produces electricity. The amount of electricity generated depends on the volume of water and the height of the water above the turbine.

Large hydroelectric power stations need dams to store the water required to produce electricity. These dams are often built to hold irrigation or drinking water, and the power station is included in the project to ensure maximum value is extracted from the water.

Hydroelectricity does not actually consume any water, as all the water is returned to the river after use.

While hydro plants can have very large capacities, the amount of electricity they generate can vary considerably from year to year depending on rainfall and electricity demand. Hydro can provide both baseload and peak load electricity, and hydro generators can start up and supply maximum power within 90 seconds.

Hydro power accounted for 23.3 per cent of total clean energy generated and 6.4 per cent of Australia’s overall electricity in 2020. There are more than 120 working hydro power stations in Australia, with most of the nation's hydroelectricity generated by Hydro Tasmania's network of power plants and the Snowy Mountains Hydro Scheme in New South Wales.

After losing its crown as Australia's leading renewable energy generator in 2019, hydro slipped to third place in 2020 as generation from the booming rooftop solar sector overtook hydro for the first time. This came despite hydro generation increasing by 473 GWh in 2020 to 14,638 GWh, its highest level since 2018.

However, while the technology's share of renewable energy generation may have shrunk in recent years, its importance to the industry's future is growing with each new megawatt of solar and wind capacity that is installed. This is because of the critical role that hydro will play in firming Australia's substantial wind and solar resources, with a number of major hydro projects under development that will enable further expansion of renewable energy in Australia.

The biggest new hydro project is Snowy 2.0, a 2000 MW/350,000 MWh project currently under construction in New South Wales. The project reached a number of significant development milestones in 2020, including state and federal environmental approval, which were both fast-tracked as part of the governments' COVID-19 recovery efforts, a $125 million transmission investment by the Clean Energy Finance Corporation and approval of a segment factory, which will manufacture 130,000 concrete tunnel segments for use during construction of the project.

Tasmania's Battery of the Nation project also continued to progress in 2020, with Hydro Tasmania naming Lake Cethana in north-west Tasmania as its first pumped hydro site for the project. Marinus Link, a second interconnector connecting Tasmania to the mainland that is a critical component of the Battery of the Nation project, also took a step closer to realisation after the Federal Government committed $94 million to take the project to the final investment decision stage.

Snowy 2.0 and the Battery of the Nation clearly show that there is considerable desire in expanding the nation's hydro resources to provide additional storage capacity to complement renewable energy such as wind and solar power.

jobs created during the lifetime of Snowy 2.0

The future of hydro also looks bright in New South Wales after the state government committed $50 million in grants to support the delivery of pumped hydro projects in the state as part of its Electricity Infrastructure Roadmap, the proposed Oven Mountain pumped hydro project was deemed as Critical State Significant Infrastructure by the state government and GE signed an agreement with Walcha Energy to develop a 500 MW pumped hydro project at Dungowan Dam.

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