Who doesn’t like a hot shower in the morning, a steaming cup of coffee to get you going, or a cold beer after work – it’s those little pleasures that make everyday life more enjoyable. And none of it would exist without water. However, did you know that water has also been responsible for running your computer, fridge, and mobile phone? That’s right, water generated electricity is just about everywhere these days, and chances are, you are using it too. Over 160 countries utilise water for power generation, according to public sector organisation Geoscience Australia. And it is making a massive difference for our planet. All the hydro energy produced last year avoided about 4 billion tonnes of greenhouse gases and pollutants, according to the International Hydropower Association’s 2018 Hydropower Status Report.
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Especially Brazil and China have taken advantage of the technology in recent decades. China, for example, is home to the world’s largest dam. The Three Gorges hydroelectric power plant has an installed capacity of 22,500 megawatt (MW) – enough to power millions of homes. Meanwhile Brazil, which has America’s third-largest electricity sector after the United States and Canada, generates two-thirds of its energy capacity through hydro. “The sector makes up 64 % of total Brazilian energy capacity and meets more than three-quarters of electricity demand,” according to the International Hydropower Association. The country is close to completing the world’s fourth largest dam, the Belo Monte project, with a generation capacity of over 11,000 MW, demonstrating that is planning to further increase its reliance on hydro energy.
The world’s largest dam, The Three Gorges, based in China
However, while such mega dams avoid huge amounts of greenhouse gas emissions compared with coal-fired power plants, they can also be controversial. The Bela Monte project has been accused of negatively affecting the lives of Indigenous groups, causing further deforestation in Brazil and changing the flora and fauna in the area. In countries like India and China, giant dams have displaced millions of people, as water now fills the homes they used to live in. The vegetation that is flooded when a river is dammed also begins to rot and over time produces methane, a greenhouse gas. And by now, damming or diverting rivers to produce electricity is a technology with limited growth potential.
There are only so many rivers on this earth you can dam, and in the developed world, most of them have already been utilised. Recent subdued growth reflects that. “The amount of new hydro capacity commissioned in 2017 was the lowest seen in the last decade. Brazil and China continued to account for most of this expansion,” according to a report by the International Renewable Energy Agency’s Renewable Capacity Statistics 2018, released in March this year.
However, not all hydropower is alike – so far we’ve addressed mostly projects designed to produce electricity, but hydropower can also help to store it. Hydroelectricity refers to the generation of power from the flow of a river, while pumped hydro storage refers to using water as an energy storage facility. With a reservoir power plant that is designed to produce electricity, you dam a river and release the water through a spillway past water turbines whenever electricity is needed. A run-of-river power plant works the same way, only that instead of damming the water you divert it temporarily past turbines.
So why would you want a hydro plant that consumes electricity on a net basis? Well, because pumped hydro is designed to store energy like a battery, and that can be very useful. Instead of taking water from a river and releasing it back, pumped storage uses the same water over and over. The facilities consist of two reservoirs, one uphill and one downhill. They need no river to function. When power is in demand, water is released past turbines from the upper to the lower reservoir, generating electricity along the way. Later, when demand is low and surplus energy is available, the plant consumes electricity to pump that same water back to the upper reservoir. When it comes to energy storage, pumped hydro leads the market, according to Professor Andrew Blakers from the Australian National University.
“Pumped storage makes up 97 % of the global market for energy storage capacity, while batteries only occupy 1 % or 2 %. It’s the overwhelming market leader because it is so much cheaper than anything else,” Prof. Blakers said. Hydro energy also responds quickly to changes in demand. Facilities can ramp up generation from zero to 100 % in no time – just by opening the spillways and letting water flow. In the past, hydro storage was mostly used to pump water uphill at night when coal-fired electricity was cheap before being released at peak times when electricity could be sold at a high price. Pumped hydro is therefore not a stand-alone system but works in conjunction with other power generation methods.
What makes the system valuable in connection with wind and solar is that it stabilises the output of these renewable energy sources. Wind doesn’t always blow, and not all days are sunny. Therefore both solar and wind energy are subject to fluctuating outputs. When you combine a wind farm or solar power plant with a pumped hydro system, electricity can be generated even when output from solar or wind is low, creating a steady and reliable supply. International Hydropower Association (IHA) Chief Executive Richard Taylor said that it would be impossible to achieve the carbon reduction targets of the Paris Climate agreement without all forms of hydropower. The Paris Agreement commits parties to limit global warming to well below 2 degrees Celsius this century.
“Hydropower offers storage services which support growth in other renewables such as wind and solar, as well as water management and protection from floods and drought,” said Mr Taylor.
So both hydroelectricity and pumped hydro play an important role, but their future outlook is very different. Prof. Andrew Blakers said the future of pumped hydro is enormous. “To generate electricity just by letting water run to the sea is a dying art, because most of the world’s rivers are already dammed,” he said. “But pumped hydro energy storage where water goes round and round a circle hundreds of times is going gangbusters.” He said the real boom in pumped hydro is still to come, because the need for storage will increase exponentially once solar and wind capacities have reached higher levels. “You don’t need pumped hydro until wind and solar get to about 50 % of generation,” Prof. Blakers said.
“And that has happened in the Australian state of South Australia and will happen in Australia as a whole in about six to eight years. And at that point, you need a lot of storage, as you push it up to 100 % of renewables.”
Australia generates about 6 % of its total power from hydroelectricity. According to Geoscience Australia, the country has more than 100 operating hydroelectric power stations with a total capacity of about 7,800 MW. The biggest one is the Snowy Mountains Hydro-electric Scheme in the state of New South Wales. It makes up close to half of the country’s overall hydro capacity. The government is planning to expand the facility and add 2,000 MW of pumped hydro storage through its proposed Snowy 2.0 plan. “It’s designed to effectively double the amount of hydro electricity generation available from the Snowy Hydro scheme,” said Simon Corbell, Transcendence’s Renewable Energy and Sustainable Development Advisor and former Deputy Chief Minister of the Australian Capital Territory.
Australia's largest Hydro-electric scheme, Snowy Mountains
“The issue with very large schemes like Snowy 2.0 is that they are very expensive projects to build,” said Mr Corbell. So while Snowy 2.0 is still in the planning phase, there are also plenty of smaller sites suitable for hydropower. The continent is pretty dry overall, but has areas of high rainfall in the states of Tasmania, Victoria and New South Wales, in particular. Tasmania is an especially strong performer on the hydro front. Many of the state’s dams are currently spilling over due to recent strong rainfall. At the start of October, Hydro Tasmania operations manager Allan Jones told the Australian Financial Review (AFR) that the state not only covered its own energy needs but also exported electricity to mainland Australia in August and September.
“Tasmania's energy supply is more secure than ever. The state is also in the enviable position of being 100 per cent powered by renewable energy for the year so far,” Mr Jones told the AFR.
Tasmania wants to consistently meet 100 % of its electricity demand through renewables by 2022. And not only Victoria, New South Wales and Tasmania want to rely on water to power forward. The state of Queensland also wants to invest more in hydro as part of its strategy to meet 50 % of its energy requirements through renewables by 2030. The government has committed AUD 150 million to develop transmission infrastructure in North and Northwest Queensland, and commissioned a hydroelectric study to assess opportunities, according to the Powering North Queensland Plan.
“The reason that off-river pumped hydro is not a problem is that you don’t need to flood any river, you don’t need to go inside any national park, and the reservoirs are very small,” Prof. Blakers said.
The technology’s impact on surrounding areas is therefore minimal. And as Australia is an ideal place for solar and wind investments, pumped hydro will play an important role to make these technologies more reliable. Former ACT Deputy Chief Minister Simon Corbell said pumped hydro schemes could deliver significant dispatchable power into the national electricity market. “This is an important area of technology, because it provides for electricity that can be dispatched as required,” said Mr Corbell. “It can help balance the variability that comes with a higher level of reliance on solar and wind energy generation.” Wind and solar are expanding rapidly in Australia, meaning pumped hydro will soon have to follow suit.
“Australia has about 6 gigawatt (GW) of large-scale renewable energy developments committed between now and 2020,” Mr Corbell said.
“Based on projections of the continuing uptake from sources such as the Clean Energy Regulator and a recent paper produced by the Australian National University’s Energy Change Institute, Australia will hit 50 % renewable electricity by the year 2030.”
How do you turn water into electricity? If you have ever swam in strong surf or gone white water rafting, you know that water can be powerful. Fortunately for us, this power can be utilised to our advantage. To produce hydroelectricity, you primarily rely on two things – water, and gravity. Water is constantly on the move in our world – liquid evaporates, clouds form, rain falls and rivers run toward the ocean. Like anything in motion, flowing water has kinetic energy, which can be converted into mechanical energy, and then electricity. To do that, you need to channel falling or flowing water through turbines. Inside, a turbine has blades that turn when water pushes against them. A guide wheel ensures that the water is led directly onto the turbine blades. The blades sit on a shaft and as they begin to spin, the shaft spins too. Thus, kinetic energy becomes mechanical energy. The spinning shaft is connected to a generator that translates the mechanical energy into electricity. And voilà – water has become the juice that powers your phone.
Despite the popularity of hydroelectric dams among humans, they have been less popular with fish. Yes, you read that right. The survival of some fish species like salmon, for example, depends on their ability to migrate up and down rivers during different stages of their lives. And fish cannot hop up and down giant spillways. Therefore, large dams come with fish ladders or even fish elevators. Wonder how that works? Enjoy taking a look at these salmon heading up a ladder.
Hydropower has been around for a long time. Already the ancient Greeks milled grain with the strength of water – more than 2,000 years ago. They put a waterwheel into a fast-flowing creek and, via a mechanism, connected its axis to a millstone. The water pushed the wheel around in circles, and as the axis turned, the millstone turned with it. Hydropower also played a big role in the industrial revolution where it was used to power textile and machine factories. Then, in 1849, a British–American civil engineer called James Francis invented the first water turbine. Such turbines were later connected to generators to produce electricity. The first proper hydroelectric power plant began operation in 1882 on the Fox River in the US state of Wisconsin. From then it took just a few years until 200 hydroelectric power plants were working across the country, and the technology soon became popular around the world.