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by Imogen Hartmann, Assistant Editor, Energy

With the demand for solar and wind energy in Australia ever increasing, so too is the demand for baseload energy options that can back these resources up. Pumped hydro is at the forefront of new energy technologies in Australia, ensuring that energy is available even when the sun and wind are not.

The pumped hydro energy storage (PHES) system is one of the most mature energy technologies to date, having been used (in various forms) for thousands of years. For decades, hydroelectricity has been providing five to seven per cent of Australia’s total electricity supply and in 2017, it made up 40 per cent of renewable energy nation-wide.

It comes as no surprise then, that the Federal Government has identified pumped hydro as a key asset to the National Electricity Market (NEM), with its potential for minimising blackouts as well as stabilising electricity prices. The Government is making a number of investments into existing and developing hydroelectricity power stations in order to utilise the increased electricity generation and reliable storage system that pumped hydro provides.

Currently, there are more than 100 hydroelectric power stations across Australia, with perhaps the most well-known being the Snowy Mountains Hydro Electric Scheme. The Government has committed to providing additional equity to Snowy Hydro Limited for the construction of Snowy 2.0, the latest expansion of the existing systems.

Also on the horizon is the Battery of the Nation, which will involve the development of further hydro energy in Tasmania, connected to the mainland by Marinus Link – Tasmania’s 1200MW second interconnector, which the Government plans to have reached a final investment decision on by 2021-22. The Government plans to develop an underwriting mechanism for the Battery of the Nation project through the Underwriting New Generation Investments program.

Advancing to the pumped method

PHES differs from conventional hydroelectricity generation in a couple of ways. Traditionally, hydroelectricity uses water (usually from a dam or reservoir where it has been stored), which is then passed through rotating turbines to convert the motion into electrical energy. 

PHES operates in a similar fashion, except that it uses two dams, with one higher than the other. When demand for energy is low, excess energy from the grid, or wind or solar farms, can be used to pump water from the lower dam into the higher one. This converts the higher dam into a giant battery, storing the energy until it is required.

The process can be essentially reversed to release the stored energy by returning the water to the lower dam using a hydroelectric turbine, aided by gravity. The generation of hydroelectricity in this manner is almost immediate, and is available to be fed into the grid quickly when demand for electricity spikes.

Snowy 2.0: the next stage in Australia’s pioneering
hydro system

Snowy 2.0 is the next advancement in the Snowy Mountains Scheme, developed to boost the existing hydro-electric generation and large-scale storage facilities to meet the increasing demands of the market. With the addition of 2000MW of energy generation and 175 hours of storage to the NEM, Snowy 2.0 is set to be the largest energy storage project in the southern hemisphere and the largest renewable energy project in Australia.

Currently, the Snowy Scheme provides critical system stability during peak demand periods with more than 4000MW of existing fast-start dispatchable generation capacity. Snowy 2.0 will increase this capacity by 50 per cent to 6100MW.

The project will connect the existing Tantangara and Talbingo dams through a 27km tunnel and an underground power station with pumping capabilities. Falling water from the upper dam (Tantangara) will spin the reversible turbines in the lower dam (Talbingo) to generate the hydro power. The same water will be recycled between the two dams to generate power more than once, ensuring the water is being used in the most economical way. 

Snowy 2.0 is expected to start generating power in 2024-25, with progressive commissioning on the six units. The Snowy Scheme says its current assets are functional for decades after installation, and it expects Snowy 2.0 to be no different.

The next link between Victoria and Tasmania

The Marinus Link is TasNetworks’ proposed second Tasmania-Victoria interconnector. The name was derived from the latin meaning ‘marine’ or ‘of or connected to the sea’. The project will function in addition to the existing interconnector, Basslink, which is privately owned, and provide 1500MW of increased transmission capacity between Tasmania and Victoria delivered in two concurrent or staged 750MW developments.

Marinus Link received $20 million initial funding from the Tasmanian Government and the Australian Renewable Energy Agency (ARENA). The Federal Government then provided $56 million to progress the project to the Design and Approval phase.

The project has been flagged as a high priority initiative by Infrastructure Australia as well as the Australian Energy Market Operator (AEMO), advising in its July 2019 insights paper that it should be progressed through feasibility, business case and approvals phases without delay.

Undersea interconnectors have been used internationally for their capacity to provide low cost, reliable energy storage. Other benefits may include; increased supply security, harnessing of load diversity and generation, utilisation of flexible converter technology.

TasNetworks also estimates that economic benefits during peak construction could include around $1.5 billion of direct economic stimulus to the Victorian economy and 1400 direct and indirect jobs; and $1.4 billion of direct economic stimulus to the Tasmanian economy and 1400 direct and indirect jobs.

Bringing SA into the mix

After recently announcing $40 million in funding to fast track the identification and development of South Australia’s first pumped hydro energy storage project, ARENA has since identified four eligible developing projects under its Advancing Renewables Program.

The four projects are: 

  • AGL’s 250MW project at a copper mine in Kanmantoo in the Adelaide Hills
  • Energy Australia’s 250MW Cultana seawater project near Wyalla
  • Rise Renewables’ 250MW project at Baroota
  • Sunset Power/Delta Electricity’s 242MW Goat Hill project near Port Augusta

South Australia is currently a nation-leader in renewable energy potential. South Australian Minister for Mining, Dan van Holst Pellekaan, said the state was predicted to reach net 100 per cent renewables by 2030. 

With South Australia passing 50 per cent renewables in 2018, up 7.4 per cent on the previous year, the transition progress is happening fast. AEMO predicts that by 2021, up to 70 per cent of South Australia’s generation will be coming from variable renewable sources.

As the capacity for renewable generation rapidly advances, the development of reliable, large-scale storage systems will become imperative for the state. 

ARENA CEO, Darren Miller, said, “With 50 per cent of total energy generation in South Australia coming from variable renewable energy in 2018, and an expectation that this will increase in the next two years, there is an increasing requirement for energy storage to firm and balance the system in that state. As part of this, pumped hydro has an important role to play in Australia’s energy transition.”

The Federal Government funding aligns with its continuing consideration of 12 shortlisted projects under the Underwriting New Generation Investment (UNGI) program announced in March 2019. Of the dozen UNGI shortlisted projects, six are pumped hydro and three of those are in South Australia. Two of the four projects being considered under the ARENA funding process are also shortlisted for UNGI. 

ARENA will collaborate with the UNGI program and the South Australian Government, who have a $50 million Grid Scale Storage Fund that will support the delivery of pumped hydro, alongside other large-scale storage technologies such as grid scale batteries and virtual power plants.

The successful large-scale energy storage will operate alongside the state’s two existing grid-scale batteries – the 100MW/129MWh Tesla battery at the Hornsdale Wind Farm and 30MW/8MWh ESCRI system at the Dalrymple substation.

Although these large batteries are effective, they don’t come cheap in comparison to pumped hydro. The system consistently demonstrates one of the most affordable, reliable forms of energy storage and generation, which is anticipated to become a growing industry in Australia’s renewable future.

PHES projects are continuing to pop up across the country, as the resource garners more interest from government, industry and the wider public. As pumped hydro systems develop, and the security and reliability of our energy system evolves, they will likely form a critical role in Australia’s energy future. 

More dispatchable energy generation and storage puts downward pressure on electricity prices, reducing Australia’s reliance on more expensive forms of generation. High profile projects like Snowy 2.0 and Marinus are expected to bring exciting new prospects to the industry, create a smooth transition to a low-cost and reliable energy supply for customers, and give the ageing energy infrastructure a much-needed refresh. 

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