Australia’s Pumped Hydro

Australia runs three pumped hydro schemes, the newest finished in 1984; the one it is building has gone from $2 billion to $12 billion and is not finished, and the one Queensland has been promised would cost more than both and has no decision to build it.

The Scale

What Exists Now

Tumut 3 in the Snowy has run since 1973 and remains the largest at 1,800 megawatts, with six generating units and three pumps. Shoalhaven, 240 megawatts at two sites in Kangaroo Valley, followed in 1977. Wivenhoe, 570 megawatts west of Brisbane, came in 1984 and holds about ten hours of water in its upper pond. Nothing has been finished since.

What Is Being Built

Snowy 2.0 links Tantangara and Talbingo, two reservoirs of the old scheme, through 27 kilometres of tunnel, about twelve Sydney Harbour Tunnels laid end to end, with six reversible turbines in a cavern 800 metres down. Four tunnel-boring machines have been at work; the first broke through into the cavern in May 2026.

In June 2026 the Auditor-General found Snowy Hydro only partly effective in managing delivery, with no agreed baseline schedule and no robust understanding of the forecast cost to complete; the project was 262 days behind at July 2025, with a line of sight to September 2029. Snowy Hydro’s public page still says complete at the end of 2028. Its own annual report targets progressive commissioning in 2030. The Commonwealth Budget carries Snowy 2.0 as a fiscal risk and a contingent liability with no dollar figure attached.

Snowy 2.0 at $12 billion works out at about $5,500 for each kilowatt of power and about $34 for each kilowatt-hour of storage, because it holds so much water. Borumba at $18.4 billion works out at $9,200 a kilowatt and $383 a kilowatt-hour. The CSIRO’s 2026 benchmark for a 24-hour scheme was reported as $5,687 a kilowatt, or $237 a kilowatt-hour.

What Remains Proposed

Borumba would raise a new dam wall 300 metres downstream of the existing Borumba Dam and build a new upper reservoir on the ridges about 330 metres above it, joined by tunnels to an underground powerhouse. Announced in 2021, it was reviewed after the October 2024 election; the review found less than a 1 percent chance of first power by the promised 2030. In January 2026 the Coordinator-General extended the project declaration to February 2028. The 2026-27 state budget gave Queensland Hydro $324.3 million for exploratory and early works, subject to a continuing review. The refreshed business case is due in 2026.

Twelve other schemes remain proposed, 8,485 megawatts between them. None has a decision to build. Two New South Wales proposals were withdrawn in 2025: Origin’s Shoalhaven expansion and the 325 megawatt Central West scheme.

How Long the Water Lasts

How Long They Take

Tumut 3 took about five years to 1973. Wivenhoe took about seven, from 1977 to 1984. Kidston, begun in May 2021, will have taken more than six years if it generates in July 2027. Snowy 2.0, contracted in April 2019, will have taken nine to eleven years on the dates now in circulation. Borumba’s own review puts completion 14 years after its 2021 announcement.

Reading the Numbers

Pumped hydro generates nothing. It moves electricity from one hour to another and gives back less than it takes, so it adds nothing to a year’s supply and is never compared with Eraring’s output. Its megawatts say how hard it can push; its megawatt-hours say for how long. A feasibility study, a business case or an exploratory-works allocation is not a decision to build, and none of the proposed schemes here has one. Kidston is registered with AEMO but had neither pumped nor generated at the status date, so it is counted as under construction.