AN ambitious plan to store renewable energy using groundwater stored in Bendigo’s vast network of disused mine shafts has taken another step forward.
The state government will announce engineering firm ARUP will carry out a $150,000 feasibility study to determine whether the plan is technically, financially and operationally viable.
How it works: Bendigo groundwater as renewable energy
The Bendigo goldfields had the largest concentration of deep shafts in the world, reaching over 1400 metres at its deepest point.
It’s a unique underground environment where seven separate mine workings remain to this day, steadily accumulating groundwater.
Potentially, these conditions are ideal to provide Bendigo’s own pumped hydro scheme.
The plan is believed to be the first of its kind in the world – certainly the first to be totally underground using man-made mines.
In daylight hours, excess solar and other renewable energy would be used to pump water from one reef system held at a low water level to an adjacent reef at a higher water level where it would be held in storage.
When a peak electricity demand comes, or overnight when the sun is not shining on solar panels, the water would run back down to the lower level, turning a turbine and generating electricity.
BSG Bendigo mines pumped hydro action group co-ordinator Ken Mann said pumped hydro should be far cheaper than building batteries, and comparably cheaper than other pumped hydro projects.
“If the concept proves feasible, construction could happen quickly because most of it is all already there,” Mr Mann said.
“There’s the potential for it to be used for power storage for the wider Bendigo region, and to store power generated from small, medium and large-scale solar and wind farms that could develop in the region.”
The Sheepshead Reef, Deborah Reef and Swan Decline, where water levels were down about 250 metres, were likely to be the source of water to be pumped to a higher level, such as the nearby Garden Gully Reef 200 metres away, where the water was 50 metres below the surface.
Underground pipes between the two reef systems and dropping into convenient shafts could be used to pump and move the water between the reefs. Infrastructure for pumps and turbines would be constructed mostly underground.
The plan will be further crystalised in the state goverment’s $150,000 feasibility study.
The proposal could work hand-in-hand with current efforts to pump out the accumulating groundwater.
The scheme could be used to move water between different workings where it is seeping into the reefs, to where the water is extracted and treated to control it from discharging out onto the surface.
BSG volunteers have spent hundreds of hours developing the plan.
Mr Mann said they had a lot of confidence in the concept but would need to see the outcome of the feasibility study before suggesting it would work in practice.
“This resource sits right under the city that needs the demand,” he said.
Vision for a community-owned energy future for Bendigo
Bendigo households and businesses spend up to $130 million on electricity per year – money which is taken out of the community and put into the hands of large corporations with much of the profits heading overseas.
As power and gas prices continue to rise as predicted, that figure will skyrocket.
It’s a situation that the Bendigo Sustainability Group wants to reverse. They pose a simple question: Why shouldn’t that money be kept in Bendigo through community-owned renewable energy projects?
BSG vice president Chris Corr said the pumped hydro mines groundwater plan could be the catalyst for generating greater growth in other local renewable energy sources.
“The BSG has a vision for much of Bendigo’s electricity to be provided from community-owned renewable energy projects, predominantly solar, keep the profits from energy local and benefiting the wider community,” he said.
“If found viable, the BSG would love to see the community be able to own the Bendigo mines pumped hydro project.
“Bendigo is the ideal mid-sized regional Australian city to be the test case and to lead down, with strong government support, a path to a large-scale community-owned renewable energy future.”
Community-owned wind projects already exist in regional Victoria, including the Hepburn wind farm and the Coonooer Bridge wind farm near Charlton.
In Bendigo, a combination of household solar PV, commercial-scale solar, wind power, and waste-to-energy and biomass could be scaled up to help the city – and possibly the region – approach 100 per cent renewable.
Pumped hydro and batteries could then provide the energy storage to meet peak demand periods and times when the renewables are generating little or no energy.
Mr Corr said their goal was for Bendigo to become a net exporter of renewable energy.
At this stage, the pumped hydro groundwater plan has the backing of the state government.
Energy minister Lily D’Ambrosio described it as an “intriguing” idea that could deliver “tremendous benefits” to Bendigo.
“We’re backing this study because solar pumped hydro has the potential to store and generate significant levels of energy capacity,” she said.
“Studies like this one help position Victoria as a world leader in renewable energy technology.”