An innovative plan to generate and store renewable energy using groundwater in Bendigo’s disused mine shafts is closer to being realised following positive results from a feasibility study.
The study, which began in June, investigated whether the historic shafts have the capacity to power and store pumped hydro electricity, and concluded there was a strong prospect for cost-effective energy storage.
It concluded the project has a generation capacity of 30 megawatts and could store six hours, or 180 MWh, of energy for the local power grid, but would cost $50 million to create.
If built, the project could create up to 60 jobs during construction and a further five operational positions.
The study, conducted by engineering firm ARUP, concluded the project could also help with long-term groundwater management.
Pumped hydro electricity would involve connecting mine voids – areas of an excavation that remain after a mine has been filled in – to underground water sources through existing mine shafts.
Theoretically, solar panels would power water pumps, bringing underground water up mine shafts when peak demand and energy prices are low.
When energy prices are high, stored water would be released down the mine shafts through turbines, and the gravitational energy of the water would help generate electricity for peak demand.
However, more work was required to assess the accuracy of 3D modelling of the mine shafts, rock stability, groundwater contamination, and mine dewatering during construction, the report states.
The state government is calling for expressions of interest from industry and other parties over the next eight weeks to progress the work.
The initial $150,000, six-month study was funded by the state government and the City of Greater Bendigo.
It is unclear who will fund the second stage of the study.
Minister for energy, environment and climate change Lily D’Ambrosio said the study results were an exciting next step for the region’s renewable energy capacity.
“There is enormous potential for Bendigo’s empty mine shafts to store dispatchable, renewable energy and support generation into the grid,” she said.
“New energy technology is delivering jobs and a more affordable and reliable energy system to regional Victoria.”
Information sessions will be held in Melbourne and Bendigo to provide interested parties with an opportunity to seek further details on the next stage of the study.
The Bendigo goldfields had the largest concentration of deep shafts in the world, reaching over 1400 metres at its deepest point.
The plan is believed to be the first of its kind – certainly the first to be totally underground using man-made mines.
The pre-feasibility study made a number of conclusions, some of which are listed below.
- The capital cost of this project is $50 million, with $1.5 million required for a further, in-depth study.
- Given pumped hydro installations generally operate much longer than 30 years, the idea is considered cost effective.
- There are several ancillary benefits of the proposed concept, including; dewatering of Central Deborah Tourist Mine, dewatering of Swan Decline below Northern Exploration Drive, reducing peak transmission network demand and easing constraints on Bendigo Terminal Station transformers, potential to contribute to long-term management of groundwater, project development process may assist with development of other sustainable energy projects around Bendigo, project would create approximately 50-60 jobs during construction and 5 jobs during operation
- The key technical risks requiring mitigation in a feasibility study are; unknown hydraulic conductivity of Garden Gully at high flow rates, rock stability, dewatering in construction, Unknown accuracy of 3D model