Pumped hydro storage: Revolutionizing Hydro powerplants

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  Quantumrun Foresight
• July 11, 2022

Insight summary

Transforming old coal mines into industrial-scale batteries using pumped hydro storage (PHS) is a rising trend in China, offering a unique solution for energy storage and electricity generation. This method, while promising for enhancing grid stability and supporting renewable energy sources, faces challenges like acidic water which can damage the infrastructure. The repurposing of closed mines for energy storage not only helps in reducing fossil fuel dependence and carbon emissions but also revitalizes local economies by creating jobs and encouraging sustainable energy practices.

Pumped hydro storage context

Scientists at China's Chongqing University and Chinese investment firm Shaanxi Investment Group are experimenting with using unoccupied coal mine goaves (the part of a mine where minerals have been entirely or predominantly extracted) to act as industrial-sized batteries. These mines can serve as upper and subsurface storage tanks for pumped hydro storage schemes and be connected to large-scale solar and wind projects.

Pumped hydro storage (PHS) projects transport water between two reservoirs at different altitudes to store and create electricity. Excess electricity is utilized to pump water to an upper reservoir during periods of low electricity consumption, such as at night or on weekends. When there is a high energy demand, the stored water is released through turbines like a traditional hydro plant, flowing downhill from the higher reservoir into the lower pool, generating electricity. The turbine can also be used as a pump to move water upward.

 

According to the university and investment corporation's investigation, 3,868 closed coal mines in China are under consideration for repurposing as pumped hydro storage schemes. A simulation using this model revealed a pumped-hydro plant built in a depleted coal mine could achieve an annual system efficiency of 82.8 percent. As a result, 2.82 kilowatts of regulated energy per cubic meter could be produced. The primary challenge is the low pH levels in these mines, with acidic water potentially eroding plant components and emitting metal ions or heavy metals that may cause damage to underground structures and pollute nearby water bodies.

Disruptive Impact

Electricity operators are increasingly looking to PHS as a viable solution for balancing electricity grids. This technology becomes particularly valuable when renewable sources like wind and solar power are insufficient to meet demand. By storing excess energy in the form of water at a higher elevation, PHS allows for quick electricity generation when needed, acting as a buffer against energy shortages. This capability enables a more consistent and reliable use of renewable energy sources, making solar and wind power more feasible as primary electricity sources.

Investments in PHS can also be economically advantageous, especially in areas with existing natural reservoirs or disused mines. Utilizing these existing structures can be more cost-effective than the large-scale procurement of industrial grid batteries. This approach not only aids in energy storage but also contributes to environmental sustainability by repurposing old industrial sites, like coal mines, for green energy purposes. As a result, governments and energy companies can expand their electricity infrastructure with lower financial and environmental costs, while also boosting local energy production and reducing carbon emissions.

In addition, regions that experienced economic decline due to the closure of coal mines may find new opportunities in the PHS sector. The existing knowledge and expertise of the local workforce, familiar with the mine's layout and structure, become invaluable in this transition. This shift not only generates employment but also supports skill development in green energy technologies, contributing to a broader economic revitalization. 

Implications of pumped hydro storage projects

Wider implications of repurposing closed mines and natural reservoirs into pumped hydro storage may include:

• Lowering renewable energy infrastructure costs in specific regions, enabling more communities to access affordable green power.


• Transforming unused mining sites into economic assets, generating jobs and reducing carbon emissions in local areas.


• Enhancing the reliability of electricity grids relying on renewable energy, minimizing power outages and disruptions.


• Encouraging a shift in energy policies towards more sustainable practices, influencing governmental focus on renewable energy sources.


• Facilitating a decrease in reliance on fossil fuels, leading to a reduction in greenhouse gas emissions and improved air quality.


• Creating new vocational training programs focused on renewable energy technologies, fostering a skilled workforce in green sectors.


• Promoting the decentralization of energy production, empowering local communities to manage and benefit from their energy resources.


• Increasing consumer interest in renewable energy sources, potentially leading to a rise in green investments and products.


• Sparking debates over land use and environmental impact, influencing future regulations and public opinion on large-scale energy projects.


• Potential protests by environmental activists against converting old mines, driven by concerns over water contamination and natural preservation.

Questions to consider

• What other abandoned forms of infrastructure do you believe can be repurposed into pumped hydro storage projects? 


• Will future mines (of all kinds, including gold, cobalt, lithium, etc.) be designed with future repurposing in mind?