Energy storage | sustainable future
Pumped storage: powering a
In an exclusive Q&A, Richard Herweynen, Technical Director at Entura, delves into the significance of pumped storage in enabling the clean energy transition, its economic advantages, and its promising role in a world increasingly reliant on renewable energy sources
In your opinion, what makes pumped storage such a crucial component of the hydropower industry?
Without a massive increase in energy storage, the clean energy transition simply can’t happen at the pace and scale that is so critical to limiting global warming. The low levelised cost of wind and solar power and the retirement of fossil-fuelled power generators are driving an urgent need for more storage solutions in increasingly complex energy grids. Pumped storage hydropower projects are a natural fit in an energy market with high penetration of renewable energy as they help to maximise the use of weather-dependent, intermittent renewables (solar and wind), fill any gaps, and make the integration of renewables into the grid much more manageable. Pumped storage provides a ‘load’ when the wind is blowing and the sun is shining, and it also provides a reliable and immediate source of dispatchable energy when the available renewable generation can’t meet demand. By pumping the water uphill when generation exceeds demand, the pumped storage scheme is essentially ‘storing’ energy for later use. With the extra storage, stability and consistency provided by pumped hydro, there’s less need for coal, gas or diesel generation. Pumped storage hydropower has an advantage over batteries, as they can provide “deeper storage”, that is much longer duration storage. A functioning AC power system needs inertia, fault level, frequency and voltage control as well as energy sources to function to an acceptable standard. Pumped storage assets can provide all of these important contributions to a stable and successful power system, levelling out the fluctuations in availability of wind and solar energy, and helping to regulate voltage and frequency. Pumped storage projects therefore help the grid to retain equilibrium, maintain stability, and quickly remedy disruptions.
In terms of system flexibility, how does pumped storage enhance the overall efficiency and reliability of hydropower operations? The flexibility provided by pumped storage allows hydropower operations to adapt and respond quickly to fast-moving energy market dynamics. Pumped storage hydropower in a hydroelectric system enables better strategic planning and optimisation of electricity
24 | October 2023 |
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generation to maximise revenue and grid support. Conventional hydro storage is typically used in a seasonal or multi-year cycle to support the power system through uneven rainfall, droughts, and above average rainfall periods. Pumped storage provides more capacity for a hydropower system to store short term energy surpluses from other renewable sources allowing greater capture of this clean energy.
What are the main advantages of pumped storage compared to other energy storage technologies? The rise of renewables will lead to a diversity of storage and supply solutions. With green hydrogen still at a very early stage in Australia, the main players in the storage market are batteries and pumped storage hydropower. Ultimately, there is a place in the market for both, and they may even complement each other in certain circumstances. The key advantage of pumped storage is its ability to
provide storage durations much longer than currently possible with batteries. It’s a proven technology with a very long lifespan and low operational costs, and is cost-effective at storing and releasing large amounts of energy. Batteries are more cost-effective at delivering small amounts of stored energy over a short time at high power levels. Pumped storage has more complex site-selection constraints and takes longer than battery energy storage systems (BESS) to move through planning, design and construction; however, once operational, the pumped storage scheme has a life expectancy many times that of utility-scale batteries. Capex costs therefore aren’t immediately comparable but need to be calculated across the estimated lifecycle. Another advantage of pumped storage hydropower is that its degradation is close to zero. With appropriate maintenance, peak output can be sustained indefinitely. In contrast, batteries degrade as they age, which decreases the amount they can store. To maintain a reliable and steady capacity for storage as batteries age and degrade, large-scale battery plants will require ongoing staged installation and replacement of batteries. In terms of grid support, pumped storage is based on well-established synchronous generation, providing critical ancillary services to the grid, through the provision of inertia, frequency and voltage support
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