Recent electricity price spikes and a state-wide blackout in South Australia have highlighted the need for reliable power to balance the potential volatility of some renewable power sources. Nick West, civil engineer from power and water consulting firm Entura, gives his thoughts about the future role for pumped storage.
Pumped storage hydropower projects are a natural fit in an energy market with a high penetration of renewable energy. This highly efficient form of large-scale energy storage could help mitigate challenges that come with the introduction of more wind and solar power into the market, with the potential to help to maximise the use of these renewables that are subject to the vagaries of weather. Furthermore, the recent completion of the feasibility study for Genex Power’s Kidston Pumped Storage Project in North Queensland by Entura shows this approach is now technically and commercially feasible.
Storage and system stability
As the proportion of renewable energy in an energy market increases, the need grows for the stability and consistency provided by utility-scale energy storage. For example, South Australia needs system-wide storage of 500MW for a period of 10hours to improve the flexibility of wind farm operators, according to the Melbourne Energy Institute. While at the smaller scale of energy storage, the buzz about various types of batteries continues – but the only storage option with a proven track record at the utility scale is pumped storage hydropower.
In a recent article, Donald Vaughan, Entura’s Principal Consultant for Primary Electrical Engineering, stated that 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.
Despite the significant potential and benefits of pumped storage hydro projects, only three projects currently exist in Australia (two in New South Wales and one in Queensland). These schemes were built in markets in which generation was mainly thermal, where the pumped storage could supplement supply at times of peak demand.
A number of possible sites have been identified for new opportunities for pumped storage hydro, but so far very few have been developed beyond concept level. This means that opportunities exist for developers in states such as South Australia and Queensland that have set ambitious renewables targets and must maintain energy security.
For successful pumped storage hydro projects, developers need to identify a viable site, achieve a technically and commercially feasible design, and make the most of the economics of the energy market. With many thousands of potential sites across the country, a developer needs smart methods of filtering to reduce the many possibilities to just a few ideal sites. An important consideration is the effect on the viability of pumped storage projects of the relative remoteness of sites, through both the efficiency of the power’s round trip and the marginal loss factors (factors applied to a generator or a load, and calculated based on the size and distance of the generator or load from a central point).
As for any development, the process of identifying sites must also consider topography, land use and environmental constraints. Pumped storage projects generally present similar but reduced environmental risks than conventional hydropower projects as they tend to have smaller footprints.
Technically and commercially feasible
Entura’s experience on Genex Power’s Kidston pumped storage hydro project has shown that it is possible to construct low-cost pumped storage projects in Australia through careful site identification and clever project design. Where a pair of suitable reservoirs don’t already exist, constructing a turkey’s nest dam may offer a solution.
A turkey’s nest dam is a reservoir built by excavating earth from the centre of the reservoir and moving it to the edge to help form a continuous embankment. Turkey’s nest dams have been used successfully around the world in pumped storage hydropower projects, providing opportunities to build projects where elevation changes significantly over a short distance. Additionally, turkey’s nest dams can help to minimise capital costs by reducing conduit lengths and maximising head.
Understanding the opportunities and constraints in the energy market is critical to a pumped storage project’s financial viability.
Selecting the optimum installed capacity of a pumped storage project also requires detailed understanding of energy markets. It is possible that a pumped storage project can act to flatten peak prices to the point where the returns on a project are insufficient to meet financiers’ hurdles, so detailed revenue modelling is essential to determine the tipping point between enough and too much installed capacity.
With careful selection of sites, clever design, and the right mix of capacity and costs, pumped storage hydro holds an important key to unlocking the full potential of renewables in Australia’s electricity market.
Nick West is a civil engineer at specialist power and water consulting firm Entura with 15 years' experience, primarily in hydraulics and hydropower. Nick’s skills range from the technical analysis of the layout of hydropower projects to the preparation of contractual project documents and computational hydraulic modelling. He was a key team member of the Kidston Pumped Storage Project Technical Feasibility Study and was involved throughout the recently completed Neusberg Hydroelectric Project in South Africa. His portfolio of successfully completed projects range from hydraulic design for small residential developments to the feasibility study of a cascade of four large hydroelectric projects in Malaysia.
Specialist power and water consulting firm Entura is part of Hydro Tasmania, Australia’s largest renewable energy producer and water manager, and is backed by more than 100 years of creating energy and maintaining power and water assets