How can mechanical engineers reduce the cost of pumped hydro energy storage?

1 Site selection

One of the main factors that affect the cost of PHES is the site selection. You need to consider the availability of water, the elevation difference, the distance between the reservoirs, the geology, the land use, and the grid connection. Ideally, you want to find a site that has a large water volume, a high head, a short penstock, a stable rock formation, a low environmental impact, and a nearby transmission line. However, such sites are rare and often already exploited. Therefore, you may need to explore alternative options, such as using existing dams, abandoned mines, offshore locations, or artificial islands. These options can reduce the construction costs and the environmental impacts of PHES, but they may also pose some technical and regulatory challenges.

2 System design

Another factor that affects the cost of PHES is the system design. You need to consider the components, the materials, the layout, and the operation of the PHES system. For example, you can choose between different types of turbines, pumps, generators, and valves, depending on the characteristics and requirements of the site and the grid. You can also use advanced materials, such as composites, ceramics, or alloys, to enhance the performance and durability of the system. Moreover, you can optimize the layout and the configuration of the system, such as using a single shaft for the pump and the turbine, or using multiple reservoirs or stages. Additionally, you can improve the operation and control of the system, such as using variable speed drives, smart algorithms, or hybrid energy storage solutions.

3 System integration

A third factor that affects the cost of PHES is the system integration. You need to consider how the PHES system interacts with the grid, the market, and the other energy sources. For example, you can use PHES to provide ancillary services, such as frequency regulation, voltage support, or spinning reserve, which can increase the revenue and the value of the system. You can also use PHES to integrate more renewable energy sources, such as wind or solar, which can reduce the greenhouse gas emissions and the fuel costs of the system. Furthermore, you can use PHES to enhance the resilience and the reliability of the grid, such as by providing backup power, islanding capability, or black start service.