Pumped storage-definition, pros, cons and development

Energy storage refers to the process of storing energy through media or equipment and releasing it when needed. As a key link in the power system, it can be applied to any link and scenario of power generation, transmission, distribution and consumption.

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Energy storage is not a new concept. Before large-scale development and utilization of new energy, the concept of energy storage is a term in oil reservoirs, representing the ability of reservoirs to store oil and gas.

The rapid development of the new energy industry in recent years has promoted the coordinated development of various energy storage technologies to a certain extent. This article will introduce pumped storage from various aspects including definition, working principle, pros, cons and so on.

What is the meaning of pumped storage

Pumped storage technology, also known as pumped storage power generation, is to use water as the energy storage medium to realize the storage and management of electric energy through the mutual transformation of electric energy and potential energy.

Use the electric energy in the low load period to pump water to the reservoir, and then release water to the lower reservoir for power generation in the peak load period.

Pumped storage can transform the surplus electric energy when the grid load is low into high-value electric energy during the peak period of the grid. It is applicable to frequency modulation and phase modulation, stabilizing the cycle and voltage of power system, and improving the efficiency of thermal power plants and nuclear power plants in the system.

Pumped storage is a green, low-carbon, clean and flexible power supply with the best degree of marketization, the most mature technology, the largest capacity and the most large-scale development conditions in the world.

Working principle of pumped storage

The pumped storage power station is composed of upper reservoir, water conveyance system, power house with unit and lower reservoir.

Use the residual power of the power system in the low power consumption period to pump the water from the lower reservoir into the upper reservoir, and then release water from the upper reservoir to generate power when the power system is at the peak load.

Advantages and disadvantages of pumped storage

Pumped storage has many incomparable advantages over other energy storage technologies. Compared with other energy storage technologies, pumped storage with a history of 100 years has been developed very mature.

Secondly, it has a long service life of 80 years or even 100 years. In addition, the current pumped storage power plants also have extremely high storage efficiency, which can achieve an overall efficiency of up to 80%. Besides the energy loss during charging and discharging, the self loss (self discharge rate) is extremely low.

The disadvantages of pumped storage technology are also obvious. Due to the distance and height requirements of upper and lower reservoirs, the construction of pumped storage power plants has great geographical restrictions. And under the condition of limited height difference, the energy density that pumped storage power plants can achieve is also limited.

In addition, the investment cost of pumped storage power plants is very high, and the return cycle is very long, usually requiring more than 30 years of return cycle, and its economy is low.

Development of pumped storage

In 1882, the world’s first pumped storage power station was born in Zurich, Switzerland. The development of global pumped storage mainly experienced the initial stage from 1882 to the end of 1940s, the rapid development stage from 1960s to 1970s, and the stable development stage since 1990s.

At present, pumped storage is the most mature, economical and large-scale energy storage mode, so it is also widely used in many countries around the world according to its dominant position in various energy storage modes.

According to statistics, the cumulative installed capacity of energy storage projects that have been put into operation around the world is 209.4GW, up 9% year on year. Among them, the cumulative installed capacity of pumped storage is the largest, about 180.7GW, with a year-on-year growth of 4.8%, accounting for 86.2%.

In China, the development of pumped storage power stations started late, and the research on the development of pumped storage power stations began in the late 1960s. However, the late start and high starting point are the characteristics of China’s pumped storage industry.

According to statistics, the cumulative installed capacity of China’s power storage projects that have been put into operation is 46.1GW, accounting for 22% of the global market, with a year-on-year growth of 30%. Among them, the cumulative installed capacity of pumped storage is the largest, 39.8GW, with a year-on-year growth of 25%, accounting for 86.3%.

Examples of pumped storage power plants in China

China Hebei Fengning Pumped Storage Power Station is the largest pumped storage power station under construction in the world independently designed and constructed by China.

It is known that Fengning Power Station will save 480,000 tons of standard coal, reduce 1.2 million tons of carbon dioxide emissions, promote energy conservation, emission reduction and air pollution prevention, and provide strong support for the clean and low-carbon transformation of energy in North China.

The hydropower station has set many world records, with the world’s first installed capacity, the world’s first energy storage capacity, the world’s first underground powerhouse scale, and the world’s first underground cavern group scale.

In recent years, China’s pumped storage industry has been supported by national policies. With the further construction of the new power system with new energy as the main body, accelerating the development of pumped storage power plants is an effective and economic means to solve the peak shaving problem of the power system and ensure the security of the regional power grid.

The development of new energy industry needs the coordinated development of energy storage industry. Although traditional energy represented by traditional coal energy will produce more pollutants when generating electricity, which will have a negative impact on environmental protection, on the other hand, traditional energy has strong stability.

For example, thermal power plants can purchase or burn coal for power generation according to power generation capacity, and coal that is not needed temporarily can be stored in a physical way. It is precisely because of its stability that traditional energy has played an important role in the long history of human development.

However, due to the high pollution of traditional energy and the non renewable nature of oil, coal and other resources, it has become the international mainstream consensus to gradually be replaced by new energy.

In a word, new energy is more dependent on energy storage industry than traditional fossil energy due to its unstable characteristics. The energy storage industry has a strong demand. With the overall growth of new energy, the scale may be further expanded in the future.