Are water batteries that store solar energy environmentally friendly or an ecological disaster?

According to NPR, the San Diego Water Department plans to use the reservoir to build a sustainable energy system so that the energy provided by the sun can be used even after the sun sets.

Solar energy can only be collected when the sun is shining. At night, when there is no sun to supply electricity, the electricity stored during the day can only be used. Assuming that there is enough solar energy collection system to charge the storage battery during the day, the capacity of the storage battery will determine how long the remaining power can be used when there is no sun.

How big a battery would be needed to store enough electricity for the people of a state? How difficult would it be to manufacture? How high would the maintenance cost be? Where would it be best to put it?

These naked questions are daunting to face.

Fortunately, people have always been good at using nature and have found a good way to store solar energy in water.

Build two reservoirs with different heights and connect them through underground pipes. When the sun is high in the sky, use solar power to pump water from the lower reservoir to the higher reservoir. In this process, solar energy is converted into electrical energy and then into water potential energy.

The water storing solar energy is stored in the higher reservoir. When the sun sets and there is no solar power generation, the water in the higher reservoir is released, and the turbine is driven by water to generate electricity to provide electricity for residents. In this process, the potential energy of water is converted into electrical energy.

It is a wonderful idea to store electrical energy by the height difference of water.

According to the plan of the Santiago government, the new reservoir will be built in a canyon near the San Vicente reservoir, and the two will be connected by a large underground pipeline. When the upper reservoir is released, it will generate 500 megawatts of electricity for 8 hours, which will be enough for 130,000 households.

After the implementation of this plan, the peaks and lows of power supply will be further smoothed. Due to the unstable power supply of solar energy, wind energy, etc., there is sometimes an excess and sometimes a shortage of electricity, which is the so-called peak and low peak of power supply. How to store and use the electricity generated during the peak of power supply has always been a troubling problem. Because electricity can only be used or stored after it is generated, the facilities or equipment available for storing electricity are obviously not enough, so the excess electricity can only be wasted. There will be a shortage of electricity during the trough of power supply. This plan is equivalent to providing a large enough power storage pool to store solar energy during peak periods and release it during trough periods.

In addition to this plan, the virtual power plant that was very popular some time ago is also a means to smooth the peaks and lows of power supply. Virtual power plants call on people to use their own power storage equipment (such as electric vehicles) to charge during peak periods and discharge during trough periods by providing rewards or using other methods.

Are these ways of storing electricity harmful? The answer is of course yes. There is no free lunch in the world. In the virtual power plant plan, individuals get money and the government gets energy storage resources that do not require maintenance. Only the battery in your hand loses its life - of course, you still need to spend your own money to replace the battery later.

In the government's water battery plan, it is the local ecological environment that is harmed.

The two reservoirs intercept water, which will inevitably damage the water resources downstream. Of course, you can say that the reservoir can regulate water resources, store water during the flood season, and release water during drought. But you have to realize that the purpose of the reservoir is to store electrical energy.

This means that the reservoir will store as much water as possible at ordinary times, no matter what period it is. After all, water volume means electricity. This also points out that the water storage of the reservoir may be counter-cyclical. Before the flood season, the reservoir has enough water. It cannot store water during the flood season, but needs to release water; during the drought period, the downstream reservoir does not release water when it lacks water - you lack it and it lacks it.

It can be foreseen that after the implementation of the plan, urban residents will benefit and there will be stronger power guarantee at night. Life downstream of the reservoir may be more difficult, and they may face more severe floods and more serious droughts.