Since entering the 21st century, with global warming, we have been exploring future grid energy storage technology, which is an important technology that humans need to develop in the fight against climate change . At present, solar and wind energy technologies are mature and can provide sufficient energy for all mankind at a part of the cost of fossil fuel power generation. In 2017, the renewable energy industry received a total of 128 billion U.S. dollars in subsidies globally, which pales in comparison with the fossil fuel industry's total of 447 billion U.S. dollars in subsidies.
Today, the main factor hindering the development of renewable energy is the "energy storage problem." lithium-ion battery and other new battery technologies are quickly becoming the first movers in our energy storage needs. However, when we were looking for the best energy storage method, we “forgot” the oldest and most important form of energy storage-pumped storage, which is one of the oldest technologies still in use in our modern power grid. By pumping water into an elevated reservoir, the electrical energy is converted into potential energy, and then the water is released to drive the turbine wheel to generate electricity when electricity is needed.
Here, take Ireland with a relatively small population and the Turlough Hill pumped storage power station as an example. It is 681 meters (2234 feet) high, owned and operated by ESB, and installed four 73 A megawatt generator can generate up to 292 megawatts of electricity during peak demand.
This is the motor , which obtains power from the grid to rotate the impeller located in the lower layer, and pump the water up the mountain. When we need to generate electricity, this valve (also at the lower level) is opened, allowing water to flow through the impeller, rotating the impeller in the opposite direction and driving the engine located under the motor,At the maximum flow rate, water rushes through the machine at a rate of 28.3 cubic meters per second. If four 73-megawatt generators are used, the total is 111.3 cubic meters per second. At this flow rate, the upper reservoir of 2.3 million cubic meters will be drained in a little more than five and a half hours.
How much energy can this water produce?
First, let us imagine a 1 cubic meter water cube, we can increase its energy by increasing its height, and then use the gravitational potential energy equation to calculate the energy increase, it is an object The mass of is multiplied by the acceleration of gravity multiplied by its height, so we define the height as the height difference between the starting point and the ending point.
We conclude that the mass of 1 cubic meter of water is 1000 kilograms. At the same time, every 1 meter increase in height will increase the energy of 9810 joules, and when we convert _strong4span _strong4 to watts , Because it is a more commonly used unit. 9810 joules is approximately equal to 2725Wh. This is not a lot, it can run a 100-watt light bulb for 98.1 seconds.
Because the pumped storage power station cannot achieve 100% conversion efficiency. The efficiency of Telo Mountain is about 80%, so it is close to 78.5 seconds. If we raise the height to 286 meters, then 1 cubic meter of water can power the light bulb for 22,451 seconds, which is 6.2 hours.
is seeing the huge potential of pumped storage power plants,In the past ten years, China's pumped storage power stations have developed rapidly. At the end of 2004, 10 pumped storage power stations had been built and put into operation throughout the country, with an installed capacity of 5.701 million kW (600,000 kW of which was for Hong Kong).
Some people may ask, since this pumped storage power station has such great potential, can we build more?
The answer is yes. However, it is extremely difficult to find a suitable location for a pumped storage power station. What we need is not one, but two reservoirs that can hold a large amount of water. Not only must the horizontal distance between the two reservoirs be relatively short, but also at least 200 meters apart. high.
Generally, the cut-off point is defined by the ratio of head height to horizontal distance. Any value greater than 1:10 is uneconomical. Therefore, the 200-meter head is the maximum level between reservoirs The distance is 2 kilometers.
It is precisely under the above constraints that finding suitable locations for pumped storage power stations has become a major problem. For this reason, experts are seeking solutions to these problems.
As an ancient, reliable and long-lasting energy storage method, pumped storage is facing competitive pressure from other renewable energy sources that have received large-scale investment of $1 billion, but it stores energy for a long time. The ability to ensure that it will not be eliminated and continue to be used.
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