Deep dive into long term energy storage - is it the future?

Windmills and solar panels are the best sources for the generation of renewable energy. They are the more sustainable, noiseless, and zero-emission sources, as well as more economical, long-term, and nature-friendly energy systems. However, these renewable energy sources have their limitations, they only generate electricity at specific times. So, how do we handle these issues? We use long term energy storage to use this energy at other times. This article is designed to provide you with all the details you need to know about long term energy storage.

1.Can electricity be stored for a long time?

It is not impossible to store electricity, but we can convert it into another energy form to store it. We can convert it back into electrical energy on demand. We commonly use compressed air, flywheels, batteries(such as lithium ion solar battery), and hydro storage to store electricity. The batteries are the most suitable and accessible systems for storing electrical energy for a long time.

2.What happens to unused electricity on the grid?

The generation of electricity entirely depends on the load. The generators will produce more energy if the load demand is high. If the demand is low, the generators will simply produce less electricity. If you turn on your air conditioner, a generator somewhere will rotate harder to produce more electricity. Likewise, if we disconnect the generators from the load, the generator will rotate freely without generating any current. In fact, the electric energy of a certain power provided by the power station will be transported everywhere with the grid. So, there is no such thing as unused electricity on the grid.

3.What happens to excess electricity from solar panels?

Solar Panels are very efficient on hot sunny days. It easily fulfills the demand of residential or commercial load on such days. Sometimes, they generate more energy than required. So, where does this excess of energy go? All the solar panels are connected to some nearby grids. When these panels generate extra electricity, the net meters feed this electricity back to the grid. The grids provide this electricity to the local feeders, and it helps reduce the local load on the grid.

4.What are the 7 different storage methods of energy?

We have developed seven energy storage methods to use later and meet the supply and demand issues. The seven energy storage methods are as follows:

• Pumped Hydroelectric

It is a conventional method to store energy. We use electricity to operate motor pumps that pull water into reservoirs placed at heights to store potential energy. When we need that electricity, the water is released down into the turbines. The flow of water rotates the turbines, and they generate electricity. This electrical energy is equivalent to the energy used to pump the water up.

• Compressed Air

This energy storage method works on the same principle as pumped hydroelectric. However, compressed air is used in this method instead of water. The air is compressed to high pressure of 1000 pounds per square inch using electricity. That gas is allowed to flow towards an expansion turbine generator when the electricity demand is high. The released pressure of the air is high enough to rotate the turbine at high speed, which generates the equivalent amount of electricity.

• Flywheel

The working principle of flywheel energy storage is to use electricity to conserve kinetic energy in the flywheel, and the flywheel’s reverse spinning is used to generate electricity.

• Thermal Energy Storage

The electricity is used to create and store thermal energy. This thermal energy is later used to produce back electricity.

• Batteries

The most common method to store electrical energy is batteries. There are many types of batteries, such as lithium-ion, lead acid, lithium-iron batteries, and others. The batteries are suitable for storing energy coming from solar panels or windmills.

• Superconducting Magnetic Energy Storage

In this method, the current is passed through a superconducting coil to generate a magnetic field. This method is unique because we store magnetic fields instead of kinetic, thermal, or potential energy. When the electricity demand is high, the magnetic field is released to generate electricity by discharging the superconducting coils.

• Liquid Air Energy Storage

The electric current is used to cool gas at a low temperature until it becomes liquid. This method is called LAES or Liquid Air Energy Storage. Some waste heat or thermal energy is used to turn the liquid back into an ambient gas, which in turn generates electricity.

5.How long can energy be stored in a battery?

It entirely depends on the type of battery. In theory, batteries will experience irreversible capacity loss when storing energy, which is mainly caused by self-discharge. Among all batteries, lithium batteries have the lowest self-discharge rate and therefore have a stronger ability to store energy.

6.What is best for long term energy storage?

Batteries are the best long term energy storage out of all energy storage methods. They are easily accessible for residential use and can last for 10 to 20 years, depending on the battery type. The other methods, like pumped hydroelectric, can last for a long time, but they can only be installed at specific places, and they are not as economical as batteries.

7.Can lithium batteries be stored for a long time? How long can a lithium battery store energy?

Yes! Energy is stored in Li-ion batteries for much longer than lead-acid batteries because of their extremely low self-discharge rate, as low as only 3.5% per month. Generally speaking, on the premise of charging and discharging once a day on average, the lithium battery can be cycled 4000 times or more (0.2C, 25℃, 80% DOD), that is, its cycle life is as long as 10 years (4000/365≈10.96), while the longest cycle life of lead-acid batteries is only 3 years.

8.What are the differences between long-term and short-term energy storage?

Energy storage is divided into short-term energy storage and long term energy storage. The short-term energy storage mainly meets the needs of electrical energy storage within a few hours. Contrary to this, long term energy storage is mainly in the form of energy conversion such as water storage and hydrogen energy storage. The biggest advantage of long term energy storage compared to short term energy storage is its marginal cost per kWh, which avoids the additional cost of unused power, and has a high degree of flexibility in switching and stacking between different application scenarios. However, many cutting-edge technologies for long term energy storage are still in the early stage of R&D and demonstration.

9.Conclusion

In a nutshell, long term energy storage is a new type of energy storage system, which can fulfill our rapidly growing demand for energy and its management, and are more efficient and economical for storing renewable energy, and may be used for home energy storage in the future. The long term energy storage are environmentally friendly as they do not leave any carbon footprints.

Related article: top 10 energy storage lithium battery companies, top 10 flywheel energy storage companies in China