What is Energy Storage? Definition & How It Works

Why is energy storage important in the renewable energy sector? Is it a must-have aspect for green energy to work effectively? Let’s find out!

Energy storage is becoming a big issue, especially with the increased use of renewable energy worldwide. It is now important to have reliable energy storage systems to capture energy produced by wind, sun, or water power.

Usually, we have different types of energy storage technologies depending on the power source. These technologies are classified into mechanical, chemical, electrical, and electrochemical. Today, we have learned everything there is to know about energy storage.

What Does Energy Storage Mean?

Energy storage involves storing power produced for use at a later time. For instance, solar panels produce power from the sun, which is then stored in solar batteries. These batteries are the main type of energy storage solution here and help to provide power when the sun goes down.

When the sun is not powering solar panels, one can use the energy from the batteries to power their home.

Is Energy Storage Important?

Energy storage is essential in the world of renewable energy. For instance, since the sun cannot shine all day, tides fluctuate, and the wind only blows for certain periods. Therefore, it is crucial to have a power backup.

Energy storage systems come in handy to help compensate for those periods when the source of energy is not available. They help store water, solar, and wind power for later use.

Here are some benefits of energy storage systems:

Power backup: Energy storage is essential for backup. On days when the source of renewable power is insufficient, in-store power could facilitate important activities.
Reducing energy wastage: A lot of energy goes into wastage simply because it is not stored properly. Using the right storage systems can help reduce wastage and save money in the long run.
Make money: With reliable energy storage systems, saving or making money is possible! You can sell the excess stored power to your community and earn money.
Encourages further use of renewable energy: Modern energy storage systems promote the shift towards renewable energy. This is because ample storage makes renewable energy reliable. In the long run, this will reduce the use of fossil fuels and lead to less carbon footprint.

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Types of Energy Storage

1. Lithium-Ion Battery Storage

Lithium-ion batteries were developed in 1970 by a British scientist named Stanley Whittingham. However, they were not used commercially until 1991. They are the most common form of energy storage technology that we have today.

With the growth of technology, lithium-ion batteries are far more advanced than in the 70s or even the 90s. Since they are becoming more reliable energy storage sources, batteries can be used for more advanced powering needs. A typical efficiency rate is 95%, with about 5% discharge.

Lithium battery systems charge and discharge energy through a combination of chemical reactions. Their use is common in mobile phones, laptops, and electric cars. However, with technological advancements, they are now used in residential solar systems and plants.

World map showing lithium, cobalt, nickel, manganese, and copper sources for battery production.

Advantages of Lithium-ion Battery Storage

Higher density: Lithium-ion batteries have a higher energy density than other batteries like lead acid. This way, they can last for a long time without the need for a recharge.
Also, these batteries can be paired with solar panels to store excess energy. The high power density of these batteries makes them ideal for residential homes.
Low self-discharge: The discharge rate is always an issue when using batteries. Fortunately, lithium-ion batteries have a low discharge rate of about 5%.
Little or no maintenance: You are good to go once you buy lithium-ion batteries. No need to keep monitoring them, as they don’t need any service!
Easy to scale: They can power complex power activities when connected in a parallel setting.

Disadvantages of Lithium-ion Battery Storage

Expensive: The initial cost of buying lithium-ion batteries for energy storage can be very high. If you plan to run a residential home on solar, you will be required to invest thousands of dollars in the initial purchase of batteries.
Aging: Unfortunately, these batteries are only useful for a certain period. Their capacity and efficiency will decrease over their lifespan. At some point, you will need to replace them. In fact, after about 1,000 cycles of fully charging and discharging, the batteries will likely need a replacement.

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2. Liquid Air Energy Storage

Liquid Air Energy Storage is common in plants and industries. The technology involves cooling air until it becomes liquid nitrogen and storing it in tanks. Later, the liquid is converted back to gas and used to power various activities.

For something so science-fictiony, this is a low-risk technology with a lifespan of up to 30 years per system. Since this is a large-scale storage technology, it needs storing at the point of use for peak efficiency.

How does Liquid Air Storage Work?

The process of liquid air storage involves three processes:

Liquefying the air – This is the first process of energy storage. It involves using electrical energy to draw energy from the surroundings and convert it into a liquid form. For every 700 liters of ambient air, you get 1 liter of liquid air.
Energy storage – After the air is converted into liquid, it is stored in insulated LNG storage tanks and can easily hold up to GWh of energy.
Power recovery – When power is needed for power turbines or other uses, the liquid air is heated back into the ambient air. The results produce high-pressure gas that can be used in different applications in running plants and factories.

LAES plants are great for large-scale industrial use. They can be used in the long term for up to 30 years and have proved to be efficient for energy storage.

3. Compressed Air Storage

Pressurized air or compressed air energy storage technology is ideal for large-scale energy storage projects. The air is stored in pressurized tanks or underground caverns and later retrieved when needed. The technology is fairly old, with the first plant established in 1978 in Germany.

The process uses specialized equipment and a power source to power the compressor, which pumps air to the tank. When the storage happens on a large scale, it is stored underground caverns. But, on a smaller scale, the storage can be in specialized tanks.

The storage tanks or caverns must be strong enough to withstand high pressure.

Compressed Air Storage Benefits

Energy savings – storing energy for use during peak demands can be important in long-term energy savings.
Good for the environment – compressed air storage is good for the environment. It has fewer carbon emissions, so you do not have to worry about polluting the environment with fossil fuels or from lithium mining, like in the case of battery manufacturing.
Reliable and stable power – power stability is important in manufacturing and other production activities. Compressed air storage can enhance power stability by ensuring operations continue running.
Little maintenance cost– you do not have to keep maintaining the energy storage tanks or caverns. Yes, they will need monitoring. However, you do not need to actively service the systems.

4. Flywheel Energy Storage

Flywheel energy storage systems store kinetic energy. They consist of a mass rotating around its axis. Experts reckon this relatively old technology is still not fully developed and may replace lead-acid batteries once advanced.

The flywheel operates in a vacuum, reducing energy loss and helping it rotate faster. In an energy grid, a flywheel regulates power in cases where power supply and demand do not match.

It helps to compensate for the excess power supply required. For instance, when power is required in the grid, the flywheel transfers power back to the grid using momentum.

This form of energy storage is actually used in buses to replace the traditional lead-acid batteries.

A simple way to understand how flywheel energy storage works is to check how amusement parks and rollercoasters work for acceleration. The flywheel technology is also found in friction toys to accelerate movement.

Advantages of Flywheel energy storage

Durable – flywheel energy storage is one of the most durable technologies. We have some storage systems that are 200 years old and are still in perfect working condition today. A good example is the James Watt steam engine, which still works two centuries later.
Energy efficiency – these systems are energy efficient, with less energy loss. They can produce a sizeable maximum output with an energy efficiency of up to 90%.
Less failure – flywheel energy storage rarely fails. It is not affected by external factors such as changes in temperature, so it lasts for a long time.
Good for the environment – the production and storage of energy here are not a threat to the environment.

5. Superconducting Magnetic Energy Storage

Superconducting Magnetic Energy Storage uses the magnetic field of the superconducting wire coil to store power. It is a stable power storage option with near-zero loss in energy, especially since all the major components are stationery. Here, the process of storing and discharging energy is almost instant since it is connected to the power grid.

The SMEs technology was invented in 1970 to store energy. These systems have high power density and are quite efficient, with up to 95% energy conversion.

However, unlike other energy storage systems, SMES systems are ideal for storing current energy. As such, they might not be an excellent choice for long-term storage.

If you are looking for an uninterrupted power supply, you need to consider superconducting magnetic energy storage. The SMEs stands out from other energy storages for being lightweight and efficient.

This form of energy storage has been in use since 1980. Unfortunately, the purchase cost is still high, which makes the uptake quite low.

Benefits of Superconducting Magnetic Energy Storage

Enhanced power quality – for operations that need carry-over energy, using SMES can be helpful. It is important to have an emergency backup during power outages or voltage drops.
Good for the environment – super magnetic energy storage is environment-friendly. No chemical reaction is needed to store energy here. Also, there are no contaminants, making it a stable form of storage.
Good performance – SMES systems offer good performance and can offer a dynamic range, with a 100% recovery rate.

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6. Redox Flow Batteries

Redox battery energy storage — Image by Radiotrefoil – Own work, CC BY-SA 4.0,

Redox flow batteries convert chemical energy into electrical energy. They work through the reduction of working fluids and reversible oxidation. These batteries are ideal for large-scale storage. They stand out from other types of batteries due to their unique design, which involves two separate tanks with electrochemical cells.

These batteries are common in utilities, electric vehicles, and microgrids. They have a bigger tank size compared to lithium-ion batteries. Due to the larger the size, they can store more energy. Redox batteries are quite efficient compared to other types of batteries. They have a lifespan of about 15 years and an efficiency of up to 70%.

Benefits of Redox Flow Batteries

Longer duration – unlike other batteries, such as lithium-ion batteries, Redox flow batteries keep the energy flowing for a long time. They can store energy for up to 12 hours, unlike some other batteries that keep it only for up to 4 hours.
Safe – these batteries are not made of dangerous chemicals like lithium-ion batteries. They are not flammable, and they also do not contain any toxins. So, they are pretty safe.
Operate in different temperatures – these batteries can operate even in negative temperatures. Therefore, you do not need ventilation when operating these batteries, as they work perfectly in different temperatures.

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7. Pumped Hydroelectric Storage

This type of energy storage is used for storing hydroelectric energy. And, with two water reservoirs at different elevations, they store hydroelectric power (in the form of water). The water is released during off-peak periods through turbines to generate power.

It is an efficient form of energy storage with 80% efficiency. And, it can provide between 6 and 20 hours of electricity back up. This is optimal compared to lithium-ion batteries, which only produce about 6 hours of electricity.

Unlike other forms of storage, pumped hydro energy storage is very durable. The plants can last up to 40 years, while dams can last for 100+ years. China is leading in hydro energy storage, followed by the United States.

Advantages of Pumped Hydroelectric Storage

Ideal for large-scale: Pumped hydro energy storage is suitable for large-scale energy storage. It is one of the most economically viable methods of energy storage.
Efficient: If you are looking for efficiency, pumped storage plants work well. The best thing is that they have an efficiency rate of over 80%.
Durable: These pumped storage plants can last up to 40 years. They are more durable than most storage systems.
Good for the environment: If you are switching to green energy, it is advisable to consider this form of energy storage. It doesn’t produce any forms of toxins in the environment.

Disadvantages of Pumped Hydro Energy Storage

High initial cost: The initial cost of setting up the plant can be quite high. You need to invest a lot of money and space to get a good plant and storage. Fortunately, the durability of the plant makes up for the high initial cost.

8. Thermal Energy Storage

Thermal energy storage (TES) is used in thermal energy systems to store heat in buildings, structures, and other materials. Usually, thermal energy is derived when a material gains and losses heat. And it is an affordable form of energy storage compared to electricity storage.

Thermal storage is used in renewable energy sources and is an excellent option for reducing energy waste by capturing surplus energy. It can also work in capturing energy from sewerage and waste systems.

Where are Energy Storage Systems Applicable?

Residential Homes

Energy storage systems are common in residential homes. With the increased use of renewable sources to generate electricity, it is important to ensure that this power can be efficiently stored for later use.

For example, for homes that are using solar energy, having good energy storage systems is necessary. This way, you’ll still have enough stored electricity to power your home even after the sun goes down.

Essentially, the sun is only available for a few hours, and excess power should be redirected elsewhere for later use. Lithium-ion batteries are the most common for residential homes’ power storage. They store power for a good amount of time, and they can power most household appliances.

Air Conditioning Systems

Energy systems are ideal for powering air conditioning systems. Thermal energy storage is common for powering air conditioning systems. During cold nights, thermal energy storage works by making the material cold and later using it for cooling during warm days.

With this method, ice storage is ideal since, unlike water, it takes less space. Currently, 3300 buildings are using thermal energy storage in 35 countries.

It is gaining popularity fast since many developers now aim to create low-impact buildings. The initial cost might be high, but the long-term energy savings are worth it.

Transportation

In the transport sector, energy storage is now a big deal. We have liquid hydrocarbon fuels and electric vehicle batteries for public transportation and private vehicles.

Getting a continuous electricity supply from renewable energy sources can be challenging. As such, it is essential to have storage in a place to store excess energy. For instance, in public transport vehicles with solar panels, it is necessary to have batteries installed to capture the surplus energy.

How to Choose the Right Type of Energy Storage Systems

Energy storage systems have seen rapid growth in the last few years. Now, we have numerous options available for energy storage.

If you are planning to switch to renewable energy, it is important to understand the different storage options for you to make the best choice. Here are some tips to help to choose suitable energy storage systems:

Source of Energy

The source of energy will determine the storage system. If you are getting your energy from renewable sources such as solar, you need to store it in batteries.

On the other hand, if you are getting power from water or wind, you can use pumped hydro energy storage. So, the energy source should be compatible with the storage system you want to use.

Fortunately, there are various storage systems, so you can always pick the one that matches your needs. Always research to ensure that your storage system will efficiently store energy from the source.

The Initial Cost of Buying and Installing the System

Buying and installing energy storage systems can be expensive. Batteries are expensive, although we have other more expensive systems like pumped hydro energy. So, before purchasing any storage system, you need to consider your budget.

Fortunately, we have financing for storage systems. If you feel that the initial cost of purchase is too high, you can look for the right loans available for renewable energy.

Note: you might need a technician to help you with the installation process. So, make sure that you put that into consideration.

Space and Infrastructure

Before considering any energy storage system, make sure that you assess to determine the right one for you. For some storage systems, you need to have enough space and infrastructure for the installation. If you have a small home and space, you might not install large batteries because they take a lot of space.

We have technicians who will survey your place to determine whether you have the right infrastructure needed for installation. Luckily, with the growth of technology, most energy storage systems are compact and take less space for installation.

Care and Maintenance

Installing energy storage systems is one thing, but ensuring they run smoothly is another. It is advisable to consider care and maintenance for your energy storage systems. While we have some systems that require zero servicing, such as lithium-ion batteries, others do.

We also have other systems that need extra care. Every once in a while, you need to contact a technician to help you with regular servicing.

It will cost money to take care of energy storage systems, but neglecting them might make them faulty or unreliable. Always make sure that you consider the care and maintenance involved in the process.

Reliability, Efficiency, and Durability

Reliability and efficiency are important factors when choosing an energy storage system. Always consider a system that is reliable and efficient.

With the growth of technology, the efficiency of most energy storage systems has greatly improved. Today most systems have an efficiency of over 80%. For example, lithium-ion batteries are quite reliable, with an efficiency of up to 95%.

When using renewable energy as your main source of power supply, it is important to have a reliable and efficient source of power. Any storage system that has an efficiency of over 80% is quite good.

The lifespan of energy storage systems also matters. For instance, we have systems with a long lifespan of up to 80 years. Others have a short lifespan of only 15 years, like lithium-ion batteries. Therefore, always consider the lifespan to determine whether they are worth the cost.

Environmental Impact

The whole point of using renewable energy is to reduce the environmental impact. If you are using renewable energy, it is advisable to consider storage systems that are safe for the environment. Lithium-ion batteries are controversial when it comes to their environmental impact.

The process of disposal creates harm to the environment. However, we have safe storage systems that do not cause any harm to the environment, like compressed air. If the energy storage system is not harmful to the environment, then that is an added advantage.

Energy Storage Capacity

Think about the energy storage capacity when choosing a system. The capacity will depend on the energy source and your power requirements. We have storage systems that have large capacities but have a low charging rate.

The most important thing is ensuring that your storage unit meets your energy requirements. If the system has a large capacity, it will take a long time to charge, but it will meet your high energy needs. Also, if you want a big energy storage capacity, you will need to pay a high cost.

Problems with Energy Storage Systems

Unfortunately, energy storage systems still come with their share of problems. Most of them are still in the initial stages of technology, so they still have some technical issues. Nevertheless, it’s recommendable to consider a storage system that is reliable and efficient.

One of the problems with these systems is that they are not 100%. Most of them still have an efficiency of under 90%. It is impossible to find a storage system that will store power for a long time and deliver an efficiency of 100%.

Additionally, there is the problem of environmental impact. Some storage systems have adverse effects on the environment when disposed of.

For example, lithium-ion batteries release toxins into the environment during disposal. This will impact the environment negatively. Also, lithium mining alone has severe environmental impacts, and it also needs to be transported long distances to factories before it can be even made into battery components.

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