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Engineering process

Energy storage is used to keep energy available for later use

Batteries just batteries
Why store energy? We store energy in order to have it later when we need it. What examples can you come up with of stored energy?

How about a battery? Batteries hold chemical potential energy. We use batteries in electric and electronic devices – like gaming consoles, smart phones, tablets, and laptops. The chemical potential energy is available as electricity when it is needed. Batteries provide a way to store energy as chemical potential energy, and then convert it later to electricity.

How about gasoline in a car? A gas tank also stores potential energy in the form of gasoline. When your car needs the gas to power the car, the gasoline is burned. The combustion (burning) of the fuel converts the chemical potential energy of the gasoline into mechanical kinetic (movement) energy in the parts of your car.

How about your body? You also store potential energy. When you eat, your body absorbs the calories and nutrition. Your body stores the energy for when you need it. You can still run two hours after lunch, can’t you? You don’t need to keep eating constantly in order to keep moving. But, you do need to eat healthy meals regularly to ensure that you have enough energy for everything you do. Energy in foods is an example of energy storage in nature.

When it comes to the electric grid, energy storage can help us save energy for when we need it. We rely on the energy grid every day, but our energy demand at any given time may not match the supply at that time.

Our energy demand does not always match our energy supply

Sometimes our supply of energy available on the grid is more or less than our demand. Energy supply is how much energy is available on the grid at a particular time. Energy demand is how much energy people want to use at that time. Energy demand varies from day to day, and even over the course of a day. On hot days, many people run their air conditioning. On cold days, many people run their heaters. Heating and air conditioning both consume a lot of power. Overnight, most people are sleeping rather than running their televisions or microwaves, so demand is lower overnight.

Our electricity consumption has increased over time, as more and more things we rely on every day require electricity to work. Look around the room – how many of the things you use every day require electricity? In the past 50 years, demand for electricity in the US alone has quadrupled.

We can use energy storage to balance out energy demand and supply

There can be issues on an electric grid if the need for electricity does not match the amount that is being produced at that time. If people are trying to use more electricity than is available at a specific time, then the result may be blackouts or brownouts.

A blackout is when all power is lost to an area, causing all the lights to go out, or “go black”. A brownout is a drop in voltage in the grid causing less energy to reach an area. This brownout may actually be created on purpose to stop the complete loss of power to an area. Alternately, the people managing the power for an area may use “rolling blackouts” to conserve energy when the available supply is low. A rolling blackout is a series of small power outages that roll through different areas in an attempt to fairly share the limited electricity available among all the people who want it.

The largest blackout in United States history happened in 2003. During this blackout over 50 million people in the northeast were impacted by the loss of power. After this occurred the United States worked to stop future events like this from happening. If we have energy stored, we can have a plan in place in case a blackout or brownout occurs. The storage of energy became a topic that was more important after these issues of blackouts and brownouts.

Energy storage is critical for renewable energy sources like wind and solar power

Renewable energy sources
Energy storage is becoming even more important as renewable energy becomes more common. Renewable energy is available when it is available, rather than when we demand it. For example, the wind blows when it blows. So, wind turbines generate electricity due to the forces of nature – not when we want more electricity. The sun shines when it shines – not when we ask it to! If you are using solar energy to power your home, you still need energy at night when the sun is not shining.

Renewable energy is made on its own schedule. However, we can make efficient use of it by storing any excess energy. This way energy can be generated whenever the sources of energy are available. Storing excess capacity can also help meet electric needs when there are times of high demand. An example of a period of high demand might be a heat wave across a large portion of the country – so that many people are running their air conditioners at the same time.

Energy can be stored in many forms

Hydroelectric power
People have developed many different ways of storing energy. We have already mentioned a few ways above. Another way to store energy on the grid is by creating dams. Dams are large man-made structures that hold back powerful bodies of water. A dam holding back water is storing the potential energy of the force of the water at the top of a dam. The water held back by a dam is higher than the water below the dam. There are turbines at the bottom of the dam. When water is allowed to flow over the dam down to the lower side, the water falls with tremendous force due to gravity. The falling water turns turbines at the bottom. These turbines generate electricity. The force of gravity allows the potential energy of the captured water to be converted to the kinetic energy of falling water. And then the turning of the turbines at the bottom of the dam converts the energy of the falling water to electricity. So, if the grid has excess electricity at any given time, one way to store it is to use the excess energy to pump water to the top of the dam. Using the excess energy to pump it back up to the top of a dam converts it back into potential energy.

There are other ways to store excess energy from the grid. As more electricity generation comes from renewable sources, there will be ongoing innovations in energy storage. Large batteries can be used to store energy for the grid. As battery costs continue to drop, using batteries for grid storage will become more cost effective. There are other technical ways to store energy for the grid, including something called a flywheel and compressed air storage. The next decade will likely see a lot of innovation in energy storage, and a lot of projects to implement storage on the grid. There are already a number of projects all over the world.

Using stored energy requires converting, or changing, the energy from one form to another

Humans use stored energy every time they go for a run, skate or even just lift up a cup off table. These actions are changing the energy that we get from food, chemical energy, into kinetic energy, or the energy of motion.

A similar change must occur when energy stored in coal, gasoline, or even water held behind a dam is changed into energy that we can use to power our devices. When coal or gasoline is burned, it heats water that changes into steam. This steam then turns turbines to create kinetic energy. Water that leaves a dam gets out through turbines as well. The act of turning a turbine generates electricity that we can then use in our homes.

Every time stored energy is accessed, it is changed from potential energy to kinetic energy. And, it is changed from some particular type of potential energy (like chemical) to some particular type of kinetic energy (motion, electricity, etc.). And, the act of storing energy does the reverse – it changes kinetic energy (like electricity) and converts it to potential energy (like water at the top of a dam). Energy conversion is critical to energy storage.

Energy storage is still changing and evolving

New innovations and advances are being made in energy storage. Some of the innovations are on a small scale, while some are on a large scale.

Previously when your cell phone ran out of power, you had to plug back into a wall in order to get more power. However, portable cell phone chargers are becoming more popular. These chargers are small batteries that can store a lot of energy. Some can even charge your phone up to three times before you have to charge the portable charger’s battery again. These portable chargers are helping make the charging process mobile.

On the other side of things, we have new large batteries that can store enough energy to power a house. The company Tesla has created a large battery for a home or business that charges from power made by solar panels on the roof. Use of solar-charged batteries to power a home is one step towards independence from the energy grid. Large batteries such as these can give homes and cities protection from blackouts and brownouts. If the electric grid has an issue, homes with these batteries can run off the energy stored in the batteries for some amount of time. Many cities in California are building areas with more storage for this reason.

A new plane being developed in Switzerland has taken advantage of batteries and energy storage to make a completely solar plane. Its goal is to be the first aircraft to make a complete trip around the world only using solar power. It has solar panels in the wings that power the motor and charge batteries during the day. Then at night the motor runs solely off the batteries. The longest flight the plane has made so far is from Japan to Hawaii. Solar-and-battery planes are not ready for everyday use. But, they do demonstrate one way that innovations in renewable energy sources and energy storage are being explored and tested.

Advances have also been made in water dams and hydroelectric energy. For example, at a water dam in China, any extra energy that is produced is stored for later times when it is needed. The extra energy is used to move the water from the low side of the dam up to the high side. When the energy is needed during peak times, the water to can be allowed to flow back over the dam and through the turbines to generate electricity.

As new technologies keep being made, we are moving into a society that uses more renewable energy and is capable of storing more energy. We can move around more with our stored energy and more further away from dependence on the energy grid.

Energysources Energyconversion Electricgrid Energystorage