Energy storage is the process in which we can capture energy that was produced today and use it in the future. For example, when you wind up a clock, energy is produced that isn?t used up all at once. Some of the energy that is generated is used at a later time.
It is important to store energy for several reasons. The primary reason is to ensure that everyone gets energy when they need it, whenever they need it. During emergency situations like power outages during storms, equipment failures or accidents, this stored energy helps to balance the supply and demand in an instant. The end result is a cleaner and more efficient energy supply that everyone can rely on 24 hours a day, 7 days a week.
Energy Storage and The Grid
Energy storage is so important for the grid for three main reasons:
- Balance Load ? This is the process of shifting energy usage into the future to use the existing generated energy more efficiently.
- Bridge Power ? This process makes sure that there is no break in power when switching from one energy generation source to a different energy generation source.
- Power Quality Management ? This process monitors and controls the electric voltage and frequency to make sure that equipment does not get damaged. Energy storage helps to reduce the pressure anywhere from a few seconds to milliseconds (and less!) throughout each day.
Another impact of energy storage on the grid includes Peak Shaving.
There are many situations where the grid experiences peak demand. Peak demand refers to particular times during the year, like during the summer months where many people, businesses and industries use their air conditioner at the same time. Many utilities will increase the cost of energy for their customers because they have to increase production. You might recognize these charges as ?time-of-use? or ?peak? line items on your bill.
Peak Shaving via energy storage, allows consumers to pick and choose when they buy and use power. This means that they don?t need to pay the above mentioned charges.
How Energy Storage Affects You
Using energy storage to help minimize electricity interruptions via the grid, generates several benefits that trickle down to you, the consumer. These benefits include,
Reduced Power Outages ? Many households, businesses and industries are greatly impacted by power outages. These incidents can cost the United States up to $130 billion each year. By implementing energy storage technologies and processes, every state can help to reduce these costs significantly.
Savings ? There are two way in which energy storage can help save money. The first is that it lowers the cost of providing energy. The second reason is that it gives customers the opportunity to avoid paying peak demand pricing. In addition, energy storage reduces the number of power outages. This helps to save lives as well as prevent significant economic costs.
Clean Energy ? The process of storing energy works seamlessly with renewable energy generation technologies such as, wind and solar. This helps to decrease the reliance on fossil fuel energy generation, which in turn helps to cut down or lower emissions.
One of the most expensive and wasteful elements of the grid is peaking generations. This is what happens when there is a high demand for energy. Energy storage helps to make the current energy generation last longer. It also helps America to reach energy independence.
Employment ? Energy storage is going to be an important element to the future state of the electricity grid. In order to remain competitive it is estimated that tens of thousands of jobs will become available.
Every state in America either has an energy storage system in place or is working towards implementing this technology. These projects vary in complexity but help to bring about an exciting change to the way that we produce energy. Philadelphia for example is using recycled energy for their mass transit system project, while South Carolina and Missouri are using energy storage on a massive scale for major reservoirs and pumping stations.
For more information on ongoing and existing projects, check out the DOE Global Energy Storage Database run by the Office of Electricity Delivery & Energy Reliability.
Energy Storage Technologies
Energy is stored in devices commonly called, accumulators. Accumulators have the ability to accept and store energy until it is needed. There are many different kinds of accumulators, and each is designed to perform a specific function. For example, some accumulators accept energy but only low power, while others can accept energy at a higher rate over a shorter period of time.
There are several different types of energy storage. These include:
- Mechanical Storage
- Electrochemical Storage
- Other Chemical
- Electrical
Each type of energy storage has several technologies that can be implemented based on particular energy requirements. They can also apply to the grid and at a commercial level.
Mechanical Storage
Mechanical energy storage refers to technologies that can pump water or solid matter to higher points of elevation or locations. Some commercial methods such as compressing air and flywheels refer to systems that can turn electric energy into kinetic energy and then turn that kinetic energy back into electric energy during peak times.
Flywheel
This technology generates energy by accelerating a rotor until it reaches very high speeds (from 20,000 to 50,000 rpm). The rotational energy that is generated is extracted and as this happens, the rotation of the rotor decreases as the energy is conserved.
Hydroelectricity
Hydroelectricity is the process in which energy is generated using water. Hydroelectric dams that have reservoirs have the ability to generate energy during peak demand. During periods of low demand, the water is stored in the reservoir. When the demand is high, the water is released.
It is important to note that a hydroelectric dam doesn?t store electricity from alternate generating systems. Its primary purpose is to lower output when there is excess energy from other systems and technologies.
Compressed Air
This technology compresses air to generate energy at a later time. When air is compressed, it generates heat. This means that the air is much warmer after it is compressed. Expansion of air requires heat. Therefore, the heat generated from compression is stored and used for expansion. This technology is typically used for commercial purposes.
An example of compressed air energy storage use can be found in mine locomotives.
Electrochemical Storage
Electrochemical energy storage technologies are typically items that can store electricity like batteries or fuel cells. Currently this technology is particularly important for powering electric vehicles.
There are several technologies classified within electrochemical energy storage including,
Rechargeable Batteries
Rechargeable batteries are a common commercial tool that helps to power many different electronic devices. They come in a wide range of shapes and sizes, including, tiny button cells and megawatt grids. These types of batteries cost much less and because they are re-chargeable have less of an impact on the environment than single use batteries.
There are many different rechargeable batteries including, lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries.
UltraBattery
Australia?s Commonwealth Scientific and Industrial Research Organization (CSIRO) invented the UltraBattery. This particular battery can handle high charge and discharge levels, which allows it to handle a larger number of cycles and charges than lead-acid batteries.
UltraBatteries work with many different applications. Due to the fact that it charges and discharges rapidly, it is the perfect technology for grid regulation and leveling.
Super Capacitor
Super capacitors store more energy than other capacitors. In fact, they can store up to 1.2 volts of energy! Their power density can be 10 to 100 times greater than batteries and will also accept a greater number of charge and discharge cycles.
This type of electrochemical storage device is meant to power many different vehicles including, cars, buses, trains, elevators, and cranes.
Other Chemical
This category of energy storage refers to energy that is manipulated from different chemicals such as hydrogen, liquid nitrogen and more.
Underground Hydrogen Storage
This type of energy storage is kept underground in areas like old oil and gas fields. Much of this stored hydrogen is used to power the grid when needed.
Biofuels
Biofuels can replace many fossil fuels. This type of fuel includes, biodiesel, alcohol fuels, and vegetable oil. Chemical processes can change these substances into methanol, dimethyl, syngas and ether.
Power to Gas
This technology converts electricity into gas. This process is achieved through using electrolysis to split water into oxygen and hydrogen. Several methods allow the generated hydrogen to be stored and used in the natural gas grid.
Electrical
Capacitor
Capacitors (can also include super capacitors) are used to store an electric charge. This technology is typically used in situations where short-term backup power is required. Since energy can still be stored when not connected, it is common to think of capacitors like a battery that can be ‘plugged in’ and used when needed.