What are the energy storage devices

Nature has given man a variety of sources of energy: the sun, wind, rivers and others. The disadvantage of these generators of free energy is the lack of stability. Therefore, during periods of excess energy, it is stored in storage tanks and expended during periods of temporary decline. Energy accumulators characterize the following parameters:

• The amount of stored energy;
• The rate of its accumulation and recoil;
• Specific gravity;
• Energy storage time;
• reliability;
• Cost of manufacturing and maintenance and others.

There are a lot of ways to organize the drives. One of the most convenient is the classification of the type of energy used in the drive, and the way it is accumulated and recycled. Energy accumulators are divided into the following main types:

• Mechanical;
• Thermal;
• Electric;
• Chemical.

Accumulation of potential energy

The essence of these devices is uncomplicated. When lifting the load, there is accumulation of potential energy, when lowering it performs useful work. The design features depend on the type of cargo. It can be a solid, liquid or loose matter. As a rule, the designs of devices of this type are extremely simple, hence the high reliability and long service life. The storage time of the stored energy depends on the longevity of the materials and can reach millennia. Unfortunately, such devices have a low specific energy intensity.

Mechanical storage of kinetic energy

In these devices, energy is stored in the motion of a body. Usually this is an oscillatory or translational motion.

The kinetic energy in the vibrational systems is concentrated in the reciprocating motion of the body. Energy is supplied and consumed in portions, in time with the movement of the body. The mechanism is quite complex and capricious in tuning. Widely used in mechanical watches. The amount of energy stored is usually small and suitable only for the operation of the device itself.

Drives that use the energy of a gyro

The kinetic energy reserve is concentrated in a rotating flywheel. The specific energy of the flywheel greatly exceeds the energy of a similar static load. It is possible in a short time to make a reception or return of considerable power. The energy storage time is short, and for most designs is limited to several hours. Modern technology allows you to bring the energy storage time to several months. Flywheels are very sensitive to concussions. The energy of the device is directly dependent on the speed of its rotation. Therefore, during the accumulation and release of energy, the speed of rotation of the flywheel changes. And for the load, as a rule, constant, low speed of rotation is required.

More promising devices are super flywheels. They are made of steel tape, synthetic fiber or wire. The design may be dense or have an empty space. In the presence of free space, the turns of the tape move to the periphery of the rotation, the moment of inertia of the flywheel changes, part of the energy is stored in the deformed spring. In such devices, the rotation speed is more stable than in solid designs, and their energy capacity is much higher. In addition, they are safer.

Modern super-flywheels are made from Kevlar fiber. They rotate in a vacuum chamber on a magnetic suspension. Are able to save energy for several months.

Mechanical storage devices using elastic forces

This type of device can store a huge specific energy. From mechanical storage it has the greatest power capacity for devices with dimensions of several centimeters. Large flywheels with very high rotational speeds have a much higher energy intensity, but they are very vulnerable to external factors and have a shorter energy storage time.

Mechanical storage using spring energy

Capable of providing the greatest mechanical power from all classes of energy storage. It is limited only by the limit of spring strength. Energy in a compressed spring can be stored for several decades. However, due to the permanent deformation in the metal, fatigue accumulates, and the capacity of the spring decreases. At the same time, high-quality steel springs under the conditions of operation can work for hundreds of years without a tangible loss of capacity.

The spring functions can be performed by any elastic elements. Rubber strands, for example, are tens of times superior to steel products in terms of stored energy per unit mass. But the service life of rubber due to chemical aging is only a few years.

Mechanical storage using compressed gas energy

In this type of device, energy is stored by compressing the gas. If there is an excess of energy, the gas is pumped under pressure into the cylinder by a compressor. As necessary, the compressed gas is used to rotate the turbine or electric generator. At small capacities, instead of a turbine, it is advisable to use a piston motor. Gas in a pressurized container of hundreds of atmospheres has a high specific energy density for several years, and in the presence of high-quality reinforcement - and tens of years.

Accumulation of thermal energy

Most of the territory of our country is located in the northern regions, so a large part of the energy is consumed for heating. In this connection, it is necessary to regularly solve the problem of heat storage in the storage device and extract it from there if necessary.

In most cases, it is not possible to achieve a high density of stored thermal energy and any significant time-frame for its conservation. Existing efficient devices due to a number of their features and high prices are not suitable for wide application.

Accumulation due to the heat capacity

This is one of the most ancient ways. It is based on the principle of accumulation of thermal energy when the substance is heated and the heat is released when it is cooled. The design of these drives is extremely simple. They can be a piece of any solid matter or a closed container with a liquid coolant. Thermal energy storage has a very long service life, virtually unlimited number of cycles of energy storage and output. But the storage time does not exceed several days.

Accumulation of electrical energy

Electric energy is the most convenient form in the modern world. That is why electric storage devices have become widespread and the most developed. Unfortunately, the specific capacity of cheap devices is low, and devices with a large specific capacity are too expensive and short-lived. The accumulators of electric energy are capacitors, ionistors, accumulators.

Capacitors

This is the most massive type of energy storage. Condensers are capable of operating at temperatures from -50 to +150 degrees. The number of cycles of energy accumulation and release is tens of billions per second. By connecting several capacitors in parallel, you can easily obtain the capacitance of the required value. In addition, there are variable capacitors. The capacitance of such capacitors can be varied by mechanical or electrical means or by exposure to temperature. Most often, variable capacitors can be found in oscillatory circuits.

Capacitors are divided into two classes - polar and nonpolar. The service life of polar (electrolytic) is less than non-polar, they are more dependent on external conditions, but at the same time have a greater specific capacity.

As energy accumulators, capacitors are not very successful devices. They have a small capacity and insignificant specific density of stored energy, and the time of its storage is calculated in seconds, minutes, rarely hours. Condensers have found application mainly in electronics and power electrical engineering.

Calculation of the capacitor, as a rule, does not cause difficulties. All the necessary information on different types of capacitors is presented in the technical reference books.

Ionistory

These devices occupy an intermediate place between polar capacitors and batteries. Sometimes they are called "supercapacitors". Accordingly, they have a huge number of charge-discharge stages, the capacitance is larger than that of capacitors, but slightly smaller than that of small batteries. The energy storage time is up to several weeks. Ionistors are very sensitive to temperature.

Power Batteries

Electrochemical batteries are used if you need to store enough energy. Lead-acid devices are best suited for this purpose. They were invented about 150 years ago. And since then, nothing fundamentally new has been introduced into the device of the battery. Many specialized models have appeared, the quality of components has significantly increased, the reliability of the battery has increased. It is noteworthy that the device battery, created by different manufacturers, for different purposes differs only in minor details.

Electrochemical batteries are divided into traction and starting batteries. Traction tractors are used in electric transport, uninterruptible power supplies, power tools. Such batteries are characterized by a long, uniform discharge and a large depth. Starting batteries can produce a large current in a short period of time, but a deep discharge for them is unacceptable.

Electrochemical batteries have a limited number of charge-discharge cycles, on average from 250 to 2000. Even in the absence of operation after a few years they fail. Electrochemical batteries are sensitive to temperature, require a long charging time and strict observance of the operating rules.

The device must be periodically recharged. The charge of the battery mounted on the vehicle is made in motion from the generator. In winter, this is not enough, a cold battery takes a bad charge, and the consumption of electricity to start the engine increases. Therefore, it is necessary to additionally charge the battery in a warm room with a special charger. One of the significant drawbacks of lead-acid devices is their heavy weight.

Accumulators for low-power devices

If mobile devices with low weight are required, the following types of batteries are chosen: nickel-cadmium, lithium-ion, metal-hybrid, polymer-ionic. They have higher specific capacity, but the price is much higher. They are used in mobile phones, laptops, cameras, video cameras and other small devices. Different types of batteries differ in their parameters: the number of charging cycles, the storage period, capacity, size, etc.

Lithium-ion batteries of high power are used in electric vehicles and hybrid vehicles. They have low weight, high specific capacity and high reliability. At the same time, lithium-ion batteries are very fire hazardous. The ignition can occur from short circuit, mechanical deformation or destruction of the case, violation of charging or discharge of the battery. Put out the fire is difficult because of the high activity of lithium.

Batteries are the basis of many devices. For example, the energy storage for the phone is a compact external battery, placed in a rugged, waterproof housing. It allows you to charge or power a cell phone. Powerful mobile energy storage devices can charge any digital devices, even laptops. In such devices, as a rule, lithium-ion batteries of large capacity are installed. Energy storage for home Also not Do without batteries. But this is a much more complex device. In addition to the battery, they include a charger, a control system, an inverter. The devices can work either from a fixed network or from other sources. The output power on the average is 5 kW.

Storage of chemical energy

There are "fuel" and "helpless" types of drives. They require special technologies and often cumbersome high-tech equipment. The processes used make it possible to obtain energy in different types. Thermochemical reactions can take place at both low and high temperatures. Components for high-temperature reactions are introduced only when it is necessary to obtain energy. Before that, they are stored separately, in different places. Components for low-temperature reactions are usually located in the same tank.

Accumulation of energy by fuel production

This method includes two completely independent stages: the accumulation of energy ("charging") and its use ("discharge"). Traditional fuel, as a rule, has a large specific energy capacity, the possibility of long-term storage, convenience of use. But life does not stand still. The introduction of new technologies poses increased requirements for fuel. The task is solved by improving the existing and creating new, high-energy fuels.

Wide introduction of new samples is hampered by insufficient workability of technological processes, great fire and explosion hazard in work, the need for highly qualified personnel, high cost of technology.

Non-fuel chemical energy storage

In this form of storage, energy is stored by converting certain chemicals into others. For example, slaked lime turns into a quickened state when heated. With "discharge" stored energy is released in the form of heat and gas. This is the case when the lime is quenched with water. In order for the reaction to begin, it is usually sufficient to connect the components. In essence, this is a type of thermochemical reaction, only it proceeds at a temperature of hundreds and thousands of degrees. Therefore, the equipment used is much more complicated and expensive.