How to save electrical energy. The problem of storing excess electricity has been solved

Have you noticed that the name of the stations where energy is produced always contains the word “electro”? That is, no matter what we supply “input”, “output” we get energy in the form of electricity.

Since it was discovered that an electric current can flow in metals, and a voltage can arise in a wire frame rotating in a magnetic field, it has become clear that an excellent method has been obtained for converting, transmitting and distributing energy.

Indeed, how can the energy of falling water or the heat released during combustion be transferred over a distance? Of course, you can use the rotation of the hydraulic wheel on site, which drives the mill. You can transfer hot water through pipes, as is done in cities to heat houses. But don’t install a multi-kilometer rotating shaft! And the water will cool down if the pipes are too long.

But electric generators, which receive energy in principle from everything that is capable of creating rotation, produce electric current, which then transfers energy through wires over hundreds and thousands of kilometers. It powers electric vehicles, lamps on city streets and in our homes, and all devices that just need to be plugged into the network. Without exaggeration, we can say that today almost the entire world depends on electricity, like a baby on a pacifier.

What to do if energy is not supplied to some place through the wires? Then batteries will help us out. This really is a lifesaver! These small sources of electricity “sit” in portable radios and tape recorders, calculators and hearing aids - in a huge number of modern devices.

In addition to these miniature devices, there are also quite large batteries, familiar to you, of course, from cars. They produce more than 100 million lead batteries per year. And diesel submarines of the fleets of all countries are equipped with similar batteries weighing up to 180 tons!

Unfortunately, the large mass, as well as the harmful chemicals used in them, still serve as an obstacle to the creation of autonomous electric vehicles.

This is a task that thousands of scientists, engineers, and inventors have been struggling with for decades. It has not yet been possible to construct a fundamentally new battery that would allow long-term movement away from other energy sources, that is, without frequent recharging.

However, it seems that the situation with the state of the environment will simply force us to make this invention. After all, they created a battery consisting entirely of plastic! It works great in both heat and cold, it can be discharged and charged up to a hundred times, it is almost non-toxic. Not everything can be compared with already known batteries, but this is an encouraging step!

And at this hour sad nature lies around, sighing heavily, and wild freedom is not dear to her. Where evil is inseparable from good. And she dreams of the shining shaft of the turbine, And the measured sound of intelligent labor, And the singing of pipes, and the glow of the dam, And the wires filled with current. N. Zabolotsky Well, serene nature did not give man peace! He couldn't wait...

More than once, archaeological scientists had to rack their brains when excavating sites of ancient people. For example, they found a stick with a burnt end. Some say they tried to sharpen a spear or arrow in a fire, others say this is how they got fire. Disputes agree that man began to make fire on his own about 100 thousand years ago. Exactly on your own, because in...

Millennia passed, but man was still unable to “harness” fire and make it work. Then his thoughts turned to the moving water. When and where did the first water wheel spin? It was apparently launched in Ancient India, the Middle East, and Ancient Rome. No matter where, such wheels have long been used by man for...

With the invention of the steam engine, and later the turbine, people were finally able to make the heat generated by combustion rotate and move various mechanisms. These were turbine blades, wheels on vehicles, and shafts of current generators. The trouble is that it is impossible to effectively use all the energy released during the combustion of fuel - to transform it into work useful to us. At…

Yes, it is ecology that already dictates, and soon, apparently, will completely determine the requirements for any energy sources. It is no wonder that people again and again turn to what nature itself has long and persistently offered. After all, if reserves of fossil fuels sooner or later come to an end, if by burning them we upset the heat balance of the Earth, then not...

Is it possible to invent such an energy source, such an engine that would operate “forever” and have no disadvantages at all? It would not pollute the environment, would not disturb the thermal balance of the planet, and would not produce anything at all except “clean” energy. In other words, it would be a kind of ideal device that would save us from all energy problems. The history of creation dates back hundreds of years...

You, of course, have heard that current can be constant or alternating. Here on batteries and accumulators there are plus and minus icons. This indicates that you have a DC source in front of you. In other words, if you connect a light bulb or device to it, then charged particles will run along the chain, forming an electric current, and in one direction. A…

Research into the smallest structure of matter led people to the discovery of atomic energy. As sad as it is, first this outstanding achievement used to make weapons. But people found a way not only to instantly, explosively release atomic energy, but were also able to curb it, that is, make nuclear reactions proceed more slowly, so to speak, under control. Then the enormous energy hidden in the smallest...

Standing under the sun's rays, we directly feel how much energy they carry with them. But we cannot yet store it the way plants do. However, there are many projects, inventions and ideas in this area. For example, semiconductor batteries, which allow the energy of solar radiation to be converted directly into electricity. These power supplies are installed on solar panels...

Archaeologists have found that the most ancient energy storage device, the flywheel, was made five and a half thousand years ago. It was a potter's wheel made of baked clay, which rotated for quite a long time after spinning, gradually using up the stored energy. Research conducted in the Arctic recently led to the conclusion that the white fur of northern animals, especially bears, has the ability to trap up to 95 percent...

Y.N.ELDYSHEV The problem of energy storage is one of the most important not only in the energy sector, but also in the economy (as well as in science) in general. It has not yet been fully resolved. Our inability to effectively store and store the resulting energy has a particularly detrimental effect on the development of such relatively “clean” methods of its production using renewable energy sources, such as hydropower, solar power or wind power. After all, we are still not able to ensure a guaranteed supply of energy to consumers from such sources due to understandable daily, seasonal, and even poorly predictable changes in their power. Therefore, any information about achievements in this area is of great interest.
Methane project
A new method of storing energy obtained from renewable energy sources (one of the main disadvantages of which is the instability and unpredictability of energy production) was recently reported by the press service of the Fraunhofer Society (the Joseph Fraunhofer Society is the German analogue of the Russian Academy of Engineering Sciences, its main goal is to promote applied research). German scientists have developed a technology in which excess electricity generated by solar or wind power plants and not needed at the moment is converted into methane. The gas thus obtained can be stored indefinitely and used as needed using the existing gas infrastructure.
The pilot project, developed by the Center for Solar Energy and Hydrogen Research, which is located in Stuttgart (Germany), is currently being implemented by cooperating companies in Austria and Germany. The launch of an industrial station with a capacity of tens of megawatts based on this technology is planned for 2012.
According to the developers, the demonstration system, built in Stuttgart, uses excess energy generated by solar panels and wind power plants (WPP) for the electrolytic dissociation of water into oxygen and hydrogen. Subsequently, the resulting hydrogen, combining with carbon dioxide supplied to the system, forms methane, which can already be stored and used to generate energy at any time. According to scientists, the efficiency of such a transformation is above 60%.
It is no secret that “classical” methods of storing electricity in capacitors and batteries require the creation of a special (additional and quite expensive) infrastructure. In contrast to such methods for storing energy in the form of methane in Germany, as in many other countries, all the necessary infrastructure already exists - this is a distributed system of large-capacity gas storage facilities. Therefore, the authors of this technology believe that it may have good prospects, because such a transformation with decent efficiency is “definitely better than a complete loss of electricity that cannot be used here and now.” But to date, not many real alternatives to “gas conversion” as a method of energy storage have been proposed.
"Achilles' heel" of hydraulic accumulators
pumped storage power plant appearance can vary greatly: many storage stations are almost impossible to distinguish from a conventional hydroelectric power station located on a river with a significant slope, but there are also those that have a very unusual storage tank, such as the Taum Sauk station in Missouri (USA) , attracting the attention of many tourists. But in any case, this method of storing and redistributing energy has a serious drawback - the need to alienate large areas for the upper and lower pools, as well as large-scale (and expensive) construction work.
Water alternative
One of the oldest energy storage devices is a pumped storage power plant (PSPP). This is the name of a type of hydroelectric power station specifically designed to level out the daily heterogeneity of the electrical load. PSPP uses a complex of electric generators and electric pumps or special reversible hydroelectric units that can operate both as generators and pumps. During the minimum energy consumption, the pumped storage power plant receives cheap electricity from the power grid and uses it to pump water to the upper pool, i.e. it acts as a pump. And during the morning and evening peaks in energy consumption, the pumped storage power plant discharges water from the upstream to the downstream, generating expensive “peak” electricity, which it sends to the power grid, i.e., it acts as an electric generator.
Since in both modes the efficiency of such a plant is less than 100%, it is clear that in the end the pumped storage power plant consumes more electricity than it produces, i.e. formally it turns out to be unprofitable. However, we should not forget that pumped storage power plants consume “cheap” energy and supply “expensive” energy to the network, so the economic result does not coincide with the energy balance and is not determined by simple arithmetic operations. The fact is that in large energy systems a significant share is made up of the capacity of thermal and nuclear power plants, which cannot quickly reduce electricity production when energy consumption falls or do so with large losses. That is why the commercial cost of electricity during the period of highest (“peak”) consumption in the energy system is much higher than during the period of its minimum consumption, and the use of pumped storage power plants turns out to be cost-effective, increasing both the uniformity of the load on other capacities of the energy system and the reliability of energy supply in general.
A pumped storage power plant looks like a simple and reliable energy storage system, which has many advantages and only one, but very significant, weakness: it cannot be built everywhere, and it takes up a lot of space.
Energy can be stored... in the refrigerator
More recently, it was proposed to store “wind energy” (electricity obtained from wind turbines) by changing the temperature in huge cold storage warehouses, which requires almost no capital expenditure. A group of researchers from universities in Bulgaria, Denmark, Spain and the Netherlands developed the Night Wind project, aimed at creating a pan-European wind energy storage system based on the use of elements of existing infrastructure.
The idea is simple: at night, when electricity consumption drops, but wind turbines continue to operate, the electricity they generate is proposed to be used to lower the temperature in the existing refrigerators of large food warehouses. Estimates have shown that it is enough to reduce the temperature by just 1 °C compared to the usual norm. In other words, energy will be “stored” as a result of the cooling of many thousands of tons of various products, which will be stored as usual somewhere in Denmark, Holland or France. During the day, when electricity consumption increases many times over, all these giant refrigerators can simply be unplugged from the network until the temperature in them gradually rises by the same 1 °C, i.e., returns to its usual value.
And although, as is well known, refrigerators themselves, even the most gigantic ones, of course, do not produce any electricity, such temperature fluctuations are only one degree with a period of a day, if they are applied to all large refrigerated warehouses in Europe, according to estimates from the authors of the project , will be equivalent to the appearance of a superbattery with a capacity of 50 GWh in the general energy grid!
The authors of the project demonstrated the effectiveness of the idea back in 2007 by installing a wind turbine next to one of the largest refrigerated warehouses in Bergen (Netherlands) and setting up an electronic refrigerator control system according to the principle described above. So now the fate of the project is in the hands of energy economists, who must decide how advisable it is to rely on this particular method of storing energy.
Flywheels
Many experts still consider flywheels to be a very promising energy storage device. Discussions about them have been going on for decades. But only in Lately Really workable projects have been developed that demonstrate the capabilities of such drives in practice.
Back in 1964, Professor N.V. Gulia (lately the head of the department at Moscow State Industrial University) proposed a new type of flywheel, which was supposed to serve as an energy storage device. It was not a solid disk, but a core with hundreds and even thousands of layers of thin steel (later plastic) tape wound around it, enclosed in a casing, inside of which a vacuum was created to reduce friction losses. As it turned out, such superflywheels could “absorb” quite a lot of energy per unit mass, because the energy they stored was determined primarily by the maximum rotation speed (since it was proportional to its square and depended linearly on the mass), which in turn was limited by the strength of the chosen material.
Modern superflywheels with carbon fiber winding have a specific energy content of up to 130 Wh/kg. This is somewhat inferior to the performance of the best lithium-ion batteries, but flywheel drives also have their advantages: they are much cheaper, more durable and safer (not only for the health of operating personnel, but also, just as important, for the environment).
The inventor himself experimented a lot with superflywheels 40 years ago, because he considered them promising energy storage devices for transport and even built several samples of such vehicles. He also thought about their use in the energy sector as an alternative to batteries, but until recently the idea of ​​using flywheels to store energy not in laboratories, but on an industrial scale and in existing energy networks seemed exotic and even utopian to specialists. Only in recent years have some companies in the West begun serious research in this area.
Thus, specialists from the American company Beacon Power have developed a set of stationary superflywheels designed for connection to industrial power grids. They are made from a huge number of layers of ultra-strong composite materials based on carbon fibers, so that they can withstand enormous loads, allowing their rotation speed to be increased to the standard 22.5 thousand rpm in a high vacuum environment. Flywheels on magnetic suspensions rotate in cylindrical containers about 1 m high (new models will be taller than a person), inside of which a vacuum is created. The weight of such a structure can reach 1 ton.
On the steel shaft of the flywheel (in the same place - inside a sealed steel cylindrical casing) there is a rotor of a reversible electric machine - a permanent magnet motor-generator, which spins the flywheel, storing energy, or releases it, generating electric current, when a load is connected.
The estimated service life of such a design is 20 years, the operating temperature range is from -40 to +50 ° C, it can withstand earthquakes with a magnitude of up to 7.6 on the Richter scale, in other words, it has characteristics that are now completely unrealistic for existing chemical batteries.
Air will save energy
The American company Magnum Energy NS is going to use underground caves at a depth of about 1.5 km to store liquefied air used to generate electricity. It is planned to create storage facilities near the city of Delta in Utah, where there are huge underground reserves of salt, which they hope to wash out using special equipment. At the first stage it is planned to arrange storage facilities for natural gas, mined nearby - in the Rocky Mountains. Having perfected the technology, the company intends to begin creating storage... for air.
According to the authors of this project, air compression can be considered one of the cheapest ways to store energy. For example, on a clear day, a solar power plant will produce excess electricity. It will be sent for compression and air injection. When electricity is needed, the air will be forced to spin turbines. In this way, the authors hope to overcome the main difficulty in the widespread introduction of renewable energy sources - the instability of their electricity production and, accordingly, the problem of storing and converting energy from them.
However, so far the amount of energy stored in this way is small - up to 25 kW/h with a maximum power of up to 200 kW. According to the developers' estimates, the loss of energy stored and withdrawn from such storage devices does not exceed 2%, which is much better than that of energy storage systems based on other principles (mentioned pumped storage power plants, chemical batteries, etc.). At the same time, it is clear that the energy storage period in flywheels, unlike these systems, is short - for now we can only talk about their use as a buffer, compensating for sharp peaks and declines in electricity consumption during the day.
Sets of many such devices connected in parallel could accumulate quite noticeable reserves of energy; in this case, the main advantage would be that this would happen very quickly (it would be possible to “claim” what had been accumulated just as quickly). But this is very important. The fact is that any of the existing industrial generating capacities (for example, at thermal power plants) cannot quickly respond to changes in load, and in general any changes in their operating modes are extremely unprofitable.
It is in such situations, associated with sudden surges in network load, that drives in the form of flywheels could become a completely reasonable solution. According to the developers, the response time of such systems is simply fantastic - about 5 ms.
Installations with similar storage devices have already demonstrated their effectiveness in tests in a number of settlements The United States, whose residents have not yet forgotten the nightmare of their de-energized cities due to chain power outages, and are ready to do a lot to reduce the likelihood of such events happening again.
However, it seems that the Russian energy system, which, due to a number of features, is noticeably more resistant to load fluctuations than the US energy network, could benefit from such storage devices.
Invention... blades
Interesting way Professor of the University of Nottingham (UK) Seamus Garvey found a way to smooth out the unevenness of electricity generation from wind turbines, concluding that wind turbines located in the open sea should not be equipped with electric generators at all, since such powerful devices that generate current even at the lowest shaft rotation speeds turn out to be very heavy and, accordingly, very expensive. Instead, he proposes making windmill blades... hollow. A heavy piston must move freely inside each of them. When the blade descends, the piston moves towards its end, and when it rises, the piston, on the contrary, slides towards the axis, compressing the air entering through the holes in the housing. Compressed air is pumped into special bags made of thin and durable synthetic fabric, floating at a depth of 500 m!
These storage facilities, kept from bursting by the pressure of the overlying water layers, serve as a kind of buffers that guarantee uniform power generation even in unpredictable wind conditions. From underwater cylinders, air is supplied through pipes to additional compact turbine generators. It is estimated that its reserve should be enough to maintain their rotation for several days, even in complete calm.
This “Integrated Compressed Air Renewable Energy Systems” (ICARES) is impressive in its scale: Harvey estimates that the turbine would have to move slowly and be very large to keep the pistons from hanging at the ends of the blades due to centrifugal forces. over 200 m in diameter (ideally 500 m). As for underwater energy storage facilities, the author sees them as gigantic clusters of huge air “cushions” (20 m in diameter).
Work on the project has been ongoing since 2006, and now the university has created the Nimrod Energy company, whose main task will be the commercialization of this technology. It is expected that ICARES systems will appear on the market within a year. But at first they will be used to store energy generated by other types of power plants. And giant offshore turbines from Nimrod, according to the developers’ forecasts, may appear in 10-15 years.
Unusual battery and some other methods
Today, quite high activity in the West is also associated with projects for storing electricity generated, in particular, by wind turbines that are very popular here, in the form of hydrogen obtained with its help. Moreover, in such projects it is proposed to use hydrogen not as fuel, but as a temporary energy carrier. However, according to experts, such schemes, which can be very efficient from an energy point of view and quite acceptable from an environmental point of view, alas, still remain too expensive.
Research continues on various technologies for pumping compressed air into underground or underwater storage facilities.
But, as already noted, each of the mentioned methods of energy storage has its own advantages and disadvantages, each of them is good in its own way, but none can be considered ideal. In this regard, recently there have even been calls to return to chemical batteries that seemed to have been studied in detail for a long time. However, not quite ordinary - molten.
In fact, the so-called hot batteries were also invented many years ago. There are many varieties of them that have enviable specific characteristics. But it is not easy to ensure the operating temperature required for them, hundreds of degrees Celsius, so this condition imposes serious restrictions on the possible areas of their application, as well as on their possible lifespan (all previous proposals to use such batteries on a large scale turned out to be uncompetitive due to for the extremely short period of their validity). However, in the Japanese prefecture of Aomori, for example, a complex of 17 large blocks of sulfur-sodium hot batteries with a capacity of 34 MW, which are connected to the network through AC/DC converters, has been operating for several years. This complex is part of the new Futamata wind farm, significantly smoothing out the unevenness of wind turbine electricity production (allowing it to satisfy the daily peak of consumption and accumulating energy at night).
But the new battery, the prototype of which was created by American scientists, according to their estimates, will be three times cheaper than today’s best batteries, much more durable and, most importantly, much more powerful. Professor Donald Sadoway and his colleagues from the Massachusetts Institute of Technology have come up with an original device for accumulating electrical energy, which, in their opinion, will in the near future make it possible to use energy obtained from solar panels (or wind energy in calm weather) at night. Such a battery, the size of a garbage container familiar to Americans in an individual home (its volume is about 150 liters), according to Sadoway, could become an integral attribute of a “green” home, providing all its energy needs even at the peak of consumption, and would be recharged it comes from “intermittent” wind turbines and solar panels. Well, large sets of such batteries, according to the developers, would be quite capable of supplying electricity to entire settlements - a storage station with a capacity of 13 GW (enough to power a large city) would occupy only 6 hectares.
How is this power density achieved? The fact is that, as the developers assure, these batteries are capable of delivering and receiving 10 times more current than all known types of chemical batteries.
Realizing that too much current could easily damage the device, simply melting the entire structure, Sadoway suggested that a melted state be the norm for all parts of the battery. In previous hot batteries, in addition to cases and contacts, there was another important solid (unmelted) element - solid electrolyte (special conductive ceramics), but in the new battery there are no solid parts inside at all, except for the outer case, everything is liquid - both the electrolyte and the electrodes. All elements of the new unusual system do not mix with each other due to different densities, just as oil and water do not mix in a vessel at rest. And since the new battery is designed to become a stationary energy storage device, there seems to be no reason for the liquids to mix.
The developed battery resembles a refractory “glass” (the body serves as the first external contact), covered with a lid (the second external contact). Between them there is a dielectric, and around there is a heat-insulating shell. The authors placed antimony at the bottom of the container (this is the first internal electrode), followed by sodium sulfide (electrolyte), and magnesium on top (the second internal electrode). All components are in molten form.
When charging, the electrolyte layer in such a battery becomes thinner, and the molten electrodes become thicker. During a discharge, everything happens in the reverse order: the material of the electrodes (ions) partially transforms into the electrolyte, so that the central liquid layer grows, and the side electrodes contract.
Such a system, which uses a rather unusual operating principle and design for chemical batteries, as it turned out, is capable of withstanding a huge number of charge and discharge cycles, many times greater than anything that previous batteries could demonstrate, and in addition, can send and receive gigantic currents without any damage (there is simply nothing in the system that fails). Finally, all the components of such a battery turned out to be surprisingly inexpensive, so such systems can be installed anywhere.
The authors built prototype melted battery. Its specific capacity is not very impressive yet. But this is not so critical - for a stationary energy storage device, the mass of the system is not very important. In addition, scientists believe that all the characteristics of the new battery can be seriously improved by maintaining the principle of operation, but selecting other components.
The developers promise to bring the created prototype to a commercial version in five years. And this is quite fast, considering that hot batteries of the previous types, although they were invented a very long time ago, are still considered exotic despite all attempts to improve them.
Based on materials from sciencedaily.com, physorg.com, membrane.ru and other sources

1. Turn off the lights when moving from room to room. Install thermal motion sensors that will turn off the lights for you.
2. Use local lighting: backlights, floor lamps, sconces. For example, in order not to turn on the main light sources every time, it is better to install LED strip lighting in the room.
3. Remember that cleanliness is the key to saving. Dirty windows and dusty lampshades reduce the level of illumination in the room by up to 35%.
4. When making repairs, keep in mind that light walls will reflect up to 80% of the light flux, and dark ones - only about 12%.
5. Replace incandescent light bulbs with energy-saving and LED ones. Replacing just one lamp will save about 1,000 rubles per year.

Let's take Moscow, for example. 1 kWh in the capital costs Electricity tariffs for the population and equivalent categories of consumers in the territory of Moscow, with the exception of the Troitsky and Novomoskovsky administrative districts 5.38 rubles. Let’s imagine that in three apartments, three light bulbs are lit for eight hours a day: LED, energy-saving and incandescent. For a more objective picture, we will choose lamps of such power that they provide approximately the same level of illumination. And this is what we get.

Lamp type	LED	Energy saving	Incandescent
Power consumption, kW	0,013	0,025	0,1
Lamp life, hours	50 000	8 000	1 000
Lamp cost, rub.	248	200	11
Cost per hour of operation Cost of an hour of operation = tariff × power + lamp cost ⁄ resource, rub.	0,0749	0,1595	0,549
Hourly savings Hourly savings = cost of operating an incandescent lamp − cost of operating a comparable lamp, rub.	0,4741	0,3895	-
Payback period Payback period in hours = (cost of lamp − cost of incandescent lamp) ⁄ hourly savings, watch	499,89	485,24	-
Payback period Payback period in days = payback period in hours ⁄ 8, days	62,49	60,65	-
Annual savings Annual savings = (8 × 365 − payback period in hours) × hourly savings, rub.	1147,37	948,34	-

It turns out that in two months one energy-saving lamp will allow you to save 40 kopecks every hour, and 10 light bulbs will save 4 rubles.

Use electrical appliances correctly

1. If there is no two-tariff option, turn off all non-essential electrical appliances at night, and charging device- after the equipment is fully recharged.
2. The refrigerator must be defrosted regularly if it does not have a special No Frost system. Make sure that the device is positioned as far as possible from heating appliances and that natural ventilation of the rear wall is provided. Place only cooled dishes in it!
3. Monitor the performance of the electric stove burners and place only suitable sized dishes with a flat bottom on them.
4. Cover pots and pans with lids: they reduce heat loss by almost three times.
5. Try not to overload the washing machine (overloading increases electricity consumption by up to 10%) and use a medium temperature setting. Washing at 30 degrees uses 35% less energy than washing at 40 degrees.
6. Use an electric kettle instead of an electric stove to heat water. This will be much more economical. Boil only the volume of liquid that is needed at the moment.
7. Clean your air conditioner fans and filters regularly.
8. Things that require low temperature regime, after turning off the iron.
9. Do not leave equipment, including microwaves, televisions, computers, scanners, printers, modems, in standby mode. This will save more than 200 kW per year.
10. Use electrical outlets with a timer.

Buy energy-saving household appliances

1. All electrical appliances are marked with Latin letters from A+++ to G. Choose equipment with low class energy consumption, marked A and B.
2. Buy appliances that use the latest energy-saving technologies. For example, induction cooktops are becoming increasingly popular, heating only the bottom of the cookware and not wasting energy. The efficiency of such stoves reaches 95%!

Install a two-tariff meter

1. A two-tariff meter allows you to save at night. Such meters are beneficial for those who can use energy-intensive Appliances: dishwasher and washing machine, bread maker - from 23.00 to 7.00. On average, the meter pays for itself in a year.

Don't waste your heat

1. Instead of using a traditional heater, use an air conditioner set to heating mode. If the manufacturer allows it, of course. Many air conditioners cannot be used at subzero temperatures.
2. An infrared heater is 30–80% more economical than others.
3. If your home has electric radiators, try to keep them clean so that dust does not absorb some of the heat and you do not have to increase the temperature.
4. When using a water heater, reduce the water heating temperature.
5. Replace the storage water heater with a flow-through one. This way you won’t waste electricity constantly maintaining a certain water temperature.
6. Heat water only when necessary. Unplug the boiler when you leave home and at night.
7. Once every three months, clean the water heater from, which increases energy consumption by 15–20%.
   • Disconnect the device from the network and turn off the water supply.
   • Drain completely.
   • Remove the boiler cover, carefully disconnect the wires and unscrew the thermostat.
   • Unscrew the nuts holding the flange. Push the flange up, rotate it and pull it out.
   • Now you can clean the heating element with a wire brush. A solution of acetic acid and hot water (1:5) will also help get rid of plaque. Just place the heating element in it for 30 minutes and make sure that the sealing rubber does not come into contact with the acid.

Ecology of consumption. Science and technology: One of the main problems of alternative energy is the unevenness of its supply from renewable sources. Let's look at how types of energy can be stored (although for practical use we will then need to turn the accumulated energy into either electricity or heat).

One of the main problems of alternative energy is the unevenness of its supply from renewable sources. The sun shines only during the day and in cloudless weather, the wind either blows or subsides. And the need for electricity is not constant, for example, less is required for lighting during the day, and more in the evening. And people like it when cities and villages are flooded with illuminations at night. Well, or at least the streets are just lit. So the task arises - to save the received energy for some time in order to use it when the need for it is maximum, and the supply is insufficient.

There are 6 main types of energy: gravitational, mechanical, thermal, chemical, electromagnetic and nuclear. By now, humanity has learned to create artificial batteries for the first five types of energy (well, except for the fact that the existing reserves of nuclear fuel are of artificial origin). So let’s look at how each of these types of energy can be accumulated and stored (although for practical use we will then need to convert the accumulated energy into either electricity or heat).

Gravitational energy storage devices

In accumulators of this type, at the stage of energy accumulation, the load rises upward, accumulating potential energy, and at the right moment it falls back, returning this energy to benefit. The use of solids or liquids as a load brings its own characteristics to the design of each type. An intermediate position between them is occupied by the use of bulk substances (sand, lead shot, small steel balls, etc.).

Gravitational solid-state energy storage devices

The essence of gravitational mechanical storage devices is that a certain load is raised to a height and released at the right time, causing the generator axis to rotate along the way. An example of the implementation of this method of energy storage is the device proposed by the Californian company Advanced Rail Energy Storage (ARES). The idea is simple: at a time when solar panels and wind turbines produce a lot of energy, special heavy cars are driven up the mountain using electric motors. At night and in the evening, when energy sources are insufficient to supply consumers, the cars go down and the motors, working as generators, return the accumulated energy back to the network.

Almost all mechanical drives of this class have a very simple design, and therefore high reliability and a long service life. The storage time of once stored energy is practically unlimited, unless the load and structural elements disintegrate over time due to age or corrosion.

The energy stored when lifting solids can be released in a very short time. The only limitation on the power received from such devices is the acceleration of gravity, which determines the maximum rate of increase in the speed of the falling load.

Unfortunately, the specific energy intensity of such devices is low and is determined by the classical formula E = m · g · h. Thus, in order to store energy to heat 1 liter of water from 20°C to 100°C, you need to lift a ton of cargo to a height of at least 35 meters (or 10 tons per 3.5 meters). Therefore, when the need arises to store more energy, this immediately leads to the need to create bulky and, as an inevitable consequence, expensive structures.

The disadvantage of such systems is also that the path along which the load moves must be free and fairly straight, and it is also necessary to exclude the possibility of things, people and animals accidentally entering this area.

Gravity fluid storage

Unlike solid loads, when using liquids there is no need to create straight shafts of large cross-section for the entire lifting height - the liquid also moves well through curved pipes, the cross-section of which should only be sufficient for the maximum design flow to pass through them. Therefore, the upper and lower reservoirs do not necessarily have to be located under each other, but can be spaced at a sufficiently large distance.

Pumped storage power plants (PSPPs) belong to this class.

There are also smaller-scale hydraulic gravitational energy storage devices. First, we pump 10 tons of water from an underground reservoir (well) to a container on the tower. Then the water from the tank flows back into the tank under the influence of gravity, rotating a turbine with an electric generator. The service life of such a drive can be 20 years or more. Advantages: when using a wind engine, the latter can directly drive the water pump; water from the tank on the tower can be used for other needs.

Unfortunately, hydraulic systems are more difficult to maintain in proper technical condition than solid-state ones - first of all, this concerns the tightness of tanks and pipelines and the serviceability of shut-off and pumping equipment. And one more important condition - at the moments of accumulation and use of energy, the working fluid (at least a fairly large part of it) must be in a liquid state of aggregation, and not in the form of ice or steam. But sometimes in such storage tanks it is possible to obtain additional free energy, say, when replenishing the upper reservoir with melt or rainwater.

Mechanical energy storage devices

Mechanical energy manifests itself during the interaction and movement of individual bodies or their particles. It includes the kinetic energy of movement or rotation of a body, the energy of deformation during bending, stretching, twisting, compression of elastic bodies (springs).

Gyroscopic energy storage devices

In gyroscopic storage devices, energy is stored in the form of kinetic energy from a rapidly rotating flywheel. The specific energy stored per kilogram of flywheel weight is significantly greater than what can be stored in a kilogram of static load, even when raised to greater height, and the latest high-tech developments promise a density of accumulated energy comparable to the reserve of chemical energy per unit mass of the most effective types chemical fuel.

Another huge advantage of the flywheel is the ability to quickly release or receive very high power, limited only by the strength of materials in the case of a mechanical transmission or the “throughput” of electrical, pneumatic or hydraulic transmissions.

Unfortunately, flywheels are sensitive to shock and rotation in planes other than the plane of rotation, since this creates enormous gyroscopic loads that tend to bend the axle. In addition, the storage time of the energy accumulated by the flywheel is relatively short and for traditional designs usually ranges from a few seconds to several hours. Further, energy losses due to friction become too noticeable... However, modern technologies make it possible to dramatically increase the storage time - up to several months.

Finally, another unpleasant moment - the energy stored by the flywheel directly depends on its rotation speed, therefore, as energy is accumulated or released, the rotation speed changes all the time. At the same time, the load very often requires a stable rotation speed not exceeding several thousand revolutions per minute. For this reason, purely mechanical systems for transferring power to and from the flywheel may be too complex to manufacture. Sometimes an electromechanical transmission using a motor-generator placed on the same shaft with the flywheel or connected to it by a rigid gearbox can simplify the situation. But then energy losses due to heating of wires and windings are inevitable, which can be much higher than losses due to friction and slippage in good variators.

Particularly promising are the so-called superflywheels, consisting of turns of steel tape, wire or high-strength synthetic fiber. The winding can be dense, or it can have a specially left empty space. In the latter case, as the flywheel unwinds, the coils of the tape move from its center to the periphery of rotation, changing the moment of inertia of the flywheel, and if the tape is spring-loaded, then storing some of the energy in the elastic deformation energy of the spring. As a result, in such flywheels the rotation speed is not so directly related to the accumulated energy and is much more stable than in the simplest solid structures, and their energy intensity is noticeably greater.

In addition to greater energy intensity, they are safer in the event of various accidents, since, unlike fragments of a large monolithic flywheel, which in their energy and destructive power are comparable to cannonballs, spring fragments have much less “damaging power” and usually quite effectively slow down a burst flywheel after due to friction against the walls of the housing. For the same reason, modern solid flywheels, designed to operate in conditions close to the limit of the material’s strength, are often made not monolithic, but woven from cables or fibers impregnated with a binder.

Modern designs with a vacuum rotation chamber and a magnetic suspension of a superflywheel made of Kevlar fiber provide a stored energy density of more than 5 MJ/kg, and can store kinetic energy for weeks and months. According to optimistic estimates, the use of ultra-strong “supercarbon” fiber for winding will allow increasing the rotation speed and specific density of stored energy many more times - up to 2-3 GJ/kg (they promise that one spin of such a flywheel weighing 100-150 kg will be enough for a mileage of a million kilometers or more, i.e. for virtually the entire life of the car!). However, the cost of this fiber is still many times higher than the cost of gold, so even Arab sheikhs cannot afford such machines... You can read more about flywheel drives in the book by Nurbey Gulia.

Gyro-resonant energy storage devices

These drives are the same flywheel, but made of elastic material (for example, rubber). As a result, it acquires fundamentally new properties. As the speed increases, “outgrowths” - “petals” begin to form on such a flywheel - first it turns into an ellipse, then into a “flower” with three, four or more “petals”... Moreover, after the formation of “petals” begins, the speed of rotation of the flywheel is already practically does not change, and the energy is stored in the resonant wave of elastic deformation of the flywheel material, which forms these “petals”.

N.Z. Garmash was engaged in such constructions in the late 1970s and early 1980s in Donetsk. The results he obtained are impressive - according to his estimates, with a flywheel operating speed of only 7-8 thousand rpm, the stored energy was enough for the car to travel 1,500 km versus 30 km with a conventional flywheel of the same size. Unfortunately, more recent information about this type of drive is unknown.

Mechanical storage using elastic forces

This class of devices has a very high specific energy storage capacity. If it is necessary to maintain small dimensions (several centimeters), its energy intensity is the highest among mechanical drives. If the requirements for weight and size characteristics are not so stringent, then large ultra-high-speed flywheels surpass it in energy intensity, but they are much more sensitive to external factors and have a much shorter energy storage time.

Spring mechanical storage

Compression and straightening of the spring can provide a very large flow and supply of energy per unit of time - perhaps the greatest mechanical power among all types of energy storage devices. As in flywheels, it is limited only by the strength limit of the materials, but springs usually implement the working translational movement directly, and in flywheels one cannot do without a rather complex transmission (it is no coincidence that pneumatic weapons use either mechanical mainsprings or gas cartridges, which, by their nature, are essentially pre-charged air springs; until firearms For combat at a distance, spring weapons were also used - bows and crossbows, which, long before the new era, completely replaced the sling with its kinetic accumulation of energy in professional troops).

The storage period of the accumulated energy in a compressed spring can be many years. However, it should be taken into account that under the influence of constant deformation, any material accumulates fatigue over time, and the crystal lattice of the metal of the spring gradually changes, and the greater the internal stresses and the higher the ambient temperature, the sooner and to a greater extent this will happen. Therefore, after several decades, a compressed spring, without changing in appearance, may turn out to be “discharged” completely or partially. However, high-quality steel springs, if they are not subjected to overheating or hypothermia, can work for centuries without any visible loss of capacity. For example, an antique mechanical wall clock from one complete winding still runs for two weeks - just like when it was made more than half a century ago.

If it is necessary to gradually evenly “charge” and “discharge” the spring, the mechanism providing this can turn out to be very complex and capricious (look at the same mechanical watch - in fact, many gears and other parts serve precisely this purpose). An electromechanical transmission can simplify the situation, but it usually imposes significant restrictions on the instantaneous power of such a device, and when working with low powers (several hundred watts or less), its efficiency is too low. A separate task is the accumulation of maximum energy in a minimum volume, since this creates mechanical stresses close to the tensile strength of the materials used, which requires particularly careful calculations and impeccable workmanship.

When talking about springs here, we need to keep in mind not only metal, but also other elastic solid elements. The most common among them are rubber bands. By the way, in terms of energy stored per unit mass, rubber exceeds steel tens of times, but it serves approximately the same number of times less, and, unlike steel, it loses its properties after just a few years even without active use and under ideal external conditions. conditions - due to the relatively rapid chemical aging and degradation of the material.

Gas mechanical accumulators

In this class of devices, energy is accumulated due to the elasticity of compressed gas. When there is excess energy, the compressor pumps gas into the cylinder. When it is necessary to use the stored energy, the compressed gas is supplied to a turbine, which directly performs the necessary mechanical work or rotates an electric generator. Instead of a turbine, you can use a piston engine, which is more efficient at low power (by the way, there are also reversible piston compressor engines).

Almost every modern industrial compressor is equipped with a similar battery - a receiver. True, the pressure there rarely exceeds 10 atm, and therefore the energy reserve in such a receiver is not very large, but this usually allows you to increase the service life of the installation several times and save energy.

Gas compressed to a pressure of tens and hundreds of atmospheres can provide a sufficiently high specific density of stored energy for an almost unlimited time (months, years, and with a high quality receiver and shut-off valves - tens of years - it is not for nothing that pneumatic weapons using compressed cartridges gas, has become so widespread). However, the compressor with a turbine or a piston engine included in the installation are quite complex, capricious devices and have a very limited resource.

A promising technology for creating energy reserves is compressing air using available energy at a time when there is no immediate need for the latter. Compressed air is cooled and stored at a pressure of 60-70 atmospheres. If it is necessary to expend the stored energy, the air is extracted from the storage device, heated, and then enters a special gas turbine, where the energy of the compressed and heated air rotates the stages of the turbine, the shaft of which is connected to an electric generator that supplies electricity to the power system.

To store compressed air, it is proposed, for example, to use suitable mine workings or specially created underground tanks in salt rocks. The concept is not new, storing compressed air in an underground cave was patented back in 1948, and the first plant with compressed air energy storage (CAES) with a capacity of 290 MW has been operating at the Huntorf power plant in Germany since 1978. During the air compression stage, a large amount of energy is lost in the form of heat. This lost energy must be compensated by compressed air before the expansion stage in the gas turbine, and for this purpose hydrocarbon fuel is used to increase the air temperature. This means that the installations are far from 100% efficient.

There is a promising direction to improve the efficiency of CAES. It consists in retaining and preserving the heat generated during the operation of the compressor at the stage of compression and cooling of air, followed by reuse when reheating cold air (so-called recuperation). However, this CAES option has significant technical difficulties, especially in creating a long-term heat storage system. If these problems are addressed, AA-CAES (Advanced Adiabatic-CAES) could pave the way for large-scale energy storage systems, an issue that has been raised by researchers around the world.

Participants in the Canadian startup Hydrostor proposed another unusual solution - pumping energy into underwater bubbles.

Thermal energy storage

In our climatic conditions, a very significant (often the main) part of the energy consumed is spent on heating. Therefore, it would be very convenient to directly accumulate heat in the storage device and then receive it back. Unfortunately, in most cases the density of stored energy is very small, and its storage time is very limited.

There are heat accumulators with solid or melting heat-storing material; liquid; steam; thermochemical; with an electric heating element. Heat accumulators can be connected to a system with a solid fuel boiler, a solar system or a combined system.

Energy storage due to heat capacity

In accumulators of this type, heat accumulation is carried out due to the heat capacity of the substance that serves as the working fluid. A classic example of a heat accumulator is the Russian stove. It was heated once a day and then it heated the house for 24 hours. Nowadays, a heat accumulator most often means containers for storing hot water, lined with material with high thermal insulation properties.

There are heat accumulators based on solid coolants, for example, in ceramic bricks.

Different substances have different heat capacities. For most, it is in the range from 0.1 to 2 kJ/(kg K). Water has an abnormally high heat capacity - its heat capacity in the liquid phase is approximately 4.2 kJ/(kg K). Only very exotic lithium has a higher heat capacity - 4.4 kJ/(kg K).

However, in addition to the specific heat capacity (by mass), it is also necessary to take into account the volumetric heat capacity, which allows us to determine how much heat is needed to change the temperature of the same volume of different substances by the same amount. It is calculated from the usual specific (mass) heat capacity by multiplying it by the specific density of the corresponding substance. You should focus on volumetric heat capacity when the volume of the heat accumulator is more important than its weight.

For example, the specific heat capacity of steel is only 0.46 kJ/(kg K), but the density is 7800 kg/cubic m, and, say, polypropylene is 1.9 kJ/(kg K) - more than 4 times higher, but its density is only 900 kg/cub.m. Therefore, with the same volume, steel can store 2.1 times more heat than polypropylene, although it will be almost 9 times heavier. However, due to the anomalously large heat capacity of water, no material can surpass it in volumetric heat capacity. However, the volumetric heat capacity of iron and its alloys (steel, cast iron) differs from water by less than 20% - in one cubic meter they can store more than 3.5 MJ of heat for each degree of temperature change, the volumetric heat capacity of copper is slightly less - 3.48 MJ /(cubic m K). The heat capacity of air under normal conditions is approximately 1 kJ/kg, or 1.3 kJ/cubic meter, so to heat a cubic meter of air by 1°, it is enough to cool a little less than 1/3 liter of water (naturally, hotter than air) by the same degree ).

Due to the simplicity of the device (what could be simpler than a stationary solid piece of solid matter or a closed reservoir with a liquid coolant?), such energy storage devices have an almost unlimited number of cycles of energy accumulation and release and a very long service life - for liquid coolants until the liquid dries out or until the tank is damaged from corrosion or other reasons, for solid-state materials there are no these restrictions. But the storage time is very limited and, as a rule, ranges from several hours to several days - conventional thermal insulation is no longer capable of retaining heat for a longer period, and the specific density of the stored energy is low.

Finally, one more circumstance should be emphasized - for efficient work Not only the heat capacity is important, but also the thermal conductivity of the heat accumulator substance. With high thermal conductivity, even to fairly rapid changes in external conditions, the heat accumulator will respond with its entire mass, and therefore with all its stored energy - that is, as efficiently as possible.

In the case of poor thermal conductivity, only the surface part of the heat accumulator will have time to react, and short-term changes in external conditions simply will not have time to reach the deeper layers, and a significant part of the substance of such a heat accumulator will actually be excluded from operation.

Polypropylene, mentioned in the example discussed just above, has a thermal conductivity almost 200 times less than steel, and therefore, despite its fairly large specific heat capacity, it cannot be an effective heat accumulator. However, technically, the problem is easily solved by organizing special channels for coolant circulation inside the heat accumulator, but it is obvious that such a solution significantly complicates the design, reduces its reliability and energy intensity, and will certainly require periodic maintenance, which is unlikely to be necessary for a monolithic piece of substance.

Strange as it may seem, sometimes it is necessary to accumulate and store not heat, but cold. In the United States, companies have been operating for more than ten years that offer ice-based “accumulators” for installation in air conditioners. At night, when there is an abundance of electricity and it is sold at reduced rates, the air conditioner freezes the water, that is, it switches to refrigerator mode. During the daytime, it consumes several times less energy, working like a fan. The energy-hungry compressor is switched off during this time. .

Energy accumulation when changing the phase state of a substance

If you look carefully at the thermal parameters of various substances, you can see that when the state of aggregation changes (melting-solidification, evaporation-condensation), significant absorption or release of energy occurs. For most substances, the thermal energy of such transformations is sufficient to change the temperature of the same amount of the same substance by many tens or even hundreds of degrees in those temperature ranges where its state of aggregation does not change. But, as you know, until the state of aggregation of the entire volume of a substance becomes the same, its temperature is practically constant! Therefore, it would be very tempting to accumulate energy by changing the state of aggregation - a lot of energy is accumulated, and the temperature changes little, so as a result there will be no need to solve problems associated with heating to high temperatures, and at the same time it is possible to obtain a good capacity of such a heat accumulator.

Melting and crystallization

Unfortunately, at present there are practically no cheap, safe and decomposition-resistant substances with great energy phase transition, the melting point of which would lie in the most relevant range - from approximately +20°C to +50°C (maximum +70°C is still a relatively safe and easily achievable temperature). As a rule, complex organic compounds melt in this temperature range, which are not at all healthy and often quickly oxidize in air.

Perhaps the most suitable substances are paraffins, the melting point of most of which, depending on the type, lies in the range of 40..65 ° C (however, there are also “liquid” paraffins with a melting point of 27 ° C or less, as well as natural ozokerite, related to paraffins, the melting point of which lies in the range of 58..100°C). Both paraffins and ozokerite are quite safe and are also used for medical purposes to directly warm sore spots on the body.

However, with good heat capacity, their thermal conductivity is very low - so low that paraffin or ozokerite applied to the body, heated to 50-60 ° C, feels only pleasantly hot, but not scalding, as would be the case with water heated to the same temperature, - this is good for medicine, but for a heat accumulator this is an absolute minus. In addition, these substances are not so cheap, say, the wholesale price for ozokerite in September 2009 was about 200 rubles per kilogram, and a kilogram of paraffin cost from 25 rubles (technical) to 50 and more (highly purified food grade, i.e. suitable for use in food packaging). These are wholesale prices for batches of several tons; at retail everything is at least one and a half times more expensive.

As a result, the economic efficiency of a paraffin heat accumulator is in big question - after all, a kilogram or two of paraffin or ozokerite is only suitable for medically warming up a cramped lower back for a couple of tens of minutes, and to ensure a stable temperature in a more or less spacious home for at least a day, the mass of a paraffin heat accumulator should be measured in tons, so its cost immediately approaches the cost of a passenger car (albeit in the lower price segment)!

And the temperature of the phase transition, ideally, should still exactly correspond to the comfortable range (20..25°C) - otherwise, you will still have to organize some kind of heat exchange regulation system. However, the melting point in the region of 50..54°C, characteristic of highly purified paraffins, in combination with the high heat of phase transition (slightly more than 200 kJ/kg) is very well suited for a heat accumulator designed to provide hot water supply and water heating, the only problem is the low thermal conductivity and high price of paraffin.

But in case of force majeure, paraffin itself can be used as fuel with good calorific value (although this is not so easy to do - unlike gasoline or kerosene, liquid and especially solid paraffin does not burn in air, you definitely need a wick or other device for feeding into the combustion zone not the paraffin itself, but only its vapor)!

An example of a thermal energy storage device based on the melting and crystallization effect is the TESS thermal energy storage system based on silicon, which was developed by the Australian company Latent Heat Storage.

Evaporation and condensation

The heat of evaporation-condensation, as a rule, is several times higher than the heat of melting-crystallization. And it seems that there are quite a few substances that evaporate in the required temperature range. In addition to the frankly toxic carbon disulfide, acetone, ethyl ether, etc., there is also ethyl alcohol (its relative safety is proven daily by personal example by millions of alcoholics around the world!). Under normal conditions, alcohol boils at 78°C, and its heat of evaporation is 2.5 times greater than the heat of fusion of water (ice) and is equivalent to heating the same amount of liquid water by 200°.

However, unlike melting, when changes in the volume of a substance rarely exceed a few percent, during evaporation the vapor occupies the entire volume provided to it. And if this volume is unlimited, then the steam will evaporate, irrevocably taking with it all the accumulated energy. In a closed volume, the pressure will immediately begin to increase, preventing the evaporation of new portions of the working fluid, as is the case in the most ordinary pressure cooker, so only a small percentage of the working substance experiences a change in state of aggregation, while the rest continues to heat up while in the liquid phase. This opens up a large field of activity for inventors - the creation of an effective heat accumulator based on evaporation and condensation with a sealed variable working volume.

Phase transitions of the second order

In addition to phase transitions associated with changes in the state of aggregation, some substances, even within one state of aggregation, can have several different phase states. A change in such phase states, as a rule, is also accompanied by a noticeable release or absorption of energy, although usually much less significant than when the aggregate state of a substance changes. In addition, in many cases, with such changes, in contrast to a change in the state of aggregation, temperature hysteresis occurs - the temperatures of the direct and reverse phase transitions can differ significantly, sometimes by tens or even hundreds of degrees.

Electric energy storage

Electricity is the most convenient and versatile form of energy in the modern world. It is not surprising that electrical energy storage devices are developing most rapidly. Unfortunately, in most cases, the specific capacity of low-cost devices is small, and devices with high specific capacity are still too expensive to store large energy reserves for mass use and are very short-lived.

Capacitors

The most common “electrical” energy storage devices are ordinary radio capacitors. They have an enormous rate of energy accumulation and release - usually from several thousand to many billions of complete cycles per second, and are able to operate in this way in a wide temperature range for many years, or even decades. By combining several capacitors in parallel, you can easily increase their total capacity to the desired value.

Capacitors can be divided into two large classes - non-polar (usually “dry”, i.e. not containing liquid electrolyte) and polar (usually electrolytic). The use of a liquid electrolyte provides a significantly higher specific capacity, but almost always requires compliance with polarity when connecting. Additionally, electrolytic capacitors are often more sensitive to external conditions, primarily to temperature and have a shorter service life (over time, the electrolyte evaporates and dries out).

However, capacitors have two main disadvantages. Firstly, this is a very low specific density of stored energy and therefore a small (relative to other types of storage) capacity. Secondly, this is a short storage time, which is usually measured in minutes and seconds and rarely exceeds several hours, and in some cases is only a small fraction of a second. As a result, the scope of application of capacitors is limited to various electronic circuits and short-term accumulation, sufficient for rectifying, correcting and filtering current in power electrical engineering - there are not yet enough of them for more.

Ionistors

Ionistors, which are sometimes called “supercapacitors,” can be considered as a kind of intermediate link between electrolytic capacitors and electrochemical batteries. From the former, they inherited an almost unlimited number of charge-discharge cycles, and from the latter, relatively low charging and discharging currents (a complete charge-discharge cycle can last a second, or even much longer). Their capacity is also in the range between the most capacitive capacitors and small batteries - usually the energy reserve ranges from a few to several hundred joules.

Additionally, it should be noted that the ionistors are quite sensitive to temperature and have a limited charge storage time - from several hours to several weeks maximum.

Electrochemical batteries

Electrochemical batteries were invented at the dawn of the development of electrical engineering, and now they can be found everywhere - from mobile phones to airplanes and ships. Generally speaking, they work on the basis of some chemical reactions and therefore they could be classified in the next section of our article - “Chemical energy storage devices”. But since this point is usually not emphasized, and attention is drawn to the fact that batteries accumulate electricity, we will consider them here.

As a rule, if it is necessary to store quite a lot of energy - from several hundred kilojoules or more - lead-acid batteries are used (for example, any car). However, they have considerable dimensions and, most importantly, weight. If light weight and mobility of the device are required, then more modern types of batteries are used - nickel-cadmium, metal hydride, lithium-ion, polymer-ion, etc. They have a much higher specific capacity, but also the specific cost of storing energy. noticeably higher, so their use is usually limited to relatively small and economical devices, such as mobile phones, photo and video cameras, laptops, etc.

Recently, powerful lithium-ion batteries have begun to be used in hybrid and electric vehicles. In addition to lighter weight and greater specific capacity, unlike lead-acid, they allow almost complete use of their nominal capacity, are considered more reliable and have a longer service life, and their energy efficiency in a full cycle exceeds 90%, while the energy efficiency of lead When charging the last 20% of batteries, their capacity can drop to 50%.

According to the mode of use, electrochemical batteries (primarily powerful ones) are also divided into two large classes - the so-called traction and starting ones. Usually, a starting battery can work quite successfully as a traction battery (the main thing is to control the degree of discharge and not bring it to such a depth that is permissible for traction batteries), but when used in reverse, too much load current can very quickly damage the traction battery.

The disadvantages of electrochemical batteries include a very limited number of charge-discharge cycles (in most cases from 250 to 2000, and if the manufacturers' recommendations are not followed - much less), and even in the absence of active use, most types of batteries degrade after a few years, losing their consumer properties .

At the same time, the service life of many types of batteries does not begin from the beginning of their operation, but from the moment of manufacture. In addition, electrochemical batteries are characterized by sensitivity to temperature, a long charge time, sometimes tens of times longer than the discharge time, and the need to comply with the method of use (avoiding deep discharge for lead batteries and, conversely, maintaining a full charge-discharge cycle for metal hydride and many other types of batteries). The charge storage time is also quite limited - usually from a week to a year. With old batteries, not only the capacity decreases, but also the storage time, and both can be reduced many times.

Developments to create new types of electric batteries and improve existing devices do not stop.

Chemical energy storage devices

Chemical energy is the energy “stored” in the atoms of substances that is released or absorbed during chemical reactions between substances. Chemical energy is either released as heat during exothermic reactions (for example, fuel combustion) or converted into electrical energy in galvanic cells and batteries. These energy sources are characterized by high efficiency (up to 98%), but low capacity.

Chemical energy storage devices make it possible to obtain energy both in the form from which it was stored and in any other form. There are “fuel” and “fuel-free” varieties. Unlike low-temperature thermochemical storage devices (more on them a little later), which can store energy simply by being placed in sufficiently warm place, here you cannot do without special technologies and high-tech equipment, sometimes very cumbersome. In particular, while in the case of low-temperature thermochemical reactions the mixture of reagents is usually not separated and is always in the same container, reagents for high-temperature reactions are stored separately from each other and are combined only when energy is needed.

Energy accumulation by fuel production

During the energy storage stage, a chemical reaction occurs that results in the reduction of fuel, for example, the liberation of hydrogen from water - by direct electrolysis, in electrochemical cells using a catalyst, or by thermal decomposition, say, an electric arc or highly concentrated sunlight. The “released” oxidizer can be collected separately (for oxygen this is necessary in a closed isolated object - under water or in space) or “thrown away” as unnecessary, since at the time of fuel use this oxidizer will be quite sufficient in environment and there is no need to waste space and money on its organized storage.

At the energy recovery stage, the accumulated fuel is oxidized to release energy directly in the desired form, regardless of how the fuel was obtained. For example, hydrogen can immediately provide heat (when burned in a burner), mechanical energy (when supplied as fuel to an internal combustion engine or turbine) or electricity (when oxidized in a fuel cell). As a rule, such oxidation reactions require additional initiation (ignition), which is very convenient for controlling the energy extraction process.

This method is very attractive due to the independence of the stages of energy accumulation (“charging”) and its use (“discharging”), the high specific capacity of the energy stored in the fuel (tens of megajoules for every kilogram of fuel) and the possibility of long-term storage (provided that the containers are properly sealed - for many years ). However, its widespread use is hampered by the incomplete development and high cost of the technology, the high fire and explosion hazard at all stages of working with such fuel, and, as a consequence, the need for highly qualified personnel when servicing and operating these systems. Despite these shortcomings, various installations using hydrogen as a backup energy source are being developed around the world.

Energy storage using thermochemical reactions

Long and widely known large group chemical reactions that, in a closed vessel, when heated, go in one direction, absorbing energy, and when cooled, go in the opposite direction, releasing energy. Such reactions are often called thermochemical. The energy efficiency of such reactions, as a rule, is less than when changing the state of aggregation of a substance, but is also very noticeable.

Such thermochemical reactions can be considered as a kind of change in the phase state of a mixture of reagents, and the problems that arise here are approximately the same - it is difficult to find a cheap, safe and effective mixture of substances that successfully acts in a similar way in the temperature range from +20°C to +70°C. However, one similar composition has been known for a long time - this is Glauber's salt.

Mirabilite (aka Glauber's salt, also known as sodium sulfate decahydrate Na2SO4 · 10H2O) is obtained as a result of elementary chemical reactions (for example, by adding table salt to sulfuric acid) or is mined in “finished form” as a mineral.

From the point of view of heat accumulation, the most interesting feature mirabilite is that when the temperature rises above 32°C bound water begins to release, and outwardly it looks like the “melting” of crystals, which dissolve in the water released from them. When the temperature drops to 32°C, free water is again bound into the crystalline hydrate structure - “crystallization” occurs. But the most important thing is that the heat of this hydration-dehydration reaction is very high and amounts to 251 kJ/kg, which is noticeably higher than the heat of “honest” melting-crystallization of paraffins, although one third less than the heat of fusion of ice (water).

Thus, a heat accumulator based on a saturated solution of mirabilite (saturated precisely at temperatures above 32°C) can effectively maintain the temperature at 32°C with a long resource for storing or releasing energy. Of course, for a full-fledged hot water supply, this temperature is too low (a shower with this temperature is, at best, perceived as “very cool”), but for heating the air, this temperature may be quite enough.

Fuel-free chemical energy storage

In this case, at the “charging” stage, others are formed from some chemical substances, and during this process, energy is stored in the new chemical bonds formed (for example, slaked lime is converted into a quicklime state by heating).

During “discharge,” a reverse reaction occurs, accompanied by the release of previously stored energy (usually in the form of heat, sometimes additionally in the form of gas, which can be supplied to the turbine) - in particular, this is exactly what happens when “quenching” lime with water. Unlike fuel methods, to start a reaction it is usually enough to simply connect the reactants with each other - no additional initiation of the process (ignition) is required.

In essence, this is a type of thermochemical reaction, but unlike the low-temperature reactions described when considering thermal energy storage devices and which do not require any special conditions, here we are talking about temperatures of many hundreds, or even thousands of degrees. As a result, the amount of energy stored in each kilogram of working substance increases significantly, but the equipment is also many times more complex, bulky and more expensive than empty plastic bottles or a simple reagent tank.

The need to consume an additional substance - say, water to slak the lime - is not a significant disadvantage (if necessary, you can collect the water released when the lime passes into the quicklime state). But the special storage conditions of this very quicklime, the violation of which is fraught not only with chemical burns, but also with an explosion, transfer this and similar methods to the category of those that are unlikely to come into wide use.

Other types of energy storage devices

In addition to those described above, there are other types of energy storage devices. However, at present they are very limited in terms of the density of stored energy and the time of its storage at a high specific cost. Therefore, for now they are used more for entertainment, and their exploitation for any serious purposes is not considered. An example is phosphorescent paints, which store energy from a bright light source and then glow for several seconds, or even long minutes. Their modern modifications have not contained toxic phosphorus for a long time and are completely safe even for use in children's toys.

Superconducting magnetic energy storage devices store it in the field of a large magnetic coil with direct current. It can be converted into alternating electrical current as needed. Low-temperature storage devices are cooled with liquid helium and are available for industrial applications. High-temperature liquid hydrogen-cooled storage devices are still under development and may become available in the future.

Superconducting magnetic energy storage devices are large in size and are typically used for short periods of time, such as during switching operations. published

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Perhaps the most old uniform modern grid-tied energy storage. The principle of operation is simple: there are two water tanks, one higher than the other. When electricity demand is low, the energy can be used to pump water upward. During peak hours, water rushes down, spinning a hydro generator and generating electricity. Similar projects are being developed, for example, by Germany in abandoned coal mines or spherical containers on the ocean floor.

Compressed air

Power South

In general, this method resembles the previous one, except that instead of water, air is pumped into the tanks. When necessary, air is released and rotates the turbines. This technology has existed in theory for several decades, but in practice, due to its high cost, there are only a few working systems and a few more test ones. Canadian company Hydrostor is developing a large adiabatic compressor in Ontario and Aruba.

Molten salt

SolarReserve

Solar energy can be used to heat salt to the desired temperature. The resulting steam is either immediately converted into electricity by a generator, or stored for several hours as molten salt to, for example, heat homes in the evening. One of these projects is the Mohammed bin Rashid Al Maktoum Solar Park - in United Arab Emirates. And in the Alphabet X laboratory, it is possible to use molten salts in combination with antifreeze in order to preserve excess solar or wind energy. Georgia Tech recently built a more efficient system that replaces salt with liquid metal.

Flow batteries

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Redox flow batteries consist of huge tanks of electrolyte that are passed through membranes and create an electrical charge. Typically, vanadium is used as an electrolyte, as well as solutions of zinc, chlorine or salt water. They are reliable, easy to use, and have a long service life. The world's largest flow battery will be built in caves in Germany.

Traditional batteries

SDG&E

Calmac

At night, the water stored in the tanks is frozen, and during the day the ice melts and cools neighboring houses, allowing you to save on air conditioning. This technology is attractive for regions with hot climates and cool nights, such as California. In May of this year, NRG Energy delivered 1,800 industrial ice batteries to Southern California Edison.

Super flywheel

Beacon Power

This technology is designed to store kinetic energy. Electricity starts the motor, which stores rotational energy in the drum. When needed, the flywheel slows down. The invention is not widely used, although it can be used to ensure uninterruptible power supply.