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Куц Тина

Home SES: competent selection of equipment

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The basic equipment of a home-type solar power station looks like this:

– solar panels;

– inverter;

– controller;

– energy storage.

At first glance, such a system is simple and straightforward. It may even seem that the full-fledged work of the SES will begin after the elementary combination of all the components together. But this is far from the case. For the effective functioning of the system components must meet certain parameters and be combined with each other. If a non-professional is engaged in the assembly of components, then there is a high risk that SES will have very low productivity indicators and simply will not pay off. In addition, you should pay attention to the high probability of failure of one of the components of the system, which would entail additional expenses and the failure of the solar power plant.

In addition to installing solar panels and connecting them to the system, the specialist must calculate the required amount of energy. It should also take into account the peak load and the average daily energy consumption of households.

The main role in the calculations is played by the mode in which the SES will function. The following power supply modes exist:

– full;

– comfortable;

– basic;

– moderate;

– emergency.

Full power supply mode means getting energy exclusively from photovoltaic modules. The use of energy from the common network is not made. To transfer the household to the full energy supply regime, a solar power station should be installed, which will generate about 600 kilowatt-hours per month. In addition, such a system should operate at a power of 5 kilowatts. On average, a household’s daily energy consumption in such conditions will be 10–20 kilowatt-hours. The maximum load will have a value of 50 kilowatt-hours.

Comfortable power supply mode is characterized by the rejection of the use of some household appliances. The list of this equipment includes a convector, an electric stove, a water heater and other appliances that require large amounts of energy daily. A consumer may include irons, computers, a washing machine, etc. Provided the daily energy consumption does not exceed 8 kilowatts, the household energy consumption per month will be about 250 kilowatt-hours.

The basic mode of providing households with electricity noticeably changes the consumer’s lifestyle. The specificity of using this mode is to constantly monitor the amount of energy used. The user should always be guided when you can connect to the network of certain appliances, depending on the load. This mode involves the inclusion of a certain technique only in case of emergency. Energy consumption per day will be approximately 3-4 kWh.

With a moderate energy supply at home restrictions on the use of electric kettles, water heaters, underfloor heating, etc. are assumed. This approach does not change the life of the user too much, although it will still be necessary to make certain concessions for the sake of economy. It is also worth paying attention to the dependence on weather conditions in this mode. Indicators of the nominal power of such a power plant will be within 3-5 kilowatts.

The most limiting is the emergency power supply mode. The user will experience all the savings in everyday life. Autonomous operation of the system will be carried out only a few days. This mode is applicable in difficult cases when it is impossible to obtain electricity in another way. The use of most electrical appliances will become impossible, in winter even a refrigerator will become an inaccessible luxury. Energy consumption per day will be about 1.5 kilowatts.

Heating and cooling with minimal costs thanks to the installation based on nitinol

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Scientists have created an innovative installation that has performance indicators 2 times higher than that of a conventional refrigerator. At the same time, the device does not require refrigerant.

The principle of operation of the installation is based on the transfer of heat through the use of metal “muscles”. Artificial muscle tissue is made of titanium-nickel. It is worth noting that the “muscles” have shape memory.

In the process of expansion, these muscle fibers absorb thermal energy, and when they return to the initial state, they release energy. The creators of the technology note the temperature difference in this process by 20 degrees Celsius.

A group of scientists notes that the strands of nitinol in tension, when unloading at room temperature, become colder by 20 degrees.

Such indicators are minimal, because obtained from the prototype in the laboratory. According to the inventors of the new technology, their development is capable of more. This system is able not only to cool effectively, but also to heat it. The efficiency of the device is 2-3 times higher than that of conventional heating or cooling devices. It should be noted that this technology is completely environmentally friendly and environmentally friendly.

The device has the form of a cylinder that rotates continuously. On the walls of the cylinder are wound threads of nitinol. During the accelerated rotation of the thread on one side of the installation stretch and absorb thermal energy from the air. When they move to the other side, a compression occurs and the nitinol bundles give off thermal energy to the outside.

For full operation, the installation should be equipped with special boxes in which the fans will be installed. The blades will drive the air in the system, thereby creating a hybrid source of heating and cooling.

As part of the Ferroic Cooling program, invested by DFG, this technology has been studied for several years. As a result of such serious scientific work, it was possible to determine the specific number of nitinol filaments, the installation rotational speed and the load level on the nitinol bundles, at which the efficiency of the device will be maximum.

With increasing area of ​​the rotating cylinder, the process of heat transfer is accelerated. Nitinol threads began to be bundled for rapid cooling. During the testing process, a television camera was used. She allowed to conduct an accurate analysis of the stages of raising and lowering the temperature.

The main secret of successful device operation is the most accurate calculation of parameters. The capacity of the installation is 30 times more than nitinol threads require for compression or expansion.

The study of the parameters of the system allowed the developers to customize its work in the smallest details for specific needs. The addition of the installation was a special software developed specifically for it. Now the setting of the heating and cooling parameters is done through the computer. At the end of the software development and modeling phase, the system can be launched.

The inventors note that the new device is 2 times more efficient than the heat pump and 3 times the refrigerator. The system does not require the inclusion of toxic substances in it, it does not have heat exchangers and pipes, because the air is cooled directly. Nitinol was not chosen as the main material. This alloy has high fatigue resistance. This allows you to guarantee the full functioning of the system for many years.

Rust as a fuel for underwater vehicles

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A group of scientists from Open Water Power managed to create a fuel cell that uses a special fuel. Aluminum and water are taken as a basis – they provide the movement of the mechanism. Representatives of the company said that this development can be an excellent alternative to lithium energy storage devices.

The use of uninhabited underwater vehicles is carried out for a number of versatile purposes. These mechanisms are able to map the bottom of the sea or ocean, to conduct a series of search or rescue operations, to carry out intelligence measures, etc. The main disadvantage of uninhabited vehicles is their dependence on the ship, which acts as a battery. The ship crew supplies electricity to power the underwater vehicles through a wire or systematically recharging batteries.

Most often, the uninhabited mechanisms are equipped with lithium energy drives. The efficiency of such batteries under water is low due to the limited energy resource and high pressure. In the process of producing such batteries, a special high-strength case is used for underwater mechanisms. It protects the contents of the lithium battery from high pressure under water, but at the same time it has a rather heavy weight. In addition, there is a danger of fire and even explosion of such batteries.

Representatives of Open Water Power have managed to create an alternative to traditional lithium batteries specifically for underwater vehicles. Their development is a power generator that runs on water instead of the usual fuel component. Innovative technology includes an aluminum anode and a nickel alloy cathode. An alternative battery is filled with electrolyte, most of which is water. Aluminum, placed in water, shows a slight reaction. If you add a little alkaline component, then the reactivity of this material increases significantly.

The process of generating electricity begins with the decomposition of water to molecular hydrogen and hydroxyl ions. This reaction is accompanied by the absorption of electrons from the electrical circuit. Further ingress of ions to the surface of the anode is accompanied by a reaction in which aluminum hydroxide enters the electrolyte medium. Thus, the electrical circuit is replenished with electrons.

The configuration of the fuel cell assumes the presence of a special trap into which the hydroxide gets when water passes through it. In addition, in this process, heat is removed, which is released during the reaction, to the external environment. Estimated battery makers, performance indicators are 1/3. The consumption of most of the energy comes from heat generation.

In the near future, the company plans to conduct development testing with the support of the United States Navy. According to the developer, their fuel cell is able to increase the range of the devices from 60 miles to several thousand.

World practice has several examples of developments in the field of underwater vehicles. These include underwater charging stations in the form of a nuclear reactor and energy storage robots. Both of these developments are not yet translated into reality. The question of the safety of such methods of obtaining energy for uninhabited apparatuses does not make it possible to implement projects, at least for now. An alternative battery, which actually works on water, can be an excellent substitute for dangerous methods of recharging underwater mechanisms.

Panasonic flexible battery

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Small electronics are mostly functioning due to lithium-ion energy storage. Globally, these batteries are the most popular and are in no hurry to take positions, giving way to analog methods of energy conservation. The scientific community is actively working to create all new configurations of lithium-ion drives. Panasonic was no exception and also took part in this race. Representatives of the company presented a new lithium-ion energy storage device, which is characterized by increased flexibility. Such a battery is able to preserve the productivity of work even after a series of bending or twisting.

Flexible gadgets are now the mainstream in the world of electronics. On the creation of all new models of such devices are working groups of scientists in many famous companies. This is due to the increased consumer interest in unusual devices and their high usability.

If we talk about the serial production of flexible devices, then things are not too bright. The fact is that some components of gadgets are not able to withstand repeated bending. The biggest problem in this area is the production of flexible batteries. This part of the gadget is extremely important, but now it was not possible to make it flexible without loss of efficiency. Significant losses in battery capacity are observed even with a relatively small deformation.

The lithium-ion battery from Panasonic showed excellent ductility without losing capacity. In the process of testing, the battery was subjected to repeated bending to a radius of 25 mm, underwent a twist to 25ᵒ. Laboratory experiments have shown that a battery, whose thickness is about half a millimeter, loses about one percent in its capacity. It occurs after 1000 bends and twists.

The developers note that a slight drop in capacity is noted after one thousand charge / discharge cycles, and the deformation does not affect this indicator in any way. It is also worth paying attention to the fact that the durability of a flexible lithium-ion battery does not decrease under mechanical stress. One thousand bends leads to a loss of capacity up to 80%. Scientists say that traditional lithium-ion energy storage devices have such a loss of capacity after 500 charge / discharge cycles.

Representatives from Panasonic said that a flexible lithium-ion battery would be an excellent solution for small electronics designed to be worn on the body. Such electronic devices have low power consumption and require extreme plasticity and safety from the battery.

The new flexible battery is available in three versions:

– weight 0.7 g, capacity 17.5 mA / h;

– weight 1.4 g, capacity 40 mA / h;

– weight 1.9 g, capacity 60 mA / h.

In the field of electronics, the best minds are working to develop not only flexible batteries, but also flexible smartphones. Lenovo has introduced a smartphone in the form of a bracelet and a tablet that folds. Representatives of the company Samsung, in turn, announced the creation of smartphones with curving screens that can be turned into a roll.

Lithium-ion storage from garbage can accumulate 4 times more energy

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A group of scientists from Riverside, California, discovered an innovative method for transforming glass waste into lithium-ion energy storage devices. These batteries have a capacity of 4 times more than traditional lithium-based drives. In addition, the researchers claim that such batteries have a long service life.

On a global scale, the use of this technology means a significant reduction in prices for mobile phones, laptops, tablets, etc. The introduction of this method of creating a battery significantly reduces the amount of waste from the glass. Researchers say that such batteries can even be used in electric cars.

The main idea of ​​the project was the use of silicon dioxide as a material for creating batteries. This component is extracted from glass waste. Two professors at the University of California, Cengiz Ozkan and Mihri Ozkan, are at the head of the research team of the project. The technology allows the use of high-frequency silicon nanoparticles for energy storage. This process can be a turning point in the release of lithium-ion batteries, which are currently the most popular in the world.

Anodes for lithium-ion batteries by Californian scientists are produced by applying three processing steps:

– glass waste undergoes the grinding process to a fine fraction (white powder);

– nanostructured silicon is created from silicon dioxide;

– silicon nanoparticles are covered with carbon.

Scientists conducted a series of laboratory tests. According to preliminary data, new lithium-ion batteries made from glass waste have a capacity larger than traditional batteries. The development of scientists at the University of California demonstrated in laboratory conditions excellent electrochemical characteristics.

According to the developers of lithium-ion batteries from glass waste, their invention can not only reduce the cost of electric cars, but also reduce the number of charges for small electronics with the same power.

Scientists at the University of Texas also succeeded in increasing the power of electric car batteries. There, a team of researchers led by John Gudenaf (known to the scientific community as a member of the group of inventors who created the lithium-ion energy storage) is developing a solid-state battery. According to scientists, their innovative battery will be able to accumulate and store 3 times more energy than traditional counterparts.

It should be noted that the successful completion of this project promises a significant increase in the course of electric transport. The charging time of electric vehicles is also noticeably reduced due to solid-state batteries (from a couple of hours to several minutes).

Solid-state energy storage instead of electrolyte in the composition have glass. This makes them safer and less expensive. The principle of operation of a traditional lithium-ion battery is to transfer lithium ions between the anode and the cathode. If you shorten the charging time, then this type of battery may explode.

Glass electrolyte makes it possible to charge such batteries much faster. The first battery with glass electrolyte, created by Texas scientists, is able to fully function at – 60 degrees Celsius. Attention should be paid to the fact that solid-state batteries allow using alkali metals to create an anode. This is not possible with traditional lithium-ion batteries.

Efficient utilization of solar modules from a company from Germany

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The lifetime of photovoltaic panels is in the range of 25-30 years. After a breakdown, solar devices are sent to a landfill marked “electronic trash”. Last year, the amount of e-waste in the world amounted to about 50 million metric tons. According to experts, by 2030, mankind will add several million tons to the total amount of recycled solar panels. By 2050, the amount of e-waste will increase to 70 million tons.

The issue of maximum safe processing of photovoltaic modules in recent years has become increasingly important on a global scale. The European Union launched a pilot project called ELSi. Thanks to large investments from the EU, the German company was able to realize its unique system of utilization of photovoltaic modules. The recycling process consists in extracting and reusing parts of solar modules.

Solar energy at this stage leads among all renewable sources of energy. Its rapid pace of development entails a number of environmental issues, of which the recycling process is paramount. Photovoltaic modules have a certain lifespan. This leads to the emergence of electronic waste every year in increasing amounts. This situation can significantly reduce the profitability of solar energy.

The technology for recycling waste from a company from Germany is based on the pyrolysis process. The use of this method of disposal allows you to extract valuable components from photovoltaic modules. A group of engineers was able to achieve the destruction of the polymers that make up the solar panels. Thus, the idea of ​​processing alternative equipment with the least losses was born.

The principle of the new technology is to separate the layers of solar panels, which are connected using polymers. The methods of utilization of the modules developed earlier did not have the ability to separate the layers mechanically. It was not possible to separate valuable materials from waste during processing.

A new method of disposal will allow gasification of the lower layers of the module. This makes it possible to separate the glass as simply as possible. In the process of processing, components of silicon, tin, copper, aluminum, and silver are extracted in pure form. Thus, the failed solar panels become a source of new raw materials. This method allows you not to throw the modules into landfills, but to reuse them with maximum productivity.

According to preliminary data, the creators of technology predict their invention widespread popularity. German engineers have stated that in the future it will be possible to recycle almost 95 percent of the materials from photovoltaic modules. The statistics state that an innovative installation has the ability to separate about 50 thousand solar panels throughout the year.

New technology allows you to convert electronic waste into real money. If you rework the estimated amount of waste that experts predict will be collected by 2030, you can get 450 million dollars. About 60 million new photovoltaic modules can be created from the selected materials, and this is 18 gigawatts of additional power on a global scale.

California made cheap zinc-based batteries

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NantEnergy has been developing low-cost energy storage batteries for a long time. At this stage, the development of zinc batteries has been completed, which, according to their creators, are among the cheapest. These batteries are rechargeable, making their performance indicators high and the price relatively low.

The process of creating these batteries took place over 6 years. Scientists have worked in 9 countries. The batteries of the company NantEnergy as a result of the painstaking work of engineers were able to reach the threshold of $ 100 per 1 kW-hour. This cost is 4 times lower than that of lithium-ion energy storage devices, which are now at the peak of their popularity.

The scope of lithium-ion batteries is very wide – ranging from budget mobile phones and ending with high-tech electric vehicles. Scientists around the world have been working for years to find new ways to store energy. Cheaper technology to save energy from alternative sources will make a big step on the path to energy independence on a global scale. That is why successful attempts to create innovations in this area attract the attention of the scientific community to themselves.

New technology company NantEnergy based on the use of zinc oxide. According to the head of the company, Patrick Soon-Shiong, his team has managed to create a completely new device, which in the long term can create radically new economies based on renewable energy sources.

During the development and testing of zinc batteries, a group of scientists of the company worked in nine countries. In addition, to test the development, more than a hundred localities were involved, in which photovoltaic modules and zinc accumulators were placed. According to the results of testing, the creators of zinc batteries stated that their energy storage systems throughout the entire test period were able to ensure the uninterrupted operation of cellular towers. It is worth noting that zinc-based accumulators were installed in remote areas where there was no connection to the general energy network.

A statement about the success of technology testing was made last fall at the international One Planet summit. This event was organized in honor of the fulfillment of the terms of the climate agreement by European countries.

Investment support for the development of zinc batteries was provided by the World Bank. NantEnergy received 5 million dollars for the development of innovative technology. Zinc batteries have already received more than 100 patents. The manufacturing company begins to actively bring innovation to the world market.

It should be noted that the company is currently taking orders for the current year. According to preliminary estimates, for the year the technology is able to bring about 50 billion dollars to the creators. Zinc batteries can be used in many manufacturing areas and not only. Experts say that the low price of such energy storage devices will make them popular for home energy storage in private SES and WES.

The creators of new zinc batteries focus on their low price for a reason. For comparison: lithium-ion drives have a price of about 300-400 dollars per 1 kW-hour, while zinc batteries have a cost of $ 100 with the same performance. As a disadvantage, innovation is characterized by its dimensions – a serial zinc battery in size corresponds to a small portfolio. The battery is charged by transforming zinc oxide to zinc and O2. The battery is discharged by oxidation of zinc. During testing, the zinc battery ensured the operation of the cell tower for 3 days without interruption.

Surl Generator

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Inventor John Searl is known to the wider scientific community for his invention, the Searl Generator. This magnetic device consists of one or more rings (disks) and a certain number of rollers having the shape of a cylinder. While driving, this whole structure generates electricity.

This invention is an entirely magnetic device. The generator has its own engine, which is independently driven and continues to work completely independently. Scientists say that this generator is able to never stop working. It is worth noting that no auxiliary energy sources for the movement of the device is required.

The principle of the Searl generator: when moving magnetic elements, the electron flow accelerates to a very high speed and this creates a vacuum around the device. In this vacuum, an area with a very low temperature appears. Today it is widely known that low temperature is a prerequisite for the appearance of superconductivity.

In addition, scientists say that in such conditions, anti-gravity occurs. As the rollers fill the coils with energy, they push the photons out. They can be seen encased in a magnetic field around a coil.

The Searl effect is a special effect of magnetism. It is based on magnetic fields. These fields push the magnetic rollers for continuous rotation around the magnetic disks. The device makes absolutely no noise during the generation of electricity. In addition, there is no heat and any vibration.

The Searl generator is valuable because with high efficiency it produces absolutely no environmental pollution and is completely safe.

The inventor himself claims that he owes the creation of a mechanism to the voice that came to him in a dream. But he could not just take and apply the algorithms dictated during sleep. He needed to test and live it all, to process the information.

There is the concept of “Searle squares”. Each such square contains a number. These numbers indicate the specific number of parts in a particular sector of the generator. The main idea of ​​the inventor was to create such a simple energy generator that everyone could make it.

All electric generators in their work are based on magnets and coils. The Searl generator also includes both elements. The passage of a magnet past a coil causes a curvature of the electron flow in a certain direction. After that, John Searle attached a lead plate to the bottom of the generator, his device took off. The thing is that a powerful stream of electrons moved down, thereby creating an overload.

The basic components of the generator are rare earth elements. Scientists say that any rare-earth element can be used as a base material, but they use neodymium. The choice of this element is fully justified by the excess electrons in it and the possibility of quickly compensating for their loss. John Searle said that to generate electricity, it is necessary to move either a magnetic field or conductors. The work of its generator is based precisely on the movement of magnetic fields. The device he created can generate large amounts of electricity with minimal investment.

In the near future, energy storage facilities can be installed in Ukraine

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Unstable generation of electricity at SES and WPPs in our country can be leveled due to the commissioning of new capacities (about 500 megawatts), Ukrenergo said. Currently, a project called “energy storage” is under development, which implies an additional 200 megawatts of energy for the country.

The total capacity of renewable energy sources on the energy map of Ukraine already by the fall of last year crossed the border of 1.8 gigawatts. It should be noted that SES occupy leading positions in the generation of “green” energy – their contribution is more than 800 megawatts of energy. The smallest amount of energy recorded from biogas stations (26 megawatts) and small hydropower plants (about 93 megawatts). Wind stations, in turn, provide about 437 megawatts.

Solar and wind power plants are characterized by instability of energy generation during the day. It should be noted that the amount of electricity consumed at different hours of the day is also unstable. To level these features, the maneuverable capacities of high-power power stations are used. This allows you to keep a constant voltage in the common network.

On the territory of Ukraine, the maneuverable capacity of hydroelectric power plants is aimed at stabilizing the voltage from nuclear power plants. The fact is that a nuclear reactor stably supplies a certain amount of energy to the network. It cannot be paused and restarted. Since network consumption varies throughout the day, HPPs are designed to smooth out fluctuations by means of maneuverable power. The growing share of electricity from renewable sources requires new maneuvering capacity.

The head of Ukrenergo last spring announced the need to build 2.5 gigawatts of maneuvering capacity. This will help to balance the unstable operation of five additional gigawatts of energy, which are planned to be obtained from renewable energy sources by 2025. At this stage, most of the technical conditions for maneuvering capacities – about 7.4 gigawatts – have already been completed. It is worth noting that the share of alternative energy in Ukraine is continuously increasing. The country’s energy system can sustain only 3 gigawatts without losing the balance.

Maintaining the balance of the system is possible due to the operational development of new KW or the return to the network of previously stored energy. The question of the choice between these options is now puzzled by a good half of the civilized world. Operational power generation is possible through the use of gas piston turbines. For their work requires a considerable amount of blue fuel. The cost of servicing such an installation will directly depend on the price of gas. Gas reciprocating turbines will cost 500-1000 euros per 1 kW.

Another way to level the differences in the network – energy storage. The most popular lithium-ion batteries. They do not require additional maintenance in the form of fuel. At the peak of energy consumption, they give out the surplus accumulated during the day, and in the morning and in the afternoon they are charged again. Their cost ranges from 750-1200 euros per 1 kW.

In terms of our country for the introduction of maneuverable capacity, 2 gigawatts are indicated for gas piston turbines and only 500 megawatts for batteries. The government is ready to spend 55 billion hryvnia on this project and raise the price of electricity by 49%. This project will not require any restrictions on generation. An increase in the share of drives in this planning would reduce the total budget by several times and reduce the pressure on consumers and the rise in prices. But in our country they are not accustomed to rely on expediency. They also do not want to refuse excessive consumption of gas.

A subsidiary company of Google Holding is actively promoting geothermal systems and allows you to get cheap energy

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Dandelion, which is part of Google’s holding, has managed to attract investments of almost $ 4.5 million. These funds are necessary to expand the geography of their activities in New York. Receiving such large financing is only one of the stages in which the company is promoting geothermal systems. Representatives of the company said that heat pumps are the most efficient and cheap alternative to conventional cooling or heating systems in private households that use fossil fuels as an energy source.

According to the co-founder of the company, at this stage they have accumulated a huge number of orders from the owners of households. People from different states seek to get a geothermal system for heating or cooling their homes, because it provides a comfortable temperature for mere pennies. Attracting more than $ 4 million by the company is a necessary measure to expand the company’s capabilities. Only thanks to funding, the Dandelion team will be able to fulfill all requests for the installation of heat pumps and introduce fundamentally new solutions for the alternative energy market.

Dandelion’s investors included world-renowned firms that are also active in the field of alternative energy. Such joint work makes it possible to increase the share of geothermal energy sources on the energy map of the world. It is worth noting that Opower, ZhenFund, Borealis Ventures and others have not only invested in the promotion of heat pumps by a subsidiary of Google, but also take an active part in the process itself. Representatives of these companies are on the board of the new team.

Attracting large investments was possible after the development of a number of innovative solutions, which reduced the financial costs of heating / cooling a house by almost 50%. Representatives of Dandelion produce drilling and installation of plastic pipes at a depth of 100-150 m. This is due to the fact that at this depth the temperature remains almost unchanged throughout the year and is about 10 degrees Celsius.

On the surface of the earth, specialists have a special pump. It allows the coolant to circulate properly. The pipes of the system have the shape of the letter U, and the heat exchanger itself can function equally well for both heating and cooling. The heat pump is controlled by the Nest thermostat. In winter, the system provides a comfortable temperature due to thermal energy from the ground. Sometimes the system uses electricity as an auxiliary source of energy. In the warm season, thanks to the reversal of this process, the room is cooled.

Such a system is ultimately financially beneficial, especially if the household is impressive. Heating large homes with fossil fuels is more expensive and more problematic. Cooling with traditional air conditioning requires a large amount of electricity.

One of the developers of this technology is Daniel Yates. The engineer said that in the next decade, homeowners from different parts of the United States would switch to geothermal energy for the most part. The Dandelion team has managed to reduce the cost of a geothermal system to 5 thousand dollars. This became possible after the introduction of high-efficiency heat pumps and the use of special drilling systems.

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