Humanity is still critically dependent on fossil fuels, although their use is not environmentally friendly, and the reserves are not endless. With the development of technology, alternative projects are becoming relevant, which until recently seemed fantastic. In the case of their implementation, people can get access to “inexhaustible” sources of energy.
Microwave in orbit
Scientists and science fiction writers have long been excited about the idea of moving the collection of solar energy into space, wh-ere it would be much more efficient than on the surface of the planet. In orbit, there is no day and night, as well as bad weather, so the space farm can work continuously. It is proposed to transmit energy to the Earth, in particular, using microwaves to a special antenna (the so-called rectenna).
The concept of space-based solar power (SBSP) has several significant dra-wbacks – from the need to build a giant receiving dev-ice in area to possible prot-ests from people who are worried about the prospect of microwave radiation from orbit. Nevertheless, the leading technological powers are actively working in this direction.
In early June, Chinese scientists tested the SBSP ground installation, according to a report from Xidian University ( Xi’an City ). The steel structure, 75 meters high, is the prototype of the energy receiver. During the tests, the researchers were able, in particular, to transfer energy to the trap using micro-waves. True, so far only fr-om a distance of 55 meters. According to the South China Morning Post, if it continues to be successful, China will launch a space solar farm as early as 2028.
Similar technology is being developed in the USA as well. Ten years ago, NASA introduced the concept of SPS-ALPHA (“arbitrarily large phased array solar energy satellite”), according to which an orbiting solar power plant should also transmit energy to Earth via microwave radiation.
In 2020, the Americans launched a secret X-37B drone into orbit, on board of which they installed a 12-inch square photovoltaic module (PRAM) to test the viability of orbiting solar power systems that convert starlight into microwave energy.
Russia is trying to keep up. At the beginning of 2022, the project of a solar power plant was presented by Russian Space Systems (RSS, part of the Rosco-smos State Corporation ). The 70-square-meter space drone collects and transmits solar energy to a ground-based battery-powered battery-powered rectenna network, which then transmits electricity over the grid. Unlike Chinese and American colleagues, domestic engineers propose to transfer energy using a laser, not microwave radiation. Independent experts, however, consider this method unreliable. Due to the fact, for example, that the laser beam passes through clouds worse.
Star in the garage
The sun heats us thanks to the thermonuclear fusion taking place inside it. Reproducing this process in a reactor on Earth would give humanity an inexhaustible source of clean energy. In addition, unlike nuclear power plants, it would not carry the threat of a nuclear catastrophe. The world scientific community has not yet been able to build a thermonuclear plant that produces more energy than it consumes. However, in recent years there has been hope for a breakthrough. In Febr-uary, an international team of scientists from the JET laboratory reported a successful experiment: in five seconds, they received 59 megajoules of usable energy (about 11 megawatts). In absolute terms, this is small, but the fact itself is important – it proves that the creation of such power plants is, in principle, possible.
Nuclear fusion in the Sun is provided by the most powerful gravity, and it cannot be reproduced in terrestrial conditions. The way out is to heat the substance to a temperature of 100 million degrees, which is ten times more than on the Sun. But no material suitable for building a reactor can withstand such temperatures. Therefore, Soviet scientists in the 1960s came up with a tokamak – a toroidal chamber with magnetic coils, in which superhot plasma does not come into contact with the walls.
Several tokamaks are currently being built around the world. One of the largest projects is the International Thermonu-clear Experimental Reactor (ITER ), which is being built in France with the participation of specialists from Russia. It should work in 2025. And by 2030, China will launch the largest tokamak in the world. Its design is being designed, among other th-ings, by scientists from the St. Petersburg Polytechnic University ( SPbPU ).
Meanwhile, Seattle -based Zap Energy recently received a $160 million investment to build the FuZE-Q compact fusion reactor. It works on an alternative principle: in a device called a Z-pinch, two electrodes pass a strong current through the plasma in the Z-axis direction. The current creates a ring magnetic field that compresses and heats the plasma. Such a system is considered much less stable than a tokamak. But startup executives say they have overcome the shortcomings of this approach. During the tests, the device generated a current of 500 kiloamperes, while payback is possible at 650 kiloamperes (according to calculations, this is the limit of a mini-reactor). Such figures should provide a new generation of installations. If successful, the company promises to mass-produce fusion reactors that can fit in a garage.
An ocean of energy
If people mastered the energy of rivers in ancient times, then it has not yet been possible to efficiently generate heat and electricity using the seas. The project of Japanese engineers can change the situation. In early June, they announced the successful completion of tests of an underwater turbine that uses the power of the ocean current.
The prototype mechanism called Kairyu weighs 330 tons and is an eleven-meter turbine connected to two cylinders, each of wh-ich houses a power generation system. A huge device “floats” under water, connecting to the seabed with an anchor cable, through which a power cable winds. The brainchild of the Japan-ese corporation IHI is able to change position, adjusting to the movement of water so as to produce energy as efficiently as possible.
The car was tested in the Pacific Kuroshio Current off the southeast coast of Japan. According to the IHI statement, this sea “river” could provide 205 gigawatts of electricity – exactly how much they are generating now in the whole country. But this is not easy to do. The fastest waters are near the surface, but it is problematic to place power plants there due to frequent typhoons, during which wave heights sometimes reach 20 meters.
In an effort to avoid the destructive effects of the elements, Kairyu was desi-gned to keep the mechanism at a safe but productive depth of about 50 meters below the surface of the water. It turned out that with a current speed of one to two meters per second (two to four knots), Kairyu is capable of producing 100 kilowatts of power. This is quite small compared to the average offshore wind turbine of 3.6 megawatts. However, inspired by the success, Japanese engineers are now planning to test a larger model – with a twenty-meter turbine that can generate two megawatts of energy. According to the manufacturer’s plan, a farm of similar generators, supplying electricity to the grid, will appear in the next decade.
Drill to hell
A potentially infinite source of energy is literally under our feet. It’s about geothermal energy. And not only residents of volcanically active regions, such as Iceland and Kamchatka, can use it: the hot interior of the planet is able to give light and warmth to anyone who digs deep enough. Water boils at three kilometers, lead melts at the eleventh (327°C), aluminum (659°C) at the twentieth, and platinum (1773°C) at the sixtieth.
The total heat flux from inside the Earth is approximately 26 terawatts. This is ten times more energy than can be extracted from all the estimated reserves of coal, oil and natural gas. Today, however, the share of geothermal sources in world electricity generation is less than 0.5 percent.
There are several projects to develop this little developed area. One of the most striking is the American startup Quaise, which plans to extract energy at a depth of 20 kilometers. In the spring, Quaise, an MIT subsidiary, raised $63 million in funding.
Drilling to this depth is a complex engineering challenge. It is necessary to figure out how to grind the material, compressed by tens of kilometers of the upper rock, and then raise it to the surface. And all this at extremely high temperatures. The record achieved at the Kola Superdeep Well is about 12.3 kilometers.
An American company found a way out in a device called a gyrotron, invented in Soviet times at the Scientific Research Institute of Radiophysics ( Gorky city ). This is an electrovacuum microwave generator, which, according to engineers, can melt hard rock, which will then be easier to dig out. By connecting a megawatt gyrotron to the latest cutting tools, Quaise expects to reach the stated depth in a few months.
At this level, the rock heats up to 500°C – enough to convert the water pumped there into a supercritical vapor state, which is ideal for generating electricity.
According to the plan, the working device will be ready within the next two years, and by 2026 there will be a system that produces electricity. In another two years, the company hopes to acquire old coal-fired power plants, turning them into steam-powered facilities. It is worth noting that geothermal energy has serious disadvantages. The extraction of heat from under the Earth can provoke earthquakes, pollution of groundwater, and toxic emissions. It is not known what consequences the development of the new project will lead to, since no one has ever climbed so far deep into the Earth.