We want to build photovoltaic power plants into space!
The wonderful idea in science fiction novels is now gradually becoming a reality.
In March this year, the British " Times " published an article, which mentioned that the British government is considering investing 16 billion pounds (approximately 130 billion yuan) to build solar power stations in space. The power station will have a diameter of 1.7 kilometers and weigh about 2,000 tons. It is planned to be completed and put into use in 2040. The plan is also regarded as a potential solution that can help the UK achieve net-zero emissions by 2050.
html On May 28, NASA spokesman said that it will follow the steps of the US military and restart research on space-based solar energy (that is, space solar power stations). The spokesperson said that the previous obstacle was that the cost of launch was high and it was not worth deploying these space solar plants. Now we see that launch has become easier and cheaper, and space transportation is no longer a limitation, which makes the space solar power station Construction becomes possible.
On June 21st, Xidian UniversityThe "Zhuri Project" led by Academician Duan Baoyan of Xi'an University of Electronic Science and Technology of China passed the acceptance inspection of the full-link, full-system space solar power station ground verification system. This means that China has taken an important step in the construction of the "Space Three Gorges", which is nearly three years ahead of the original technical route node.
Entering 2022, affected by the European energy crisis caused by the Russia-Ukraine conflict, countries are increasingly pursuing space solar power stations . Experts analyze that in the context of the global energy crisis, solar energy, an inexhaustible energy source, is expected to become an important option for mankind to solve energy problems with the completion of space solar power stations.
Space photovoltaic power station
It is understood that the space solar power station concept was first proposed by American scientist Glaser in 1968, which is to establish a solar power station in the earth's orbit and continuously provide power to the ground through wireless transmission.
Compared with terrestrial solar power stations, space solar power stations are not affected by natural factors such as day and night, weather, and have a higher utilization rate of solar energy.
In 2007, the U.S. Pentagon submitted a 75-page research report to the National Security Space Office. The
report pointed out that space solar energy may become a new energy source that can be utilized. If a "photovoltaic panel (a power generation device that generates direct current when exposed to sunlight)" can be placed in space, all problems will be solved. By then, the amount of solar energy that the Earth can receive will increase to 100% instead of 70%, because the energy radiated from the sun to the Earth is affected by dark nights, cloudy skies and the atmosphere, and its reception capacity is limited.
The original purpose of the Pentagon was to collect space energy through solar panels installed on the giant satellite to provide energy for US military bases located everywhere on the ground.
Today, as energy shortages and global climate and environmental problems caused by traditional fossil energy become increasingly severe, it has become a global consensus to develop clean energy and renewable energy to gradually replace traditional fossil energy. Building photovoltaic power stations in space to achieve large-scale and stable utilization of solar energy has become one of the main strategic choices for the world's major scientific and technological countries to solve future energy and environmental problems.
Multi-national research and development, brainstorming
In terms of research on space solar power stations, the United States has always been at the forefront of the world. Institutions such as , the U.S. Air Force Research Laboratory and Northrop Grumman are continuously increasing their research and development efforts in this field, and have stated that they will carry out space verification of key technologies by 2025. According to news released by NASA, the U.S. Naval Research Laboratory tested a solar module and power conversion system in space in 2020, taking a key step towards building a space solar power station.
Information from the European Space Agency's official website shows that Europe has been conducting research on space solar power stations since 1998, and has proposed the conceptual design of a "solar sail tower" and plans to use the "solar sail tower" as a "Sail Tower" was moved into space to continuously deliver clean power resources to Europe.
As the world's third largest space power, Japan has conducted extensive research on key technologies for space solar power stations since the 1980s. On this basis, Japan has included space solar power generation in its national development plan and proposed a development roadmap for the construction of commercial space solar power stations before 2050.
Japan plans to build a space power station with a power generation capacity of 1 billion kilowatts in the earth's geostationary orbit, about 36,000 kilometers away from the earth. To this end, researchers from multiple institutions and research institutes have brainstormed and proposed multiple design plans. The solar panels designed by the Institute of Japan Aerospace Exploration Agency are like two huge mirrors. The two "mirrors" are 1.25 kilometers in diameter. After focusing sunlight on them, the energy is transmitted to the earth through microwave transmitters. .
China wants to build the "Three Gorges in Space"
On the other side, the Chinese scientific community is also following the world trend.
According to an article published by Academician Ge Changchun in " Chinese Science Journal " in 2021, with the support of relevant national departments, my country has officially started research on space solar power stations from the "Eleventh Five-Year Plan". Currently, it is in the system design and key technologies Some important results have been achieved in this regard.
In 2010, 12 Chinese academicians and more than 100 experts in related fields released my country’s Space Solar Power Plant Technology Seminar held by China Academy of Space Technology The development roadmap for space solar power stations proposes a "three-step" plan to build a megawatt-class small space solar power test power station by 2030: first, carry out ground and aerostat test verification of key technologies, secondly, carry out high-altitude ultra-high voltage power generation and transmission verification, Finally, a space wireless energy transmission test was carried out. The roadmap also sets the goal of having the ability to build gigawatt-scale commercial space solar power plants by 2050.
In 2014, 16 ministries and commissions including the Ministry of Industry and Information Technology, the National Development and Reform Commission, and the Ministry of Science and Technology organized more than 130 domestic experts to carry out demonstration work for nearly a year. The demonstration team finally completed the "China Space Power Station Development Plan and Key Technology System Planning Demonstration Report" 》.
On June 18, 2021, China’s first space solar power station experimental base was officially launched in Bishan, Chongqing. It plans to build the “Space Three Gorges” at an altitude of 36,000 kilometers above the earth’s surface. The base will focus on early demonstration, simulation and verification of technologies such as space solar power stations, wireless microwave energy transmission and space information networks.
On December 23 of the same year, the "Zhuri Project" was launched, kicking off the outdoor ground verification challenge of the "Zhuri Project" space solar power plant.
On June 5, 2022, good news came from the "Zhuri Project" research team led by Academician Duan Baoyan of Xi'an University of Electronic Science and Technology. The world's first full-link and full-system space solar power station ground verification system successfully passed the acceptance by the expert group. The test was successful nearly three years earlier than the original technical route node.
This verification system has broken through and verified many key technologies such as high-efficiency light concentration and photoelectric conversion, microwave conversion, microwave emission and waveform optimization, microwave beam pointing measurement and control, microwave reception and rectification, and smart mechanical structure design.
Advantages and Disadvantages of Space Solar Power Plants
If construction costs and technological maturity are not considered, in simple terms, the advantages of space solar power plants include the following three points:
First, space solar energy is a green, clean and renewable energy source. If space solar power plants can be used maturely, they can overcome various problems caused by fossil energy. Unlike wind power and hydropower, which have special requirements for the geographical environment, they are also unlike nuclear power plants that consume nuclear fuel and produce nuclear pollution risk.
Second, the energy utilization efficiency is high. can increase solar energy conversion efficiency by 14 times in space. In northwest China, one square meter of solar cells can produce 0.4 kilowatts of electricity, while in Chongqing, which has less sunshine, it only produces 0.1 kilowatts of electricity. But if it is in space separated from the troposphere , it can generate 10 to 14 kilowatts of electricity. But in a geosynchronous orbit about 36,000 kilometers above the earth's surface, the power generation can reach 10 to 14 kilowatts.
Third, it can realize ultra-long-distance energy transmission and scheduling. space solar power station uses wireless energy transmission technology to quickly transmit energy to remote environments, such as seas, deserts and other areas lacking power grid facilities. Not only that, antenna equipment for receiving microwave energy can also be mounted on aircraft, satellites, ships, deep space spacecraft and even on other planets, allowing these mobile platforms to conveniently receive microwave energy from space when needed, achieving "freedom of charging" .
Of course, space solar power stations also face many difficulties and challenges, mainly in the following three aspects:
First, the equipment is easily damaged and aged. The space environment is very complex, with strong environmental radiation and drastic temperature changes. Therefore, the aging rate of photovoltaic panels in space is much faster than that on the earth (it is calculated to be about 7 times faster than on the earth). In addition, space solar power stations require a very large volume, especially deployed photovoltaic panels or reflective mirrors, so they are more susceptible to collisions with space debris.
The second is difficult to assemble, build and repair. It is very simple to maintain and replace solar panels on the ground, but in space, remote control robots are often required to assemble and repair space solar power stations. The United States has previously achieved the maintenance of the Hubble Space Telescope (the orbital altitude is about 570 kilometers) through astronauts' space walks many times. However, if space solar energy is built and maintained in geosynchronous orbit (36,000 kilometers), The difficulty and risks of power stations far exceed those of previous space maintenance tasks.
Third, microwave transmission may interfere with the communication band. At present, the typical wireless energy transmission design uses microwaves in the frequency range of 1 to 10GHz, such as the commonly used 2.45GHz (common frequency of microwave ovens) or 5.8GHz microwaves. Because this frequency band is the window for atmospheric microwave transmission, microwave energy loss Minimum. However, , Bluetooth, , wireless networks (WiFi) and some special microwave communication frequencies are also within this range, and some astronomical observations may also target this frequency band, which may cause spectrum interference problems and require management coordination.
Conclusion
A century ago, when a Russian scientist proposed building a giant solar power station in space to continuously provide sufficient clean energy to the earth, this bold idea has always been regarded as the material of science fiction novels. In 1941, the short story "Inference" published by the famous science fiction writer Isaac Asimov described such a space station that could collect solar energy and transmit energy to the planet through microwaves. In 1968, American scientists Dr. Peter Grasse proposed a space solar power station plan that relies on solar power satellites to convert solar energy into electrical energy and transmit the energy to the ground through a wireless energy transmission system. Subsequently, many countries around the world started research on space solar power stations and initially confirmed the feasibility of the system.
A century has passed since the initial conception of the space solar power station. With the advancement of human space exploration technology, scientists’ predictions are becoming reality.
It can be imagined that in the not-too-distant future, when huge solar power stations float in space and continuously transport countless energy to all parts of the earth, the electrical energy used by people will be obtained from the space power stations and transported back As described by Peter Glasser in the book "Energy from the Sun: Its Future", a solar power station is first built in space, and then the electrical energy is converted into electromagnetic energy and transmitted to the ground through wireless transmission. The receiving station converts the electromagnetic energy back into electrical energy and provides it to the power supply network.
By then, people will no longer worry about the lack of electricity, nor will they be anxious about power outages. The goal of net-zero emissions will be achieved, earth pollution will be greatly reduced, the atmospheric environment will be fundamentally improved, and humans will be able to enjoy clean energy from space. .
