The bold idea of building power plants in space to illuminate the Earth with clean energy, which used to only appear in science fiction works, is now accelerating towards reality. With the deepening of the global energy transition and the continuous decline in space launch costs, the concept of space solar power stations as a "future energy" has become a new highland for major technological powers to compete in layout. China is steadily advancing the "daily project" of space solar power stations, with plans to conduct megawatt level in orbit tests around 2030. American entrepreneur Elon Musk recently announced plans to deploy a 100 million kilowatt solar powered artificial intelligence satellite energy network into space annually. The reason why this technology attracts global attention is that it has advantages that traditional energy sources cannot match, and is regarded as one of the ultimate solutions to solve the human energy crisis. The advantages and difficulties of space power generation. The concept of a space solar power station was first proposed by American scientist Peter Grasse in 1968. Its working principle is similar to that of a communication satellite: the solar panel orbits the Earth and always faces the sun through its own rotation, receiving sunlight at the optimal angle; Subsequently, the collected energy is transmitted in microwave form to the receiving station on the ground, converted into electrical energy, and connected to the existing power grid infrastructure. Compared with ground-based solar power generation, the power generation conditions in space are perfect: no cloud cover, no day night alternation, and no atmospheric attenuation. In geostationary orbit or Earth Sun synchronous orbit, a unit solar panel can receive 8 to 10 times the amount of solar radiation on the ground, and can achieve 24-hour continuous power generation, with the potential to become a stable "base load power source" (the basic power source for continuous and stable operation). At the same time, the expansion capability of space solar power plants is extremely strong, and by expanding their scale, they can meet the global energy growth demand. If a one kilometer wide solar panel strip is laid in geostationary orbit, the energy received in one year is equivalent to the total amount of oil that can be extracted from the Earth. Space solar power plants can also bring multiple additional values: firstly, reducing the burden on satellites, freeing them from bulky solar wings (sails), and replacing them with compact receiving antennas to obtain power from "space charging piles", significantly improving flexibility and endurance; The second is to achieve dual transmission of energy and information, allowing the antennas of communication and navigation satellites to simultaneously receive power; The third is to optimize space information processing, directly completing data processing in space to avoid packet loss, distortion, and other problems caused by the current "space compression, sky ground transmission, ground decompression" mode; The fourth is to provide remote wireless power supply for deep space exploration facilities such as lunar bases and Mars outposts. However, building a super power station in space is not an easy task. Various design schemes for space solar power stations have been proposed internationally, which are mainly divided into two categories based on the different forms of solar energy collection: concentrated and non concentrated. The core idea of a spotlighting space solar power station is to use a special spotlighting system to concentrate sunlight onto the surface of the solar cell, thereby improving the photoelectric conversion efficiency; On the other hand, the microwave beam emitted by the transmitting antenna is precisely aimed at the antenna of the spacecraft or ground receiving station. Representative proposals include the "Alpha" from the United States and the "Omega" from China, which have the advantages of compact structure and light weight, but require high thermal management and directional accuracy. Non concentrated space solar power stations directly lay large-area flexible photovoltaic arrays, combined with independent microwave transmitting antennas. For example, Japan's proposed "rope structure" scheme and China's "multi rotation joint" configuration. This type of design is more concise, but it needs to solve problems such as the deployment of ultra large flexible structures in orbit and high-precision dual axis pointing, just like making a huge "space sail" constantly aim at two different targets in high-speed motion, which is a great challenge. No matter which solution is adopted, as a super large energy supply system connecting "space space" and "space ground", space solar power plants need to break through multiple key core technologies. For example, long-distance high-power and high-efficiency microwave wireless energy transmission, in orbit ultra large structure assembly, extreme thermal environment control, long-term reliable operation, etc. These technologies are interrelated and require systematic breakthroughs. In recent years, the research and development of space energy has pressed the "fast forward button". Space solar power plants have moved from theoretical exploration to a critical stage of engineering verification, and many countries have accelerated key technology research and prototype testing. A series of breakthrough developments have made the landing prospects of this technology increasingly clear. The UK will include the construction of space solar power stations in its national comprehensive energy strategy and space development strategy, providing key funding and policy support. The European Space Agency has positioned space solar power plants as a "clean base load power option with long-term feasibility", continuously investing in research and development efforts, and steadily advancing related technology verification. NASA, the Department of Defense, and other agencies in the United States are continuously advancing space validation of critical components and technologies. In 2023, the California Institute of Technology launched a set of small microwave transmission and reception antennas in orbit, using a distributed slot type spotlight design. The distance between the two antennas was only one foot, successfully transmitting microwave beams to the ground, marking an important breakthrough in miniaturized energy transmission equipment and accumulating experience for the development of large-scale equipment in the future. Japan is exploring in scenario experiments. In December 2024, the Japan Aerospace Exploration Agency, in collaboration with industry, conducted a microwave transmission test from commercial aircraft to the ground in Nagano Prefecture. A plane cruising at 700 kilometers per hour at an altitude of 7000 meters transmitted 270 watts of microwave power to 13 receiving points on the ground, verifying the feasibility of high-precision microwave power transmission technology for high-speed mobile platforms. Although China started late in this field, it has made rapid progress. In June 2022, Xi'an University of Electronic Science and Technology led the construction of the "Daily Project" - a 75 meter high test tower, which is the world's first ground verification system for a fully connected and full system space solar power station. Recently, the "Daily Engineering" has achieved a series of new breakthroughs: in the "one to many" mobile target energy transmission technology, a launch system can simultaneously supply power to multiple mobile targets, solving the problem of precise control of multi-target power supply. In the future, it is expected to supply power to multiple spacecraft or ground mobile devices simultaneously; In high-precision pointing control, further improving the pointing accuracy of microwave beams and reducing energy loss; Significant progress has been made in the integration, miniaturization, and lightweighting of transmitting and receiving antennas, laying the foundation for the deployment of equipment in space. In addition, the Fifth Academy of China Aerospace Science and Technology Group, Chongqing University, Sichuan University, Shanghai University, Institute of Electrical Engineering of the Chinese Academy of Sciences, Harbin Institute of Technology, Shanghai Jiaotong University and other units also actively participate in the key technology research, forming a multidisciplinary collaborative innovation pattern. In the future, there will be rich application scenarios. Once the space solar power station is built and put into operation, it will profoundly reshape the energy pattern of human society, and the application scenarios will far exceed imagination. In the field of ground power supply, traditional power grids are constrained by terrain and economic costs, making it difficult and costly to install transmission lines in remote mountainous areas, deserts, oceans, and other regions. Space solar power stations are based on space and have a complete coverage of all regions and terrains of the Earth. Through microwave wireless energy transmission, these regions can obtain sustained and stable power supply, which helps promote global energy accessibility. In the field of emergency relief, disasters such as earthquakes, typhoons, and floods often lead to widespread power outages. The microwave wireless transmission of space solar power stations can provide flexible emergency power supply, which can quickly provide "aerial power support" for medical rescue, communication support, temporary resettlement power supply, etc. at the disaster relief site, and save valuable time for life rescue. In the field of aerospace, with the arrival of the era of big space, more and more satellites, space stations, and deep space probes will enter space, and the demand for electricity will continue to grow. Space solar power plants can provide long-distance, high-power power support for these spacecraft, making the satellite's operating cycle longer and more powerful, allowing deep space probes to fly farther, and conducting more scientific experiments in space stations, greatly expanding the scope and time of human space exploration. The future "space Internet" or moon base may rely on this "space-based power pack". Even more imaginative is that space solar power plants may become a new tool for addressing extreme weather conditions. Extreme weather events such as typhoons often bring huge disasters to coastal areas, and the use of microwave wireless energy injection can continuously heat the water vapor in the sinking cold airflow in the typhoon area. When the energy is large enough, it is expected to change the regional atmospheric circulation, thereby changing the intensity and direction of the typhoon and reducing the losses caused by typhoon disasters. Of course, space solar power plants still have a long way to go from scientific experiments to commercially viable industries. In addition to scientists tackling a series of key technologies, it is also necessary for countries to share technological achievements, research and development costs, and jointly address challenges. At the same time, the participation of commercial institutions is also crucial. It is necessary to form an innovative ecosystem guided by the government, driven by the market, and combining industry, academia, and research to reduce construction and operation costs, so that clean space energy can enter ordinary people's homes and truly become a sustainable energy solution that benefits all mankind. (Liao Xinshe) (The author is an academician of the CAE Member and a professor of Xi'an University of Electronic Science and Technology)