[Reading Science] Wireless Charging Anytime, Anywhere... Energy Revolution Accelerates

Rapid Progress in Space Solar Power Generation, US and UK Launch Full-Scale R&D
China, Europe, Japan Plan Commercialization in 2030s
Korea at 'Fundamental Technology' Stage... "Need Full-Scale Investment"

The biggest concern when traveling to Earth or exploring the Moon and Mars is energy supply. But what if you could wirelessly charge power anytime, anywhere? Space solar power, once thought to be a far-future technology, is expected to be commercialized faster than anticipated. The United States and the United Kingdom have finally begun to actively move forward decades after the idea first emerged. China, the most advanced, is already steadily preparing at the national level, and Japan has accelerated its schedule to commercialize in the 2030s. South Korea is still at the basic research stage, but there are calls to consider more active research and development (R&D) investments to secure renewable energy.

Governments in Motion

Hesitant space powers have recently turned actively toward space solar power. Grant Shapps, UK Secretary of State for Energy Security, announced at the London Tech Week event held on the 12th that he would invest a total of 4.3 million euros (about 6 billion KRW) in space solar power R&D. This funding will be evenly distributed among industry, academia, and research institutions, including the University of Cambridge, which is developing ultra-light solar panels for space, and Queen Mary University of London, which is developing long-distance wireless power transmission and reception systems. The UK daily 'The Guardian' reported that Secretary Shapps said, "The technology to generate power using solar panels installed on satellites and transmit it to Earth has enormous potential to enhance the UK's energy security," adding, "If we win this new space race, the UK can change the way power is supplied and provide cheaper, cleaner, and safer energy for the next generation." This investment by the UK government was anticipated. In an official report released in 2021, the UK government analyzed that by 2050, it would be possible to produce and use 10 gigawatts (GW) of power annually from space. This corresponds to one-quarter of the UK's current total power demand. The industrial ripple effect is expected to reach billions of pounds, creating about 143,000 jobs. Accordingly, in March last year, the UK government formed the Space Energy Initiative consortium to develop the concept of the CASSIOPeiA solar power satellite. The plan is to launch 4 to 5 relatively small power satellites in low Earth orbit to reduce costs while increasing efficiency.

The United States has finally started moving as well. On the 14th, the U.S. House Committee on Science, Space, and Technology unanimously passed an amendment to include space solar power in the list of key R&D cooperative projects between NASA and the Department of Energy (DOE) in next year's budget. This is the first time in over 50 years since the idea of space solar power was proposed in the 1970s. If this amendment is confirmed through the House plenary session and the Senate, related research by NASA and other U.S. government and research institutions is expected to be formalized and intensified. In fact, it is well known that NASA and the National Oceanic and Atmospheric Administration (NOAA) already possess many related core technologies. NASA has reportedly been conducting secret research on wireless power transmission and reception in space aboard the secret mission spacecraft X-37B, operated jointly with Boeing for the past 10 years. Notably, NASA announced last year at the International Space Development Conference (ISDC) that it had begun value assessment research on space solar power. This research report is expected to be released by the end of this month or next month.

Japan is also moving quickly. At the end of last month, Japan's public-private space solar power research cooperation project announced plans to develop and launch small satellites for space power transmission experiments as early as 2025. Japan has been developing related core technologies since the 2000s. In 2015, the Japan Aerospace Exploration Agency (JAXA) succeeded in an experiment transmitting 1.8 kW of power wirelessly over a distance of more than 50 meters, lighting a single electric candle. The Japanese government plans to invest about 7 billion USD in the 2030s to launch 1 GW-class space solar power satellites and commercialize the technology.

The most advanced is China. It is already actively promoting the project at the national level. At its self-built space station 'Tiangong,' completed last year, China is demonstrating and developing power transmission technology by 2028. It plans to launch a 10-megawatt-class satellite into geostationary orbit at an altitude of 36,000 km by 2035 and commercialize 2 GW-class satellites by 2050. Additionally, the European Space Agency (ESA) approved the 'Solaris' project last December, aiming to commercialize a 2 GW-class space solar power plant by 2040.

The California Institute of Technology in the United States has achieved the first successful demonstration of wireless power transmission and reception technology in outer space. Photo by California Institute of Technology website

Challenges Being Solved

Space solar power has no atmospheric scattering effects and can generate power 24 hours a day. It is more than eight times more efficient than on Earth's surface. It emits no carbon during power generation. Through wireless power transmission and reception, electricity can be sent without infrastructure not only to Earth but also to the Moon and Mars. With a simple device, unlimited power supply can be received anytime, anywhere. It is also optimal for emergency supply in war zones or disaster areas. The biggest challenges are technology development, efficiency, safety, and cost. However, the feasibility is increasing. This is why space powers have recently begun serious investment.

Recently, wireless power transmission and reception experiments in space succeeded for the first time in history. The California Institute of Technology announced at the end of last month that the Space Solar Power Demonstration Satellite (SSPD-1), launched in January this year, succeeded in demonstrating wireless power transmission and reception. Power generated by ultra-light flexible solar panels was converted into microwaves and transmitted and received inside the satellite to light an LED lamp. A demonstration of sending microwaves to Earth for reception was also conducted. This is the first time this technology has been realized in actual space.

Transmission and reception efficiency remains a hurdle. With current technology, 40% of power is lost in the process of converting power into microwaves. Junmin Choi, principal researcher at the Korea Aerospace Research Institute (KARI), explained, "Losses occurring when passing through space and the atmosphere or converting microwaves back into power are surprisingly low, about 10-20%," adding, "If a space solar power satellite with a diameter of 1 km is launched, the receiving antenna area should be about 4 square kilometers." He further stated, "The biggest challenge is to reduce the large-scale losses occurring during power conversion to microwaves and to improve efficiency."

Safety issues are not a major challenge. Although household microwave ovens are widely used, the harmful effects of microwaves on the human body have not yet been objectively proven. Even if dangerous, access can be controlled near designated receiving stations and protective equipment can be provided to sufficiently prepare. Principal researcher Choi said, "Fine dust from coal-fired power plants cannot be avoided by anyone, but microwaves only need to be avoided in designated areas and can be shielded as much as needed," adding, "For Korea, which has high latitudes and unfavorable weather, space solar power at the current technology level could be the best way to achieve carbon neutrality."

Regarding costs, they are expected to be resolved much faster than anticipated due to recycling and the emergence of large rockets. To build a 1 GW-class space solar power satellite, at least about 10,000 tons of materials and equipment must be transported. Thousands of rocket launches, which cost enormous amounts of money, were inevitable, and in the 1970s, it was estimated that building a 1 kW-class space solar power plant would cost up to 1 trillion USD. However, launch costs have recently dropped sharply. SpaceX's Falcon Heavy has lowered launch costs to about 1,400 USD per kilogram. When the Starship, capable of carrying 150 tons of cargo per launch, is completed, costs will be even cheaper. Especially in the long term, if the Luna Gateway planned by the U.S. is built in low Earth orbit and long-term lunar bases and production facilities are established, costs and time for constructing large structures like space solar power plants are expected to be drastically reduced.

South Korea is still at an early stage but has secured considerable core technologies. The Korea Electrotechnology Research Institute (KERI) began developing wireless power transmission and reception and succeeded in sending 4.8 kW of power up to 100 meters. Together with the Korea Aerospace Research Institute (KARI), they designed a satellite wireless power transmission and reception system and demonstrated it at an international space development event held in Paris last year. They received applause for showcasing sophisticated technology capable of accurately tracking and transmitting power to fast-moving targets. KERI and KARI aim to develop two small satellites by 2029 to demonstrate power transmission and reception technology in space. However, there is no official national-level R&D on space solar power yet. Sanghwa Lee, principal researcher at KERI, said, "Our country has world-class technology for high-capacity semiconductor-based wireless power transmission and reception systems," adding, "We have developed the necessary technology for space demonstration and have started research on technology to transmit power from satellites to the ground." He added, "Due to budget shortages, practical research such as scaling up or satellite development has not yet been conducted. To commercialize early, more investment and collaboration among related research institutions and researchers are needed."