Solutions are emerging to address solar power's challenges, such as limited installation sites and low capacity utilization. Japan is leading the development of two innovative technologies aimed at maximizing solar energy generation: space-based solar power and next-generation flexible solar cells.
Sunlight not only illuminates and warms the Earth but is also the ultimate source of all biological activity. Solar power, which converts the Sun's energy into electricity, is a key focus in the global effort to build a decarbonized society.
While solar power has been in use since the 1970s, it has not yet become a dominant energy source worldwide. This is due to the limited availability of suitable installation sites and the low capacity utilization, as energy generation decreases at night, during poor weather, or when panels become dirty.
To overcome these challenges and maximize solar energy usage, two promising technologies have been developed: space-based solar power (SBSP) and next-generation flexible solar cells. Japan is making significant strides toward the practical deployment of both.
Japan has been advancing space-based solar power (SBSP) research for several decades through collaboration between industry, academia, and government. Kyoto University has been a leader in developing wireless power transmission technology using microwaves, a key component of SBSP. In 1990, Professor SHINOHARA Naoki was inspired to enter the field by his mentor, Professor MATSUMOTO Hiroshi, who predicted, "SBSP is a technology that will enable the human race to survive for the next 10,000 years." Reflecting on his mentor's words, Shinohara remarked, "As the Earth's population grows, so will electricity demand, and ground-based generation will be insufficient to meet this need. That's why we must look to space."
Since the 1980s, Japan has conducted numerous SBSP experiments in space, gathering valuable data even while research has stalled elsewhere. In 1983, Japan performed the world's first Microwave Ionosphere Nonlinear Interaction Experiment (MINIX), successfully transmitting power between two rockets in space plasma. In 1993, Japan followed up with another successful rocket experiment using a newly developed phased array antenna, improving power transmission accuracy in space plasma. The country also possesses advanced satellite system design capabilities, allowing for optimized power generation efficiency and precise transmission of energy to the Earth.
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What are the key challenges and potential breakthroughs in harnessing solar power from space to meet global energy demands sustainably?
Key challenges include high launch costs, efficient energy transmission to Earth, and minimizing space debris. Potential breakthroughs involve advanced wireless power transmission, cost-effective satellite deployment, and scalable space-based solar technologies.