Japan is poised to make history with its OHISAMA project, aiming to become the first country to transmit solar power from space to Earth.
This ambitious initiative seeks to harness the sun’s energy in space and beam it back to our planet, potentially revolutionizing how we generate and distribute clean energy.
The OHISAMA Project: A Leap Towards Orbital Energy Harvesting
Spearheaded by Japan Space Systems, the OHISAMA project involves launching a compact satellite weighing approximately 180 kilograms (400 pounds) into low Earth orbit at an altitude of 400 kilometers (250 miles).
Equipped with a 2-square-meter photovoltaic panel, the satellite will collect solar energy, store it in onboard batteries, and convert it into microwave energy for transmission to Earth. This demonstration is expected to transmit about 1 kilowatt of power—sufficient to run a small household appliance for an hour.
Koichi Ijichi, an adviser at Japan Space Systems, highlighted the project’s significance at the International Conference on Energy from Space in London, stating, “This mission marks a pivotal step towards realizing space-based solar power stations that could provide clean energy irrespective of weather conditions on Earth.”
Technical Challenges and Innovations
Microwave Transmission and Ground Reception
One of the project’s critical components is the precise transmission of microwave energy from the satellite to Earth.
Given the satellite’s rapid orbiting speed of approximately 28,000 km/h (17,400 mph), the ground-based receiving antennas must be strategically distributed over a 40-kilometer (25-mile) area, spaced 5 kilometers (3 miles) apart, to effectively capture the transmitted energy.
Safety and Environmental Considerations
Addressing public concerns about the safety of microwave energy transmission, researchers emphasize that the power density of the microwave beams will be comparable to that of sunlight, posing no harm to humans, animals, or aircraft.
Sanjay Vijendran, leader of the European Space Agency’s Solaris initiative, remarked, “You could walk under the beam and have more danger from sunburn from the sunlight than from the microwave beam itself.”
Japan’s Legacy and Future in Space-Based Solar Power
Japan has been at the forefront of space-based solar power (SBSP) research since the 1980s. In 2015, the Japan Aerospace Exploration Agency (JAXA) successfully transmitted 1.8 kilowatts of power over a distance of 55 meters using microwave technology.
Building on these achievements, the OHISAMA project represents a significant advancement towards practical applications of SBSP.
Looking ahead, Japan envisions deploying large-scale solar power satellites into geostationary orbit, each capable of generating up to 1 gigawatt of electricity—enough to power hundreds of thousands of homes. Such satellites would provide a continuous, weather-independent energy source, with potential applications in disaster relief and powering remote areas.
Global Perspectives and Collaborative Efforts
Japan’s endeavors in SBSP are part of a broader international interest in harnessing solar energy from space.
The European Space Agency’s Solaris program aims to explore the feasibility of SBSP, with plans to initiate a development program in 2025. Similarly, the United States and China are investing in research to overcome the technical challenges associated with space-based energy transmission.
These collaborative efforts underscore the global recognition of SBSP’s potential to provide a sustainable and reliable energy source, contributing significantly to the reduction of greenhouse gas emissions and the mitigation of climate change.
A New Era of Clean Energy
The OHISAMA project symbolizes a transformative approach to energy generation, leveraging space-based technologies to meet Earth’s growing energy demands sustainably. While challenges remain, the successful demonstration of microwave energy transmission from space could pave the way for a new era of clean, uninterrupted power supply, reinforcing Japan’s position as a leader in innovative energy solutions.
