For over a century, the concept of space-based solar power has fascinated scientists and engineers. 

By launching enormous solar panel arrays into orbit and transmitting their electricity back to Earth, the concept promises a continuous power supply, in contrast to intermittent renewable energy sources on land. 

Recent technological advancements and decreasing space launch costs have made this concept more reliable than ever before. Teams worldwide are developing essential components for space-based solar power systems, and this month, orbital tests utilising a prototype developed by Caltech researchers are expected to begin.

Historiographically, the concept of space-based solar power can be traced back to the 1968 publication of a concept paper by Peter Glaser. Since then, researchers and space agencies have investigated the concept’s viability and potential benefits.

Comparable to nuclear power economically, space-based solar power could provide a competitive alternative to conventional energy sources.

To be practicable, scientists propose erecting solar panel arrays that would orbit the Earth at a distance of approximately 36,000 kilometres. These arrays would convert the energy they collect into microwaves and transmit it to surface-based receivers with even larger footprints.

China intends to launch a megawatt-scale demonstration unit into low-Earth orbit in 2028, followed by the deployment of a second system into geosynchronous orbit in 2030. Carpenter suggests that, with sufficient funding, the first multi-gigawatt solar power plant could be operational by 2040.  However, substantial technical obstacles must be surmounted.

This article investigates the five major obstacles to space-based solar power, as well as their potential applications, environmental impacts, and policy implications.

Space construction of a solar farm

To generate one gigawatt of power, comparable to a terrestrial power facility, the circling arrays would have to be larger than one square kilometre. This structure is one hundred times larger than the ten-year-old International Space Station. Diverse designs, including the helical structure proposed by the ESA’s Solaris initiative and the crown-shaped solar collector by Xidian University in Xi’an, China, investigate the use of remote assembly by robotics in orbit.

Launching and assembling components once per week at the required rate poses logistical challenges. The experiment at Caltech intends to unfold a tightly folded structure into a solar panel platform roughly the size of a dinner table, thereby avoiding the difficulty of flying flexible panels in formation.

Selecting appropriate photovoltaic cells

Solar cells must be lightweight, functional, and resistant to space’s severe radiation. Most designs employ concentrators, mirrors, and other devices to increase the exposure of solar cells to light. The Caltech prototype will evaluate the orbital durability of 32 lightweight solar cells, including inexpensive perovskites.

Transmission of solar energy to the planet

The greatest obstacle is the transmission of energy from space to Earth. While laser beams can efficiently transmit energy, clouds can impede them. Researchers are working to convert solar-generated electricity into microwaves that can travel through the atmosphere with minimal energy loss. Engineers must synchronise the emission of electromagnetic waves and deploy kilometres-wide receiving stations to collect them.

Enhancements in energy conversion technologies are required to minimise energy transmission losses. According to the ESA, for a system to be profitable, only 10–15% of the solar energy falling on a spaced array must be transmitted to the electrical infrastructure.

Consequences for the Environment and international relations

Space-based solar power presents both environmental benefits, such as reduced greenhouse gas emissions, and prospective concerns, such as the impact of space debris and microwave transmissions on the atmosphere. To address these issues and ensure the safe and sustainable development of space-based solar energy, exhaustive environmental assessments and international cooperation will be required.

Applications Beyond Earth and Impacts on energy policy

Space-based solar power could also be used to power bases on the moon or Mars, allowing for further exploration and possible colonisation of other celestial bodies. In addition, the technology could influence future energy policies, promoting a transition towards cleaner energy sources and influencing the dynamics of the global energy market.

In conclusion, while space-based solar power bears great promise as a renewable and continuous source of energy, significant technical, logistical, and environmental challenges must be overcome. 

With global teams working on various aspects of this technology and demonstrations planned for the coming years, space-based solar power may soon become a reality, revolutionising how we generate and consume energy on Earth and beyond.