The United States would be foolish to pursue development of space-based solar power (SBSP). Peter Garretson argues for a significant investment in SBSP in his article “Solar Power in Space?” However, his arguments are ill-considered. The costs of SBSP are enormous, requiring tens of thousands of space launches to establish reasonable capacity. The SBSP concept entails a large, risky, long-term investment in a power source that could be obsolete when deployed. The sequencing is illogical, as development of space-based manufacturing is a necessary precursor to any economically viable, large-scale industrial deployment in space. And the policy justification is insufficient as there is no overriding national security context requiring a national investment on the scale of the Apollo Mission or Manhattan Project.
SBSP would place a constellation of very large satellites into geosynchronous orbit where they would convert solar energy into microwaves that would be beamed back to airport-sized collecting stations on Earth. The potential benefits are appealing. Earth-based solar power must contend with night and weather while space based solar systems would receive sunlight 99% of the time. Once fully deployed, SPSB could provide nearly-unlimited, environmentally-friendly energy to any receiving point on Earth. That’s the optimist’s shiny vision.
Beneath the glitter, SBSP has major issues. The costs of such a system are enormous. Each satellite would be kilometers long, weigh thousands of metric tons and require hundreds of launches to deploy its parts. Launch prices — currently ~$1200/kg at the low end — would need to decline to under $350/kg for even a reasonable R&D program. Even the most optimistic economic viability models require SBSP to service nearly 100% of Earth’s power needs. Garretson also ignores the fact that the technologies for assembling and maintaining a SBSP system — likely autonomous robots — do not yet exist. The financial costs are in the hundreds of billions of dollars, if not trillions, for a full system.
I believe the risk-reward balance is not favorable to make such an investment in SBSP. As I noted in my article “Peak Stuff” the combination of cheaper renewable energy and new sources of non-renewables means that we’ve probably hit peak oil demand. Clean energy investments already outnumber non-renewables 2:1. The costs for renewables will only fall further. Additionally, even SBSP optimists claim a deployable system is decades away. Why bet on a high-risk, high-cost potential energy source when we have emerging cheap, clean energy now? And better energy sources, like fusion or hydrogen power, might emerge in the near future,. SBSP is a very risky bet.
Garretson also ignores a key element in the SBSP logic chain: large space systems should not be launched from Earth, but should be manufactured in space. The cost to escape Earth’s gravity is large. You can launch six times as much mass from the Moon as from the Earth using the same amount of fuel. The cost to deploy manufactured goods from captured asteroids would be even lower. As Justin Lewis-Webster argues in his article “Lunar Based Self-Replicating Solar Factory,” there are significant cost benefits to manufacturing SBSP systems on the Moon. Granted, the technology for space resource extraction and space-based manufacturing do not exist yet either. But since they are enabling technologies for multiple technologies and programs, including any sustained human presence in space, we should focus the expenditure of national treasure on space-based manufacturing. That investment will enable permanent human settlements in space and will allow a far cheaper deployment of SBSP in the future, if we so choose.
Garretson also trots out the tired argument that we need to commit to an Apollo or Manhattan-like program to spur a massive expansion in space capabilities, maintain competitiveness internationally and (for lack of a better description) make America great again. As I noted in my article “Presidential Space Leadership Depends on the Enabling Context,” the Apollo program arose because of overriding U.S. national security interests in beating the Soviet Union to the Moon. Similarly, the huge investment in the Manhattan Project was driven by the need for a weapon to end World War II. There is no such overriding national security need driving the U.S. to develop SBSP. Conversely, China and Japan are investing in SBSP because of their vulnerabilities, not their strengths. Both countries have poor domestic energy supplies and must seek alternative energy sources, even expensive and risky options like SBSP.
While the U.S. could dedicate modest resources to researching the potential for SBSP, our money is better spent on the real gold: deploying technologies like space-based manufacturing that enable a wide range of human and industrial activities in space.
All of the opinions expressed are personal and do not necessarily represent the positions of the U.S. Department of State or the U.S. government.