Space-Based Solar Power

a public discussion sponsored by the Space Frontier Foundation

About Space-Based Solar Power

Space-based solar power can be developed into a source of clean energy to augment power grids around the World, on the Moon, and anywhere else humans are likely to go.

Solar power already energizes our satellites and space stations in orbit around Earth. The trick is to collect enough solar energy on orbit, convert it into a form of power that can be broadcast safely to Earth, and to do so economically. We are not there yet.

Figuring out how to do this has been the subject of a number of studies over the past few decades. All of them concluded that space-based solar power as a source of safe, clean energy on the Earth is scientifically feasible, but not technologically or economically viable at the time of those studies, the last occurring in the late 1990s. However, the studies also find that space-based solar power is becoming more viable as time progresses because related technologies are making huge strides forward in many cases.

In 2007 we arrived at a general and growing consensus among most of humanity that the global demand for energy will soon exceed our ability to produce it. Complicating matters is environmental contamination brought about by the consumption of our traditional carbon-based fuels. Many believe our consumption of these fuels has irreparably damaged the environment though global warming.

If the technical hurdles associated with space-based solar power can be overcome, it will provide a clean alternative to carbon-based fuels. We do NOT want it to become the one-and-only energy source. We think prudent energy policy should dictate that numerous clean energy sources be developed and should be coupled with appropriate conservation efforts.

There are three basic reasons why going to space is preferred to ground-based solar power. First, the sun is many times more intense on orbit than on the surface of the Earth. This means there is more energy to be collected. Second, unlike ground-based solar power systems which spend roughly half of their time in the darkness of night, space-based systems can be perpetually bathed in sunlight. This is an instant doubling of efficiency. Finally, ground-based systems suffer from weather phenomena such as clouds, precipitation, and dust. These are not worries in space.

Space-based solar power also has three major drawbacks. First, despite fifty years of spacefaring experience, getting to space is still hard and expensive. It costs thousands of dollars per pound to lift anything into space from Earth. Second, we have no experience assembling and sustaining objects on orbit of the scale that space-based solar power will require. Some designs suggest systems that are literally several square kilometers in size. Finally, although the efficiencies of collecting power on orbit are many times greater than what can be done on the surface of the Earth, there are significant power losses in converting raw solar energy into electricity to feed a broadcast system on orbit, during transmission to Earth receivers, and from the receiver into terrestrial power grids. Some calculations suggest space solar power can deliver only ten percent of the original collected power.

To make space-based solar power viable, the benefits have to outweigh the costs at a rate that ultimately makes it profitable for a commercial venture to take on such an enterprise.

A word about semantics. We started the study using the term space-based solar power with the acronym SBSP. You will see it throughout this website that way. More commonly it is known as space solar power (SSP). Why did we do that? (You’re going to laugh…) When the we started researching space solar power, the acronym “SSP” triggered some anti-virus reaction inside our email system inside the Pentagon and trashed the email and attachments. The Green Hornet, Lips, the Evil Dr Mankins, and I had a terrible time communicating as a result. So, I changed it to space-based solar power (SBSP) as a result. Sorry for any confusion it may have caused, but it does make for a good story.

 
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