Are space-based solar power stations feasible?

Recently, the UK government has provided £3 million in funding for the development of space-based solar power stations, but while this may sound like an interesting path to renewable energy, it is not without many challenges. What is a space-based power station, what has the government announced, and are space-based systems really worth it.

What is a space-based solar power station?

A space-based solar power station, as the name suggests, is a solar power plant located in space. The idea was first conceived by famous science fiction writer Isaac Asimov in 1941 as a method for utilising the vastness of space to draw power from a star and beam that energy to various planets. Instead of relying on large amounts of valuable land, a space-based system can be as large as it needs to be while also being exposed to constant sunlight whose energy is greater.

Not only is the amount of solar radiation in space greater than on the earth's surface, but a system could also potentially orbit the sun closer and transmit a concentrated beam to outer planets. This would reduce the size of the solar power station (as the energy density of solar radiation is greater) while also providing power to places where solar radiation is harder to extract.

While solar-based power plants are yet to be tested, solar panels have been widely used in space to power satellites and space stations. For example, the international space station is currently the largest orbiting body that generates all its power solely from solar panels. Despite being blocked by the earth's shadow for half of its orbit, the use of on-board batteries ensures that the station continues to operate 24/7 (fortunately for the ISS, the orbit time is 90 minutes meaning that the on-board batteries only need to operate for 45 minutes at a time).

UK government announces £3 million fund for space power station development

Recently, the UK government announced that it will provide £3m of grant funding for UK projects working on space-based power stations. The goal of the grant is to determine the technologies needed to develop such a system and see if space-based power can be utilised to help reduce human dependency on fossil fuels. 

Of all renewable technologies, solar panels are arguably one of the most ideal due to their high-energy density, low material use, and ability to directly generate electricity from sunlight. However, their inability to operate during the night and the need for constant sunshine makes them challenging to deploy economically. A space-based solar station, however, would be able to receive energy at all times, and the lack of size restrictions helps to account for losses during power transmission (i.e., a 30% efficiency loss can be easily made up with the addition of more solar panels).

Considering that the UK space industry is quickly growing (with an estimated 47,000 employees and 190,000 in supply chains), it is believed that the grant money will help to continue the development of space-based technologies. Additionally, the UK government is also looking to fund the Hyperspectral Microwave Sounder (HYMS), which will develop cutting-edge sensors for improved weather forecasting. The ability to provide better weather forecasting can greatly help shipping industries while providing better early warning alarms for flood prediction.

Are space-based power stations viable?

While it may be exciting that the UK government is funding the development of space-based power stations, the truth is that this funding will amount to little (if anything at all). The reason for this becomes highly apparent when considering the challenges a space-based power station faces and the current status of space flight technology.

To start, the first major challenge faced by a space-based solar power station is the massive inefficiency involved with transmitting power from space to earth. In an ideal world, a space-based power station would use a cable between the orbiting power station and an anchor point on earth, but no material currently known to man can withstand the forces involved (see space elevators). As such, wireless power transmission would be needed to beam the energy back down to earth.

Due to inefficiencies in receivers, the great distance between the power station and the receiver, and the natural divergence of the beam, it is likely that a significant proportion of energy is lost. Worse, the great distance between the transmitter and receiver will see a considerable amount of divergence that may require a receiver whose diameter is tens of kilometres.

The second major challenge of a space-based power station is the presence of space debris. Solar panels are notoriously sensitive to damage, and depending on how an array is wired, the damage of a single cell can knock out an entire panel. The growing presence of space debris continues to put existing satellites at risk, and considering that larger satellites are ten meters across, a power station with a cross-sectional area of hundreds of kilometres would likely face collisions on an hourly basis.

The third major challenge of such a project is its construction and eventual maintenance. Even though great strides have been made in reducing the price of sending cargo to space, it is still extraordinarily expensive, meaning that constructing a sizeable space-based power station would be economically unfeasible. To make matters worse, once the project has been completed, it requires maintenance which would be a continuing expense. Simply put, it would likely be cheaper to level a mountain and install solar panels than it would be to launch them into space.

The idea of solar-based power stations may sound like a cool idea for fighting climate change, but the numerous challenges faced make space-based power stations as feasible as the hyperloop. If solar power is to become more reliable, it is better to invest in energy storage solutions that can operate during periods of low-energy output.