US firm patents space solar systems

The race to become the first company to successfully harness solar power using orbiting satellites is hotting up, after Washington-based startup PowerSat announced last week that it has filed two patents that it hopes will bring space-based power generation closer to reality.

The company, which hopes to put solar arrays into space, filed a patent that would enable it to get solar arrays into an optimal orbit with minimal use of fuel. Once there, another patent protects technology that would enable multiple solar arrays to work together in unison, spreading the risk of failure and making the whole venture more commercially viable.

The announcement comes just two months after rival space solar technology startup Solaren Corp said it plans to begin generating power using its orbitting solar system from 2016 and has already signed a deal with US energy giant PG&E to provide the utility with 200MW of power over a 15-year period.

Advocates of space solar systems argue that solar arrays in space collect power more effectively than ground-based systems, due to the intensity of the sun's rays outside the atmosphere, and the absence of weather conditions.

However, they need to communicate power wirelessly down to earth, which requires them to be in a geo-stationary orbit. This orbit, which is around 22,000 miles up, enables a satellite to stay in a single position relative to the earth, making it easier to beam power to the ground. But the satellite also has to be much higher up than the low earth orbit occupied by other satellites, which only requires them to be between 300-1,000 miles up.

PowerSat's patent will enable the equipment to bridge that distance using solar-powered electronic thrusters, instead of chemically fuelled "space tugs". The technology reduces the weight of the equipment by 67 per cent, according to the company.

The other technology being patented, called BrightStar, enables multiple solar arrays to be used in unison. They can be used together to create a single transmission beam to transmit power to the ground. This eliminates the need for a single solar array to handle gigawatts of power, explains the company, while also reducing the risk of a single point of failure.

PowerSat hopes that the technology to harvest solar power from space will be deployable within 10 years. The two patents will reduce the cost of launching a space-based solar array by roughly $1bn, it added.