
NASA has developed several concepts for a space-based solar power station. This one is called the Sun Tower and would involve an array of inflatable circular solar concentrators. Even before any energy is produced, it is estimated to cost at least $12 billion.

This wine glass-shaped solar power station known at NASA as SPS-ALPHA - short for Solar Power Satellite via Arbitrarily Large Phased Array - is a solar collector made of thin-film mirrors. The Earth-pointing side of the circular array has a microwave-power transmission panel that transmits the energy to Earth.

The logistics of building a solar power station in space are formidable and one solution would be to create 'space tugboats' to ferry payloads from low to higher orbits. In this artist's concept, an electrically powered space tug equipped with a solar disk is used to bring materials from low earth orbit to geosynchronous earth orbit.

NASA's Space Solar Power Exploratory Research and Technology program (SERT) came up with a sandwich concept where solar collectors work either side of a transmission unit. Part of these innovative concepts involve tens of thousands of small individual element working together and biomimetics - where technology mimics nature - has been a strong element in the research of space-based solar power.

Dr Paul Jaffe of the US Naval Research Laboratory holds a module he designed for space solar power in front of a customized vacuum chamber used to test it. He says that while space-based solar power is likely decades away, many countries, in particular Japan, are still pursuing research into the power source.


