By Meagan Clark - The world’s largest oil consumer, the Pentagon, is looking to space to harvest energy.
The U.S. Naval Research Laboratory (NRL) is building solar panels to launch into space and beam down energy to power military operations, especially in remote areas where running diesel generators and driving fuel over hostile areas is dangerous and expensive.
Robots would assemble the solar panels into a kilometer-long reflecting mass. That’s the length of nine American football fields. The International Space Station is the only satellite that comes close to that size, only a little longer than one football field.
"Hard to tell if it's nuts until you've actually tried,” Paul Jaffe, a spacecraft engineer at NRL, said in a statement.
The NRL has tested two prototypes of what it calls a “sandwich” module, made up of a photovoltaic panel on top that absorbs the sun’s radiation, an electronics system in the middle that converts the energy to a radio frequency and an antenna on bottom that shoots the radio waves toward a target on the earth’s surface. NRL’s Space Robotics Group is working on building robots capable of assembling many of the sandwich modules into one powerful satellite.
The second type of module modifies the sandwich design by opening up the panels, allowing more sun absorption without overheating.
Space solar would produce more energy than on-the-ground solar because it can soak up sunlight 24 hours a day, free from changing weather conditions. Ideally, a solar power satellite would provide power at about 10 cents per kilowatt hour, a competitive local price in many places.
Many companies are also interested in space solar, including California utility company Pacific Gas & Electric, which has a contract with Solaren to buy space solar power by 2016. The Shimizu Corporation in Japan announced plans in February to build a solar strip across 11,000 miles on the moon. That project, if completed, would transfer energy through microwaves and laser light to earth several decades from now.
The idea of space solar power has circulated since the 1970s, after a American scientist powered a helicopter by beaming microwaves from space. The International Academy of Astronautics recently concluded in a report that space solar power technology would be viable within the next 30 years.