Scientists at the Japan Aerospace Exploration Agency (JAXA) have a plan underway for a 1-gigawatt space-based solar power generator within just 25 years. JAXA is working directly on the main problems.
Orbital solar power’s main problem is once the energy is harvested all the huge reservoir of energy is still out there in space. Early in the orbital energy history lasers were thought to be the best solution because of the ease in aiming to a ground receiver. But lasers have become a research dead-end because of “bloom” effect when light traveling through the atmosphere where the air diffuses the light causes the laser beam to lose focus.
Microwaves however look like the solution now. Even with the rational public fear of getting “cooked” as with a microwave oven, research shows that even multiple generations of microwave-blasted animals show zero negative health effects. Its a worthy fear until the kinds and power of microwaves are compared.
We had a look at an experiment on this site five years ago when a pioneering team out in Hawaii transmitted 20 watts of power between the island of Maui and the island of Hawaii, more than 150 kilometers (93 miles) away. Though only about a microwatt was collected at the receiver, the study was seen as a major success.
The JAXA team notes that an orbital transmission projector would only need to transmit its power through roughly 2 kilometers of near sea level dense air, not 150 kilometers, thus making the case for the concept to be feasible for space to earth transmissions.
The draw to orbital solar power over ground solar is the raw dimensions, no atmosphere to diffuse out the energy and the lack of intermittency from night, weather, and storage costs. On a per collection area orbital solar could have a 43 to 1 advantage on to the deliverable power.
With that advantage in mind the JAXA main design proposal incorporates two enormous mirrors, articulated to dynamically bounce sunlight onto the solar panels 24 hours per day. The design allows optimistic estimates to suggest that a well-designed space array could harvest than 40 times the energy of a ground based array.
The real world problems though aren’t going to be the solar power harvesting or energy transmission to earth. It will be lifting the mass of equipment to orbit and *money*.
For now JAXA is offering a mass to lift estimate of 10,000 metric tons. A loaded semi truck rig at about 35 tons would equate to almost 300 truck sized rocket launches. At hundreds of millions of dollars each for now, the *money* issue is quite real.
That’s not to say the Elon Musk or Richard Branson kinds of folks won’t break though the cost barrier. Its also a very good perspective that technology improvements will continue on solar cells and likely the lift weights will come down.
After all, the Japanese have the innate and huge East Asian advantage of taking the very long view. As noted, the project is already looking 25 years ahead, working at the problems that are understood now.
There are also the side effects and new technologies thrown out into the market place much as NASA and America’s moon landing effort showered and in many ways seeded the technological progress seen and driving a growing world economy over the past 50 years.
The International Academy of Astronautics (IAA) recently published a huge study supporting space solar power. Much to Japan’s credit and the embarrassment of the other technology based economies, the study names JAXA as the most likely source of early space-based power projects.
Go JAXA GO! And may the others around the world who are interested, get in there and compete!