Baited Switch

The New York Pravda, today.

As we face $4.50 a gallon gas, we also know that alternative energy sources — coal, oil shale, ethanol, wind and ground-based solar — are either of limited potential, very expensive, require huge energy storage systems or harm the environment. There is, however, one potential future energy source that is environmentally friendly, has essentially unlimited potential and can be cost competitive with any renewable source: space solar power.



Science fiction? Actually, no — the technology already exists. A space solar power system would involve building large solar energy collectors in orbit around the Earth. These panels would collect far more energy than land-based units, which are hampered by weather, low angles of the sun in northern climes and, of course, the darkness of night.

Once collected, the solar energy would be safely beamed to Earth via wireless radio transmission, where it would be received by antennas near cities and other places where large amounts of power are used. The received energy would then be converted to electric power for distribution over the existing grid. Government scientists have projected that the cost of electric power generation from such a system could be as low as 8 to 10 cents per kilowatt-hour, which is within the range of what consumers pay now...

...Much of the progress has come in the private sector. Companies like Space Exploration Technologies and Orbital Sciences, working in conjunction with NASA’s public-private Commercial Orbital Transportation Services initiative, have been developing the capacity for very low cost launchings to the International Space Station. This same technology could be adapted to sending up a solar power satellite system...

[O. Glenn Smith is a former manager of science and applications experiments for the International Space Station at NASA’s Johnson Space Center.]

There's nothing likely a smiley sunshiny face to grab me. Somewhere.

But hey, what could be wrong with this idea? Other than that it's been impossible to broadcast power using radio waves.

Until recently. The principle is outlined for the financier's mindset by CNN:

...Broadcasting power through the air isn't a new idea. Researchers have experimented with capturing the radiation in radio frequency at high power but had difficulty capturing it at consumer-friendly low power. "You'd have energy bouncing off the walls and arriving in a wide range of voltages," says Zoya Popovic, an electrical engineering professor at the University of Colorado who works on wireless electricity projects for the U.S. military.

That's where Shearer came in. A former physicist based in Pittsburgh, he and his team spent four years poring over wireless electricity research in a lab hidden behind his family's coffee house. He figured much of the energy bouncing off walls could be captured. All you had to do was build a receiver that could act like a radio tuned to many frequencies at once.

"I realized we wanted to grab that static and harness it," Shearer says. "It's all energy..."

So the Powercast team set about creating and patenting that receiver. Its tiny but hyperefficient receiving circuits can adjust to variations in load and field strength while maintaining a constant DC voltage. Thanks to the fact that it transmits only safe low wattages, the Powercast system quickly won FCC approval--and $10 million from private investors.

Powercast says it has signed nondisclosure agreements to develop products with more than 100 companies, including major manufacturers of cell phones, MP3 players, automotive parts, temperature sensors, hearing aids, and medical implants.

The last of those alone could be a multibillion-dollar market: Pacemakers, defibrillators, and the like require surgery to replace dead batteries. But with a built-in Powercast receiver, those batteries could last a lifetime.

"Everyone's looking to cut that last cord," says Alex Slawsby, a consultant at Innosight who specializes in disruptive innovation. "Think of the billion cell phones sold last year. If you could get Powercast into a small percentage of the high-end models, those would be huge numbers."

Could Powercast's technology also work for larger devices? Perhaps, but not quite yet. Laptop computers, for example, use more than 10 times the wattage of Powercast transmissions.

But industry trends are on Shearer's side: Thanks to less energy-hungry LCD screens and processors, PC power consumption is slowly diminishing. Within five years, Shearer says, laptops will be down to single-digit wattage--making his revenue potential even more electrifying.

This doesn't seem anything on the order of what the ex-NASA writer's talking about. What might? Wikipedia has a recent entry that discusses the alternatives:

...Power beaming by microwaves has the difficulty that for most space applications the required aperture sizes are very large. For example, the 1978 NASA Study of solar power satellites required a 1-km diameter transmitting antenna, and a 10 km diameter receiving rectenna, for a microwave beam at 2.45 GHz. These sizes can be somewhat decreased by using shorter wavelengths, although short wavelengths may have difficulties with atmospheric absorption and beam blockage by rain or water droplets. Because of the Thinned array curse, it is not possible to make a narrower beam by combining the beams of several smaller satellites.

For earthbound applications a large area 10 km diameter receiving array allows large total power levels to be used while operating at the low power density suggested for human electromagnetic exposure safety. A human safe power density of 1 mW/cm² distributed across a 10 km diameter area corresponds to 750 megawatts total power level. This is the power level found in many modern electric power plants.

High power

Wireless Power Transmission (using microwaves) is well proven. Experiments in the tens of kilowatts have been performed at Goldstone in California in 1975 and more recently (1997) at Grand Bassin on Reunion Island.

These methods achieve distances on the order of a kilometer.

Low power

A new company, Powercast introduced wireless power transfer technology using RF energy at the 2007 Consumer Electronics Show, winning best Emerging Technology.[22] The Powercast system is applicable for a number of devices with low power requirements. This could include LEDs, computer peripherals, wireless sensors, and medical implants. Currently, it achieves a maximum output of 6 volts for a little over one meter. It is expected for arrival late 2007.[23]

A different low-power wireless power technology has been proposed by Landis.

Laser

In the case of light, power can be transmitted by converting electricity into a laser beam that is then fired at a solar cell receiver. This is generally known as "powerbeaming". Its drawbacks are:

1. Conversion to light, such as with a laser, is moderately inefficient (although quantum cascade lasers improve this)
2. Conversion back into electricity is moderately inefficient, with photovoltaic cells achieving 40%-50% efficiency. (Note that conversion efficiency is rather higher with monochromatic light than with insolation of solar panels).
3. Atmospheric absorption causes losses.
4. As with microwave beaming, this method requires a direct line of sight with the target.

NASA has demonstrated flight of a lightweight model plane powered by a laser beam...

This raises an interesting possibility.



What better way to hide a Star Wars- or Akira style- weapons platform capable of vaporizing any enemy anywhere than as a series of orbiting "power stations" whose high intensity lasers normally beamed power across the globe?