The concept is at least as old as Nikola Tesla, the turn-of-the-20th-century icon who used to demonstrate the wonders of electricity by letting it course through his body as crowds gawked in wonder.
Tesla was so fascinated with electricity and wireless frequencies that he spent the early 1900s constructing the Wardenclyffe Tower on land near Long Island Sound, partly to demonstrate that he could beam energy from one point to another without any wires.
But, alas, Tesla experienced a horror that many technology pioneers of today understand all too well: His investors pulled out before he could finish the project.
Since then, however, scientists have shown that one can generate power, convert it to lasers or microwaves, beam it to another point and reconvert it into electricity. Such a system could beam power to hard-to-reach rural areas without running expensive power lines – or could even beam it down to Earth from power stations in space.
But while proponents argue that wireless power beams could solve the world's energy problems, skeptics aren't so sure. In addition, the concept hasn't proven itself as a practical energy alternative: at least not yet.
"The power beam thing comes and goes," said Leonard David, a space expert who helped gather research on beaming microwave power from solar-powered satellites for the U.S. Department of Energy in the mid-'70s and now writes for Space.com. "The whole concept was a dream-machine solar collection array that would collect energy in outer space. The physics of it look intriguing, but these things have been waylaid."
The government also got distracted with other potential applications. "Before long, somebody said, 'Hey wait. We can make this into a weapon,'" he said.
Indeed, the U.S. military is developing a new class of potentially non-lethal "directed-energy weapons" that could create a Star Trek-esque world of warfare. Set the phaser to stun or kill, depending on the situation.
Defense contractor Raytheon actually delivered an energy-weapon prototype to the Pentagon earlier this year, and some believe such weapons could see combat in Iraq and Afghanistan by late 2006.
Meanwhile, the idea of wireless energy transmission continues to evoke on-and-off interest from governments around the world.
One long-sought application is aviation. In 1987, Canada successfully flew its Stationary High Altitude Relay Platform aircraft using power generated from a microwave beam on the ground. In 1992, Japan successfully flew its own version of a microwave-powered plane as part of a project known as MILAX.
And in October 2003, NASA actually used a ground-based laser beam to power the flight of a tiny 11-ounce aircraft made of balsa wood and carbon fiber tubing, and covered in Mylar film.
Others have imagined terrestrial networks of power-beaming stations that could fuel electric cars and other vehicles, which would essentially "top off" every time they passed by a station. Some could power up vehicles at stoplights.
These are still just concepts, but proponents hope that at least in the United States, the post-Sept. 11 desire to wean the country from foreign sources of energy could renew interest in alternative concepts, including wireless power.
Even the boldest concepts are getting a hearing at the highest levels.
In November 2003, David Criswell, director of the Institute for Space Systems Operations at the University of Houston, testified before the Senate Commerce Committee's subcommittee on science, technology and space to pitch a Lunar Solar Power system. LSP would use colossal solar arrays on the surface of the moon that would beam microwave energy down to Earth.
Criswell's concept is massive in scale: It would involve building 20,000 to 30,000 reception stations on Earth to accept the power beams and convert them into electricity that could be distributed to the population (The solar panels would be constructed on the moon with raw materials in the soil in "basically a glass-making process," he said).
Meanwhile, a series of moon bases housing up to 5,000 human beings (but possibly only a few hundred because of recent advances in automation and robotics) would be required on the lunar surface. "I hope they're Americans," Criswell told Wired News. "We'd be extending ourselves off of the Earth permanently."
Criswell predicts that the LSP system could produce a steady 20-terawatt stream that he predicts the estimated 10 billion people living on Earth by 2050 will need. "It actually provides you with such clean, sustainable energy that we can correct our past errors," he said.
Of course, Criswell's enthusiasm isn't shared by everyone. One problem is the price tag: Criswell said the project would cost at least $500 billion before it started to break even, after which it would start paying for itself and increasing global wealth exponentially. Still, it's a hefty bill for an untested concept.
And then there's the issue of sending thousands of microwave-energy beams down to Earth. The prospect of bathing the planet in radiation hardly sounds appealing. "I walked away from the (Department of Energy) project a little bit worried," said Space.com's David. "You start adding up all the microwave-generating sources bombarding people, and you start to say, 'Wait a minute. What's an acceptable level'"?
Criswell dismisses such concerns, arguing that the microwaves could be directed at human-free zones around power stations and made so weak that radiation exposure would amount to standing in the sunlight or talking on a cell phone.
Other concepts revolve around using satellites in Earth orbit rather than a lunar solar array.
One idea involves dangling a tether from a satellite into the Earth's atmosphere, which naturally emanates energy, and then feeding that power back up to the satellite, which would beam microwaves or lasers down the Earth for conversion into electricity. Others advocate vast solar panels in Earth orbit that would collect energy from the sun and beam it back down the same way.
The major downside is the cost. "This is not cheap technology," said Craig Mathias, a principal at advisory firm Farpoint Group. "The problem is the expense of launching the satellites. You're looking at the equivalent of paying hundreds of dollars per gallon of oil. You'd have to put up acres of solar cells – so many that it would literally darken the day."
NASA, for its part, has in fact been trying to find a cheaper way to get materials into space, even toying with a "space elevator" concept in which a tether would dangle down to Earth from a geostationary satellite, and climbing robots would carry materials up and down the structure.
The problem is that they would need to travel thousands of miles to reach high Earth orbit, and that's where wireless power comes in.
"Space elevators need power beaming," said Brant Sponberg, manager of NASA's Centennial Challenges project. "They can't carry an extension cord all the way down to the ground."
As a result, NASA has created the 2005 "Beam Power Challenge" to award $50,000 to the team whose climbing bot can lift the most mass in three minutes by most efficiently converting beam power into electricity. Second and third place will receive $20,000 and $10,000, respectively.
At this year’s Oct. 21 competition, all teams will receive power from the same photonic source: a 10-kilowatt Xenon searchlight. But next year’s competition will allow each team to also build their own beam-power device, which could use photons, lasers or microwaves. Sponberg said the purse for the 2006 competition will be $150,000 ($100,000, $40,000 and $10,000 to the three best teams).
But Sponberg also pointed out that "NASA has no plans to build a space elevator in the near future," which means that such power-beaming innovations may not be applied for years, if ever.
