A rectenna for Palau? (was 'Drilling Up' Into Space for Energy)

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'Drilling Up' Into Space for Energy

By CHARLES J. HANLEY 1 day ago

BALI, Indonesia (AP) While great nations fretted over coal, oil and
global warming, one of the smallest at the U.N. climate conference was
looking toward the heavens for its energy.

The annual meeting's corridors can be a sounding board for unlikely
"solutions" to climate change from filling the skies with soot to
block the sun, to cultivating oceans of seaweed to absorb the
atmosphere's heat-trapping carbon dioxide.

Unlike other ideas, however, one this year had an influential backer,
the Pentagon, which is investigating whether space-based solar power
beaming energy down from satellites will provide "affordable, clean,
safe, reliable, sustainable and expandable energy for mankind."

Tommy Remengesau Jr. is interested, too. "We'd like to look at it,"
said the president of the tiny western Pacific nation of Palau.

The Defense Department this October quietly issued a 75-page study
conducted for its National Security Space Office concluding that space
power collection of energy by vast arrays of solar panels aboard
mammoth satellites offers a potential energy source for global U.S.
military operations.

It could be done with today's technology, experts say. But the
prohibitive cost of lifting thousands of tons of equipment into space
makes it uneconomical.

That's where Palau, a scattering of islands and 20,000 islanders,
comes in.

In September, American entrepreneur Kevin Reed proposed at the 58th
International Astronautical Congress in Hyderabad, India, that Palau's
uninhabited Helen Island would be an ideal spot for a small
demonstration project, a 260-foot-diameter "rectifying antenna," or
rectenna, to take in 1 megawatt of power transmitted earthward by a
satellite orbiting 300 miles above Earth.

That's enough electricity to power 1,000 homes, but on that empty
island the project would "be intended to show its safety for
everywhere else," Reed said in a telephone interview from California.

Reed said he expects his U.S.-Swiss-German consortium to begin
manufacturing the necessary ultralight solar panels within two years,
and to attract financial support from manufacturers wanting to show
how their technology launch vehicles, satellites, transmission
technology could make such a system work. He estimates project costs
at $800 million and completion as early as 2012.

At the U.N. climate conference here this month, a Reed partner
discussed the idea with the Palauans, who Reed said could benefit from
beamed-down energy if the project is expanded to populated areas.

"We are keen on alternative energy," Palau's Remengesau said. "And if
this is something that can benefit Palau, I'm sure we'd like to look
at it."

Space power has been explored since the 1960s by NASA and the Japanese
and European space agencies, based on the fundamental fact that solar
energy is eight times more powerful in outer space than it is after
passing through Earth's atmosphere.

The energy captured by space-based photovoltaic arrays would be
converted into microwaves for transmission to Earth, where it would be
transformed into direct-current electricity.

Low-orbiting satellites, as proposed for Palau, would pass over once
every 90 minutes or so, transmitting power to a rectenna for perhaps
five minutes, requiring long-term battery storage or immediate use
for example, in recharging electric automobiles via built-in rectennas.

Most studies have focused instead on geostationary satellites, those
whose orbit 22,300 miles above the Earth keeps them over a single
location, to which they would transmit a continuous flow of power.

The scale of that vision is enormous: One NASA study visualized solar-
panel arrays 3 by 6 miles in size, transmitting power to similarly
sized rectennas on Earth.

Each such mega-orbiter might produce 5 gigawatts of power, more than
twice the output of a Hoover Dam.
But how safe would those beams be?

Patrick Collins of Japan's Azabu University, who participated in
Japanese government studies of space power, said a lower-power beam,
because of its breadth, might be no more powerful than the energy
emanating from a microwave oven's door. The beams from giant
satellites would likely require precautionary no-go zones for aircraft
and people on the ground, he said.

Rising oil costs and fears of global warming will lead more people to
look seriously at space power, boosters believe.

"The climate change implications are pretty clear. You can get
basically unlimited carbon-free power from this," said Mark Hopkins,
senior vice president of the National Space Society in Washington.
"You just have to find a way to make it cost-effective."

Advocates say the U.S. and other governments must invest in developing
lower-cost space-launch vehicles. "It is imperative that this work for
`drilling up' vs. drilling down for energy security begins
immediately," concludes October's Pentagon report.

Some seem to hear the call. The European Space Agency has scheduled a
conference on space-based solar power for next Feb. 29. Space Island
Group, another entrepreneurial U.S. endeavor, reports "very positive"
discussions with a European utility and the Indian government about
buying future power from satellite systems.

To Robert N. Schock, an expert on future energy with the U.N.'s
Intergovernmental Panel on Climate Change, space power doesn't look
like science fiction.

The panel's 2007 reports didn't address space power's potential,
Schock explained, because his team's time horizon didn't extend beyond
2030. But, he said, "I wouldn't be surprised at the beginning of the
next century to see significant power utilized on Earth from space
and maybe sooner."