iPhone 2.0: Solar-Powered Mobility

How many solar watches would it take to power an iPhone?

Solar energy is far from a new idea, but Apple (nasdaq: AAPL - news - people ) may be taking the technology to new limits. Many questions have been raised about the possibility–or probability–of Apple using solar energy to power portable devices such as its popular iPhones. It recently became known that employees at the computer, phone and software company have filed a patent to place solar cells on portable devices. (See " Apple’s Solar Strategy")

It’s not a new technology. Rudimentary findings of the potential to harness the sun’s powerful rays for conversion into electricity were first reported in the mid-1800s. The “photovoltaic effect” was discovered by then 19-year-old French physicist Edmund Becquerel in 1839.

Pocket calculators and wristwatches that operate on solar energy have been on the market for many years and are widely used. In 1957, two Pennsylvania engineers marketed a solar powered radio that was smaller than today’s iPod. The technology has come a long way since then and Apple may be the next to capitalize on it.

The biggest difference between those technologies and the patent for which Apple filed is the amount of power consumed by the product, said Michael Filler, a Caltech postdoctoral scholar specializing in photovoltaics.

iPhones are remarkably advanced devices that are small but consume considerable amounts of power. According to Filler’s calculations, it would take 250,000 to 1 million solar-powered wrist watches to generate the energy needed to power one iPhone (and keep the watches ticking). In other words, “the rate of energy consumption of the iPhone is about 250,000 to 1 million times larger than a standard sports wrist watch.” Filler’s calculation is for power consumption rates when both are being used, and take into account that the watch is used 24/7 while the iPhone is used for periods of time and then stored.

Concerns exist over the application of solar energy in portable devices such as cell phones, which are typically stored in pockets or purses and therefore are not constantly exposed to light. Also, while silicon solar cells do not need direct sunlight to work, they will collect a lot less energy indoors or on a cloudy day. Still, Filler said that a solar-powered iPhone “seems reasonable enough.”

The most efficient solar cells on the market convert the sun’s energy into electricity at about 20% efficiency, Filler said. In an optimal use environment, say on a cloudless sunny day in the desert outside Las Vegas, an iPhone equipped with Apple’s potential new technology could generate around 1 watt of energy, Filler explained. “It’s not going to be able to power the entire device but could extend battery life.” Almost anything solar-powered would still need to have a battery to store the captured energy.

Filler also pointed out that there are solar cells that operate at closer to 40% efficiency rates, but they are so expensive that they are mainly used by NASA for spacecraft, satellites and other space-related applications.

According to Apple’s pending patent, devices would integrate the solar cells underneath the liquid crystal display, or LCD, screens. Sandwiching the solar cells inside the device would block some light out and knock down power conversion efficiency even further, Filler cautioned. The light-emitting diode, or LED, of devices like the iPhone are designed to reflect light outwards toward the user. Theoretically, Filler said, if some fraction of the LED were projected backwards into the system, embedded solar cells could capture some of that light as well.

Perhaps the most obvious obstacle Apple may face will be the potential limitation for a gadget meant to be so small to have a large enough surface area on which to embed the solar cells. “Apple has done such a superb job packing so much function into such a small package, that not much area is available to harvest sunlight, even if you were standing in the middle of the desert somewhere in Nevada,” Filler said.

Scott Bourne, executive producer of the Apple iPhone Show on iTunes said he would not expect to see the implementation of a product of this kind for at least five years, but said that it is exciting to consider that it could happen. “Cell phone battery power is always an issue for users who inevitably want longer-lasting power than they have,” he said.

An Apple spokesperson would not comment on anything beyond what was written in the patent.

Apple devotees will just have to wait and wonder. Or buy the company's anti-gravitational stock: Shares of Apple traded up $5.18, or 2.9%, to close at $186.35 in trading Tuesday.

Filler added that those in the photovoltaic field hope to see solar conversional devices in everything we own, including roof shingles, sign posts, clothing, etc. “We want to see solar go beyond major power generation. The iPhone is one example.”

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Wisconsin governor signs Great Lakes compact

(AP) -- Gov. Jim Doyle has signed legislation making Wisconsin the fifth state to approve an interstate compact aimed at protecting the Great Lakes.

"This historic accord means that we will be managing our Great Lakes water in a sustainable way that will protect one of the world's greatest natural resources," Doyle said during a windy ceremony Tuesday on the Lake Michigan shoreline.

The compact would ban most diversions of water from the lakes' basin. Cities that straddle the basin's border or lie within counties that straddle the border could apply for an exemption. But any Great Lakes governor could block an exemption as well as withdrawals from outside the basin.

The eight Great Lakes governors signed the compact in 2005 after four years of negotiations, but it must be approved by each of the states and ratified by Congress before it can become law.

Wisconsin, Illinois, Indiana, Minnesota and New York, have now approved the measure, as have the Canadian provinces of Quebec and Ontario. Michigan, Ohio and Pennsylvania have yet to do so.

The pact was motivated largely by fears that states such as Arizona and Nevada in the booming but arid Southwest will try tapping into the lakes, which hold 90 percent of the nation's fresh surface water.

"People are already looking enviously at this water," Doyle said. "The Great Lakes define this region, and their waters sustain our recreation, our way of life, and our economy."

The lakes generate $55 billion a year in tourism for the region and provide more than 11,000 jobs in Wisconsin's ports, Doyle said.

© 2008 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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PayPal Founder Predicts: Solar Will Kick Coal's Ass

Elon Musk, the founder of PayPal and chairman of electric car company Tesla, recently said that he believed most of the world's power would come from solar by 2040. That seems remarkably optimistic to me.

At the Future in Review Conference, Musk said that in 30 years, solar thermal and solar photovoltaic power will, combined, produce more electricity than any other source. That title is currently held (and held firmly) by coal. Displacing the coal industry with renewables would require massive capital investments and innovations, particularly in power storage.

I have to say, my mind doesn't have to stretch too far to see how it would be possible. But a few things need to happen first. Solar needs to get cheaper, and photovoltaics have to stop relying on raw materials (indium / monosilicon) that are difficult to acquire. And then we need to figure out how to store the power so we can use it at night. This could be through a combination of utility-scale power storage and distributed power storage through home fuel-cell and hydrogen creation systems.

Musk, as the chairman of Solar City, a company that installs panels on houses, sometimes with no down payment at all, obviously believe in the distributed power model. The goal of Solar City is to have people pay, not for the $30,000 panels on their roof, but for the 30 years of electricity those panels will generate. Already Solar City is projecting $80 M in revenue for this year.

The final piece of the puzzle in getting to solar supremacy came out in Musk's speech as well. Very simply, "There should be a carbon tax."

It's unclear that, without one, whether solar will ever be able to do any more than nip at the heels of big daddy coal.

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