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Solar - Aug 3

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Let the Sun Shine In

Greg Blonder, Business Week
Too much energy is wasted by converting it. We could cut energy use by as much as 30% in 10 years by removing some links from the energy chain
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Sometimes the best solutions to the energy crisis are the simplest, and often they're right in front of our eyes. Consider the use of solar power to light a home. Even the most advanced photovoltaic solar panels convert just 20% of the available sunlight to electricity. The resulting direct current (DC) then must undergo conversion to alternating current (AC), losing another 20%. If that AC goes on to light an incandescent bulb, which is only 5% efficient, you end up using a fraction of 1% of the original sunlight as room light. (Even switching to compact florescent bulbs, which are 15% efficient, makes little difference in overall energy efficiency.) But if you were to simply leave sunlight as light-via proper skylights, window orientation, and louvers-nearly 80% of the light ends up as illumination.

Or take the multiple conversions required to produce alternative biofuels. The efficiency of converting sunlight into plants such as corn and switch grass and then into ethanol or biodiesel is one-tenth of 1%, or less. Algae looks like it will perform slightly better, but at these rates, why bother? The best way to convert plants to energy, frankly, is to eat them.

The more links we put in the energy conversion chain, the greater the losses and the more improbable and inappropriate the solution. We need, wherever possible, to keep light as light and heat as heat and food as food. And as much as we enjoy endlessly debating which approach to take, the best solutions may very well be those closest to home.

Fortunately, a number of such straightforward solutions are emerging.

Greg Blonder is a partner at Morgenthaler Ventures and is based in Princeton, N.J. Morgenthaler has investments in both RFID and sensor companies.
(31 July 2007)


Under the sun

Scott Carlson, Baltimore Sun
In the heat of summer, a solar oven saves energy as it cooks food to fill your stomach
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A thought occurs to me now and then, when I turn on a burner and watch a ring of blue flame bloom underneath a pot: If I didn't have easy access to gas, electricity or even firewood, how would I feed myself?

There are millions of people around the world who have difficulty getting their hands on cooking fuels like wood or coal, let alone natural gas.

But a growing number of people are cooking with an abundant, clean power source: nuclear fusion - or, in other words, the sun. This summer, I became one of them. Using some scrap materials and plans I found online, I built a solar oven whose temperature gets up to 240 degrees. It bakes potatoes, roasts vegetables and slow-cooks meat - all while sitting on my front lawn on a sunny day.

Solar cooking is enjoying attention that it hasn't seen since the energy crisis and environmental awareness of the 1970s.
(1 August 2007)


Thin Film's Time in the Sun

Peter Fairley, Technology Review (MIT)
First Solar's thin-film technology is now challenging silicon panels at large-scale solar-power facilities.
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The low manufacturing cost of photovoltaics that employ thin films of cadmium-telluride semiconductor have long been seen as having the potential for lifting solar power from its niche status as a very expensive power source, delivering less than a twentieth of 1 percent of U.S. electricity.

Now, after two decades in which cadmium-telluride technology was dogged by low power output and reliability problems, it's suddenly elbowing its way into renewable-energy markets and competing with today's dominant solar technology: silicon solar panels. The company behind this technology turnaround is Phoenix-based First Solar, which says that the technology could eventually be cost competitive with conventional fossil-fuel sources of electricity.
(27 July 2007)

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