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It’s a serious question of course, and my column noted a dearth of new developments. One reason for this seeming slowdown, I noted, was the fact that solar cell technology – also known as photovoltaic or PV technology – is basically passive. That is, you can’t generate more energy than you collect. Manufacturers can make a more efficient solar cell, but it’s only going to be a few percentage points of improvement – not the orders of magnitude that are necessary.
Further, since it’s very difficult and expensive to save that energy to batteries, the technology is basically only useful in daylight hours and far too costly to convert to round-the-clock use.
Then last week, Microsoft founder Bill Gates said something remarkably similar at the Techonomy conference in Tahoe. His remarks were reflective of inside knowledge he has gained as a major investor in several alternative technology startups, so they provided a little more insight into why innovation has been slow in coming.
For one thing, he noted, while solar cell manufacturing is similar to semiconductor manufacturing, it has to be at least 50 times cheaper than it is today to be truly marketable. The math is simple to understand if you realize that semiconductor manufacturers create hundreds of thousands of chips in the same area that occupies just one solar panel. The only way solar manufacturing can be profitable enough to encourage large-scale arrays is to reduce the cost of producing these panels.
Another key point was with respect to battery technology. Fundamentally, there just aren’t any new battery innovations out there.
“Batteries haven’t improved hardly at all,” he said. “There are deep physical limits. I’m funding five battery startups, there’s probably 50 out there. It may not be solvable in an economic way.”
Surprisingly, this realization seemed to have stop him cold.
“There are things that don’t move forward,” he said. “Nuclear energy stopped in the 1970′s. We have to have a blended model, the optimism of our IT, and the realism of the energy sector.”
But there are innovations in solar technology that are moving forward. Just not in the United States.
One of the most innovative developments I’ve seen – perhaps the first real solar innovation in years – is the Archimede solar project in Sicily. Organized by an Italian team and with roots back to the work of Italian nuclear physicist and Nobel prize winner Carlo Rubbia, the project uses an array of mirrors to focus light on a solar energy collector – a technique known as Concentrating Solar Power or CSP. And while that technology in itself is not new, the team has made some novel modifications that improve the solar collector while adding an inexpensive storage component.
What the team has done is replaced the material in the condenser tube. In the past, these arrays focused the light on a tube of water to create steam power. Later, the water was replaced with oil, which could be heated to higher temperatures (generally about 390 degrees Celsius) and then passed through a heat exchanger to create steam. This was found to be more reliable, but obviously, also more expensive.
The new innovation focuses the mirror array on a tube containing a purified salt compound. The compound heats up to about 550 degrees Celsius, much higher than the oils, changing into a molten state as it does. Clearly, this enables a much more efficient heat exchange, and as a molten material, it holds its temperature for much longer time periods than oil. In fact, it can power a small plant for several days without sunlight. Archimede is the first plant in the world to use molten salts to collect and store heat – a major cost savings and competitive advantage.
The project has been deemed successful enough to encourage commercial production at the project facility in Sicily. The new plant generates about 5MW of energy. ENEA and the Archimede Solar Energy Company, a private energy concern, plan to roll out several new plants in the near future.
Meanwhile in the US, several new CSP projects are on a fast track for development, but it’s not clear how many of them will employ molten salts technology.