(This is Part 10 of a series. Go back to Part 9.)
It seems to me that solar power will over time become the established leader in providing humanity's energy needs, because it will be likely to provide the most advantages while posing few if any drawbacks.
Solar power is the direct mainline. Wind power ultimately derives its energy from the sun, but it does so indirectly. Biofuels derive their energy from the sun too, but like wind they do so indirectly. The same for tidal energy and hydropower. And of course petroleum derives its energy from sunlight as well—but again, indirectly. The tremendous advantage of solar power is that it isn't wasting energy going through indirect mediums. Solar power is being made directly from the sun.
Because of that fact, power from solar cells has a number of powerful advantages: It is about as clean as a technology can get. Once put into operation, it produces no greenhouse gases or other noxious emissions. It is renewable every morning when the sun rises. In general, it is not competing with humans and/or crops for water or land.
Also important, solar cells can provide power in both very large settings and very small ones—and everything in-between—from power plants to little gadgets. In other words, solar power is not only sustainable, clean and renewable, but extremely flexible as well.
There are two key statistics to keep in mind concerning solar power:
1) energy efficiency, and 2) cost-per-watt.
When silicon solar cells were first invented at Bell Labs in the 1950s, their energy efficiency was only about 6%. (That is, of the solar energy falling upon the solar cell, 6% was being converted to useful energy.) Now, on average, solar cells are about 15% efficient, a figure that is slowly but steadily rising.
The second important statistic in the solar field is the cost per watt. That number has made enormous strides, falling from $200 per watt half a century ago to about $4 per watt now—a 50 times reduction in just 50 years—a remarkable achievement. Many experts now expect the cost-per-watt of solar to match that of the electrical grid within a few years. That in itself will cause a revolution.
The real promise in the field is coming from so-called "thin-film" solar cells. Standard solar cells are made from the same silicon that goes into computer and memory chips. Consequently, because of the competition for silicon, there is currently a worldwide shortage of that material.
Thin-film solar cells use less than 1% of the silicon required in ordinary silicon cells, so that the whole silicon-shortage issue goes away. And thin-film cells also have two other significant advantages:
First, their energy efficiency has now reached nearly 20% and is rising. (Experimental "triple-junction" cells have reached almost 40% in the lab.) Second, since thin-film solar cells are, in effect, "printed" on thin flexible materials they could eventually be produced using a technology similar to today's high-speed web presses which turn out millions of newspapers every day. High-efficiency thin-film solar cells will likely be manufactured some day in enormous quantities at a fraction of the cost of solar cells today.
When that occurs the cost-per-watt of solar cells will be far below the cost of electricity from the grid—at which point a real transformation will occur. Cheap, high-efficiency solar cells will become absolutely ubiquitous, and in combination with improved battery technology, will likely become the energy source of choice: providing clean, renewable and low-cost power just about everywhere. This will surely not happen overnight, of course, but does seem quite probable long-term.
Then combine that notion of ubiquitous solar power with the notion of a worldwide electrical grid spanning the globe, and we have the vision of a world that provides sustainable energy from anywhere, perhaps solar power from the Sahara Desert and wind power from Siberia and so on, and delivers that energy through high-voltage DC lines to anywhere on the planet where it's needed.
In addition to being an integral part of the global energy grid, solar will also probably go more and more "local" too, in the sense of powering all sort of local things locally. It's likely that solar cells (and hydrogen fuel cells as batteries?) could become just as completely ubiquitous in the future as computers, robots and adaptive networks.
Complementary to solar technology will be cheap and highly efficient batteries and capacitors—the latter enabling solar power to potentially be easily stored and drawn down as needed. A recent breakthrough at Rensselaer Polytechnic Institute will enable batteries and capacitors to be inexpensively “printed” on thin sheets of cellulose which then can be folded or cut up without affecting performance. And the sheets can be stacked to create greater amounts of power or storage.
Very promising. Yet, as we’ll see later, technology by itself cannot solve humanity’s challenges.
(This is the end of Part 10. Go to Part 11.)
—jim sloman, 3.23.07
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