If you want to learn more about something pretty recent, the internet will do ok. Its better if its a subject commonly referred to by geeks, but even basic stuff might get some treatment out there if you're willing to dig far enough. If you want to further back, looking for information on old topics, you've got to think out-of-the-box; or rather off-of-the-net. My favorite place is the local library.
Take any topic that was important/interesting/popular 20 years ago, and there's a good chance that your local library has all kinds of information on it. I've found lots of great stuff on metal casting (including a couple of styles of casting that have been subsequently banned by EPA); information on working with Beryllium (now recognized as a highly hazardous material), and other kinds of great stuff there. Its especially good at topics that were at the peak of their hype curve 20-25 years ago, then fell into a lull, only to return recently. (For those of you less that 30 years old, the one I'm currently thinking of has to do with one particular solution offered for the energy crisis of the late 70s: solar power).
In the mid fifties, researchers at Bell Labs had put together one of the first practical solar cells (or solar batteries as they were called back then), based on silicon (which is what most modules use today). While the price was horrifying, and the efficiency wasn't that great (around 6%); it was a solution made to order for space based applications where it got its first use. By the 70s its use in space, by the government and the invention of the amorphous crystal cell (which was used in solar powered calculators and the like), helped bring the cost down from the hundreds of dollars per watt, down to around $10 a watt. As the government started throwing massive amounts of money at further research into solar, the possibilities became endless and future looked bright.
Into this environment came a number of books, including: Photovoltaics: Sunlight to Electricity in One Step.
This is actually a quite brilliant book, with quite a few excellent illustrations, tables of facts, and information about the solar cell and the electricity industry in the early 80s. While the projections of the DOE and those of the authors are off by a mile (by 1985 gasoline was back down to 80¢/a gallon and nobody cared about alternative energy any more, especially not the government), the analysis was quite good on what was possible at the time, and what should have been possible in the future.
Fast forward 25 years, and gasoline is back over $3 a gallon, and everyone is screaming for alternatives. According to the book, 178 trillion killowatts strike the earth every second. Now a bunch gets reflected, and a bunch more gets turned into heat; but there's still at least 40 million gigawatts getting down to us at ground level. Given the 9.6 million square kilometers of land of the united states, and a hypothetical six hour solar exposure every day; that's 71,971 Quads of energy per year hitting this country from the sun. Putting this in perspective, the US used 98.2 Quads of energy in 2003 (pdf). Of that 40 Quads of energy (fuel) were used to create 12.5 Quads of usable electricity; so clearly there is the potential to harness the great deal of sunlight striking us to generate some (if not most) of our electrical power.
The book is full of physics, presenting concepts that I've struggled with for decades in such a clear way as to instantly provide enlightenment. There's also interesting data on different types of solar cells (historic, current and possible future). One interesting table for instance lists the issues of efficiency in the typical silicon cell:
| Energy loss due to | percent lost |
|---|---|
| Overly energetic photons | 32 |
| Under energetic photons | 24 |
| Internal cell losses | 21 |
| Front surface reflection | 3 |
| Shading by electrical contacts | 3 |
| Cell packing gaps | 2 |
| Total | 85 |
I hope to post more figures & tables from this book over time, if nothing else, for my own personal reference.
