Five Interesting Things I Heard About: Solar Energy

One of the great things about living in a university town like Madison, Wis. is that there is a never-ending supply of interesting talks to attend and scholars willing to give those talks. While the talks are rarely dull and I do my best to pay attention, I’ve found that much of the material presented often escapes me soon afterward. You know, you get to worrying about work or school or what’s on your grocery list (daily life, in other words) and you forget the interesting stem cell development, the surprising statistic about corn ethanol production, or the fascinating hypothesis about mantle hotspot dynamics that you just heard. It’s not easy retaining so much information, even when it is interesting, surprising and fascinating stuff.

(Image credit: (c) pixor, CC BY-NC-SA 2.0)

In the spirit of trying to preserve some of this awesome info that might otherwise be lost, I thought I’d mix things up with the blog here and introduce a new series of posts entitled “Five Interesting Things I Heard About: [blank].” This is a largely self-motivated exercise of course, but I hope I manage to keep it interesting for you, the reader, as well.

The first installment comes from a guest lecture by Sandy Klein, a professor of mechanical engineering and director of the Solar Energy Lab at the University of Wisconsin at Madison, as part of a course about energy resources. Klein spoke about the basics of energy use in the U.S., including solar, where solar technology is now and where it’s headed:

1a. Quoting a figure of 7.2 billion tons of coal consumed worldwide in 2008: “The annual coal that is used worldwide … it would be represented by a hole in the ground that is 10 meters deep — 33 feet deep — and 181 square miles, in one year.”

1b. Based on 108 trillion cubic feet of natural gas use worldwide in 2007, and a volume of 126 billion gallons for Lake Mendota in Madison, Wis.: “The amount of energy that we use each year in the form of natural gas is enough to … boil all the water in [Lake Mendota] 100 times.”

1c. In terms of annual worldwide oil consumption, quoted as 84 million barrels per day for 2006: “Think of 10 Lake Mendotas out there filled with oil. That’s what we use in one year.”

Note: While I wasn’t able to recreate his numbers exactly, Klein’s estimates agree with my calculations (see figures below) to the same order of magnitude. If anything, it appears that his numbers are fairly conservative. Bear in mind that mine are only rough calculations.

 













2. “The amount of energy that is hitting the Earth from the sun during one year [5.5 x 10²⁴ Joules] is nearly 12,000 times more than all of the energy that we use [4.75 x 10²⁰ Joules], which is enormous. … The only nagging little problem left is how do you get it? To get the 12,000 times more [energy], you would have to have a solar collector that covered half the planet at any one time. And of course you’d have to move it as it went from day to night.”

3. “Water heating is the low-hanging fruit for solar energy applications. It’s the easiest and should be the most cost-effective application of solar energy.”

4. “China has more solar water heating systems than the United States has water heating systems.”

5. “Where is research going now? I would say water heating and space heating, these are not research topics any more, this is a mature technology. … Research is all going into large-scale production of electrical energy.” (Klein went on to discuss examples of such large-scale production including solar power troughs, power towers and dish engines.)

For more information about solar energy, check out these pages:

National Renewable Energy Laboratory

U.S. Energy Information Administration

UW-Madison Solar Energy Laboratory