Saturday, October 18, 2008

So, my friend Jennifer asked the following about my previous post about nuclear energy:

So am I seeing here that you are an advocate of nuclear energy assuming we were not going to put more effort into solar and wind power?

I'd be interested in hearing more about the nuclear process and the pros/cons of it as a reliable and safe energy source.
Warning: This is going to be rather opinionated, ranting, and preachy. :)

The first question is easier. I'm an advocate of reducing pollution, greenhouse gases, and reducing how much of the aeons-old materials we pull from the ground. As was made clear in my first post, basically everything we use comes from the ground. In my opinion, we should take as little mass from the ground as possible. How do we do that?

It's the old mantra: Reduce, Reuse, Recycle. This can be accomplished in many ways, and there are many blogs out there about what specific people do. My bestest friend in the whole wide world (and also my wife) has a bunch of blogs she follows that discuss all different aspects of doing just that.

So, if we reduce the amount of material we're using, we'll very quickly notice that a lot of the energy generation we "needed" is also reduced. We'll notice that the atmospheric pollution we generate is greatly reduced. If we also reduce the amount of energy we directly use (drive less, turn off lights, use more efficient lights and appliances, etc.), we'll notice another, greater drop in pollution.

So, first, I think we should just stop using as much (of energy and stuff) as we use now.

Now, there is some amount of energy we'll need to continue generating to maintain our "standard of living." We can get a lot of that energy from solar, wind, hydrothermal, and hydroelectric. I dare say that we could generate ALL of our energy needs from those four sources. Let me back that up:

There was a math error in the paragraph below. I've corrected it, and had to reduce the fudge factor to a factor of two instead of ten. The point is still the same, it's just not as wildly liberal with how easy it would be to replace all US electricity generation with solar. Corrections are in purple while bad values are in red.

Solar panels are about 12% efficient right now. That means that a cell that covers 0.01 m^2 generates about 1.2 Watts on a clear day. The US uses about 3.2x10^12 watts per year. That means we would need about 2.7*10^12 solar cells that cover 0.01 m^2 each to generate all of our power needs. That's 2.7x10^9 m^2. This is incorrect; the correct value is 2.7*10^10 m^2. That's 27000 km^2. The surface area of the US is 9.2 million km^2 of land. Arizona has about 300,000 km^2. So, let's add 50% of the solar panel surface area to account for the infrastructure. The following statement is a little too liberal due to the math error above. This is a wild guess--we could even double or increase by a factor of 10---it doesn't really matter. Naw, let's use a factor of 10 more, to account for infrastructure, more panels because of the fact that not 100% of the Arizona days are clear, etc. Instead, let's increase by a factor of two to account for infrastructure, etc. So, 54000 km^2 is needed for solar panels to generate 100% of the United State's energy needs. That's about 1/5 of Arizona's land. That's a lot. However, we have a lot of land in the southwest: New Mexico, California, etc. We also have a LOT of roofs in the southwest. We could easily provide more energy than the entire US needs with solar panels alone, at today's efficiencies.

It would be extremely difficult to get all of that energy across the US using the current power grid. Let's add some wind generators in the midwest, some hydrothermal in areas like Yellowstone and Alaska, maybe some wave (I don't like wave much, mostly because I don't know enough about it) on the coasts and Hawaii, etc. We can, with current technology and just a little bit of will, completely stop using coal- and natural-gas fired power plants in a decade or less if we had real leaders in technology and politics, and it wouldn't require the use of ANY nuclear plants.

My next post will directly address nuclear, because I don't think we should necessarily take it off of the table; 27,000 km^2 of solar panels is a LOT of mining for silicon.

1 comment:

Grumpator said...

I'm definitely looking forward to your post on nuclear power. While I know that the actual generation of power is pretty safe these days, I'm concerned about the waste. As far as I know (which admittedly is little), there is still no safe way to dispose of it, other than to hide it under Yucca Mountain. Something I think is unacceptable. Will you address this in your post, too?

Wow, it's nice having our very own scientist to answer these questions! :-)