| Monday, July 3 2006 |
"Alternative Energy": For people who can't add.
Sigh. I'm continually amazed how many "scientists" can't do basic math. Like this nutwad who thinks we can solve all our problems by using solar power to light up the country.
"If 2 percent of the continental United States were covered with photovoltaic systems with a net efficiency of 10 percent, we would be able to supply all the U.S. energy needs," said Bulovic, the KDD Associate Professor of Communications and Technology in MIT's Department of Electrical Engineering and Computer Science.
And how big is 2 percent of the continental US? As Will Collier
points out, slightly larger than the state of Georgia.
He also does the math on how many
orbiting, and thereby much more efficient solar panels, would be required to match the output of a nuclear plant.
The Space Station solar panels are fairly large as such things go, about 8,740 square feet in area. At 64 kilowatts of power for every 8,740 square feet of solar panel, you'd need about 136 million square feet of panels to generate a single megawatt of electricity. Just for comparison's sake, the Farley Nuclear Power Plant near Dothan, Alabama, can produce as much as 1,776 megawatts of power. That kind of output would require approximately 242 billion square feet of orbiting solar cells--about 8,700 square miles, an area larger than the state of New Jersey.
Both of these pie (or state-sized satellite) in the sky concepts have one
little problem that happens to come up every time MIT professors who know absolutely jack about grid power generation start spouting off. You can
not generate
base power with solar energy. Nor can you do it with wind energy. Nor can you do it with tide energy. Why? Well, here's a little primer on power generation.
There are three kinds of generation that need to happen in order for the buttons to light up on your microwave. But before I get into that, one needs to understand the concept of
load. Most people would tend to think that power generation works in a positive flow model, in that when you generate a given amount of juice, it goes on the grid and is then consumed. This is wrong. In fact, power generation works in a negative flow model, meaning that there is a given
demand on a grid at any given time, that demand is
load, and it is not a static thing. Now, if you were to go and build a power turbine in your back yard and hook it up to the grid, you would find a rather interesting display of physics, in that you could throttle the generator based on how much
load you put on it, not how much fuel you dump into whatever you have spinning it.
Base generation, or base load, is what keeps the lights on all the time. It is a constant power generation, the output of which rarely if
ever fluctuates as a result of its power source. There are only three kinds of fuel that can currently be used to generate base power: Hydro dams, Nuclear plants, and Fossil fuel burning plants. Why? Because those are the only methods one can use to produce a given amount of power, and be absolutely certain that it will be putting out that same amount of power next week, or next month, or next year. If you did not have base power generation, you would have massive power fluctuations with different supply loads, and the whole grid would collapse. (This is what happened on the east coast a few years ago. Imagine it happening on an hourly basis.).
The second type of generator is a ramp, or load control generator. This type of power generation is used to provide juice for
demand loads, like when everyone gets home from work at 17:00 and cranks up the AC. Load control is, again, almost entirely done by fossil, nuke or hydro plants, because certain demand models are built for various locations at various times of the year, and those demands
have to be met. That means one needs a power source that can be ramped up on demand, or to use the correct slag, more load can be placed on a given generator to match demand, and the power system for said generator is able to keep up with it.
The third type of generator is a peak generator. THIS is where solar, wind and other hippie-brand, spotted-owl dicing power generation comes into play. See, solar and wind generators are
never constant, because their output, or the amount of load they can accept, varies
greatly with environmental conditions. Cloudy day? Solar plants are screwed. Wind dropping off? Wind plants are screwed. It is because of this dramatic fluctuation in load handling that every wind and/or solar station on the grid,
has a fossil generator running right next to it to manage load. These peakers can produce energy at specific times, and when they can, that energy can be put on the grid (via a load balancing generator). However, as soon as their generation rate drops below a certain level, the load balancing fossil generator can no longer keep up, and the load demand needs to be transfered away from the peak plant and put on to either a ramp or base plant.
So, feel free to point out, the next time so tofu-munching sprout fairy goes on about how clean and pretty wind and solar plants are, that there's a big horkin' turbine right next to every single one, burning natural gas or oil.
Anyway, that is how power generation works. That's how it
has to work, because there is currently no way of storing really, really big amounts of power in a manner that is even remotely efficient. Load must be managed, and in order to manage dynamic load, you need base generation via a static power source.
You would
think a frickin' Associate Professor would understand such a simple concept, but evidently that's not the case.
posted by Mr. Lion
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