Wednesday, October 29, 2008

Wind Power

A few days ago we visited my sister in Indiana (State motto: corn!). We decided to take the scenic route back to Chicago and just took our time driving north on old route 41. When we got into Benton county we discovered a huge wind farm. (Check out the link to Benton County for cool construction pics). There are 87 huge wind turbines. It makes the otherwise boring landscape of northern Indiana look like something from a science fiction movie. But, what a great old idea! Using the free power of the wind to generate electricity.

I say it is an old idea since farms typically had a "wind mill" not for milling actually but for charging batteries (much like we do on the boat) in the years before the nation's electrical grid reached into farm country.

Of course wind energy grabs the attention of any cruising sailor. We get OUR energy from the wind two ways. It makes us go (when we are going) and we also have a wind generator for our electrical needs. The principles involved are exactly the same for these giant 1.5 mega watt monsters as our KISS generator. When ever you are using the power of the wind, for sailing or generating, the power you receive goes with the CUBE of the wind speed.

P = \begin{matrix}\frac{1}{2}\end{matrix}\alpha\rho\pi r^2 v^3

That means if you double the speed of the wind you get 8x the power. Not unlike a sail the vanes of the generators are actually air foils to redirect the wind and provide lift for making them spin. The vanes can be turned to provide optimum attack angle to the wind.

We noticed that there seemed to be no pattern to how the towers were laid out. Later I discovered by reading (yes!) that they have to stagger them because the turbulence off the back end of one would disturb the next one if they were placed in line. That sound familiar to any of you racers out there?

The towers are quite tall (~130 feet) for obvious reasons. One to allow for huge vanes which are 65 - 130 feet long but also, as sailors know, the wind speed increases with height. The power from the wind also goes with the square of the radius so long vanes are good.

It would be nice if we could line the country with these things from North Dakota to Texas. It's free energy and it's clean. Unfortunately energy farms cannot account for much more than 20 -25% of our current energy needs. Still everything added to the grid that doesn't harm the environment and reduces emissions is a good thing. In 1999 total US power consumption was about 100 Tw. That's 100,000,000,000,000 watts (10^14). Let's say each wind generator can produce 1 mega watt (1,000,000 watts) Then it would take one hundred MILLION such generators to completey replace all our current power plants. Ain't going to happen. So, I'm for wind generators but people shouldn't think that we can live on that alone.

Disadvantages: Control. Can't MAKE the wind blow harder when you need more electricity. Dead Bats. They are finding a disturbing number of bat carcasses littered around these things. It's not clear why bats, who are known to be good at not running into things, are dying. Some think that the disturbed air around the vanes causes huge pressure differences that can disrupt the bat's lungs and capillaries. Asthetics - Do we really want to make such places as Franconia Ridge in New Hampshire look like this? It's one thing to dot the corn fields of Indiana with huge generators and another to put them in beautiful wilderness places.

Farms like this are popping up all over the world. Germany's farms contribute 5-6% to their total energy needs. England is proposing building wind farms out on the ocean where prevailing winds are stronger and more predictable. They have a plan for 7000 wind generators which would provide HALF the energy needs for England allowing tea twice a day perhaps! A plan has been approved to install 40 turbines 3 miles off of Jones Beach Long Island.

Of course the other side of the power consumption coin is to not USE as much. Building homes and office buildings to be more energy efficient. New fluorescent and LED lighting devices. Opening windows instead of air conditioning. Remember, the earth is a closed system. Except for solar (which keeps on streaming in) we have all the energy we're ever going to have. All we do is convert it from one form (typically chemical) to another (electrical). We won't ever run out of solar or wind (actually a form of solar since it is the unequal heating of the planet that causes the wind to blow) but we WILL run out of oil, gas, coal. Not soon but someday.


Anonymous said...

VERY interesting! As Johnny Carson might have said, "I did not know that!".

Thanks again, Mr. Science!

Rich P

jonathan said...

Great points on wind and I think it is going to take diverse power sources, wind, solar, thermal, wave, and even nuclear to replace fossil fuels. For wind power I reccomend checking out which talks about offshore ones as well.