Greetings. Back to Energy 101.
And another exciting day in energy resources.
We're going to look at wind today. We looked at solar last time.
We looked at fossil fuels. we're looking at the renewable energy
resources. know, before we know how to use them, we
need to know how you get them, where they are, how much there is, and how diffuse
they are. So, let's look at wind today.
Wind energy is the biggest contributor from renewable energy of all the sources,
much more higher than solar and much higher than the renewable biomass,
and so, it's, it's an important renewable energy resource.
the way we reap the energy, of course the wind energy, is with wind turbines.
Here's just a shot of a small wind farm. on land, wind farms are generally fairly
small relative to offshore wind farms, which we'll look at also.
But unless they're out in the middle of the desert, which of course is good,
because they, they generally have good wind resources with high average wind out
in the deserts. This is an offshore wind farm that is
very prevalent in Europe. Here's a shot of a beautiful view of, if you go out and
look at them. I made a trip in 19, in 2005, I guess it
Six over, visited several of the offshore wind farms in Europe.
of course, servicing them is more expensive constructing them is more
expensive out of the water than on land. one good thing, though, it's easier to
ship for very long blades that you have. And so those are the, you notice they're
on pylons and those pylons of course, put them up off the surface of the earth,
whether it be land or water, and one thing we find is that energy
resources, the average wind speed increases with the
height above the earth's surface of water or land.
it also varies with geographical location.
Some areas is meteorologically have a higher average wind speed, which is what
we want for high energy density and lots, lots of resources versus other
geographical locations. I just mentioned height above the surface
of the earth is, turns out very important as well see,
so we'll like to put them on a very high pylon.
That's economically, that's very viable when you have a very large wind turbine,
because the pylon is only 15% of the total cost of the wind turbines.
But if you're putting up a small, one horsepower, one kilowatt sized turbine if
you put it up too high, you'll be spending more money on your pylon than
you will on the, wind turbine yourself. But it course, it varies by weather, and
if you're, get a stormy condition, you get high winds,
if you get a calm, it's calm. You have differences in night and day
because of solar heating of the earth, and of course, by as that, we already
said, the different geographical location.
So, again, it varies, by the way, the average is vary from winter to summer.
it's the opposite of what sometimes we might assume regarding month of year, is
that the average wind speed is generally almost all, all the regions is higher in
the winter than the summer. that's good if you have peak demand for
electricity in the winter for heating versus summer, but when you get into the
south for instance, you would like to have more electricity and need more
electricity in the summers for air conditioning. So [COUGH] wind energy,
particularly where you have summer peaking energy demand, electrical demand,
doesn't really match the annualized load, but we'll look at the average, the annual
average on wind maps like we looked at the wind maps for solar.
But they're a little more straightforward because this time it doesn't depend on
the orientation. We can always point the wind turbine into
the wind. These turbines will pivot around the
pylon on huge bearings, and so that they're always pointing into
the wind, and, that's not a big deal by the way.
You, you notice the, blades, in that case, the case we're looking at here is
pitched so that they're basically perpendicular to the, to the wind,
and so, the, that's in the stop lock position.
If the wind gets below a certain speed or it gets above a certain speed that could
cause damage to the turbine they turn the blades into the wind and lock it down,
they could do prevent damage. But let's look at the, how we classify
winds. You, you classify winds by wind power,
class one through seven and that indicates the range of wind power density
and that's the watts per, when it says they're a class one, 0-200 watts of
kinetic energy in the wind per cube or square meter of the area that you're
capturing of the wind. So if your rotor blade is, in its
circumference circle is capturing 10 square meters, then that means that the
total watts of kinetic, kinetic energy or power in that, in that 10 square meters
is up to 200 watts, watts per up to 2,000 for the class one.
the power density is a little bit nonintuitive.
You would think that the, because of the kinetic energy is all we
think about, is always 1/2*mv^2 that as the wind speed goes up, the power would
go up as the square of the velocity. But it actually goes up as a cube and the
reason it does is, because is, is the, kinetic energy per unit mass of air goes
up as the as the speed goes up. So if you double the wind speed, the
kinetic energy per unit mass goes up by a factor of four,
two squared is four, two times two. But the power density goes up by the
cube, because the amount of mass is flowing through the wind turbine, goes up
proportional to the velocity. So, the power density in watts is, goes
up by the cube, which is really makes the higher wind speeds pay off liberally,
because if you double the wind speed, the power that you get out of the turbine in
kilowatts, a given turbine will go up by the, a factor of eight.
If you double the wind speed, the power coming out by the generator goes up by
factor of eight. So it's really sensitive to wind speed.
The economics of wind farms is really sensitive to wind speeds because of that
cubic relationship. We'll look at that a little more later.
Here's a wind map. Again, this one comes from NREL,
they got good map resources. and we've said that it varies with the
wind speed, as this one shows, varies with the height above the surface
and this is at about at 100 feet. So wind maps aren't any good unless you
know at what height it's taken. This one, as you look across the top up
here look across the top, it's at 30 meters.
U, U.S. annual average windspeed at 30 meters
there about 3.3 feet per meter. So that's about 100 feet that's 100 feet
above the surface. looking at the diagram or looking at the
map, we can see that over here in the southeast, where I am, in Atlanta, is
dark green, which is way down here with a average wind speed of aroud four meters
per second. That's not economical.
It's it's, you can, you can get electricity from a wind turbine at that
speed, but the economics are really not going to work and by any stretch of the
imagination. if you get out here and get the, the red
areas, now you're up to about seven meters per second if we look there.
If we take meters per second times 2.5, you get miles per hour.
So a wind speed of seven, I mentioned that the, that the, the orange and red
out here is about seven, six, and half to seven meters per second.
Well, that's two, two and a half tiems seven is about 17 miles per hour,
so that's a pretty good wind speed on average.
That's the average wind speed 24 hours a day, 365 days a year.
sometimes it's higher than 17 miles per hour, but sometimes it's lower.
So you can see why the wind turbines tend to be out here in the midwest and over
here, again at, at a 100 feet above the surface out here in the northwest,
there, there's not much. Now, there are some regions that
particularly around the Portland area, that does have some good wind speeds,
but that's a very localized situation. Let's move up to a higher height now.
Let's move up to 300 feet, because the new larger wind turbines are placed on
pylons about 100 feet. Now, the color coding for the wind speed
is exactly the same as it was in the previous map, the same,
same color coding. We'll get it here in a minute.
the same color coding that we had before, but you notice, the dark green is
essentially totally gone away. So the lowest, now that we're showing,
even in the southeast, is around four and a half, five meters per second.
So, that's five meters per second with the lighter green here would be about 12
miles per hour, average speed of about 12 miles per hour.
That's still not, not really economically viable,
but you notice, you got to spend some money to put it up on a high pylon of 300
feet. 300 feet is a football length in, in,
height above the surface of the earth, It, it's 80 meters, 80 meters, again.
It is in conversion factors, that is 3.3, 3.3 to give you feet, so 80 times, times,
3.3 is about 270, 280 somewhere in there. I used approximate science that we don't,
no need to get bogged down in decimal points here. But you notice, you're
really out here in, in the Rockies, you really get some high wind speeds out
there around above eight, eight, nine meters per second,
which is averaging over 20 miles per hour.
Now, this also shows offshore, which the previous slide didn't shows
offshore. But the first thing to notice about the
offshore, is as soon as you get to the coast to move offshore,
looking over here in the Atlantic coast, the wind speed goes up,
because when you look at the chart, it goes up dramatically compared to on line,
on land. So on land, you really don't have any
commercially viable wind energy, wind resource out in the eastern coast there,
but as soon as you move offshore, you get some dark purples at the same as it is
out here. But as I've already mentioned,
unfortunately, it takes more money to build the turbines out In the ocean and
requires more to maintain them. Same way on the west coast, but another
thing you've got to be worried about when you put in an offshore is the depth of
the water. current technology, 75, a 100 feet depth
is about as deep as you, we really go down with the pylons.
the, the next slide, this one shows the just offshore by itself,
but you can see again, same, same same chart here and see if I can get it.
This oh, there we go, same chart and this actually shows miles
per hour as well as meters per second here,
But, that's the reason offshore, looks a lot better, and people are pushing,
trying to get more offshore a wind. The first offshore wind farm in the U.S.
has been permitted only recently, hasn't started construction yet, it's Cape Wind
off the Nantucket, and hopefully will, supposed to be operational 2014 or so.
they've had some obstacles they've had to overcome, but offshore wind has, has a
good wind, good potential because of the high resources offshore relative to on
land as we see from these maps. Oh, and if we go to the source of these
maps, we find NREL again, and you can download these and take a look at them.
And this is the page here that has got all the maps and has got some row, low
resolution and high resolution. you see, you pick the map [COUGH] and
take a look at it yourself and we'll have you do that.
Okay. So that gives us an overview of wind
resources and why a lot of the wind farms are out in the mid, midwest and southwest
and why there not, not any wind farms in the southeast and eastern coast in
general. Okay. Thank you.
See you next time.