Photo found at
http://www.richard-seaman.com
That's the subject of this diary...big ol honkin wind generators! Coming soon to an electrical grid near you! In all seriousness, look below the fold for more on the power of wind!
Wind energy is one of the most environmentally friendly ways to harness the power of the Earth and the Sun. Power produced with wind turbines creates little pollution. That pollution is produced by routine maintenance, the initial installation, and the capital production of parts for the power systems.
Before we broach the subject of capacity and production of wind energy, let me take a moment and just briefly review how wind energy works.
The motion of the earth's surface "drags" the air with it as the earth rotates. Wind, taken in isolation, is simply the fact that we are standing on a moving body and the air is moving relative to the ground. At 0 altitude, the air doesn't move at all. As you move away from the ground, the wind speed increases. This is called "vertical wind shear". It is the change in wind speed and direction as you gain altitude. This is an important consideration for wind energy and comes up in discussion of available wind energy at a proposed site. Throw in convection from solar heating and the fact that we're standing on a 3D sphere and you get our complex weather patterns.
When discussing wind energy, it is important to consider the winds seen by a given locale on an annual scale. One of the biggest criticisms of wind power is "Well, the wind doesn't blow all the time!" Well, that's very true...and rather meaningless, since we're not talking about little 10" rotors on top of our chimneys. What IS important is what we call "prevailing winds."
In any given location, you generally have breezes that come out of one predictable direction. Consider the earlier example of standing on the equator. At the equator, you'll have generally easterly winds. It may be NE, or ESE, or even dead east, but it always comes from the easterly half of the compass. In the Caribbean, these winds are called "the trade winds."
In North America, our prevailing winds generally are from the west. This is due to the "Ferrell Cell." Wikipedia has a great entry on wind. There are regional differences caused by seasons and/or geography. Down at ground level in most areas, winds are variable and turbulent as there are numerous features to break up the wind flow. However, as you climb above the tops of the trees/buildings, you pick up stronger, steadier flows. It is this cleaner airflow we care about for wind energy.
Not every location, though, has sustained winds that can generate good power. The Department of Energy has collated and performed quite a bit of work in this area.
For example:
Large Version Wind Maps for many of the 50 States exist and show wind speed at 50m! (Yes, that's meters! 150+ feet) The reason for this is that wind speed increases dramatically, as a function of height, as you begin to get above the terrain. If you've taken a private plane up or gone hang-gliding, etc. you know how the wind picks up when you're clear of the ground. 50m is an industry benchmark for above-surface winds.
If you're wondering about that height above the ground (5 times the height of the average house), go look again at the picture that prefaces this diary. See the scale? As I said: "Big Ol Honkin Wind Generators!"
Specifically the wind turbine at the head of the page is owned by ECNZ in Wellington, New Zealand. It is an older Vesta generator and puts out a max capacity of 225 kilowatts (kW). It stands 32 meters high at the hub and has 13.5 meter long blades. Modern large-scale utility wind turbines routinely have hub heights of over 60 meters and blades that can reach 100 feet long. The increase in rotor-swept area and improvements in bearings, rotors, airfoils, materials, etc. mean that newer turbines can crank out 600 to 2,000 kW! Older generators like the one at the top of the page (Brooklyn Hill Turbine in Wellington, NZ) are still in use, but have been greatly surpassed by the march of technology.
Wind power itself has been around so long that we even have old colloquialisms associated with it: "She's tilting at windmills!" The traditional use of the wind-generator has been for transmitting kinetic energy to a work site. Example: Grain-grinding windmills like this one:
The rotational energy of the windmill's rotors would be routed through a cog and gear transmission into the grain-mill. This energy could be used to grind grain, operate hoists, etc. One of the other uses of windmills was to run water wells. This was a good way to pull water up with minimal capital equipment back in the old days. It still can be used for such applications. Indeed AWEA recommends a small <500 watt windmill as a good way to run a water pump on a well. The capital investment is just a few thousand dollars, and it is very reliable! Instead of using the direct transmission of mechanical energy, though, the system provides DC power to a power regulator and is used to run an electric pump.
Modern wind turbines are configured as shown in the below picture. The wind drives rotors which turn an induction generator. These generators produce DC or AC power, depending on their configuration and intended use. There are gearboxes to control shaft speeds inside the generator, brakes to slow/stop the rotor if needed, blade pitch adjusters, etc. All of these components are manufactured and designed much like automobiles or other capital equipment. This is why alternative energy should be one of the big new paradigm shifting industries in the 21st century.
Referring back to the Montana wind resource map, I want to shift the discussion back to implementation and possibilities for public utility usage of large-scale wind power in this country. If you note the legend of the colors on the map, you can see that they are ranked by "Power Density at 50m (W/m2)." This means that areas shown as red could produce on average (annual average) 600 Watts per square meter of rotor swept area. Take what AWEA calls the large end of utility wind power: A 90 meter diameter rotor on a 90 meter height hub. This means the "rotor swept area" is (A=Pi*R^2) 6,361m^2. If you multiply that swept area by the power density, you get 3.82x10^6 W of wind power passing through ONE turbine's rotors, annually averaged. If we assume conversion efficiency and capacity-usage of ~40%, that turns into 1.5x10^6 W or 1.5 MW. If you consider that the footprint of one wind turbine is about 120m by 120m, it becomes clear that there is a GREAT opportunity for scaling up the usage of wind power.
The Danish website http://www.windpower.org/... has a great "basics guide." Wind farms are generally arranged in a staggered row configuration. That way, the interference of one wind turbine doesn't reduce the output of another. From the below picture you can see that these fifteen turbines fit in a theoretical box some 1400 meters by 1200 meters. That's roughly 0.7 square miles. If each of these generators was 2MW rated, you'd have 30 MW of capacity installed, which would be enough power to power 24,000 homes, on an annual average basis. That's a plot effectively 1 mile by 1 mile. A community could make this decision as a collective and probably sell the excess power to help defray the costs. If this was combined with solar electric and solar thermal, you could almost make a community a net energy exporter!
That's 1 mile by 1 mile! Imagine what you could do for a major metropolitan area if you put a 25 square mile array in a nearby rural area!? That would be 25 times the power and take up not much more land area than a major new shopping development. Conservatively you could get the net power for 300,000 homes! This potential is scarcely touched in the current electrical grid. See the below line taken from the DOE's report on annual energy. Note: The numbers below, though all from the DOE's own reports, do not convert/add up between tables. Fossil and Nuclear (GOT THAT GEORGE!?!?!? NU-KLEEE-AR!) make up 93.8% of this nation's energy supply. Wind energy only contributes 1/10th of 1% of this nation's energy supply. Let's see the breakdowns, shall we?
(Units in Quadrillion BTU)
Fossil Nuclear Hydro Wood Geo Solar Wind TOTAL
2004P 85.649 8.232 2.725 2.845 0.340 0.063 0.143 99.7
This table shows the provisional 2004 numbers from the Dept. of Energy Annual Energy Review. Wind would appear to be a very minor player in the energy production of the U.S., what with such a gargantuan (I love that word 'gargantuan' - I so rarely get the chance to use it in a sentence) amount of energy coming from Dino-Fuel. In fact, most "renewable energy sources" are miniscule. However, from the following table it is easy to see that Wind, unlike the others, is SKYROCKETING.
(Units in 1000s kW-hour)
Type 2000 2001 2002 2003 2004 00 to 04
Renewables 3.20x10^8 2.62x10^8 3.15x10^8 3.28x10^8 3.22x10^8 +2.19x10^6(+.68%)
Biomass 2.92x10^7 2.77x10^7 2.91x10^7 3.03x10^7 2.93x10^7 +0.12x10^6(+.43%)
Geo 1.40x10^7 1.37x10^7 1.44x10^7 1.44x10^7 1.43x10^7 +0.26x10^6(+1.9%)
Hydro 2.71x10^8 2.13x10^8 2.60x10^8 2.71x10^8 2.64x10^8 -6.84x10^6(-2.5%)
Solar 0.49x10^6 0.54x10^6 0.55x10^6 0.53x10^6 0.57x10^6 +0.09x10^6(+17%)
Wind 5.59x10^6 6.73x10^6 1.03x10^7 1.11x10^7 1.41x10^7 +8.56x10^6(+153%)
To summarize that table: Wind energy accounted for enough of an increase to offset the drop in hydro-electic generation and still get an increase in renewable source generation. How much power are we talking about, anyways? To give you an idea, according to AWEA (American Wind Energy Association), the average home requires 10,655 kW-hr of energy per year (average power generation of 1.25kW). That means that the 2004 production numbers for Wind equate to 1.3 million homes. We've only just scratched the surface. According to the US Census, there are over 100 MILLION households in the U.S. The numbers bear up well, in that approx. 1% of the energy consumed by this country is from wind.
The distribution of wind energy production can be found in some great breakdowns at the DOE renewable energy site. They offer 2003 through 2005 data on Full Color Maps like this one:
There are various plans for expanding the use of wind power, but it's not yet a widely pushed option. Minnesota has some grassroots push to grow their exploitation. Montana itself has grown from virtually NO wind power (one small Indian tribe's turbine) to a moderate player in wind power. California and Texas are taking advantage of their mountains and plains (refer to that Danish site above for the effects of these geographical features), respectively, to generate large amounts of electric power. If you take a look at the general US DOE map of wind resources for the Northwest, it is also apparent that Idaho, Wyoming, Utah, etc. have GREAT potential for wind farming. What we need is a strong Top-Down push for wind electric power. If you consider the capital expense, most collectives or communities have a heckuva hard time fronting the cash to get it built. So how would a regional or national wind policy work? Well, let's approach it logically...
Take my own current state of residence: Michigan. The DOE map shows the following:
See that big red band down the west side of the state? You see similar trends shown for Oregon, Washington, California, Maine, etc. This is a wonderful sign for future wind energy extraction. Those areas offshore have significant advantages over land-based areas. The parts can be carried there aboard barges and ships, which would allow us to Go Big (Or Go Home). Whereas the largest feasible land-based wind turbine is around 90m high with a set of 3 45-m long blades, the larger offshore equipment available from G.E. are on the order of 110m off the ground and possessed of blades of over 50 m in length. These generators are rated at 3.6MW and can be spaced similarly to the above diagram. These would cover a larger footprint, but imagine how many you could put in designated strips along the shore of one of these states! You wouldn't need many miles of shoreline to get these to work in a BIG way. Get a block of 30 of these installed spread in 3 groups, and you can generate enough power for 90,000 homes! Those 30 would cover a relatively insignificant amount of space off the west coast of Michigan!
These resources need to be developed. That's too much available electrical power to continue avoiding it. When a wind turbine is brought online, you can't necessarily dismantle an older power plant, but you can reduce its output (thereby lowering its emissions) in all but the worst cases, where the wind stops. Other challenges are related to infrastructure. There are too few high-power lines running near these areas to make them feasible, at present. We'd need to improve the quality/availability of high power transmission equipment to make this truly work on a regional/national scale.
I'd love to see someone like Gov. Schweitzer embrace a state-wide policy of the following: Bring online enough wind power generation to obviate the need for one coal-fired power plant (with room to spare so that the other plants could handle any wind drop-off). Utilize the coal that WOULD have been used at that coal-fired plant to feed his Oil-from-Coal plan and sell the oil as a commodity. Go in stages and diversify the renewable energy sources so you don't wager it all on wind or solar etc. Combine this with a project to expand the high-power transmission infrastructure and you've got a complete work.
Rather than advocate a position of yanking the coal resources wantonly out of Montana's crust, show how a combination of renewable sources (wind turbines, solar panels, biodiesel) and alternative fuel sources (coal-to-liquids, etc.) can help buy us energy independence!
Comments are appreciated; let me know what you think of my first real, detailed diary!