The basic mechanics of electric power generation has been around for thousands of years. Historical accounts vary, but the Persians and the Chinese were using wind to power grain mills as early as 600BC. Even longer if you consider oxen or even slaves turning a millstone to be the earliest incarnation of the mechanics.
The early colonists here used the same machine, turned sideways, and with falling water as the energy source, to mill grain and power limited industry such as sawmills. That was pretty much the only large-scale energy source, other than coal which was later used to power industrial plants, forges, and such. Petroleum and hydro-electric coming later in the 19th Century.
After Anyos Jedlik’s invention of the dynamo in 1827 the possibilities of electric energy started to be explored. The first hydro-electric dam came online near Niagra Falls in 1881.
All electric generation plants work on this same ancient idea. Let’s find some plentiful energy source to turn a wheel, (turbine), which then turns the generator’s input shaft. The biggest drawback, from an efficiency standpoint, is the first law of thermodynamics. Stated simply, energy can be changed from one form to another, but it cannot be created or destroyed. The generator takes some of the energy from the falling water and changes it into electricity. And heat. Once the water, (or in the case of wind, airflow), has passed over the turbine blades any energy left over is of no more use. It’s gone until captured by another generating plant downstream. Or downwind. ((It’s still the way we power diesel locomotives. The diesel engine turns a generator to power electric motors.)
Fossil fuel plants improve on this by recycling spent steam back into the boiler, reducing the amount of fuel required to return it to its workable state. Even so, the most efficient gas turbine plant has only achieved just under 60% thermal efficiency. Not bad when you consider that 100% is impossible and we’ve only been at this for around 120 years.
The idea of using wind power instead of water or steam began about the same time as hydro-electric. Until WWII wind machines were not large enough, reliable enough, or efficient enough for use off the farm. Grandpa’s Knob, a mountain in Vermont, was the site of the first megawatt-sized wind turbine, coming online in October of 1941. It only lasted for 1000 hours before mechanical failure took it out. Materials shortages during the war prevented the repair of that unit. But it did show that wind energy could be harvested on a large-scale.
But was it efficient? After only 1000 hours there was not enough data to make that determination.
Since then we’ve accumulated some data, so let’s take quick look at some of it.
You’ve heard confusing terms like “capacity factor” and “rated power output” from wind farm advocates.
Let’s start with the latter since it’s the most misleading. Nothing more than an engineering statement, rated power output is the amount of electrical energy the machine should produce at its ideal wind speed. Typically between 25 and 55 mph and most often expressed in megawatts or MW. One Megawatt is enough power for roughly 900 homes if it is constant power. You could compare it to the speedometer in your car. You may never achieve that highest number, but under ideal conditions you might. And you’ll probably get a speeding ticket. That brings us to the next phrase.
Capacity factor is what actually comes out the other end. Worldwide this is usually 15 to 30% of rated power. For example, if a 1.5-MW turbine generates power over one year at an average rate of 0.5 MW, its capacity factor is 33% for that year. You will find that capacity factor runs in the low to mid 20% range worldwide and often as low as 1% or less. In other words, your mileage may vary. And it may vary a lot.
You’ll also hear the word “availability”. Got a bicycle in your garage? It’s “available” 100% of the time. If it does not have a flat tire like mine does. Wind turbines are classified “available” roughly 90% of the time. Basically anytime they are not down due to maintenance. But if the wind ain’t blowing, they ain’t really available. That downtime is not counted as unavailable, it just reduces the capacity factor.
OK, but a wind turbine is generating any time the wind is blowing, right? Wind turbines do generate power when the wind is blowing between 7 and 60 mph. Above 60 or so, depending on the design of the installation, the blades are feathered into the wind to cut stress on the materials and output either drops dramatically or stops. Below about 30 mph the output is very small. Typically they produce at or above their average rate about 40% of the time. In other words, most of the time they produce little or no electrical power.
Because wind power output swings widely from zero output to maximum output there must always be backup available. Backup that equals 100% of the wind farm’s rated output. These erratic fluctuations of output cause many headaches to the grid operator. As a result, PJM Interconnection LLC, The Pennsylvania based company that manages the grid for an area that includes Virginia, forecasts wind farms at 13% of their rated power output. They also monitor data from wind farms constantly and adjust other plants as needed to keep the grid evenly loaded.
This is why many opponents say wind power, while itself indisputably clean, may actually increase carbon emissions. The logic goes like this: The throttling up and down of conventional power plants in order to balance out the wind farm’s inherently erratic contribution reduces efficiency and increases pollution. While the logic seems reasonable, I’ve found no studies to support it. I’ve not found any studies that debunk it either. There simply seems to be little or no data from either side, so I suppose I have to go with the logic.
Today, many Virginia localities are looking at wind farms, sited along some of our most beautiful ridges, as a possible source of tax revenue and maybe even a “green” statement for our environment. Floyd county has been the site of two proposals, one on Willis Ridge, and another a bit further south on Indian Ridge. Two more wind energy companies are also looking into Floyd County. Roanoke county’s Poor Mountain is another site being explored. There is one cooking in Highland county, another in Wise. Tazewell and Patrick counties have each passed an ordinance to prevent be-spoiling their ridges.
I want to state here that I am neither pro nor con on the wind issue. I live in reality, truth matters most to me. Let’s examine some of the claims from the wind industry.
Wind energy companies promise the most efficient energy, at the least cost, all while being environmentally friendly. Invenergy founder and CEO Michael Polsky stated, in a 3/28/11 Op-Ed at the Hill’s Congress Blog, “Costs to build renewable power plants, such as wind farms, sit in between lower-cost natural gas plants and higher-cost coal and nuclear plants. Yet operating costs of renewable power are very low because the fuel is free, 365 days a year.”
Erik Duncan, development manager for Invenergy’s Beech Ridge [WV] project, said in a June 12, 2011 article in the Roanoke Times, “Even if it’s variable, you’re producing energy out of thin air, so I don’t know how it gets better than that.”
What they do not tell you is that the fuel is not free. Sure if you only consider the wind as fuel, that’s free, but if they are evasive on this issue, can they be trusted on others?
Wind turbines, (and all other large, heavy equipment that depends on a shaft to transfer power), must slowly turn almost constantly to prevent warping and bending of that shaft.
Ask your friends and relatives in the Navy about the term, “jacking the shaft”, (this is from an old guy, older than me even. The term may have changed). I’ve been told ships at port keep their engines and screws turning slowly to prevent this bending. (Never having been in the Navy, or being invited into an engine room, I don’t know if they turn them the entire time in port, or at specific intervals. But they do turn. (From an old salt friend I’ve since received confirmation. They turn continuously. They are also reversed daily.)
If you see a wind turbine standing idle chances are some sort of maintenance is going on. When wind does not provide enough energy to turn the blades they must be turned by using the generator as a motor. That energy comes off the grid. And it’s often unmetered. I suppose in that case it really is free, at least to Invenergy. Somebody else, (That would be you, the utility customer.), is paying real dollars for it.
If you’ve toured a wind farm on a day of little or no wind and the blades were turning, that may have just been for show. The wind farm was actually consuming energy off the grid. Each turbine also uses power off the grid for other purposes. In Winter the gearbox oil may need to be heated. The nacelle,that streamlined housing around the generator and related mechanics, may have a to be dehumidified. When the wind speed accelerates toward a usable speed the blades may need a “kick start”, and the rotating machinery, which keeps the blades facing into the wind, may need adjustment. Before an AC generator will begin to produce electric current the field windings must be excited by an electric current. Again, this energy comes from the grid.
Invenergy also states on their website, “natural gas is the fuel of choice for Invenergy’s natural gas power facilities because it is the cleanest fossil fuel available for power generation.” (Never mind the pleonasm. Natural gas is the ONLY fuel of choice for a “natural gas power facility”.) What he doesn’t say is that natural gas, (along with hydro), can most easily be throttled up and down to even out the demand from available wind.
Remember what I said before about backup generation? Invenergy just said the same thing, without actually saying it. You’ve witnessed this. At a campground your neighbor may have had a generator going. Perhaps you or your neighbor have a back-up generator at home. You’ve heard the engine RPM rise and fall according to the current load. Same principle happens at a fossil fuel power plant. Natural gas boilers and hydro-electric dams can do this relatively efficiently. Coal and oil not so much. Not only does your new Chevy Volt run on coal, your neighborhood wind farm probably will too.
We’ve not discussed government incentives. The Production Tax Credit, which expired at the end of 2012, wind farms received a taxpayer-funded credit at the rate of 2.2 cents per kilowatt-hour. A thorough discussion of these issues is beyond the scope of this article. (Let’s just say I hope it stays expired.) I also will stay away from bird deaths.
Opponents of coal, who are often wind farm zealots, usually color their arguments with the emotionally charged phrase, “mountain top removal”. Go find a few pictures of wind farm ridge top installations.
That my friend is truly “mountain top removal”. Former surface coal mines are now airports, golf courses, hospitals, housing developments, farms, and industrial sites. I know of another that has become a drive-in theater. I once considered one as a site for a home, its only drawback was its location in Kentucky. (I’m a Virginia guy. It would take a lot to get me to settle outside.) I suppose you could use the area around a wind farm as cattle grazing/pasture land or farmland. Any other commercial use is probably out of the question.
Imagine the southbound lanes of I81 going up the side of Poor Mountain near Roanoke. In order to get the equipment to the ridgetop would require a road something like that. Wind turbine blades are 150 feet long. The blades have to get up to the ridgetop somehow. The normal truck passing you by on the interstate has a trailer that is 53 feet long. The road necessarily would be limited in curve radius, dip and rise, and maintain a minimum width. In the case of Poor Mountain I suppose they could be off-loaded at a site like Elliston and transported by heavy lift helicopter. That still requires a trip up or down I81 with a vehicle over 160 feet long. More than three times the length of the normal I81 truck traffic. And three helicopter trips per tower.
There’s much more to consider before you consent to a wind farm on your nearby ridge. This is just a start. And a place to generate questions that must be asked. My conclusions? (This is, after all an opinion piece.)
Windmills could be a major part of a solution to our energy woes. Certainly it is something a large farm owner may want to investigate, on a smaller scale of course. A wind turbine of about 600KW along with a well designed installation which includes battery storage, could take you completely off the grid. For the rest of us they will work well in some areas of the US, but I really would rather not have great big scabs on top of Virginia’s beautiful mountains. Someone closer to the coast will have to comment on offshore wind farms. I’ve seen the wind farms on the high desert near Mohave. With that landscape they posses a certain artistic/poetry value.
I believe in personal property rights, so Patrick and Tazewell counties may have jumped the gun. I also believe part of someone’s property rights should at least consider their view-shed. Each Virginia county must decide on their own, after serious research, input from residents, and local concerns. With offshore installations the needs and concerns of the Navy must be considered.
Just then they came in sight of thirty or forty windmills that rise from that plain. And no sooner did Don Quixote see them that he said to his squire, “Fortune is guiding our affairs better than we ourselves could have wished. Do you see over yonder, friend Sancho, thirty or forty hulking giants? I intend to do battle with them and slay them. With their spoils we shall begin to be rich for this is a righteous war and the removal of so foul a brood from off the face of the earth is a service God will bless.”
“What giants?” asked Sancho Panza.
“Those you see over there,” replied his master, “with their long arms. Some of them have arms well-nigh two leagues in length.”
“Take care, sir,” cried Sancho. “Those over there are not giants but windmills. Those things that seem to be their arms are sails which, when they are whirled around by the wind, turn the millstone.”
You’ve heard the song. To dream the impossible dream … To reach the unreachable star.
(BTW, forgive the Schwartzian length of this. It simply can’t be told in a short version.)