Wind Turbines versus a Coal-Fired Power Plant

Posted by PITHOCRATES - August 26th, 2013

Economics 101

The Diameter of a 6 Megawatt 3-Blade Rotor is Greater than two 747-400s parked Wingtip to Wingtip

One of the largest coal-fired power plants in the world is in Macon, Georgia.  Plant Scherer.  Whose furnaces consume some 31,000 tons of coal a day.  Producing 3,500 megawatts of electric power.  Enough to power three good sized American cities.  A few million households.

One of the largest offshore wind turbines available on the market is 6 megawatt.  Which is huge.  One blade can be as long as 250 feet.  A typical 3-blade rotor can have a diameter of just over 500 feet.  To get a feel of this magnitude the wingspan of the world’s most common jumbo jet, the Boeing 747-400, is about 211 feet.  Which means one blade of a 6 megawatt wind turbine is longer than the wingspan of a Boeing 747-400.  And the diameter of a 3-blade rotor is greater than two 747-400s parked wingtip to wingtip.

A 6 megawatt wind turbine requires a tower of about 300 feet tall.  So the blades can spin without hitting the ground.  Which is about the same height of a 20 story building.  And if it’s an offshore turbine you can add another 2 stories or so for the tower below the surface of the water.  So these things are big.  And tall.  Some of the largest manmade machines built.  And some of the most costly.  It takes a huge investment to install a 6 megawatt wind turbine.  That can only produce 0.171% of the electric power that Plant Scherer can produce.

There is a Small Window of Wind Velocities that we can use to Generate Electric Power with Wind Turbines

So how many 6 megawatt turbines does it take to match the power output of Plant Scherer?  Well, to match the nameplate capacity you’ll need about 584 turbines.  If we install these offshore in a line that line would extend some 56 miles.  About an hour’s drive time at 55 mph.  Which is a very long line of very large and very costly wind turbines.

We said ‘nameplate capacity’ for a reason.  If 584 wind turbines were spinning in the right kind of wind they could match the output of Plant Scherer.  And what is the right kind of wind?  Not too slow.  And not too fast.  These turbines have gear boxes to speed up the rotational speed of the rotors.  And they vary the pitch of the blades on the rotors.  So the turbine can keep a constant rotational input to the electric generator.  If the wind is blowing slower than optimum the blades can catch more air to spin faster.  If the wind is blowing pretty strong the blades will turn to catch less air to spin slower.

In other words, there is a small window of wind velocities that we can use to generate electric power with wind turbines.  Too slow or no wind at all they produce no power.  If the wind is too great the blades turn parallel to the wind.  So the wind blows across the blades without turning them.  They also have brakes to lock down the rotors in very high winds to prevent any damage.  So if a storm blows through 584 offshore turbines they’ll produce no electric power.  Which means they can’t replace a Plant Scherer.  They can only operate with a Plant Scherer in backup.  To provide power then the winds just aren’t right.

The more Wind Turbines we install the more Costly our Electric Power Gets

Now back to that nameplate capacity.  This is the amount of power a power plant could produce.  It doesn’t mean what it will produce.  The capacity factor divides actual power produced over a period of time with the maximum amount of power that could have been produced.  A coal-fired power plant has a higher capacity factor than a wind turbine.  Because they can produce electricity pretty much whenever we want them to.  While a wind turbine can only produce electricity when the winds are blowing not too slow and not too fast.

So, if the winds aren’t blowing, or if they’re blowing too strongly, it is as if those wind turbines aren’t there.  Which means something else must be there.  Something more reliable.  Something that isn’t weather-dependent.  Such as a Plant Scherer.  In other words, even if we installed 584 turbines to match the output of Plant Scherer we could never get rid of Plant Scherer.  Because there will be times when those windmills will produce no power.  Requiring Plant Scherer to produce power as if we never had installed those wind turbines.  And because it takes time to bring a coal-fired power plant on line it has to keep burning coal even when the wind turbines are providing power.  So it can be ready to provide power when the windmills stop spinning.

Wind may be free but 584 wind turbines cost a fortune to install.  And this investment is in addition to the cost of building, maintaining and operating a coal-fired power plant like Plant Scherer.  All of which the consumer has to pay for.  Either in their electric bill (adding a surcharge for ‘clean energy investments’).  Or in higher taxes (property tax, income tax, etc.) that pays for renewable energy grants and subsidies.  Which means the more wind turbines we build the poorer we get.  Because we have duplicate power generation capacity when a single power plant could have sufficed.


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Spain’s Massive Investment in Solar Power has Greatly increased the Cost of their Electric Power

Posted by PITHOCRATES - August 24th, 2013

Week in Review

People think renewable energy is the answer to all our energy problems.  But that isn’t quite so.  In fact, all it does is increase the cost of our electric power.  For sunshine and wind may be free.  But the equipment to harness the energy in sunshine and wind is not free.  It is very, very expensive.  And you need a lot of it.  You will not see one wind turbine service the power needs of one metropolitan area.  You may see a wind farm providing a small percentage of the electric power needs of a large metropolitan area.  And only when the wind blows.

Wind can blow day or night.  But it can also NOT blow day and night.  While solar panels will not work at all at night.  So you have massive investments to install renewable energy generation capacity.  And there will be times when they will provide no power.  So what do you do?  What do you do when the wind doesn’t blow and the sun doesn’t shine?  You turn to old reliable.  The electric grid.

This is why renewable energy is so costly.  It cannot replace our fossil-fuel power plants that can provide reliable power day or night in any type of weather.  It can only supplement what we call our baseload power.  Like our beloved coal-fired power plants.  One of the most cost-efficient ways to produce reliable electric power.  Which the power companies have to still run and maintain day and night.  For those who don’t have a wind turbine or a solar array providing their electric power.  And to light up the night.  So instead of one cost-efficient power generation system we have two systems.  One cost-efficient and one cost-inefficient.  And those who invested heavily into renewable energy are now having to deal with these very real problems (see Out Of Ideas And In Debt, Spain Sets Sights On Taxing The Sun by Kelly Phillips Erb posted 8/19/2013 on Forbes).

With so much sunshine at its disposal, Spain has aggressively pursued the development of solar energy: over the past ten years, the government has made significant advances in pressing solar energy and is one of the top countries in the world with respect to installed photovoltaic (PV) solar energy capacity.

It might, however, be too much of a good thing. Spain is generating so much solar power, according to its government, that production capacity exceeds demand by more than 60%. That imbalance has created a problem for the government which now finds itself in debt to producers. And not by a little bit. The debt is said to have grown to nearly 26 billion euros ($34.73 billion U.S.).

So how do you get out of that kind of debt? You propose incredibly onerous taxes and fines, of course. And you do it on exactly the behavior that you encouraged in the first place: the use of solar energy panels. That’s right. Spain is now attempting to scale back the use of solar panels – the use of which they have encouraged and subsidized over the last decade – by imposing a tax on those who use the panels…

…many residents in Spain generate enough electricity from solar that they get paid to selling the excess energy back to producers. This, it turns out, is a problem. The government is putting a stop to that, too: as part of the reform efforts (read: desperate measures), there will be a prohibition on selling extra energy.

If the power companies are providing all the power at night they have to maintain their power plants.  And their power distribution system.  Which means they even have to trim the trees away from their overhead power lines from people who use solar power during the day.  Nothing changes for the power companies.  Except that they can’t sell as much power as they once did.  So their costs of producing power remain the same.  But their revenue has fallen.  Forcing them to operate at a loss.  Or find other ways to replace their lost revenue.  Which they have to.  Because they must have the same capacity available during the day that they have at night.  Even if they aren’t selling as much power during the day as they are at night.  And the last thing they want to do is buy excess power back from homeowners with solar panels on their house when they’re producing their own power that they can’t sell.

Baseload power plants like coal and nuclear take time to bring on line.  They have to produce the heat that boils water into steam.  Then superheat the steam to remove all water from it.  So the steam can spin the generator turbines without damaging the vanes on the turbine.  And once they start these plants up they run these systems at full capacity where they produce power most cost-efficiently.  During peak demand they may bring on some gas-fired turbines that can start and produce power quickly.  And add them to the grid.  When the peak subsides they can shut down these gas-fired turbines and let the baseload generation carry the remaining load.

The Spanish government invested heavily into solar power for whatever reason.  It’s ‘free’ power.  It’s ‘clean’ power.  Or it was just a good way to create a lot of jobs.  But what Spain has now is a surplus of peak power generation during the day that doesn’t eliminate the need to maintain baseload power generation during the day.  Creating a surplus of electric power during the day no one wants.  While requiring power companies to maintain their baseload power during the day so they can provide power at night.  Incurring great costs on the power companies.  Which must be passed on to the same people who paid for the renewable energies subsidies.  The electric power consumer.

This is a classic example of a Hayekian malinvestment.  Friedrich Hayek of the Austrian school of economics said this is what happens when governments interfere with free markets.  They make investments to produce what they think is best while the market demands something else.  The market demanded low-cost electric power.  Which baseload power plants (coal and nuclear) provided.  But the government intervened and subsidized the more costly solar power.  This bad investment—or malinvestment—has only increased the cost of electric power for the Spanish consumer.  And now the Spanish have a big problem on their hands.  What to do with this surplus of peak power no one wants to pay for?  And how to replace the lost revenue of the power companies so they can cover their costs?  Two problems they didn’t have until the government intervened into the free market.


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Environmentalists are Killing Birds with their Big Spinning Wind Turbine Killing Machines

Posted by PITHOCRATES - June 29th, 2013

Week in Review

Wind turbines are bird killers.  As their large blades slice through the air.  Chopping anything that is unfortunate enough to get in the way of those large, heavy, rotating blades.  Birds die flying into these killing machines whether they’re part of a large wind farm.  Or just one solitary wind turbine providing green energy to save the planet (see Rare white-throated needletail bird dies after flying into wind turbine off coast of Scotland by Euan Stretch posted 6/28/2013 on the Mirror).

Hundreds of twitchers travelled the length of the country to see the “bird of the century” – only for it to fly into a wind turbine and die.

Bird-spotters were ecstatic about the first UK sighting of the rare white-throated needletail since 1991.

But their excitement soon turned to horror when it hit the 120ft structure’s rotating blades…

The bird’s body has since been handed over to local conservationists.

James, 38, was joined by fellow twitcher Mark Batten, 49, who said wind turbines were a serious danger for birds.

He added: “This wasn’t even a turbine on a huge wind farm, it was a solitary turbine to provide power to a small community.

“There is huge concern in Scotland about plans for big wind farms and the danger they would pose to big birds of prey like golden eagles and sea eagles…

Website recorded the death today and said it was “widely dubbed the bird of the century”.

It’s rather ironic, really.  The environmentalists won’t let firefighters cut firebreaks in forests because it may disturb the forest habit of the spotted owl.  Or the kangaroo rat.  And farmers can’t irrigate their land in California’s Central Valley because delta smelt are getting sucked up into irrigation pumps.  So they shut the pumps down.  And interrupt our food supply.  So something else way down the food chain can eat and procreate.  For these are endangered species.  Protected by the federal government.  So forest habitats burn down.  Killing these forest dwellers wholesale.  Destroying homes.  As well as killing people.  Just so we don’t disturb their environment.

These same environmentalists are pushing to reduce greenhouse emissions to save the environment.  So their beloved creatures can frolic on a pristine planet.  Unspoiled by man.  So they push for more wind energy.  Things with moving parts that can and do kill birds.  While the coal-burning power plants sit there with no moving parts that are a hazard to flying birds.  It is even not that uncommon for a bird to enter a power plant through a broken window to build a nest out of the elements.  That’s how dangerous these plants are to the birds.

There is no manmade global warming.  At least none that we can’t explain away by other means.  The environmentalists have been predicting since the Nineties that if we don’t act right now it will be too late to save ourselves from manmade global warming.  That the dying would only be years away.  And here we are.  Some 3 decades away and still living strong.  Even going through a cooling period.  Thanks to the Pacific Decadal Oscillation (PDO).  Warming and cooling cycles of the oceans (due to sunspot activity) redirecting the low-level jet stream.  Which real scientists have actually found the historical record supports.  Unlike those models that project doom and gloom if we don’t act right now.  Because 5 minutes from now will be just too late.


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Wind Power is both Costly to Build and to Maintain

Posted by PITHOCRATES - December 9th, 2012

Week in Review

Green energy enthusiasts love wind power.  For they think it’s free and as good and reliable a source of electric power as is coal.  Because you don’t have to buy wind.  It’s just there for the taking.  As long as the wind is blowing.  But wind power isn’t free power.  For one you have to build a lot of wind turbines to get close to what a coal-fired power plant can generate.  Covering acres of land (or water).  That’s a lot of moving parts that someone has to maintain.  And a lot of gearboxes to wear out (see Deval-ued Wind Power by Kevin D. Williamson posted 12/3/2012 on National Review Online).

Last September in the tiny town of Princeton, Mass., the general manager of the local utility authority sent out an extraordinary little memo that is one part standard bureaucratic posterior-covering and one part cry for help, noting that a modest wind-energy project already has lost nearly $2 million — a whopping number for a community of only 3,413…

“As best I can look into the future,” general manager Brian Allen wrote, “I would expect the wind turbine losses to continue at the rate of around $600,000 a year. This assumes current wholesale electricity rates, no need for extraordinary repairs, and that both turbines continue operating. If any major repairs are required, this will be an additional expense for the PMLD. The original warranties on the turbines have expired, and extended warranty options are not available.”

Those warranties are an acute concern: After becoming operational in 2010, one of Princeton’s two wind turbines broke down in August 2011 and was not back online until nearly a year later. Princeton had a warranty from the turbine’s manufacturer, the German firm Fuhrländer, but the usual political cluster of agents and subcontractors meant that the whole mess still is in litigation. If Princeton does not prevail in its lawsuit, it will suffer hundreds of thousands of dollars in additional expenses. The cost of replacing a gearbox on one of the Fuhrländer turbines is estimated at $600,000.

Those breakdowns are real concerns. According to the trade publication, Wind Energy Update, the typical wind turbine is out of commission more than 20 percent of the time — and regularly scheduled maintenance accounts for only 0.5 percent of that downtime. The group also estimates that some $40 billion worth of wind turbines will go out of warranty by the end of 2012, leaving the Princetons of the world looking at a heap of expensive repair bills. In Europe, the largest wind-energy market, operations-and-maintenance expenses already are running into billions of dollars a year.

So, if you have a wind farm with let’s say 600 wind turbines that would be approximately $360 million to replace all of those gearboxes.  But if they’re lucky enough to only have to replace 20% each year that’s only $72 million a year.  That’s a lot of money for ‘free’ electricity from the wind.  Especially when you consider routine maintenance comes in at around $600,000 a year.  And even that number is a lot higher than anyone dreamed it would be for free electricity.

The truth is this.  Wind power isn’t free.  It’s very, very expensive.  And this for generating equipment that is offline 20% of the time.  Worse, for those that are online their capacity factor is only about 30%.  Meaning that over a period of time a wind farm will provide only about 30% of their nameplate capacity.  So not only is this power costly but it is intermittent.  Which is why no one builds wind farms without massive government subsidies.  As they are about the worst energy investment anyone can make.  With the only way of funding these projects is by bleeding the taxpayers dry.

It’s different with coal.  Green governments have to impose costly regulations to try and shut down coal-fired power plants.  Because they are such a good energy investment the only way they can stop the free market from building and operating them is reducing the return on investment through costly regulation.  Which increases our electric bills.  So with coal money flows from the power producers to the government.  And we get less expensive electricity.  For wind power money flows from the government to the power producers.  And we get more costly electricity.  Which makes no sense whatsoever for the taxpayer.  But it makes a lot of sense if you’re getting campaign contributions from your friends in green energy.


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Wind Power cannot work in the Free Market without Massive State Subsidies

Posted by PITHOCRATES - December 9th, 2012

Week in Review

A typical size of a wind turbine is around 3 megawatts.  Whereas a typical steam turbine (the kind spun by a coal-fired power plant) can be as big as 500 megawatts.  So you would need about 167 wind turbines to produce the output of one steam turbine.  But even then they won’t produce the same amount of useable power.  Because the wind doesn’t blow all of the time.  Making wind power a very expensive, intermittent power.  So expensive that no free market solution exists.  Which is why the government heavily subsidizes wind power (see 7 Myths About the Wind Production Tax Credit by David Kreutzer, Ph.D., posted 12/4/2012 on The Foundry).

The wind production tax credit (PTC) has created an industry that produces overpriced, intermittent power, and it will continue to produce overpriced, intermittent power so as long as there is a PTC to pay for it…

… if wind were already cheaper, then it could compete right now. If it is on the verge, then wind-power producers could enter into long-term contracts (which they already do) that would allow them to recoup their investments in the near future when wind will supposedly be so cheap. Neither case argues for subsidies…

The legislation in force has been very clear ever since it was written: Wind turbines put in place by December 31, 2012, qualify for 10 years of production tax credits. Windmills placed in service this year will continue to receive credits—which are worth 40 percent or more of the wholesale value of electricity—for every kilowatt-hour generated until 2022…

Subsidies may well provide jobs and income for those receiving the subsidies, but, as the Spanish experience illustrates, whatever job-creating mechanism the subsidies put in play is offset by running this same mechanism in reverse elsewhere: Financing the subsidies requires taxing other parts of the economy.

A 40 percent or more subsidy?  Anyone that needs a 40% subsidy to stay in business shouldn’t be in business.  That’s a lot of money pulled out of the private sector to produce substandard electric power.  If we went with reliable electric power from coal-fired power plants we wouldn’t need to pull a 40% subsidy from the private sector.  And the power would be first-rate.  Whether the wind blows or not.  Which is why coal-fired power plants work in a free market economy.  And wind power does not.


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Windmills, Rotational Energy, Wing, Lift, Rotary Wing, Angle of Attack, Variable-Pitch Propellers, Drag, AC Power and Wind Turbine

Posted by PITHOCRATES - June 27th, 2012

Technology 101

When an Aircraft Rotates for Takeoff it increases the Angle of Attack of the Wing to Create more Lift

Early windmills turned when the wind pushed a sail or vane.  Thereby converting wind energy into rotational energy.  Mechanical linkages and shafts transferred this rotational motion to power a mill.  Or pump water.  As well as an assortment of other tasks.  Whatever the task it was important to regulate the speed at which the shaft rotated.  Which meant turning the windmill into the wind.  And adjusting the amount of sail catching the wind.  Much like on a sailing ship.  At first by shutting the windmill down and manually adjusting the sails.  Then later automating this process while the windmill was turning.  If the winds were too strong they’d lock the windmill to prevent it from turning.  To prevent damaging the windmill.

They regulated the speed to protect the equipment attached to the windmill, too.  To prevent a mill stone from spinning too fast.  Risking damage to it.  And harm to the people working with the equipment.  Or to protect a water pump form pumping too fast.  Even the small farm windmills had over-speed protection.   These sat atop a well.  The windmill drove a small piston to pump the water up the well shaft.  To prevent this windmill from flying apart in high winds over-speed features either furled the blades or rotated the windmill parallel to the wind.  Shutting the pump down.

But wind just doesn’t push.  It can also lift.  A lateen (triangular) sail on a sailing vessel is similar to an aircraft wing.  The leading edge of the sail splits the wind apart.  Part of it fills the sail and pushes it.  Bowing it out into a curved surface.  The wind passing on the other side of the sail travels across this curved surface and creates lift.  Similar to how a wing operates during takeoff on a large aircraft.  With the trailing edge flaps extended it creates a large curve in the wing.  When the aircraft rotates (increasing the angle of attack of the wing) to take off wind passing under the wing pushes it up.  And the wind travelling over the wing pulls it up.  These lift forces are so strong that planes carry their fuel in the wings and mount engines on the wing to keep the wings from bending up too much from these forces of lift.

A Pilot will Feather the Propeller on a Failed Engine in Flight to Minimize Drag 

When an aircraft carrier launches its aircraft it turns into the wind.  To maximize the wind speed travelling across the wings of the aircraft.  For the faster the wind moves across the wing the great lift it creates.  Commercial airports don’t have the luxury of turning into the wind.  So they lay their runways out to correspond to the prevailing wind directions.  As weather systems move through the region they often reverse the direction of the wind.  When they do planes take off in the other direction.  If the winds are somewhere in between these two extremes some airports have another set of runways called ‘crosswind’ runways.  Or trust in the highly skilled pilots flying out of their airports to adjust the control surfaces on their planes quickly and delicately to correct for less than optimal winds.

Helicopters don’t have this problem.  They can take off facing in any direction.  Because that big propeller on top is a rotary wing.  Or rotor.  A fixed wing airplane needs forward velocity to move air over their wings to create lift.  A helicopter moves air over its rotary wing by spinning it through the air.  To create lift the pilot tilts the rotor blades to change their angle of attack.  And tilts the whole rotor in the direction of travel.  The helicopter’s engine runs at a constant RPM.  To increase lift the angle of attack is increased.  This also creates drag that increases the load on the engine, slowing it down.  So the pilot increases the throttle of the engine to return the rotor to that constant RPM.

Propeller-powered airplanes also have variable-pitch propellers.  To create the maximum possible lift at the lowest amount of drag.  So it’s not just engine speed determining aircraft speed.  When running up the engines while on the ground the pilot will feather the propellers.  So that the blade pitch is parallel to the airflow and moves no air.  This allows the engines to be run up to a high RPM without producing a strong blast of air behind it.  A pilot will also feather the prop on a failed engine in flight to minimize drag.  Allowing a single-engine plane to glide and a multiple engine plane to continue under the power of the remaining engines.  A pilot can even reverse the pitch of the propeller blades to reverse the direction of airflow through the propeller.  Helping planes to come to a stop on short runways.

By varying the Blade Pitch for Different Wind Speeds Wind Turbines can Maintain a Constant RPM

Thomas Edison developed DC electrical power.  George Westinghouse developed AC electrical power.  And these two went to war to prove the superiority of their system.  The War of the Currents.  Westinghouse won.  Because AC is economically superior.  One power plant can power a very large geographic area.  Because alternating current (AC) works with transformers.  Which stepped up voltages for long-distance power transmission.  And then stepped them back down to the voltages we use.  Power equals voltage times current.  Increasing the voltages allows lower currents.  Which allows thinner wires.  And fewer generating plants.  Which saves money.  Hence the economic superiority of AC power.

Alternating current works with transformers because the current alternates directions 60 times a second (or 60 cycles or hertz).  Every time the currents reverse an electrical field collapses in one set of windings of a transformer, inducing a voltage in another set of windings.  A generator (or, alternator) creates this alternating current by converting rotational energy into electrical energy.  Which brings us back to windmills.  A source of rotational energy.  Which we can also use to generate electrical energy.  But unlike windmills of old, today’s windmills, or wind turbines, turn from lift.   The wind doesn’t push the blades.  The wind passes over them producing lift.  Like on a wing.  Pulling them into rotation.

The typical wind turbine design is a three-bladed propeller attached to a nacelle sitting on top of a tall pylon.  The nacelle is about as large as a big garden shed or a small garage.  Inside the nacelle are the alternator and a gearbox.  And various control equipment.  Like windmills of old wind turbines still have to face into the wind.  We could do this easily and automatically by placing the propeller on the downwind side of the nacelle.  Making it a weathervane as well.  But doing this would put the pylon between the wind and the blades.  The pylon would block the wind causing uneven loading on the propeller producing vibrations and reducing the service life.  So they mount the propeller on the upwind side.  And use a complex control system to turn the wind turbine into the wind.

When it comes to electrical generation a constant rotation is critical.  How does this happen when the wind doesn’t blow at a constant speed?  With variable-pitched blades on the propeller.  By varying the blade pitch for different wind speeds they can maintain a constant number of revolutions per minute (RPM).  For a limited range of wind conditions, that is.  If the wind isn’t fast enough to produce 60 hertz they shut down the wind turbine.  They also shut them down in high winds to prevent damaging the wind turbine.  They can do this by feathering the blades.  Turning the propeller blades parallel to the wind.  Or with a mechanical brake.  The actual rotation of the propeller is not 60 cycles per second.  But it will be constant.  And the gearbox will gear it up to turn the alternator at 60 cycles per second.  Allowing them to attach the power they produce to the electric grid.


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