You just can’t Replace a Coal-Fired Power Plant with a Solar Farm

Posted by PITHOCRATES - March 23rd, 2014

Week in Review

What’s unique about Windsor, Ontario?  The city across the river from Detroit?  It’s the only place you can drive south from the United States to get to Canada.  So it’s about as far south you can get in Canada.  But it’s no Florida.  No.  They have cold winters in Windsor.  They also have snow.  And clouds.  So it’s probably not the best place to build a solar farm.  Any rational person would see this.  So guess what the government in southern Ontario is doing?  Building a solar farm (see Airport land leased for Samsung solar farm by Chris Vander Doelen posted 3/19/2014 on The Windsor Star).

A “major” developer of solar power will lease hundreds of acres at Windsor Airport for a green energy farm, city council has agreed after years of negotiations with the company…

He said the company picked Windsor as the site for its investment because “we have more sun days than any other jurisdiction in Ontario.” That clearly suggests a solar farm, but Francis wouldn’t confirm that…

The agreement approved Wednesday – the meeting was closed to the public for legal reasons, Francis said – is believed to be the final, long-delayed piece of a massive deal the Province of Ontario and Samsung announced in January 2010.

That’s when former premier Dalton McGuinty announced that the province had signed a $7-billion agreement to produce renewable power with the Korean industrial giant – a contract that became so controversial parts of it were later renegotiated…

But the deal also became controversial as the costs starting driving up residential and industrial power bills, all of which will be affected by the renewable energy plan.

The controversy eventually led to reductions in some of the feed-in tariffs paid to producers of solar and wind power, which likely added to the delays of the solar farm not announced until this week. It also led to the renegotiation of additional incentives for Samsung, which were reduced to $110 million over 20 years…

Installation of the panels would generate many years of employment for an undetermined number of labourers and IBEW electricians. But once built there wouldn’t be much employment generated by the static field of passive solar collectors.

The solar farms were to be part of something called the Ontario Alternative Energy Cluster, claimed by Samsung to be “the largest of its kind in the world” at 1,369 megawatts of output.

They may have more sun days in Windsor than any place else in Canada.  But Canada is a northern country.  Even Windsor is in a northern clime.  And they just don’t get as much sun as they do in more southern climes (see The Climate and Weather of Windsor, Ontario).  In the sunniest month they have 9.5 average hours of sun per day.  Which means they have 14.5 (24-9.5) average hours of no sun per day.  And during these hours of ‘no sun’ a solar farm will not produce electric power.  Which means on average this solar farm will produce no electric power for half of the day.

And it gets worse.  The average hours of sun per day declines going into winter.  October (5.5 hours of sun and 18.5 hours of no sun).  November (4.1 hours of sun and 19.9 hours of no sun).  December (2.6 hours of sun and 21.4 hours of no sun).  January (3.4 hours of sun and 20.6 hours of no sun).  February (4.4 hours of sun and 19.6 hours of no sun).  March (5.4 hours of sun and 18.6 hours of no sun).  So, on average, there are 5 hours of no sun for every hour of sun for half of the year.  So you can install solar panels that could produce 1,369 megawatts of output.  But they seldom will.  So you will need another power source to provide electric power when the solar panels don’t.  Which means a solar farm can’t replace something like a coal-fired power plant.  For that coal-fired power plant will have to on average provide power 82% of the time.  Which is why building a solar farm is a real bad idea.

And it gets even worse.  December has 10 days of snowfall on average.  January has 12.  And February has 9.  Just under half the days in the winter months will have snow which will have to melt off when the sun comes out from behind the clouds.  If it comes out.  Or someone will have to clear the snow from the solar panels by hand.

Windsor also has some other climate statistics (see National Climate Data and Information Archive).  They have the most thunderstorm days.  So they have more high winds, hail and tornados to damage delicate solar panels pointed skyward than any other part of Canada.  And more black overcast days to block out the sun.  They have the most smoke and haze days to filter out some of the sun from hitting the solar panels.  They have the most humid summer which will coat the solar panels with early morning dew that will run down and drain off in blackened streaks.  Reducing the efficiency of the solar panels.

This is why no one is building solar farms without taxpayer subsidies.  Which raises the cost of electric utility bills to pay for the subsidies.  Eating into household budgets forcing families to get by on less.  And for what?  You can’t shut down a coal-fired power plant during the day and turn it back on at night.  It takes time to make high pressure steam.  That’s why they use these plants for baseload power.  They’re on all the time.  And when demand picks up they add a natural gas-fired turbine ‘peaker plant’ to provide that peak demand.  Or some other source that they can bring on line quickly.  Like another turbine at a hydroelectric dam.  So the good people of Ontario will pay more for their electric power without getting anything in return.  Not even a cleaner environment.  Because you just can’t replace a coal-fired power plant with a solar farm.

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Wind Power for the People and Fossil Fuel for Gold Mines and Hospitals

Posted by PITHOCRATES - December 1st, 2013

Week in Review

Energy firm RWE just backed out of a £4 billion ($6.6 billion) offshore wind farm.  The Atlantic Array project in the Bristol Channel.  Because of higher than expected costs.  And lower than expected government subsidies.  Meanwhile a new power plant was delivered in the Dominican Republic this year.  A nation that shares an island with Haiti surrounded by the Atlantic Ocean and the Caribbean Sea.  With a lot of sea wind to spin wind turbines.  Just as they filled the sails of the colonial powers’ ships centuries ago.  But they didn’t build a wind farm (see Quisqueya I & II, Dominican Republic posted on Wärtsilä).

Sometimes, one plus one does not equal two. The 25,000 inhabitants of Quisqueya, a small town close to San Pedro de Macorís, in the Dominican Republic, know so.

In September 2011, Barrick Gold Corporation acquired a majority share in a soon-to-be-opened gold mine, some 100 kilometres away from the Dominican capital, Santo Domingo. As soon as the mining company understood the needs of their new power-hungry mine, they decided to place an order for a state-of-the-art Wärtsilä power plant. The way in which Barrick, its host country and Wärtsilä would cooperate for the greater good came to exceed the initial expectations of any of the three involved parties and strike gold in an unforeseen way.

The Quisqueya project is a rare combination of two power plants. Due to clever project design it satisfies not only the gold mine’s power needs, but also those of the local population, who often deals with blackouts and an unstable power grid. The dual function came to be as the largest utility in the country, EGE Haina, decided to jump on the boat of efficient and  reliable power generation, turning the initial project to a synergetic effort where the total value exceeds the sum of its parts.

While Quisqueya I is owned and used by Barrick Gold, its twin sister Quisqueya II is run by EGE Haina. Although ordered by different parties, the plants are being built on the same site and together form the largest power plant complex in the world ever delivered by Wärtsilä at the time of the order, setting a new standard for the 21st century power plants. As an outsider, you cannot clearly draw a line between the power supplied to the mine and that supplied to the local community, nor between the corporate profit and the social one. Quisqueya I & II is a beautiful example of how a sensible and responsible utilization of natural resources can directly improve a community’s way of life.

Both Quisqueya plants will feature Wärtsilä Flexicycle™ combined cycle technology and operate on 12 Wärtsilä 50DF dual-fuel engines each. The primary fuel is to be natural gas with liquid fuel as back-up, and the combined output from the two plants will be 430 MW. Wärtsilä’s scope of supply for the Quisqueya power plant includes full engineering, procurement, and construction (EPC). The power plant will have a net efficiencyof 48 %, which is an astonishingly high figure in tropical conditions, with soaring humidity and temperatures above 35°C.

Lucky are the people living near this power-hungry gold mine.  Because it gets top of the line electric power.  That furnished by fossil fuels.  Which can burn no matter what the winds are doing.  Keeping this gold mine in operation.  And giving the people around it reliable electric power.  And if the winds stop blowing these people will still have their power.  And if a hurricane blows through it may down some power lines.  Which can be replaced to restore electric power.  Whereas if a hurricane takes out an offshore wind farm power will be out a lot longer.  Either until they rebuild those very expensive wind turbines (probably requiring huge green tariffs to cover the costs of building this wind farm twice).  Or until they build a new power plant that uses a fossil fuel.

Interesting when a power plant is to power a million homes like the Atlantic Array project in the Bristol Channel a government looks to spend $6.6 billion for unreliable power.  But when a power plant is furnishing something that produces revenue and economic output they don’t build a wind farm power plant.  No, when they need to count on that electric power to be there they turn to fossil fuels.  For the same reason hospitals don’t put wind turbines on their roof for backup electric power during a blackout.  They use backup generators that burn a fossil fuel.  Because they need to count on that electric power to be there.

Fossil fuel is reliable.  While wind power is not.  Which is why governments use fossil fuels for gold mines and hospitals.  And wind power for the people.  Because governments can screw the people to meet silly green power targets with little blowback.  Because, hey, it’s for the environment.

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After Fukushima Meltdown shuts down Nuclear Power Industry Japan turns to Solar Power

Posted by PITHOCRATES - November 10th, 2013

Week in Review

Japan shows how easy it is to go green after the Fukushima Nuclear Power Plant meltdown.  Nuclear power is unsafe.  Coal-fired power plants are too dirty.  So what to do?  Why, go solar, of course (see Kyocera launches 70-megawatt solar plant, largest in Japan by Tim Hornyak posted 11/8/2013 on CNET).

Smartphone maker Kyocera recently launched the Kagoshima Nanatsujima Mega Solar Power Plant, a 70-megawatt facility that can generate enough electricity to power about 22,000 homes.

The move comes as Japan struggles with energy sources as nuclear power plants were shut down after meltdowns hit Tokyo Electric Power Co.’s Fukushima plant in 2011.

Set on Kagoshima Bay, the sprawling Nanatsujima plant commands sweeping views of Sakurajima, an active stratovolcano that soars to 3,665 feet.

It has 290,000 solar panels and takes up about 314 acres, roughly three times the total area of Vatican City.

Wow, 70 megawatts.  Sounds big, doesn’t it?  With 290,000 solar panels on 314 acres.  An installed capacity of 0.22 megawatts per acre.  It must have cost a fortune to build.  And they built it on a bay.  At sea level.  In the shadow of an active volcano.  It would be a shame if that volcano erupts and covers those solar panels in a layer of ash.  Or if another typhoon hits Japan.  An earthquake.  Or a storm surge.  For if any of these things happen those 22,000 homes will lose their electric power.

So how does this compare to the Fukushima Daiichi Nuclear Power Plant?  Well, that plant sits on 860 acres.  And has an installed capacity of 4700 megawatts.  Or the installed capacity of 67 Kagoshima Nanatsujima Mega Solar Power Plants.  And an installed capacity of 5.47 megawatts per acre.  Which is perhaps why they built this on the bay.  Because it is such an inefficient use of real estate in a nation that has one of the highest population densities that they put it on the water.  To save the land for something that has value. 

We used the term ‘installed capacity’ for a reason.  That reason being the capacity factor.  Which is the actual amount of power produced over a given amount of time divided by the maximum amount of power that could have been produced (i.e., the installed capacity).  Nuclear plants can produce power day or night.  Covered in volcanic ash or not.  On a sunny day or when it’s pouring rain.  Which is why a nuclear power plant has a much higher capacity factor (about 90%) than a solar plant (about 15%).  So the actual power people consume from the Kagoshima Nanatsujima Mega Solar Power Plant will be far less than its 70 megawatts of installed capacity.

So in other words, solar power is not a replacement for nuclear power.  Or any other baseload power such as coal-fired power plants.  Power demand will far exceed power supply.  Leading to higher costs as they try to ration electric power.  And a lot of power outages.  Some longer than others.  Especially when powerful typhoons and/or storm surges blow in.  As they often do in the Pacific Ocean.

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Green Energy Policies raise the Cost of Heating this Winter in Canada

Posted by PITHOCRATES - October 19th, 2013

Week in Review

‘Manmade’ global warming is not science.  It’s politics.  Where those on the left secure their liberal base by pushing costly green energy policies that increase our electric bills (see Ontario electricity rates rising due to Liberal mistakes, opposition says posted 10/18/2013 on CBC News Toronto).

The governing Liberals’ politically motivated interference in the energy sector is hurting ratepayers who are trying to conserve electricity, Ontario’s opposition parties said Friday…

The price for off-peak power will rise by 7.5 per cent for a kilowatt hour, while peak hour rates will rise by four per cent, the board announced Thursday…

It’s another sign that the energy system under the Liberals has become an “expensive mess,” said Progressive Conservative Leader Tim Hudak.

Cancelling two gas plants in Oakville and Mississauga — which the province’s auditor general says will cost taxpayers up to $1.1 billion — to save Liberal seats is driving up prices, he said, just like putting wind turbines in communities that don’t want them, then paying to get rid of the surplus power…

The OEB said the Nov. 1 increase is based on estimates for the coming year that include more generation from renewable sources along with a higher price for natural gas.

Sunlight and wind may be free.  But the massive infrastructure to pull the energy from sunlight and wind is not.  That infrastructure is very, very costly.  Because you need a lot of it to produce useable energy.  Unlike a coal-fired or gas-fired power plant.  These plants are very costly.  But they produce so much electric power that the cost per unit of power produced is negligible.  The fuel (coal and natural gas) being the greater cost.   Of course, that’s only when they are running at capacity and people are buying what they produce.

Those two power plants would have produced inexpensive electric power.  Now not only are they going to be replaced with renewable sources the cost of that massive renewable infrastructure has to be added to the people’s hydro (electric utility) bill.  With renewable sources providing a fraction of what coal and gas provide the cost per unit from renewable sources is very high.  Requiring taxpayer subsidies.  And if that wasn’t bad enough because of the intermittent nature of wind those coal-fired and gas-fired power plants have to produce power even when the wind is blowing so it’s there when the wind isn’t.  Creating surplus power.  Very expensive power that no one is buying.

If only manmade global was real.  For if it were we could raise the temperature during the winter so we wouldn’t have to spend so much on costly and polluting power to heat our homes.  Why, the warmer winters would even make it easier for our wildlife to find food.  That’s right.  With manmade global warming everyone would be a winner.  But it’s not.  So we have more and more expensive heating bills to look forward to.

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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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With a Great Trust in Technology Germany may go all Green in Power Generation

Posted by PITHOCRATES - April 7th, 2013

Week in Review

In 2003 one power plant went off line for maintenance in Ohio.  As their electrical load switched over to other power lines the extra current in them caused them to heat up and sag.  Coming into contact with some tall trees.  And the electric power flashed over to the trees.  This surge in current opened some breakers and transferred this electric load to other cables.  Overloading these lines.  More breakers opened.  More lines disconnected.  And with the electric load switching around it caused some electric generators to spin a little wildly.  So they disconnected from the grid as designed to protect themselves.

Eventually this cascade of failures would cause one of the greatest power outages in history.  The Northeast blackout of 2003.  Affecting some 55 million people.  And taking 256 power plants offline.  Apparently there was a software bug in the computer control system that didn’t warn them in time to rebalance the grid on other power sources before this cascade of failures began.  Once the event was over it took a lot of time to bring the power back online.  Three days before all power was restored.  Because you have to reconnect generators slowly and carefully.  As you are connecting generators together.  If these generators are not running in phase with each other fault currents can flow between them.  Damaging them and starting another cascade of failures.

So the electric grid is a very complex network of generators, cables, switches and computer control systems.  The more generation plants added to the grid the more complicated the switching and the computer controls.  Which makes having large-capacity power generation plants highly desirable.  For it reduces the complexity of the system.  And their large power capacity makes it easier for them to take on additional loads when another plant goes offline or a cable fails.  It provides a safe margin of error when trying to balance electric loads between available generation.  In Germany, though, the politics of green energy may take precedence over good engineering practices (see Linked Renewables Could Help Germany Avoid Blackouts by Paul Brown and The Daily Climate posted 4/5/2013 on Scientific American).

Critics of renewables have always claimed that sun and wind are only intermittent producers of electricity and need fossil fuel plants as back-up to make them viable. But German engineers have proved this is not so.

By skillfully combining the output of a number of solar, wind and biogas plants the grid can be provided with stable energy 24 hours a day without fear of blackouts, according to the Fraunhofer Institute for Wind Energy and Energy System Technology (IWES) in Kassel.

For Germany, having turned its back on nuclear power and investing heavily in all forms of renewables to reduce its carbon dioxide emissions, this is an important breakthrough…

Kurt Rohrig, deputy director of IWES, said: “Each source of energy – be it wind, sun or biogas – has its strengths and weaknesses. If we manage to skillfully combine the different characteristics of the regenerative energies, we can ensure the power supply for Germany.”

The idea is that many small power plant operators can feed their electricity into the grid but act as a single power plant using computers to control the level of power…

The current system of supplying the grid with electricity is geared to a few large producers. In the new system, with dozens of small producers, there will need to be extra facilities at intervals on the system to stabilize voltage. Part of the project is designed to find out how many of these the country will need.

The project has the backing of Germany’s large and increasingly important renewable companies and industrial giants like Siemans.

If you are a heavy electric power consumer in Germany you might want to build your own power plant on site.  For if they go ahead with this they are going to create one complex and costly monster.  Which is why IWES and Siemens no doubt are on board with this.  For it would give them a lot of business in a recession-plagued Eurozone.  But the amount of switching and computer controls to make this work just boggles the mind.

Just imagine a night of high winds that shuts down all wind farms.  Which is something a wind turbine does to protect itself.  You can’t switch over to solar at night.  So you will have to switch that load over to the remaining power lines that are connected to active generation.  Heating those wires up.  Causing them to sag.  Perhaps flashing over to a tall tree.  If these lines disconnect from the grid will those small producers be able to pick up the demand?  Or will they disconnect to protect themselves from an overload?  Once the event is over how long would it take to bring all of these generation sources back in phase and back online?

If they move forward with this chances are that the Germans are going to learn a very painful and costly lesson about green energy.  It may make you look like you care but it won’t keep the lights on like a coal-fired or a nuclear power plant can.  Which they may learn.  The hard way.

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Electric Power, Alternating Current, Transformers, Magnetic Flux, Turns Ratio, Electric Panel and Circuit Breakers

Posted by PITHOCRATES - February 6th, 2013

Technology 101

AC Power is Superior to DC Power because it can Travel Farther and it Works with Transformers

Thanks to Nikola Tesla and his alternating current electric power we live in the world we have today.  The first electric power was direct current.  The stuff that Thomas Edison gave us.  But it had some serious drawbacks.  You needed a generator for each voltage you used.  The low-voltage of telephone systems would need a generator.  The voltage we used in our homes would need another generator.  And the higher voltages we used in our factories and businesses would need another generator.  Requiring a lot of power cables to hang from power poles along our streets.  Almost enough to block out the sun.

Another drawback is that direct currents travel a long way.  And spend a lot of time moving through wires.  Generating heat.  And dropping some power along the way due to the resistance in the wires.  Greatly minimizing the area a power plant can provide power to.  Requiring many power plants in our cities and suburbs.  Just imagine having three coal-fired power plants around your neighborhood.  The logistics and costs were just prohibitive for a modern electric world.  Which is why Thomas Edison lost the War of Currents to Nikola Tesla.

So why is alternating current (AC) superior to direct current (DC) for electric power?  AC is more like a reciprocating motion in an internal combustion engine or a steam locomotive.  Where short up & down and back & forth motion is converted into rotation motion.  Alternating current travels short distances back and forth in the power cables.  Because they travel shorter distances in the wires they lose less power in power transmission.  In fact, AC power lines can travel great distances.  Allowing power plants tucked away in the middle of nowhere power large geographic areas.  But there is another thing that makes AC power superior to DC power.  Transformers.

The Voltage induced onto the Secondary Windings is the Primary Voltage multiplied by the Turns Ratio

When an alternating current flows through a coiled wire it produces an alternating magnetic flux.  Magnetic flux is a measure of the strength and concentration of the magnetic field created by that current.  When this flux passes through another coiled wire it induces a voltage on that coil.  This is a transformer.  A primary and secondary winding where an alternating current applied on the primary winding induces a voltage on the secondary winding.  Allowing you to step up or step down a voltage.  Allowing one generator to produce one voltage.  While transformers throughout the power distribution network can produce the many voltages needed for doorbells, electrical outlets in our homes and the equipment in our factories and businesses.  And any other voltage for any other need.

We accomplish this remarkable feat by varying the number of turns in the windings.  If the number of turns is equal in the primary and the secondary windings then so is the voltage.  If the number of turns in the primary windings is greater than the number of turns in the secondary windings the transformer steps down the voltage.  If the number of turns in the secondary windings is greater than the number of turns in the primary windings the transformer steps up the voltage.  To determine the voltage induced onto the secondary windings we divide the secondary turns by the primary turns.  Giving us the turns ratio.  Multiplying the turns ratio by the voltage applied to the primary windings gives us the voltage on the secondary windings.  (Approximately.  There are some losses.  But for the sake of discussion assume ideal conditions.)

If the turns ratio is 20:1 it means the number of turns on the primary windings is twenty times the turns on the secondary windings.  Which means the voltage on the primary windings will be twenty times the voltage on the secondary windings.  Making this a step-down transformer.  So if you connected 4800 volts to the primary windings the voltage across the secondary windings will be 240 volts (4800/20).  If you attached a wire to the center of the secondary coil you can get both a 20:1 turns ratio and a 40:1 turns ratio.  If you measure a voltage across the entire secondary windings you will get 240 volts.  If you measure from the center of the secondary and either end of the secondary windings you will get 120 volts.

The Power Lines running to your House are Two Insulated Phase Conductors and a Bare Neutral Conductor

This is a common transformer you’ll see atop a pole in your backyard.  Where it is common to have 4800-volt power lines running at the top of poles running between houses.  On some of these poles you will see a transformer mounted below these 4800-volt lines.  The primary windings of these transformers connect to the 4800-volt lines.  And three wires from the secondary windings connect to wires running across these poles below the transformers.  Two of these wires (phase conductors) connect to either end of the secondary windings.  Providing 240 volts.  The third wire attaches to the center of the secondary windings (the neutral conductor).  We get 120 volts between a phase conductor and the neutral conductor.

The power lines running to your house are three conductors twisted together in a triplex cable.  Two insulated phase conductors.  And a bare neutral conductor.  These enter your house and terminate in an electric panel.  The two phase conductors connect to two bus bars inside the panel.  The neutral conductor connects to a neutral bus inside the panel.  Each bus feeds circuit breaker positions on both sides of the panel.  The circuit breaker positions going down the left side of the panel alternate between the two buss bars.  Ditto for the circuit breaker positions on the right side.

A single-pole circuit breaker attaches to one of the bus bars.  Then a wire from the circuit breaker and a wire from the neutral bus leave the panel and terminate at an electrical load.  Providing 120 volts to things like wall receptacles where you plug things into.  And your lighting.  A 2-pole circuit breaker attaches to both bus bars.  Then two wires from the circuit breaker leave the panel and attach to an electrical load.  Providing 240 volts to things like an electric stove or an air conditioner.  Then a reciprocating (push-pull) alternating current runs through these electric loads.  Driven by the push-pull between the two bus bars.  And between a bus bar and the neutral bus.  Which is driven by the push-pull between the conductors of the triplex cable.  Driven by the push pull of secondary windings in the transformer.  Driven by the push-pull of the primary windings.  Driven by the push-pull in the primary cables connected to the primary windings.  And all the way back to the push-pull of the electric generator.  All made possible thanks to Nikola Tesla.  And his alternating current electric power.

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Electricity, Heat Engine, Superheated Dry Steam, Coal-Fired Power Plant, Geothermal Power Plant and Waste-to-Energy Plant

Posted by PITHOCRATES - November 7th, 2012

Technology 101

(Originally published August 1, 2012)

Geothermal Power Plants and Waste-to-Energy Plants each produce less than Half of 1% of our Electricity

We produce the majority of our electricity with heat engines.  Where we boil water into steam to spin a turbine.  Or use the expanding gases of combustion to spin a turbine.  The primary heat engines we use are coal-fired power plants, natural gas-power plants and nuclear power plants.  The next big source of electricity generation is hydroelectric.  A renewable energy source.  In 2011 it produced less than 8% of our electricity.  These sources combined produce in excess of 95% of all electricity.  While renewable energy sources (other than hydroelectric) make up a very small percentage of the total.  Wind power comes in under 3%.  And solar comes in at less than 0.2% of the total.  So we are a very long way from abandoning coal, natural gas and nuclear power.

Two other renewable energy sources appear to hold promise.  Two heat engines.  One powered by geothermal energy in the earth.  The other by burning our garbage.  In a waste-to-energy plant.  These appear attractive.  Geothermal power appears to be as clean as it gets.  For this heat isn’t man-made.  It’s planet-made.  And it’s just there for the taking.  But the taking of it gets a little complicated.  As is burning our trash.  Not to mention the fact that few people want trash incinerators in their neighborhoods.  For these reasons they each provide a very small percentage of the total electric power we produce.  Both coming in at less than half of 1%.

So why steam?  Why is it that we make so much of our electrical power by boiling water?  Because of the different states of matter.  Matter can be a solid, liquid or a gas.  And generally passes from one state to another in that order.  Although there are exceptions.  Such as dry ice that skips the liquid phase.  It sublimates from a solid directly into a gas.  And goes from a gas to a solid by deposition.  Water, though, follows the general rule.  Ice melts into water at 32 degrees Fahrenheit (or 0 degrees Celsius).  Or water freezes into ice at the same temperature.  Water vaporizes into steam at 212 degrees Fahrenheit (or 100 degrees Celsius).  Or steam condenses into water at the same temperature.  These changes in the state of matter are easy to produce.  At temperatures that we can easily attain.  Water is readily available to vaporize into steam.  It’s safe and easy to handle.  Making it the liquid of choice in a heat engine.

Today’s Coal-Fired Power Plant pulverizes Coal into a Dust and Blows it into the Firebox

A given amount of water will increase about 1600 times in volume when converted to steam.  It’s this expansion that we put to work.  It’s what pushed pistons in steam engines.  It’s what drove steam locomotives.  And it’s what spins the turbines in our power plants.  The plumes of steam you see is not steam, though.  What you see is water droplets in the steam.  Steam itself is an invisible gas.  And the hotter and drier (no water) it is the better.  For water droplets in steam will pit and wear the blades on a steam turbine.  Which is why the firebox of a coal-fired plant reaches temperatures up to 3,000 degrees Fahrenheit (about 1,650 degrees Celsius).  To superheat the steam.  And to use this heat elsewhere in the power plant such as preheating water entering the boiler.  So it takes less energy to vaporize it.

To get a fire that hot isn’t easy.  And you don’t get it by shoveling coal into the fire box.  Today’s coal-fired power plant pulverizes coal into a dust and blows it into the firebox.  Because small particles can burn easier and more completely than large chunks of coal.  As one fan blows in fuel another blows in air.  To help the fire burn hot.  The better and finer the fuel the better it burns.  The better the fuel burns the hotter the fire.  And the drier the steam it makes.  Which can spin a turbine with a minimum of wear.

In a geothermal power plant we pipe steam out of the ground to spin a turbine.  If it’s hot enough.  Unfortunately, there aren’t a lot of geothermal wells that produce superheated dry steam.  Which limits how many of these plants we can build.  And the steam that the planet produces is not as clean as what man produces.  Steam out of the earth can contain a lot of contaminants.  Requiring additional equipment to process these contaminants out.  We can use cooler geothermal wells that produce wet steam but they require additional equipment to remove the water from the steam.  The earth may produce heat reliably but not water.  When we pipe this steam away the wells can run dry.  So these plants require condensers to condense the used steam back into water so we can pump it back to the well.  A typical plant may have several wells piped to a common plant.  Requiring a lot of piping both for steam and condensate.  You put all this together and a geothermal plant is an expensive plant.  And it is a plant that we can build in few places.  Which explains why geothermal power makes less than half of 1% of our electricity.

We generate approximately 87% of our Electricity from Coal, Natural Gas and Nuclear Power

So these are some the problems with geothermal.  Burning trash has even more problems.  The biggest problem is that trash is a terrible fuel.  We pulverize coal into a dust and blow into the firebox.  This allows a hot and uniform fire.  Trash on the other hand contains wet mattresses, wet bags of grass, car batteries, newspapers and everything else you’ve ever thrown away.  And if you ever lit a campfire or a BBQ you know some things burn better than other things.  And wet things just don’t burn at all.  So some of this fuel entering the furnace can act like throwing water on a hot fire.  Which makes it difficult to maintain a hot and uniform fire.  They load fuel on a long, sloping grate that enters the furnace.  Mechanical agitators shake the trash down this grate slowly.  As the trash approaches the fire it heats up and dries out as much as possible before entering the fire.  Still the fire burns unevenly.  They try to keep the temperature above 1,000 degrees Fahrenheit (about 538 degrees Celsius) .  But they’re not always successful.

They can improve the quality of the fuel by processing it first.  Tearing open bags with machinery so people can hand pick through the trash.  They will remove things that won’t burn.  Then send what will burn to a shredder.  Chopping it up into smaller pieces.  This can help make for a more uniform burn.  But it adds a lot of cost.  So these plants tend to be expensive.  And nowhere as efficient as a coal-fired power plant (or nuclear power plant) in boiling water into superheated dry steam.  Also, raw trash tends to stink.  And no one really knows what’s in it when it burns.  Making people nervous about what comes out of their smoke stacks.  You add all of these things up and you see why less than half of 1% of our electricity comes from burning our trash.

This is why we generate approximately 87% of our electricity from coal, natural gas and nuclear power.  Coal and nuclear power can make some of the hottest and driest steam.  But making a hot fire or bringing a nuclear reactor on line takes time.  A lot of time.  So we use these as baseload power plants.  They generate the supply that meets the minimum demand.  Power that we use at all times.  Day or night.  Winter or summer.  They run 24/7 all year long.  Natural gas plants add to the baseload.  And handle peak demands over the baseload.  Because they don’t boil water they can come on line very quickly to pickup spikes in electrical demand.  Hydroelectric power shares this attribute, too.  As long as there is enough water in the reservoir to bring another generator on line.  The other 5% (wind, solar, geothermal, trash incinerators, etc.) is more of a novelty than serious power generation.

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Australia to build 20 Megawatt Solar Farm in Canberra that may Provide 3.6 Megawatts of Useful Electric Power

Posted by PITHOCRATES - September 8th, 2012

Week in Review

Australia is working hard to save the planet.  They’re building a new solar farm that will be the biggest in all of Australia.  Allowing the environmentalists to feel good.  But it will do little if anything (see Canberra to get Aust’s biggest solar farm posted 9/5/2012 on 9NEWS).

International solar power company Fotowatio Renewable Ventures (FRV) will construct and operate the 20 megawatt facility, the ACT Government announced on Wednesday…

ACT Environment Minister Simon Corbell said the solar farm would be able to power 4400 more Canberra homes with only a $13 annual increase to all householder power bills.

Canberra, Australia, is located at about 35° south latitude.  Which puts it between the Tropic of Cancer and the Antarctic Circle.  So the sun never gets directly overhead.  The Tropic of Capricorn at about 23° south latitude (above Canberra) being the cutoff point for that.  Which means Canberra gets about 6 hours or less of sunshine during the months of May, June and July.  The month of December sees about 9.4 hours of sunshine each day.  On average their mean daily sunshine is approximately 32.1% each year (about 7.7 hours of sunshine out of the 24-hour day).  According to the same website linked to above their mean number of clear days averages to about 27.5% each year.

When you factored these together (as well as blowing dirt, bird droppings, etc.) you can understand why the capacity factor for solar power is only about 18% of the total possible output over a period of time.  So that 20 megawatt rated solar power plant may only provide about 3.6 megawatts of useful electric power.  Which would be the equivalent of power for maybe 300 homes (with a 100 amp service at 240 volts).

Their claim of powering 4400 homes is questionable.  If you divide that 20 megawatts by 4400 homes and then divide that number by 120 volts you get 37.88 amps.  Which is just over two fully loaded 20-amp circuits.  Or just over three fully loaded 15-amp circuits.  Take a look in your electric panel in your house and see what that will get you.  If you have a typical panel you probably have 20 circuits.  Divided up between 15-amp and 20-amp circuits.  With maybe a 2-pole breaker (240V) for an electric stove or central air conditioning.  So that 37.88 amps at 120 volts isn’t going to power a lot in anyone’s house.

This new power plant will add to the electric grid during those few daylight hours.  But it will be all fossil fuel-powered plants powering these homes once the sun sets.  Unless they add a lot of equipment to store excess power when the sun does shine to use when it doesn’t shine.  But if a typical house uses more than 37.88 amps at 120 volts (or 18.94 amps at 240 volts) there probably will be no excess power to store.  Meaning this new solar power plant will have little impact on the electric grid.  It will just cost the electrical consumer more.  While making little if any impact to the carbon footprint of their fossil fuel-powered plants.

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Electric Grid, Voltage, Current, Power, Phase Conductor, Neutral Conductor, 3-Phase Power, Transmission Towers and Corona Discharge

Posted by PITHOCRATES - August 15th, 2012

Technology 101

The Electric Grid is the Highways and Byways for Electric Power from the Power Plant to our Homes

Even our gasoline-powered cars operate on electricity.  The very thing that ignites the air-fuel mixture is an electric spark.  Pushed across an air-gap by a high voltage.  Because that’s something that high voltages do.  Push electrons with such great force that they can actually leave a conductor and travel through the air to another conductor.  Something we don’t want to happen most of the time.  Unless it’s in a spark plug in our gasoline engine.  Or in some movie prop in a cheap science fiction movie.

No.  When we use high voltage to push electrons through a conductor the last thing we want to happen is for the electrons to leave that conductor.  Because we spend a pretty penny to push those electrons out of a power plant.  And if we push the electrons out of the conductor they won’t do much work for us.  Which is the whole point of putting electricity into the electric grid.  To do work for us.

The electric grid.  What exactly is it?  The highways and byways for electric power.  Power plants produce electric power.  And send it to our homes.  As well as our businesses.  Power is the product of voltage and current.  In our homes something we plug into a 120V outlet that draws 8 amps of current consumes 960 watts.  Which is pretty big for a house.  But negligible for a power plant generator producing current at 20,000 volts.  For at 20,000 volts a generator only has to produce 0.48 amps (20,000 X 0.48 = 960).  Or about 6% of the current at 120V.

Between our Homes and the Power Plant we can Change that Current by Changing the Voltage

Current is money.  Just as time is money.  In fact current used over time helps to determine your electric bill.  Where the utility charges you for kilowatt hours (voltage X current X time).  (This would actually give you watt-hours.  You need to divide by 1000 to get kilowatt hours.)  The electric service to your house is a constant voltage.  So it’s the amount of current you use that determines your electric bill.  The more current you use the greater the power you use.  Because in the power equation (voltage X current) voltage is constant while current increases.

Current travels in conductors.  The size of the conductor determines a lot of costs.  Think of automobile traffic.  Areas that have high traffic volumes between them may have a very expensive 8-lane Interstate expressway interconnecting them.  Whereas a lone farmer living in the ‘middle of nowhere’ may only have a much less expensive dirt road leading to his or her home.  And so it is with the electric grid.  Large consumers of electric power need an Interstate expressway.  To move a lot of current.  Which is what actually spins our electrical meters.  Current.  However, between our homes and the power plant we can change that current.  By changing the voltage.  Thereby reducing the cost of that electric power Interstate expressway.

The current flowing through our electric grid is an alternating current.  It leaves the power plant.  Travels in the conductors for about 1/120 of a second.  Then reverses direction and heads back to the power plant.  And reverses again in another 1/120 of a second.  One complete cycle (travel in both directions) takes 1/60 of a second.  And there are 60 of these complete cycles per second.  Hence the alternating current.  If you’re wondering how this back and forth motion in a wire can do any work just think of a steam locomotive.  Or a gasoline engine.  Where a reciprocating (back and forth) motion is converted into rotational motion that can drive a steam locomotive.  Or an automobile.

The Voltages of our Electric Grid balance the Cost Savings (Smaller Wires) with the Higher Costs (Larger Towers)

An electric circuit needs two conductors.  When current is flowing away from the power plant in one it is flowing back to the power plant in the other.  As the current changes direction is has to stop first.  And when it stops flowing the current is zero.  Using the power formula this means there are zero watts twice a cycle.  Or 120 times a second.  Which isn’t very efficient.  However, if you bring two other sets of conductors to the work load and time the current in them properly you can remove these zero-power moments.  You send the first current out in one set of conductors and wait 1/3 of a cycle.  Then you send the second current out in the second set of conductors and wait another 1/3 cycle.  Then you send the third current out in the third set of conductors.  Which guarantees that when a current is slowing to stop to reverse direction there are other currents moving faster towards their peak currents in the other conductors.  Making 3-phase power more efficient than single-phase power.  And the choice for all large consumers of electric power.

Anyone who has ever done any electrical wiring in their home knows you can share neutral conductors.  Meaning more than one circuit coming from your electrical panel can share the return path back to the panel.  If you’ve ever been shocked while working on a circuit you switched off in your panel you have a shared neutral conductor.  Even though you switched off the circuit you were working on another circuit sharing that neutral was still switched on and placing a current on that shared neutral.  Which is what shocked you.  So if we can share neutral conductors we don’t need a total of 6 conductors as noted above.  We only need 4.  Because each circuit leaving the power plant (i.e., phase conductor) can share a common neutral conductor on its way back to the power plant.  But the interesting thing about 3-phase power is that you don’t even need this neutral conductor.  Because in a balanced 3-phase circuit (equal current per phase) there is no current in this neutral conductor.  So it’s not needed as all the back and forth current movement happens in the phase conductors.

Electric power travels in feeders that include three conductors per feeder.  If you look at overhead power lines you will notice they all come in sets of threes when they get upstream of the final transformer that feeds your house.  The lines running along your backyard will have three conductors across the top of the poles.  As they move back to the power plant they pass through additional transformers that increase their voltage (and reduce their current).  And the electric transmission towers get bigger.  With some having two sets of 3-conductor feeders.  The higher the voltage the higher off the ground they have to be.  And the farther apart the phase conductors have to be so the high voltage doesn’t cause an arc to jump the ‘air gap’ between phase conductors.  As you move further away from your home back towards the power plant the voltage will step up to values like 2.4kV (or 2,400 volts), 4.8kV and13.2kV that will typically take you back to a substation.  And then from these substations the big power lines head back towards the power plant.  On even bigger towers.  At voltages of 115kV, 138kV, 230kV, 345kv, 500kV and as high as 765kV.  When they approach the power plant they step down the voltage to match the voltage produced by its generators.

They select the voltages of our electric grid to balance the cost savings (smaller wires) with the higher costs (larger towers taking up more land).  If they increase the voltage so high that they can use very thin and inexpensive conductors the towers required to transmit that voltage safely may be so costly that they exceed the cost savings of the thinner conductors.  So there is an economic limit on voltage levels  As well as other considerations of very high voltages (such as corona discharge where high voltages create such a power magnetic field around the conductors that it may ionize the air around it causing a sizzling sound and a fuzzy blue glow around the cable.  Not to mention causing radio interference.  As well as creating some smog-causing pollutants like ozone and nitrogen oxides.)

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