Manual Hand Brake, Dynamic Braking and George Westinghouse’s Failsafe Railway Air Brake

Posted by PITHOCRATES - July 17th, 2013

Technology 101

Getting a Long and Heavy Train Moving was no good unless you could Stop It

Trains shrank countries.  Allowing people to travel greater distances faster than ever before.  And move more freight than ever before.  Freight so heavy that no horse could have ever pulled it.  The only limitation was the power of the locomotive.  Well, that.  And one other thing.  The ability to stop a long and heavy train.  For getting one moving was pretty easy.  Tracks were typically level.  And steel wheels on steel rails offered little resistance.  So once a train got moving it didn’t take much to keep it moving.  Especially when there was the slightest of inclines to roll down.

Getting a long and heavy train moving was no good unless you could stop it.  And stopping one was easier said than done.  As trains grew longer it proved impossible for the locomotive to stop it alone.  So each car in the consist (the rolling stock the locomotive pulls behind it) had a manual brake.  Operated by hand.  By brakemen.  Running along the tops of cars while the train was moving.  Turning wheels that applied the brakes on each car.  Not the safest of jobs.  One that couldn’t exist today.  Because of the number of brakemen that died on the job.  Due to the inherent danger of running along the top of a moving train.  Luckily, today, all brakemen have lost their jobs.  As we have safer ways to stop trains.

Of course, we don’t need to just stop trains.  A lot of the time we just need to slow them down a little.  Such as when approaching a curve.  Going through a reduced speed zone (bad track, wooden bridge, going through a city, etc.).  Or going down a slight incline.  In fact slowing down on an incline is crucial.  For if gravity is allowed to accelerate a train down an incline it can lead to a runaway.  That’s when a train gathers speed with no way of stopping it.  It can derail in a curve.  It can run into another train.  Or crash into a terminal building full of people.   All things that have happened.  The most recent disaster being the Montreal, Maine & Atlantic Railway disaster in Lac-Megantic, Quebec.  Where a parked oil train rolled away down an incline, derailed and exploded.  Killing some 38 people.  While many more are still missing and feared dead.

Dynamic Breaking can Slow a Train but to Stop a Train you need to Engage the Air Brakes

Trains basically have two braking systems today.  Air brakes.  And dynamic braking.  Dynamic braking involves changing the traction motors into generators.  The traction motors are underneath the locomotive.  The big diesel engine in the locomotive turns a generator making electric power.  This power creates powerful magnetic fields in the traction motors that rotate the axles.  The heavier the train the more power it takes to rotate these axles.  It takes a little skill to get a long and heavy train rolling.  Too much power and the steel wheels may slip on the steel rails.  Or the motors may require more power than the generator can provide.  As the torque required to move the train may be greater than traction motors can provide.  Thus ‘stalling’ the motor.  As it approaches stall torque it slows the rotation of the motor to zero while increasing the current from the generator to maximum.  As it struggles to rotate an axle it is not strong enough to rotate.  If this continues the maximum flow of current will cause excessive heat buildup in the motor windings.  Causing great damage.

Dynamic breaking reverses this process.  The traction motors become the generator.  Using the forward motion of the train to rotate the axles.  The electric power this produces feeds a resistive load that draws a heavy current form these traction motors.  Typically it’s the section of the locomotive directly behind the cab.  It draws more than the motors can provide.  Bringing them towards stall torque.  Thus slowing their rotation.  And slowing the train.  Converting the kinetic energy of the moving train into heat in the resistive load.  Which has a large cooling fan located above it to keep it from getting so hot that it starts melting.

Dynamic breaking can slow a train.  But it cannot stop it.  For as it slows the axles spin slower producing less electric power.  And as the electric current falls away it cannot ‘stall’ the generator (the traction motors operating as generators during dynamic braking).  Which is where the air brakes come in.  Which they can use in conjunction with dynamic braking on a steep incline.  To bring a train to a complete stop.  Or to a ‘quick’ stop (in a mile or so) in an emergency.  Either when the engineer activates the emergency brake.  Or something happens to break open the train line.  The air brake line that runs the length of the train.

When Parking a Train they Manually set the Hand Brakes BEFORE shutting down the Locomotive

The first air brake system used increasing air pressure to stop the train.  Think of the brake in a car.  When you press the brake pedal you force brake fluid to a cylinder at each wheel.  Forcing brake shoes or pads to come into contact with the rotating wheel.  The first train air brake worked similarly.  When the engineer wanted to stop the train he forced air to cylinders at each wheel.  Which moved linkages that forced brake shoes into contact with the rotating wheel.  It was a great improvement to having men run along the top of a moving train.  But it had one serious drawback.  If some cars separated from the train it would break open the train line.  So the air the engineer forced into it vented to the atmosphere without moving the brake linkages.  Which caused a runaway or two in its day.  George Westinghouse solved that problem.  By creating a failsafe railway air brake system.

The Westinghouse air brake system dates back to 1868.  And we still use his design today.  Which includes an air compressor at the engine.  Which provides air pressure to the train line.  Metal pipes below cars.  And rubber hoses between cars.  Running the full length of the train.  At each car is an air reservoir.  Or air tank.  And a triple valve.  Before a train moves it must charge the system (train line and reservoirs at each car) to, say, 90 pounds per square inch (PSI) of air pressure.  Once charged the train can move.  To apply the air brakes the engineer reduces the pressure by a few PSI in the train line.  The triple valve senses this and allows air to exit the air reservoir and enter the brake cylinder.  Pushing the linkages to bring the brake shoes into contact with the train wheels.  Providing a little resistance.  Slowing the train a little.  Once the pressure in the reservoir equals the pressure in the train line the triple valve stops the air from exiting the reservoir.  To slow the train more the engineer reduces the pressure by a few more PSI.  The triple valve senses this and lets more air out of the reservoir to again equalize the pressure in the reservoir and train line.  When the air leaves the reservoir it goes to the brake cylinder.  Moving the linkage more.  Increasing the pressure of the brake shoes on the wheels.  Further slowing the train.  The engineer continues this process until the train stops.  Or he is ready to increase speed (such as at the bottom of an incline).  To release the brakes the engineer increases the pressure in the train line.  Once the triple valve senses the pressure in the train line is greater than in the reservoir the air in the brake cylinders vents to the atmosphere.  Releasing the brakes.  While the train line brings the pressure in the reservoir back to 90 PSI.

This system is failsafe because the brakes apply with a loss of air pressure in the train line.  And if there is a rapid decline in air pressure the triple valve will sense that, too.  Say a coupler fails, separating two cars.  And the train line.  Causing the air pressure to fall from 90 PSI to zero very quickly.  When this happens the triple valve dumps the air in an emergency air reservoir along with the regular air reservoir into the brake cylinder.  Slamming the brake shoes onto the train wheels.  But as failsafe as the Westinghouse air brake system is it can still fail.  If an engineer applies the brakes and releases them a few times in a short period (something an experienced engineer wouldn’t do) the air pressure will slowly fall in both the train line and the reservoirs.  Because it takes time to recharge the air system (train line and reservoirs).  And if you don’t give it the time you will decrease your braking ability.  As there is less air in the reservoir available to go to the brake cylinder to move the linkages.  To the point the air pressure is so low that there isn’t enough pressure to push the brake shoes into the train wheels.  At this point you lose all braking.  With no ability to stop or slow the train.  Causing a runaway.

So, obviously, air pressure is key to a train’s air brake system.  Even if the train is just parked air will leak out of the train line.  If you’re standing near a locomotive (say at a passenger train station) and hear an air compressor start running it is most likely recharging the train line.  For it needs air pressure in the system to hold the brake shoes on the train wheels.  Which is why when they park a train they manually set the hand brakes (on a number of cars they determined will be sufficient to prevent the train from rolling) BEFORE shutting down the locomotive.  Once the ‘parking brake’ is set then and only then will they shut down the locomotive.  Letting the air bleed out of the air brake system.  Which appears to be what happened in Lac-Megantic, Quebec.  Preliminary reports suggest that the engineer may not have set enough hand brakes to prevent the train from rolling on the incline it was on when he parked the train for the night.  On a main line.  Because another train was on a siding.  And leaving the lead locomotive in a five locomotive lashup unmanned and running to maintain the air pressure.  Later that night there was a fire in that locomotive.  Before fighting that fire the fire department shut it down.  Which shut down the air compressor that was keeping the train line charged.  Later that night as the air pressure bled away the air brakes released and the hand brakes didn’t hold the train on the incline.  Resulting in the runaway (that may have reached a speed of 63 mph).  Derailment at a sharp curve.  And the explosion of some of its tank cars filled with crude oil.  Showing just how dangerous long, heavy trains can be when you can’t stop them.  Or keep them stopped.

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Cowboy Coffee, Percolator and Electric Drip Coffee Maker

Posted by PITHOCRATES - June 26th, 2013

Technology 101

Done Right Cowboy Coffee is one of the Finest Cups of Coffee you will ever Have

The British love their tea.  They love it so much they call lunch ‘tea’ in Britain.  Their world stops when it’s time for tea.  As they place a kettle of boiled water, cups on saucers, milk, sugar and lemon on a tray and bring it in to a warm gathering of friends and colleagues.  Then prim and proper British gentlemen and ladies prepare their tea.  Sit with good posture.  And sip their tea with pinky extended.

The British brought their treasured tea to the New World.  And British Americans continued the tradition.  Until the Boston Tea Party and the Revolutionary War.  And the War of 1812.  Interrupting the British-controlled tea trade.  It was these events and a general dislike of all things British during those turbulent times that changed American tea drinkers into coffee drinkers.  Something we didn’t have to do with such dainty British manners.  As Americans were not quite as prim and proper.  Or refined.  Americans were more rough and tumble.  As epitomized by the American cowboy.  (Caution: The following clip from Mel Brooks’ Blazing Saddles has crude and sophomoric humor featuring cowboys breaking wind.)

Not quite the refined British tea.  Note the beverage they were drinking.  Hanging on the tripod over the campfire is a large coffee pot.  Where these cowboys make ‘cowboy coffee’.  Course coffee grounds go into the coffee pot.  Fill with water.  Place over campfire.  Heat water to just below a boil.  Carefully pour out coffee without stirring up coffee grounds from the bottom of the pot.  Enjoy.  Done right and it will be one of the finest cups of coffee you will ever have.  And something that really hits the spot on the trail after a long hard day.  Though not as refined as British tea it is just as comforting.

A Common Complaint about Coffee Percolators was that they made Bitter Coffee

Cowboy coffee can be delicious.  Or it can be horrible.  For temperature and brew time are critical in making coffee.  As well as the proportion of coffee grounds to water.  The proper temperature to brew coffee is between 195 and 205 degrees Fahrenheit.  This will release the oils from the coffee beans.  But if the temperature reaches boiling the coffee will be bitter.  So for good cowboy coffee you needed to put in just the right amount of ground coffee beans with just the right amount of water.  And keep the water just below the boiling point.  And once the coffee brewed you needed to drink it.  For sitting on the heat too long will just evaporate the water away leaving a strong, bitter, muddy water.

Around the time of the American Civil War we started using coffee percolators.  Where instead of placing ground coffee beans in a pot of water we dripped water through a basket that contained the ground coffee beans above the water.  In the center of this basket was a tube that went from the bottom of the percolator to the top.  We placed this percolator onto the stove.  This heated the water.  As the temperature rose the water expanded.  The water in the narrow tube expanded so much in that small tube that it pushed all the way up and out at the top of the tube.  And dripped onto the top of the coffee grounds.  Dripped through them.  And out the bottom into the heated water below.

This cycle continued over and over until the water in the pot started getting darker.  The top of the pot, above the tube, was a glass knob.  Which we could see through.  And observe the color of the water percolating up from the bottom of the pot.  When it turned to the appropriate ‘coffee color’ we removed the percolator form the stove.  And served the brewed coffee.  Using a stove, though, made it easy to boil the water.  Which would make the coffee bitter.  A common complaint about percolators.  As well as some coffee grounds that passed through the basket into the pot.  And poured into our cup.  But some preferred the full robust flavor percolating gave.  Even if it was bitter from overheating the water.

A Quality Electric Drip Coffee Maker can pour 195-205 Degree Water over Coffee Grounds in under 8 Minutes

Thanks to Nikola Tesla and his AC power Americans soon had electricity in their homes.  And a whole sort of electric appliances to use with that electricity.  Including an electric coffee percolator.  Which reduced the chances of boiling the water by controlling the temperature of the water.  There was a temperature sensor that shut off the heating element if the water temperate approached boiling.  When the temperature fell below the optimum temperature range (195-205 degrees Fahrenheit) the temperature sensor turned the heating element back on.  Making it easier to make a good cup of coffee in the home.  Until the Seventies came around.  And the electric drip coffee maker.

The electric drip coffee maker is a staple of most American kitchens today.  It is now the way we make coffee at home.  By heating water to an appropriate temperature and dripping that heated water through a coffee filter full of ground coffee beans.  Once brewed the coffee drips into a carafe.  Which sits on a warming plate.  Unlike the percolator which sent brewed coffee back through the basket holding the coffee grounds over and over again.  The electric drip coffee maker has a reservoir of cold water.  At the bottom of this reservoir is a tube with a check-valve.  Which allows water to flow only one way through the valve.  Past this check-valve is a horseshoe-shaped metal tube.  Attached to this metal tube is a heating element.  Past this metal tube is a hose that runs up to the top of the coffee maker.  And out through a spray-head onto the coffee grounds.

As the heating element heats the water in the metal tube it expands.  Because it can’t go back into the reservoir thanks to that check-valve the water rises up the tube and out through the spray-head.  As the water moves up the tube the siphon it creates pulls water from the reservoir through the check-valve into the metal tube.  When it heats and expands it rises up the tube to the drip-head.  And this cycle repeats again and again until the water reservoir is empty.  A temperature sensor turns the heating element on and off to maintain the proper water temperature.  Like the electric coffee percolator.  But the addition of a coffee filter prevents any grounds from ending up in our cup.  Also, a well-designed drip coffee maker can pour this properly heated water over the coffee grounds in under 8 minutes.  Another key to making an excellent cup of coffee.  Other advances include a timer.  Allowing us to set up the drip coffee maker the night before so we can have a freshly brewed cup of coffee first thing in the morning.  So we can grab a cup on the way out the door.  American style.  In a hurry.  Unlike the British.  Who stop the world when it’s time for tea.

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Quill Pen, Dip Pen, Fountain Pen and Ballpoint Pen

Posted by PITHOCRATES - June 19th, 2013

Technology 101

The Quill Pen was nothing more than a Bird’s Feather and some Ingenious Thinking

The pen is mightier than the sword.  For while the sword can kill a person they cannot kill that person’s words.  Even the words ‘sword’ and ‘words’ are interesting in themselves.  For if you drop the ‘s’ from both you have ‘word’.  That thing that makes us human.  Putting our thoughts into words onto paper.  So that others can read these words.  And understand our thoughts.  Our ideas.  Our perspectives.  Our wisdom.  So we can pass these words down through the ages.  Or on to others in our current age.

The Egyptians, the Sumerians, the Harappa and the Nanzhuangtou all wrote.  A stylus on a clay tablet was probably the first form of writing.  Not quite the communications we have today.  But this writing gave us the four great ancient civilizations.  But only a select few wrote in these early civilizations.  No.  Writing didn’t really take off until much later.  And the introduction of the first great writing tool.  The quill pen.  Which was nothing more than a bird’s feather.  And some ingenious thinking.

What happens when you place a paper towel on a spill?  The towel absorbs the liquid.  By rising up into the paper towel.  This is capillary action.  And is the basis of the quill pen.  Without getting too technical molecules in a liquid are attracted to the surface of a round tube.  Everyone no doubt remembers seeing this in a high school chemistry class using a graduated cylinder.  That tall tube of glass we measured liquids in by reading the scale off of the glass.  The surface of the glass attracted and pulled up the liquid on the sides of the glass.  Forming a concave surface on top.  The narrower the tube the greater this pulling force.  And the higher this attraction will pull a liquid up the tube.

Thanks to the Dip Pen most Americans were Well-Informed and Literate at the time of the Civil War

A bird’s feather is hollow.  A long narrow tube.  When dipped in a well of ink capillary forces will pull this ink up the hollow tube of the feather.  And hold it there.  Not a long column of ink.  But enough to let us write words.  Before we did, though, we used a pen knife to cut a nib in the end.  You make a 45-degree cut across the bottom.  Then you cut again to remove most of the round cylinder.  If you were looking into the end of the feather and imagine the face of a clock you would remove everything from 1:00 to 11:00.  Or thereabouts.  So you are left with a flat-like extension from the tube of the feather.  You then cut the tip of this flat extension to get a nice chisel point.  Then, finally, you slice or score this flat extension of the tube from the tip of the nub to the tube holding the ink.  This allowed the ink to flow from the tube to the point.  As one wrote the ink at the tip would wipe off on the paper.  And when it did it would pull fresh ink from the tube reservoir above.

This was a remarkable tool.  And one we used for a very long time.  Roughly from the 6th to the 19th century.  This is what the scribes used in those monasteries when they translated all those Greek texts the Crusaders brought back to Europe.  Quills penned Magna Carta.  It’s what Shakespeare used.  It gave us the King James Bible.  The works of the Enlightenment.  The Declaration of Independence.  The U.S. Constitution.  And the Declaration of the Rights of Man and of the Citizen.  We used it that long because it was that good.  Simple.  And we only stopped using it when manufacturing techniques advanced to the point that could create the quill nib in steel.  Giving us the dip pen.  And once we did we said goodbye to the quill pen.

The dip pen was basically the quill nib made out of steel.  Only it was sturdier.  And didn’t require anyone having to become skilled with a pen knife.  We began manufacturing the dip pen around the 1820s.  Mass production techniques brought down prices.  Allowing anyone to write.  Even children with poor pen knife skills.  School desks had holes in the upper right corner.  To hold an ink well.  So children in school could dip their pens.  And put words to paper.  Literacy rates soared.  As did education.  Americans were probably not more informed and literate than they were at the time of the Civil War.  Thanks to the inexpensive and easy-to-use dip pen.

Penmanship and Cursive Writing were once Important Parts of the School Curriculum

The dip pen had a much shorter life than the quill pen.  Replaced by the fountain pen.  Pretty much the same as the dip pen.  Only with an internal ink reservoir.  Other advancements made the fountain pen portable.  Such as a retractable nib.  Or a cap that covered the nib.  Allowing us to slip the fountain pen in a pocket without ink staining our shirt.  We filled early reservoirs with an eyedropper.  Which was messy.  The next development was adding a mechanism that when operated drew ink up through the nib into the reservoir.  And a breather hole helped the ink flow to the paper by allowing air to enter the reservoir to replace the ink as it left.  Filling a fountain pen through the nib was neater to fill than using an eye dropper.  But still required an open ink well.  Which could spill or leave excess ink on the nib after filling.  The next advancement was an ink cartridge.  Removing the need to have an open well of ink.  Removing the chance of an ink spill.  And there was no excess ink on the nib after refilling.

The fountain pen was about as good as it got.  Until the ballpoint pen arrived.  Cheap.  Disposable.  Convenient.  And clean.  Up until the ballpoint pen the mechanics of the pen remained the same from the quill pen to the dip pen to the fountain pen.  They all had a nib with a slit that drew ink from a reservoir.  The ballpoint pen was a completely different technology.  Where we replaced the nib with a very small ball inserted into a point.  Hence ballpoint pen.  We make the ball from a very hard metal such as tungsten carbide and machine it into a perfect sphere.  The ball snaps into a socket in the point.  Attached to this nib assembly is an ink-filled plastic tube.  The ball fits so snuggly that it can’t slip out of the point or slip up into the ink reservoir.  And it holds back the ink from running out of the reservoir.  When you write you drag the point across the paper.  This rotates the ball in the point.  Bringing ink from behind the ball onto the paper.  Producing a very uniform ink line.

The ink pen created civilization.  By allowing us to put our thoughts into words.  And putting those words onto paper for others to read.  Penmanship and writing in cursive were once important parts of the school curriculum.  As they were the gateway to literacy and education.  But that has all changed.  Few people write today.  Instead they type.  Or text.  Bastardizing our words into shorthand gibberish.  A long cry from the elegant words of William Shakespeare.  Or the impassioned words of the Declaration of Independence.  Where we raised our words to the level of art and put them to paper.  Ushering in the golden era of civilization.  Where we were our most human.  Expressing our thoughts.  Our ideas.  Our perspectives.  And our wisdom.  Replaced today with truncated efficiency.  As we dehumanize ourselves to live in a digital world.

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Rising Water, Flood Stage, Dams, Sluice Gates and Flood Control

Posted by PITHOCRATES - February 27th, 2013

Technology 101

We have spent much of our History trying to Tame the Awesome Power of Water

Water can be scary.  And very powerful.  Which helps with it being scary.  We saw what happened when that storm surge hit the East Coast.  It just swept everything in its path.  For water has mass.  Making it heavy.  Just try holding a couple of buckets of water with your arms outstretched.  You won’t be able to hold them up long.  Now think about the weight of a few billion buckets.  An amount no one could move.  But there are few things this amount of water can’t move.  Except maybe a levee.  A floodwall.  Or a dam.

Also making water scary is that you don’t know what is lurking beneath the surface.  During periods of heavy rains storm sewers quickly fill to capacity.  Water backs out onto streets.  Flooding intersections.  And basements.  Streams and rivers rise above their flood stage.  And overflow their banks.  Water saturating the soil may wash it away from underneath.  Creating large sink holes.  That from the surface may look like a puddle of water.  Water overflowing riverbanks can hide many dangers.  Submerged debris that can entangle you.  That have swift and dangerous currents flowing through them.

Rising water can get into areas where it doesn’t belong.  It got into the subway tunnels in New York.  Causing a lot of damage.  It got into the basement electrical rooms at the Fukushima Daiichi nuclear power plant in Japan.  Causing a lot of damage.  Including a partial meltdown of the reactor core.  A failed levee can flood a city.  Like New Orleans.  So untamed water can do a lot of damage.  And we have spent much of our history trying to tame the awesome power of water.

Each Spring the Snows melt and the Rains come Swelling Rivers beyond their Flood Stage

Early cities rose on rivers.  For rivers were our first highways.  The river’s current turned water wheels to power our mills and factories.  Provided irrigation for our farms.  Etc.  Rivers allowed cities to come to life.  Which is why a lot of our cities today have rivers flowing through them.  Yes, a river view is beautiful.  And the recreational opportunities are plentiful.  But they are not why we founded these cities on rivers.  It was all the benefits the river provided.  Things that allowed a civilization to grow.  But it wasn’t all good.

Each spring the snows melted.  And the rains came.  Swelling rivers beyond their flood stage.  Overflowing their banks.  Bringing great damage to life along the rivers.  Especially to the towns on its banks.  So we did something with these rivers that were prone to such damaging flooding.  And built a dam upstream.  To control that flooding.

They would choose an appropriate location upstream.  Some place where the river valley narrowed a bit.  So they could build a dam across the valley.  Once they did the water upstream of the dam rose into a lake or reservoir.  Providing a source of drinking water.  Irrigation water.  Recreation.  Or power generation with a hydroelectric dam.  Very beneficial things.  But all secondary to its main purpose.  To eliminate that recurring flooding.

A Dam’s Sluice Gates are the Key to Flood Control

If you’ve ever seen a dam on a river you probably noticed some things.  Turbulent water at the base of the dam on the downstream side.  Warning signs and some sort of a barricade (such as a chain stretched across the river held up with floats) a hundred feet or so in front of the dam on the upstream side.  Signs you would be wise to heed.  For great danger lurks beneath the surface of the water.  In that dam are underwater openings.  That have moving gates to make these openings bigger or smaller.  Sluice gates.  And you don’t want to be anywhere near these gates whenever they’re open.  For the weight of a few billion gallons of water creates a powerful force of water moving towards those gates and through the openings.  If you ever thought of diving off a small dam don’t.  You would be sucked quickly to these openings.  If they are not opened enough for your body to fit through the force of the water would hold you against the openings until you drowned.  If the opening is large enough the water will flush you through with great force and violence.  Discharging you into the turbulent water on the downstream side of the dam.

These gates are the key to flood control.  During the snowmelt runoff and heavy rains of spring we can close these gates to allow only a trickle of water flow.  Maintaining a safe river level downstream.  The excess snowmelt runoff and the rains will fill the lake or the reservoir upstream of the dam.  After the rains stop they can open the gates a little more to bring down the level of the lake or reservoir.  Without sending the river downstream above its flood stage.  If the level rises too high behind the dam the water will enter a spillway and flow over/around/through the dam.  Like an overflow in a sink.  Allowing the water to rise only to a maximum level behind the dam before spilling over/around/through the dam.  Joining that turbulent water on the downstream side.  Which you want to avoid as much as the dangers on the upstream side of the dam.

We haven’t always been successful in controlling the awesome power of water.  Some dams we’ve built have failed.  Like the Teton Dam in Idaho.  An earthen dam.  Just upstream of Wilford.  Built for flood control.  To protect the towns and farmlands downstream of the dam.  As it turned out, though, the Bureau of Reclamation did a poor job building the dam.  And the rains were heavy that year.  Raising the level behind the dam 3 feet a day instead of the designed 1 foot.  Water started leaking through the dam.  Saturating the soil making up the dam.  The water rose rapidly.  But before it could reach the spillway the dam gave way.  Sending some 80 billion gallons of water rushing downstream.  Wiping out Wilford.  And destroying most of Sugar City.  And Rexburg.  Causing damage as far away as 30 miles downstream in Idaho Falls.  Illustrating the awesome power of water.  And the price we pay when we don’t give it the proper respect.

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FT142: “Solar and wind power would take the longest to restore after a devastating weather event.” —Old Pithy

Posted by PITHOCRATES - November 2nd, 2012

Fundamental Truth

Neither Snow nor Rain nor Heat nor Gloom of Night Stays the Production of Electric Power from Coal

What’s the best way to generate electric power?  This is not a trick question.  There is an answer.  And there is only one correct answer.  Coal.  A coal-fired power plant is the best way to generate electric power.  Coal-fired power plants can run 24 hours a day, 7 days a week, 365 days a year.  You never have to turn them off.  They can produce an enormous amount of power for the given infrastructure.  You can put these power plants anywhere.  Where it’s snowy and cold.  Where it’s bright and sunny.  Where it’s cloudy and rainy.  It doesn’t matter.  Coal-fired power plants are like the US Postal Service.  Neither snow nor rain nor heat nor gloom of night stays the production of electric power from coal.

Coal is a highly concentrated form of energy.  Burning a little of it goes a long way.  This is why one coal-fired power plant can add over 2,000 megawatts to the electric grid.  And why about 600 coal-fired power plants can provide over half of our electric power needs.  Coal is one of the most abundant fuel sources in the world, too.  In fact, America has more coal than we can use.  This high domestic supply makes coal cheap.  Which is why coal-produced electric power is some of the cheapest electricity we have.

The only thing that will shut down a coal-fired power plant is running out of coal.  Which doesn’t happen easily.  Look around a power plant and you will see mountains of coal.  And conveyor systems that move that coal to the firebox that burns it.  You’ll probably see more coal arriving.  By unit train.  Trains with nothing but coal cars stretching a mile long.  By river barge.  Or Great Lakes freighter.  Making round-trip after round-trip from the coal mines to the power plants.  We’ve even built power plants near coal mines.  And fed those plants with coal on conveyor systems from the mines to the power plants.  Trains, barges and freighters use self-contained fuel to transport that coal.  And electric power energizes those conveyor systems.  Electric power that comes from the power plant.  Making it difficult to interrupt that flow of coal to our power plants.  Onsite stockpiles of coal can power the plant during brief interruptions in this coal flow.  When the lakes freeze they can get their coal via train.  And if there is a train wreck or a track washout they can reroute trains onto other tracks.  Finally, coal-fired power plants are least dependent on other systems.  Whereas a natural gas-fired power plant is dependent on the natural gas infrastructure (pipelines, pumps, valves, pressure regulators, etc.).  If that system fails so do the natural gas-fired power plants.

Solar Panels produce low DC Currents and Voltages that we have to Convert to AC to Connect them to the Electric Grid

Neither snow nor rain nor heat nor gloom of night stays the production of electric power from coal.  But they sure can interrupt solar power.  Which won’t produce much power if there is snow or rain or night.  Giving it one of the lowest capacity factors.  Meaning that you get a small fraction of useful power from the installed capacity.  Wind power is a little better.  But sometimes the wind doesn’t blow.  And sometimes it blows too strong.  So wind power is not all that reliable either.  Hydroelectric power is more reliable.  But sometimes the rains don’t come.  And if there isn’t enough water behind a hydroelectric dam they have to take some generators offline.  For if they draw down the water level too much the water level behind the dam will be below the inlet to the turbines.  Which would shut off all the generators.

Of course, hydroelectric dams often have reservoirs.  These fill with water when the rains come.  So they can release their water to raise the water level behind a dam when the rains don’t come.  These reservoirs are, then, stored electric power.  For a minimal cost these can store a lot of electric power.  But it’s not an endless supply.  If there is a prolonged draught (or less snow in the mountains to melt and run off) even the water level in the reservoirs can fall too low to raise the water level behind the dam high enough to reach the water inlets to the turbines.

Storing electric power is something they can do with solar power, too.  Only it’s a lot more complex.  And a lot more costly.  Solar panels produce low DC currents and voltages.  Like small batteries in our flashlights.  So they have to have massive arrays of these solar panels connected together.  Like multiple batteries in a large flashlight.  They have to convert the DC power to AC power to connect it to the grid.  With some complicated and costly electronics.  And any excess power these solar arrays produce that they don’t feed into the grid they can store in a battery of batteries.  And as we know from the news on our electric cars, current battery technology does not hold a lot of charge.  Barely enough to drive a 75 mile round-trip.  So you’d need a lot of batteries to hold enough useful power to release into the grid after the sun goes down.

Storms like Sandy would wipe out Solar Arrays and Wind Farms with their High Winds and Storm Surges

When a 9.0 magnitude earthquake hit Japan in 2011 the Fukushima Daiichi Nuclear Power Plant suffered no damage.  Then the storm surge came.  Flooding the electrical equipment with highly conductive and highly corrosive seawater.  Shorting out and destroying that electrical equipment.  Shutting down the reactor cooling pumps.  Leading to a partial reactor core meltdown.  Proving what great damage can result when you mix water and electric equipment.  Especially when that water is seawater.

Hurricane Sandy hammered the Northeastern seaboard.  High winds and a storm surge destroyed cities and neighborhoods, flooded subway tunnels and left tens of millions of people without power.  And they may be without power for a week or more.  Restoring that power will consist primarily of fixing the electric grid.  To reconnect these homes and businesses to the power plants serving the electric grid.  They don’t have to build new power plants.  Now if these areas were powered by solar and wind power it would be a different story.  First of all, they would have lost power a lot earlier as the driving rains and cloud cover would have blocked out most of the sun.  The high winds would have taken the windmills offline.  For they shut down automatically when the winds blow too hard to prevent any damage.  Of course, the high winds and the storm surge would probably have damaged these as well as the power lines.  While shorting out and destroying all of that electronic equipment (to convert the DC power to AC power) and the battery storage system

So instead of just installing new power lines they would have to install new windmills, solar arrays, electronic equipment and storage batteries.  Requiring long manufacturing times.  Then time to transport.  And then time to install.  At a far greater cost than just replacing downed wires.  Leaving people without electric power for weeks.  Perhaps months.  Or longer.  This is why using coal-fired power plants is the best way to generate electric power.  They’re less costly.  Less fragile.  And less complicated.  You just don’t need such a large generating infrastructure.  Whereas solar arrays and wind farms would cover acres of land.  And water (for the wind farms).  And storms like Sandy could wipe these out with their high winds and storm surges.

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Conservation of Energy, Potential Energy, Kinetic Energy, Waterwheels, Water Turbine, Niagara Falls, Dams, and Hydroelectric Power

Posted by PITHOCRATES - July 25th, 2012

Technology 101

Roller Coasters use Gravity to Convert Energy back and forth between Potential Energy and Kinetic Energy

We cannot destroy energy.  All we can do is convert it.  It’s a law of physics.  The law of conservation of energy.  A roller coaster shows this.  Where roller coasters move by converting potential energy into kinetic energy.  And then by converting kinetic energy back into potential energy.

The best roller coasters race down tall inclines gaining incredible speed.  The taller the coaster the faster the speed.  That’s because of potential energy (stated in units of joules).  Which is equal to the mass times the force of gravity times the height.  The last component is what makes tall roller coasters fast.  Height.  As the cars inch over the summit gravity begins pulling them down.  And the longer gravity can pull them down the more speed they can gain.  At the bottom of the hill the height is zero so the potential energy is zero.  All energy having been converted into kinetic energy (also stated in units of joules).

Roller coasters travel the fastest at the lowest points in the track.  Where potential energy equals zero.  While kinetic energy is at its highest.  Which is equal to one half times the mass times the velocity squared.  So the higher the track the more time gravity has to accelerate these cars.  At their fastest speed they start up the next incline.  Where the force of gravity begins to pull on them.  Slowing them down as they climb up the next hill.  Converting that kinetic energy back into potential energy.  When they crest the hill for a moment their speed is zero so their kinetic energy is zero.  All energy having been converted back into potential energy.  Where gravity tugs those cars down the next incline.  And so on up and down each successive hill.  Where at all times the sum of potential energy and kinetic energy equals the same amount of joules.  Maximum potential energy is at the top.  Maximum kinetic energy is at the bottom.  And somewhere in the middle they each equal half of their maximum amounts.

(This is a simplified explanation.  Additional forces are ignored for simplicity to illustrate the relation between potential energy and kinetic energy.)

We build Dams on Rivers  to do what Niagara Falls does Naturally

So once over the first hill roller coasters run only on gravity.  And the conversion of energy from potential to kinetic energy and back again.  Except for that first incline.  Where man-made power pulls the cars up.  Electric power.  Produced by generators.  Spun by kinetic energy.  Produced from the expanding gases of combustion in a natural gas-powered plant.  Or from high-pressure steam produced in a coal-fired power plant or nuclear power plant.  Or in another type of power plant that converts potential energy into kinetic energy.  In a hydroelectric dam.

Using water power dates back to our first civilizations.  Then we just used the kinetic energy of a moving stream to turn a waterwheel.  These waterwheels turned shafts and pulleys to transfer this power to work stations.  So they couldn’t spin too fast.  Which wasn’t a problem because people only used rivers and streams with moderate currents.  So these wheels didn’t spin fast.  But they could turn a mill stone.  Or run a sawmill.  With far more efficiency than people working with hand tools.  But there isn’t enough energy in a slow moving river or stream to produce electricity.  Which is why we built some of our first hydroelectric power plants at Niagara Falls.  Where there was a lot of water at a high elevation that fell to a lower elevation.  And if you stick a water turbine in the path of that water you can generate electricity.

Of course, there aren’t Niagara Falls all around the country.  Where nature made water fall from a high elevation to a low elevation.  So we had to step in to shape nature to do what Niagara Falls does naturally.  By building dams on rivers.  As we blocked the flow of water the water backed up behind the dam.  And the water level climbed up the river banks to from a large reservoir.  Or lake.  Raising the water level on one side of the dam much higher than the other side.  Creating a huge pool of potential energy (mass times gravity times height).  Just waiting to be converted into kinetic energy.  To drive a water turbine.  The higher the height of the water behind the dam (or the higher the head) the greater the potential energy.  And the greater the kinetic energy of the water flow.  When it flows.

Hydroelectric Power is the Cleanest and Most Reliable Source of Renewable Energy-Generated Power

Near the water level behind the dam are water inlets into channels through the dam or external penstocks (large pipes) that channels the water from the high elevation to the low elevation and into the vanes of the water turbine.  The water flows into these curved vanes which redirects this water flow down through the turbine.  Creating rotational motion that drives a generator.  After exiting the turbine the water discharges back into the river below the dam.

Our electricity is an alternating current at 60 hertz (or cycles per second).  These turbines, though, don’t spin at 60 revolutions per second.  So to create 60 hertz they have to use different generators than they use with steam turbines.  Steam turbines spin a generator with only one rotating magnetic field to induce a current in the stator (i.e., stationary) windings of the generator.  They can produce an alternating current at 60 hertz because the high pressure steam can spin these generators at 60 revolutions per second.  The water flowing through a turbine can’t.  So they add additional rotational magnetic fields in the generator.  Twelve rotational magnetic fields can produce 60 hertz of alternating current while the generator only spins at 5 revolutions per second.  Adjustable gates open and close to let more or less water to flow through the turbine to maintain a constant rotation.

The hydroelectric power plant is one of the simplest of power generating plants.  There is no fuel needed to generate heat to make steam.  No steam pressure to monitor closely to prevent explosions.  No fires to worry about in the mountains of coal stored at a plant.  No nuclear meltdown to worry about.  And no emissions.  All you need is water.  From snow in the winter that melts in the spring.  And rain.  Not to mention a good river to dam.  If the water comes the necessary head behind the dam will be there to spin those turbines.  But sometimes the water isn’t there.  And the dams have to shut down generators because there isn’t enough water.  But hydroelectric power is still the cleanest and most reliable source of electric power generated from renewable energy we have.  But it does have one serious drawback.  You need a river to dam.  And the best spots already have a dam on them.  Leaving little room for expansion of hydroelectric power.  Which is why we generate about half of our electric power from coal.  Because we can build a coal-fired power plant pretty much anywhere we want to.  And they will run whether or not we have snow or rain.  Because they are that reliable.

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