Generator, Current, Voltage, Diesel Electric Locomotive, Traction Motors, Head-End Power, Jet, Refined Petroleum and Plug-in Hybrid

Posted by PITHOCRATES - June 6th, 2012

Technology 101

When the Engineer advances the Throttle to ‘Run 1’ there is a Surge of Current into the Traction Motors

Once when my father suffered a power outage at his home I helped him hook up his backup generator.  This was the first time he used it.  He had sized it to be large enough to run the air conditioner as Mom had health issues and didn’t breathe well in hot and humid weather.  This outage was in the middle of a hot, sweltering summer.  So they were eager to get the air conditioner running again.  Only one problem.  Although the generator was large enough to run the air conditioner, it was not large enough to start it.  The starting in-rush of current was too much for the generator.  The current surged and the voltage dropped as the generator was pushed beyond its operating limit.  Suffice it to say Mom suffered during that power outage.

Getting a diesel-electric locomotive moving is very similar.  The massive diesel engine turns a generator.  When the engineer advances the throttle to ‘Run 1’ (the first notch) there is a surge of current into the traction motors.  And a drop in voltage.  As the current moves through the rotor windings in the traction motors it creates an electrical field that fights with the stator electrical field.  Creating a tremendous amount of torque.  Which slowly begins to turn the wheels.  As the wheels begin to rotate less torque is required and the current decreases and voltage increases.  Then the engineer advances the throttle to ‘Run 2’ and the current to the traction motors increases again.  And the voltage falls again.  Until the train picks up more speed.  Then the current falls and the voltage rises.  And so on until the engineer advances the throttle all the way to ‘Run 8’ and the train is running at speed. 

The actual speed is controlled by the RPMs of the diesel engine and fuel flow to the cylinders. Which is what the engineer is doing by advancing the throttle.  In a passenger train there are additional power needs for the passenger cars.  Heating, cooling, lights, etc.  The locomotive typically provides this Head-End Power (HEP).  The General Electric Genesis Series I locomotive (the aerodynamic locomotive engines on the majority of Amtrak’s trains), for example, has a maximum of 800 kilowatts of HEP available.  But there is a tradeoff in traction power that moves the train towards its destination.  With a full HEP load a 4,250 horsepower rated engine can only produce 2,525 horsepower of traction power.  Or a decrease of about 41% in traction horsepower due to the heating, cooling, lighting, etc., requirements of the passenger cars.  But because passenger cars are so light they can still pull many of them with one engine.  Unlike their freight counterparts.  Where it can take a lashup of three engines or more to move a heavy freight train to its destination.  Without any HEP sapping traction horsepower.

There is so much Energy available in Refined Petroleum that we can carry Small Amounts that take us Great Distances

The largest cost of flying a passenger jet is jet fuel.  That’s why they make planes out of aluminum.  To make them light.  Airbus and Boeing are using ever more composite materials in their latest planes to reduce the weight further still.  New engine designs improve fuel economy.  Advances in engine design allow bigger and more powerful engines.  So 2 engines can do the work it took 4 engines to do a decade or more ago.  Fewer engines mean less weight.  And less fuel.  Making the plane lighter and more fuel efficient.  They measure all cargo and count people to determine the total weight of plane, cargo, passengers and fuel.  So the pilot can calculate the minimum amount of fuel to carry.  For the less fuel they carry the lighter the plane and the more fuel efficient it is.   During times of high fuel costs airlines charge extra for every extra pound you bring aboard.  To either dissuade you from bringing a lot of extra dead weight aboard.  Or to help pay the fuel cost for the extra weight when they can’t dissuade you.

It’s similar with cars.  To meet strict CAFE standards manufacturers have been aggressively trying to reduce the weight of their vehicles.  Using front-wheel drive on cars saved the excess weight of a drive shaft.  Unibody construction removed the heavy frame.  Aerodynamic designs reduced wind resistance.  Use of composite materials instead of metal reduced weight.  Shrinking the size of cars made them lighter.  Controlling the engine by a computer increased engine efficiencies and improved fuel economy.  Everywhere manufacturers can they have reduced the weight of cars and improved the efficiencies of the engine.  While still providing the creature comforts we enjoy in a car.  In particular heating and air conditioning.  All the while driving great distances on a weekend getaway to an amusement park.  Or a drive across the country on a summer vacation.  Or on a winter ski trip.

This is something trains, planes and automobiles share.  The ability to take you great distances in comfort.  And what makes this all possible?  One thing.  Refined petroleum.  There is so much energy available in refined petroleum that we can carry small amounts of it in our trains, planes and automobiles that will take us great distances.  Planes can fly halfway across the planet on one fill-up.  Trains can travel across numerous states on one fill-up.  A car can drive up to 6 hours or more doing 70 MPH on the interstate on one fill-up.  And keep you warm while doing it in the winter.  And cool in the summer.  For the engine cooling system transfers the wasted heat of the internal combustion engine to a heating core inside the passenger compartment to heat the car.  And another belt slung around an engine pulley drives an air conditioner compressor under the hood to cool the passenger compartment.  Thanks to that abundant energy in refined petroleum creating all the power under the hood we need.

The Opportunity Cost of the Plug-in Hybrid is giving up what the Car Originally gave us – Freedom 

And then there’s the plug-in hybrid car.  That shares some things in common with the train, plane and (gasoline-powered) automobile.  Only it doesn’t do anything as well.  Primarily because of the limited range of the battery.  Electric traction motors draw a lot of current.  But a battery’s storage capacity is limited.  Some batteries offer only about 20-30 miles of driving distance on a charge.  Which is great if you use a car for very, very short commutes.  But as few do manufacturers add a backup gasoline engine so the car can go almost as far as a gasoline-powered car.  It probably could go as far if it wasn’t for that heavy battery and generator it was dragging around with it.

This is but one of many tradeoffs required in a plug-in hybrid car.  Most of these cars are tiny to make them as light as possible.  For the lighter the car is the less current it takes to get it moving.  But adding a backup gasoline engine and generator only makes the car heavier.  Thus reducing its electric range.  Making it more like a conventional car for a trip longer than 20-30 miles.  Only one that gets a poorer fuel economy.  Because of the extra weight of the battery and generator.  Manufacturers have even addressed this problem by reducing the range of the car.  If people don’t drive more than 10 miles on a typical trip they don’t need such a large battery.  Which is ideal if you use your car to go no further than you normally walk.  A smaller battery means less weight due to the lesser storage capacity required to travel that lesser range.  Another tradeoff is the heating and cooling of the car.  Without a gasoline engine on all of the time these cars have to use electric heat.  And an electric motor to drive the air conditioner compressor.  (Some heating and cooling systems will operate when the car is plugged in to conserve battery charge for the initial climate adjustment).  So in the heat of summer and the cold of winter you can scratch off another 20% of your electric range (bringing that 20 miles down to 16 miles).  Not as bad as on a passenger locomotive.  But with its large tanks of diesel fuel that train can still take you across the country.

The opportunity cost of the plug-in hybrid is giving up what the car originally gave us.  Freedom.  To get out on the open road just to see where it would take us.  For if you drive a long commute or like to take long trips your hybrid is just going to be using the backup gasoline engine for most of that driving.  While dragging around a lot of excess weight.  To make up for some lost fuel economy some manufacturers use a gasoline engine with high compression.  Unfortunately, high compression engines require the more expensive premium (higher octane) gasoline.  Which costs more at the pump.  There eventually comes the point we should ask ourselves why bother?  Wouldn’t life and driving be so much simpler with a gasoline-powered car?  Get fuel economy with a range of over 300 miles?  Guess it all depends on what’s more important.  Being sensible.  Or showing others that you’re saving the planet.

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Steam Locomotive, Diesel Electric Locomotive, Interstate Highway System, Airplane, Air Travel, Refined Petroleum Products and Pipelines

Posted by PITHOCRATES - March 21st, 2012

Technology 101

The Diesel Electric Locomotive could pull a Train Cross Country and into the Heart of a City with Minimal Pollution

The 1920s were transformative years.  The Roaring Twenties.  It’s when we moved from animal power to mechanical power.  From the horse and plow to the tractor.  From steam power to electric power.  From the telegraph to the telephone.  From the gas lamp to the electric light.  From crowded mass transit to the freedom of the automobile.  From manual labor to the assembly line. 

You can see a glimpse of that world in 1920’s Steam Train Journey Across the United States – Westward Ho!  The beginning of the modern city.  With modern street lighting.  Electric power and telephone overhead wiring.  Streets crowded with automobiles.  Tractors and mechanical harvesters on the farm.  And, of course, the steam locomotive.  Connecting distant cities.  Transferring the freight to feed the modern industrial economy.  And shipping the finished goods.  As well as all that food from the farm to our grocer’s shelves.  Proving the 1920s were vibrant economic times.  With real economic growth.  And not a speculative bubble.  For there was nothing speculative about all of this technology becoming a part of our way of life.

Of course the technology wasn’t perfect.  The coal-burning locomotives belched black smoke and ash wherever they went.  Which wasn’t all that bad in the open country where a train or two passed.  But it was pretty dangerous in tunnels.  Which had to be short lest they suffocated their passengers.  (One of the reasons why all subways use electric trains).  Making for some long and winding railroads in mountainous terrain.  To go around mountains instead of under them.  Slowing trains and increasing travel time.  And they were pretty unpleasant in the cities.  Where the several rail lines converged.  Bringing a lot of coal-burning locomotives together.  Creating a smoky haze in these cities.  And leaving a layer of ash everywhere.  The cleaner diesel-burning locomotives changed that.  The diesel electric locomotive could pull a train cross country and into the heart of a city with a minimal amount of pollution.  As long as they kept their engines from burning rich.  Which they would if they operated them with dirty air filters.  Reducing fuel efficiency by having the air-fuel mixture contain too much fuel.  And causing these engines to belch black smoke.  Similar to diesel trucks running with dirty air filters.

Airplanes can travel between Two Points in a Direct Line at Faster Speeds than a Train or Bus with Minimal Infrastructure

Trains shrunk our country.  Brought distant cities together.  Allowing people to visit anywhere in the continental United States.  And the railroads profited well from all of this travel.  Until two later developments.  One was the interstate highway system.  That transferred a lot of freight from the trains to trucks.  As well as people from trains to buses and cars.  And then air travel.  That transferred even more people from trains to airplanes.  This competition really weakening railroads’ profits.  And pretty much put an end to passenger rail.  For people used the interstate highway system for short trips.  And flew on the long ones.  Which was quicker.  And less expensive.  Primarily because airplanes flew over terrain that was costly to avoid.

Highways and railroads have to negotiate terrain.  They have to wind around obstacles.  Go up and down mountainous regions.  Cross rivers and valleys on bridges.  Travel under hilly terrain through tunnels.  And everywhere they go they have to travel on something built by man.  All the way from point A to point B.  Now trucks, buses and cars have an advantage here.  We subsidize highway travel with fuel taxes.  Trucking companies, bus lines and car owners didn’t have to build the road and infrastructure connecting point A to point B.  Like the railroads do.  The railroads had to supply that very extensive and very expensive infrastructure themselves.  Paid for by their freight rates and their passenger ticket sales.  And when there were less expensive alternatives it was difficult to sell your rates and fares at prices high enough to support that infrastructure.  Especially when that lower-priced alternative got you where you were going faster.  Like the airplane did.

Man had always wanted to fly.  Like a bird.  But no amount of flapping of man-made wings got anyone off the ground.  We’re too heavy and lacked the necessary breast muscles to flap anything fast enough.  Not to mention that if we could we didn’t have any means to stabilize ourselves in flight.  We don’t have a streamline body or tail feathers.  But then we learned we could create lift.  Not by flapping but my pushing a curved wing through the air.  As the air passes over this curved surface it creates lift.  Generate enough speed and you could lift quite a load with those wings.  Including people.  Cargo.  Engines.  And fuel.  Add in some control elements and we could stabilize this in flight.  A tail fin to prevent yawing (twisting left and right) from the direction of flight.  Like a weathercock turns to point in the direction of the wind.  And an elevator (small ‘wing’ at the tail of the plane) to control pitch (nose up and nose down).  Ailerons correct for rolling.  Or turn the plane by rolling.  By tipping the wings up or down to bank the airplane (to turn left the left aileron goes up and the right aileron goes down).  And using the elevator on the take-off roll to pitch the nose up to allow the plane to gain altitude.  And in flight it allows the plane to ascend or descend to different altitudes.  Put all of this together and it allows an airplane to travel between points A and B while avoiding all terrain.  In a direct line between these two points.  At a much faster speed than a train, bus or car can travel.  And the only infrastructure required for this are the airports at points A and B.  And the few en route air traffic controllers between points A and B. Which consisted of radar installations and dark rooms with people staring at monitors.  Communicating to the aircraft.  Helping them to negotiate the air highways without colliding into other aircraft.  And air travel took off, of course, in the 1920s.  The Roaring Twenties.  Those glorious transformative years.

Refined Petroleum Products have Large Concentrations of Energy and are the Only Fuel that allows Air Travel

The most expensive cost of flying is the fuel cost.  The costlier it is the costlier it is to fly.  Not so for the railroads.  Because their fuel costs aren’t the most expensive cost they have.  Maintaining their infrastructure is.  They can carry incredible loads cross country for a small price per unit weight.  Without swings in fuel prices eating into their profits.  Making them ideal to transfer very large and/or heavy loads over great distances.  Despite dealing with all the headaches of terrain.  For neither a plane nor a truck can carry the same volume a train can.  And heavier loads on a plane take far greater amounts of fuel.  This additional fuel itself adding a great amount of weight to the aircraft.  Thus limiting its flight distance.  Requiring refueling stops along the way.  Making it a very expensive way to transport heavy loads.  Which is why we ship coal on trains.  Not on planes.

Trains are profitable again.  But they’re not making their money moving people around.  Their money is in heavy freight.  Iron ore.  Coke.  And, of course, coal.  To feed the modern industrial economy.  Stuff too heavy for our paved roads.  And needed in such bulk that it would take caravans of trucks to carry what one train can carry.  But even trains can’t transport something in enough bulk to make it cost efficient.  Refined petroleum.  Gasoline.  Diesel.  And jet fuel.  For these we use pipelines.  From pipelines we load gas and diesel onto trucks and deliver it to your local gas station.  We run pipelines directly to the fuel racks in rail yards.   And run pipelines to our airports.  Where we pump jet fuel into onsite storage tanks in large fuel farms.  Which we then pump out in another set of pipelines to fueling hydrants located right at aircraft gates.

These refined petroleum products carry large concentrations of energy.  Are easy to transport in pipelines.  Are portable.  And are very convenient.  Planes and trains (as well as ships, busses and cars) can carry them.  Allowing them to travel great distances.  Something currently no renewable energy can do.  And doing without them would put an end to air travel.  Greatly increase the cost of rail transport (by electrifying ALL our tracks).  Or simply abandoning track we don’t electrify.  Making those far distant cities ever more distant.  And our traveling options far more limited than they were in the 1920s.  Turning the hands of time back about a hundred years.  Only we’ll have less.  And life will be less enjoyable.

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