Internal Combustion Engine, Electric Motor, Fuel Economy, Emissions, Electric Range, Parallel Hybrid, Series Hybrid and Plug-In

Posted by PITHOCRATES - September 5th, 2012

Technology 101

We started the First Cars with a Hand Crank and Nearly Broke an Arm if the Hand Crank Kicked Back

The king of car engines is the internal combustion engine (ICE).  We tried other motors such as a steam engine.  But a steam engine is a heat engine.  Meaning it first has to get hot enough to boil water into steam.  Which meant any trip in a car took a little extra time to bring the boiler up to operating temperatures.  Boilers tend to be big and heavy.  And dangerous.  Should something happen and a dangerous level of steam pressure built up they could explode.  Despite those drawbacks, though, a steam engine-powered car took you places.  And as long as there was fuel for the firebox and water for the boiler you could keep driving.

Another engine we tried was the electric motor.  These didn’t have any of the drawbacks of a steam engine.  You didn’t have to wait for a boiler to get to operating temperatures before driving.  Nothing was in danger of exploding.  An electric motor was lighter than a cast-iron boiler.  And an electric motor could make a car zip along.  However, an electric motor requires continuous electricity to operate.  Provided by charged batteries.  Which didn’t last long.  And took hours to recharge.  Giving the electric car limited range.  And little convenience.  For the heavier it was and/or the faster you went the faster you drained those batteries.  Which could be a problem taking the family on vacation.  But they worked well in a forklift on a loading dock.  Because of the battery-power they produced no emissions so they’re safe to use indoors.  They had limited auxiliary systems to run (other than a horn and maybe a light).  And when they were running low on charge you rarely needed to drive more than 20 or 30 feet to a charging station.

The first ICE-powered cars took some manly strength to operate.  They didn’t have power brakes, power steering, automatic transmissions or starters.  We started the first ICE-powered cars with a hand crank.  That took a lot of strength to turn.  And if it backfired while starting the kick of the handle could easily break a wrist or an arm.  Putting a damper on any Sunday afternoon drive.  This limited the spread of the automobile.  They were complex machines that required some strength to operate.  And they could be very dangerous.  Then along came the electric starter.  Which was an electric motor that spun the ICE to life.  Making the car much safer to start.  Expanding the popularity of the automobile.  For there was no longer a good chance that you could break your arm trying to start it.  And through the years came all those accessories making it easier and more comfortable to drive.  Today automatic transmissions, power steering, power brakes, headlights, interior lights, power locks, power windows, powered seats, a fairly decent audio system, heat, air conditioning and more are standard on most cars.  All effortless powered by that internal combustion engine.

Current Battery Technology does not give the All-Electric Car a Great Range

The reason why an ICE can do all of this is because gasoline is a very concentrated energy source.  It doesn’t take a lot of it to go a long way.  And it can accelerate you up a hill.  It even has the energy to pass someone on a hill. It’s a fuel source we can take with us.  A small amount of it stores conveniently and safely in a gas tank slung underneath a car.  And when it’s empty it takes very little time to refill.  A ten minute stop at a gas station and you’re back on the road able to drive another 500 miles or so.  Even in the dark of night with headlights blazing.  While keeping toasty warm in the winter.  Or comfortably cool in the summer.  Things an electric battery just can’t do.  So why would we even want to trade one for the other?  In a word—emissions.

The internal combustion engine pollutes.  The more fuel a car burns the more it pollutes.  So to cut pollution you try to make cars burn less fuel.  You increase the fuel economy.  And you can do that in a couple of ways.  You can cut the weight of the vehicle.  And put in a smaller engine.  Because a smaller engine can power a lighter car.  But a smaller car carries fewer people comfortably.  And can carry less stuff.  A motor cycle gets very good fuel economy but you can’t take the family on a Sunday drive on one.  And you can’t pack up your things on a motorcycle when going off to college.  So the tradeoff between fuel economy and weight has consequences.

An electric car does not pollute.  At all.  (Though the power plant that charges its batteries does pollute.  A lot.)  But current battery technology does not give the all-electric car a great range.  Typically coming in at less than 75 miles per charge.  Which is great if you’re operating a forklift on a loading dock.  But it’s pretty bad if you’re actually driving on a road going someplace.  And hope to return.  The heavier the car is the shorter that driving range.  If you want to use your headlights, heater or air conditioner it’ll be shorter still.  On top of this short range recharging your battery isn’t like stopping at the gas station for 10 minutes.  No.  What one typically does is pray that he or she gets home.  Then plugs in.  And by morning the car would be fully charge for another 75 miles or so of driving.

To Maximize the Benefit of a Hybrid you’d want to Carry the Absolute Minimum of Batteries to Serve your Needs

So all-electric cars are clean but they won’t really take us places.  The ICE-powered car will take us places but it’s not really clean.  Enter the gas/electric hybrid.  Which combines the best of the all-electric car (clean) and the best of the ICE-powered car (range).  There are a few varieties.  The parallel hybrid has both an ICE and an electric motor connected to a transmission that powers the wheels.  The ICE also drives a small generator.  Batteries power the electric motor.  And a gas tank feeds the ICE.  The generator keeps the batteries charged.  The battery powers the electric motor to accelerate the car from a stop.  After a certain speed the small ICE takes over.  When the car needs to accelerate the electric motor assists the ICE.  The small ICE has excellent fuel economy thus reducing emissions.  The electric motor/battery provides the additional horsepower when needed to compensate for an undersized ICE.  And the gasoline-powered engine provides extended range.

In addition to the parallel hybrid there is the series hybrid.  It has the same parts but they are connected differently.  The series hybrid is more like a diesel-electric locomotive.  Gasoline feeds the ICE.  The ICE drives a generator.  The generator charges the batteries and/or drives the electric motor.  The electric motor drives a transmission that spins the wheels.  This car drives on batteries until the charge runs out and then switches over to the ICE.  For short commutes this provides excellent fuel economy.  For longer drives (well over 75 miles or so) it’s more like a standard ICE-powered car with a roundabout way of turning the wheels.

Then there’s the plug-in variety.  In addition to all of the above you can plug your car into a charger to further save on gasoline use and reduce emissions (produced by the car; not by the electric power plant).  Letting you recharge the battery overnight in a standard 120V outlet.  In a slightly shorter time with a 240 volt outlet.  And quicker still in a 480 volt outlet.  If your commute to and from work is 50 miles or less you can probably charge up at home and not have to carry a charger with you (to convert the AC power to the DC power of the batteries).  Saving even more weight.  But if you plan on charging on the road you’ll need to carry a charger with you.  Adding additional weight.  Which will, of course, reduce your battery range.  Also, you can adjust the number of batteries to match your typical daily commute.  The shorter your commute the less charge you need to store.  Which lets you get by on fewer batteries.  Greatly reducing the weight of the car (and extending your battery range).  A gallon of gas weighs about 7 pounds and can take a car 30 miles or more.  You would need about 1,000 pounds of batteries to provide a similar range.  So range doesn’t come cheap.  To maximize the benefit of a hybrid you’d want to carry the absolute minimum of batteries to serve your needs.  Knowing that if you got a new job with a longer commute you could rely on the ICE in your hybrid to get you to work and back home safe again.


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