Tag Archives: Gas

Gas…whats that??

I was reading the newspaper the other day; an article about how truck sales will be going up now that gas prices have fallen towards $3/gallon. It then dawned on me: “$3/gallon? when did that happen?” Yes dear reader: drive an EV and it won’t take you very long to forget completely about gas prices. Gas stations are everywhere, I drive by quite a few of them on my commute in to work and home every day. You’d think that I’d know gas prices simply because I see so many stations with their prices prominently displayed out front. No, not so much.

Before when driving an ICE vehicle I’d pay attention now and then simply to make note of the cheapest station and remind myself to fill up there when I need to. Now I just silently ride by not even paying attention to them anymore.. I think the last time I actually filled up a gas car was a couple of months ago when I was helping out the wife–had to fill up her car.

I still find it amazing how fast you acclimate yourself to driving an EV around vs ICE car. For the family it is no longer an anomaly riding around in it–the novelty has warn off for them. This is probably hurried along by the fact that our Focus Electric on the inside is identical to our ICE Focus (minus the engine vibrations). Inside the only real difference is the dashboard–so only the driver knows s/he is in an EV.

For me the novelty has not warn off. It is still my favorite car to drive around. Plugging it in every day has become the new habit–just like plugging in the cell phone, or the leaf blower, or the trimmer, or the lawn mower..etc. (yes I’ve also been converting the yard power tools all over to electric as well–started with the lawn mower about a year before even getting the EV–the last one, a snow blower, may not be converted as the only cordless snow blower I could find was well over $1k in price!)


Taking a break from the story for a bit.

Here I am going to go into a general discussion of the differences between various vehicle propulsion methods: Gas engine, hybrid, and electric motor.

Your normal gas engine operates at about 18%-20% efficiency. Much the losses associated with gas engines are attributed to heat loss through the exhaust and friction in the drive train. This can be increased slightly by adding turbo or super chargers but they only bring the engine closer to its theoretical maximum efficiency (37%).
Electric motors, on the other hand, have an efficiency in the range of 85%-90% thus more of the “fuel” will go to moving the car. This also poses a problem as there isn’t enough waste heat to be used for other purposes (heating the cabin, warming the batteries, etc.). This large difference gives the electric car an advantage in “fuel” economy.

Now lets look at other aspects of the vehicle: What is the one thing that a car does that wastes the most energy? Its not acceleration; its stopping. Think about it: What do brakes do? Brakes turn the forward momentum of the vehicle into heat at the braking mechanism. All of this heat is dissipated into the air–just thrown away.

How can we recover that lost heat? There is no way to feed that back into a gas engine and re-create gasoline. What you can do is spin up a generator and store the electricity. This is the exact principle used by hybrid vehicles: There is a motor/generator that recovers the stopping momentum and puts it back into a battery for use during acceleration (this is what regenerative braking does). Hybrids aren’t designed to run on electricity alone–the battery isn’t large enough–they are only designed to capture and re-use the deceleration energy (for the most part).

Now adding all the equipment for a hybrid increases the vehicles weight by a significant amount (we now have two “engines” and two “fuel” tanks). Manufacturers make a tradeoff between the sizes of the engine, motor, fuel tank, and battery when designing the hybrid car.

An electric car does not suffer from that limitation–only one motor is present and one “fuel” tank. In addition the electric car can make full use of regenerative braking.

Given all these advantages an electric car has one huge drawback to it (as you are probably screaming at your screen about now LOL): The energy density in today’s batteries is nowhere even close to the energy in a tank of gas. There is a ton of electricity storage research (battery, super capacitor, air-battery, etc.) going on with the goal of giving today’s electric vehicles more range. I’ve read of a few people posting their opinions for the battery criteria required for BEV’s to go mainstream. Jumping into the fray here is my guess as what is required for mass adoption of BEVs:

  • BEVs must have a range of 250+ miles (Not saying 300+ miles because one of my ICE vehicles (a rather large truck) only has a range of 250 miles on a tank)
  • The battery in said BEV of range 250+ miles must be not much larger than the average tank of gas (note that the battery doesn’t have to have the same energy density of gas due to the electric motors higher efficiency)
  • There must be available charging stations to allow the 250+ miles to be replaced in approx 10 minutes or so

Easy as pie right? The Tesla Model S comes really close to all of those above with a luxury price tag. The sub $30k planned Tesla model should take the market by storm..