Friday, March 2, 2012

The Must-Have, $10,000 Add-on for Your Chevy Volt

If there's one thing I've made fun of in my time here, it's the Chevy Volt from Glorious People's Automotive Collective Number 1.  To use a quote from here:
"So while it will work for many commuters (as would an electric golf cart), it still seems to be a $40,000 car with all the room and comfort of a $15,000 car." 
I've also poked fun at another over-hyped technology, the smart-grid (see It's not about you) although I'll be the first to say I haven't poked enough fun at smart grid. 

According to an industry magazine, Energy Efficiency & Technology, these two technologies seem to have combined to produce the must-have accessory for the Volt.  "Must have" in the sense that you're going to be forced to buy it and billed for it by your power company: a new distribution transformer.  The reason is the way electricity is distributed.  AC is used in most places on the power grid because it's the easiest way to move electricity around. 

The problem is described in the editorial of the January/February issue of EE&T (digital edition, p.6).  Prof. Saifur Rahman of Virginia Tech has analyzed this problem and is quoted throughout the editorial.  The higher voltage going into the neighborhood is dropped to the 120 that goes to your house (in the US, of course) by these distribution transformers.  There is usually one of these to every five houses, and it's rated for 25 kVA (kilo Volt*Amps not kW - a topic for another day).  They budget 6kVA for the average house and you can quickly see that 5 houses makes 30 kVa not 25, but they rationalize that by saying it's not likely everyone will be using the full 6 kVA at the same time.  And they're usually right - it's by the same logic that the phone companies have a dedicated pair of wires for only about 10% of the houses they serve. 

Enter the electric cars like the Glorious Volt (what's that smell?) , Nissan Leaf or the Tesla.  As the market share grows for these cars, it's not unlikely that five owners could arrive home at the same time and plug in their chargers.  The chargers for these smaller electric cars might be 40A, the same as a central air conditioner load.  That smell might be a burning distribution transformer.  When the utility comes around to install the transformer, who gets the bill?  Probably the last guy who plugged in his car.
"I know a Tesla owner in California who had to pay $10,000 to have his transformer upgraded", says Rahman.  "That's a bigger EV and its charger draws 100A.  But he'd just shelled out over $100,000 on his Tesla, so spending another $10,000 was not a big deal for him."
Now think of this problem in terms of the solar panel project.  First, it gives us a reasonable  estimate for a home power - 6 kVA, not the 20 I was talking about.  Second, think of adding a 120V charger at 100 Amps!   At 12V that's 1000A, and if that doesn't make your head spin, I don't know what will. Even the 40A charger for the smaller cars turns into 400A at 12V; that's a crazy amount of current.  That's the kind of current you need to run in copper wires bigger than your thumb. 

What's the smart grid connection?   First, the main point in that post "It's Not About You" was that a smart grid can't generate new electricity, it can only ship it around to places where more is needed from places that have excess capacity.  If nobody has excess capacity because everyone is plugging in cars, nobody gets extra power.  Every penny we spend on smart grid is a penny not spent on power generation (which is opposed by the anti-progress crowd). Second, to quote that post:
Another thing to control is an outlet you might plug your electric car or hybrid into for recharging.  The power that you would get out of gasoline has to come from somewhere; in this case, you've moved your expense from the gas station to the electric company.  These chargers can consume large amounts of current in their fast-charge mode.  In turn, what the electric company wants to do is to not allow your charger to run during the early evening when TVs, dishwashers and other appliances are on.  They want to turn on your charger in the early morning hours; if everyone in your neighborhood had an electric car, say, they might time stagger the charging time for users to minimize the load on a transformer.   
If they try to charge everyone's car in the midnight to 6AM block, what if you can't live with that?  What if you work then, and need to charge your car during the prime time for power use?  

Look, if you want a Volt or a Leaf, go for it.  Buy your $10,000 transformer, or your $50,000 worth of solar panels.  But with each of these cars being subsidized by the rest of us to the tune of about a quarter of a million dollars, don't come looking to me to pay for your toy.  I'd rather spend my money on more power generation. 


  1. Transformers are engineered for a cool off period at night, since night time loads tend to be lower, and the temperature is lower as well. With what ammount to 100% full load or close to it, your going to have to replace every transformer in the US. with upgraded service and lines to the house as well.

    1. Interesting - but how much affect does that have on the actual power dissipation ratings? During summer around here, it doesn't get to be under 80 until midnight, and then only for a few hours. It would seem the transformers would have to be designed with no cooling off period.

  2. Must some of those "Shovel ready jobs" 0bummer was talking about.

  3. Correct me if I am wrong,but don't most of these electric vehicles operate at much higher voltages than 12v? Aren't the battery banks/packs engineered with cells in series to operate at 240v or higher? If so, that would bring the amps down to 50, which would be much more manageable.

    On my recent trip up into Wyoming and Montana, I saw a couple of service stations with charging stations for EVs. I didn't look at them to see what volts or amps they charged at, but the connecting cords didn't appear to be much larger than the cord on a Lincoln stick welder or an electric dryer, either of which (IIRC) can draw up to 50 amps. Still, that might work when there are only a few EVs running around. No way it will work if they were to become more prevalent.

    Not trying to be a butthead here, SG. Just asking :-) I certainly agree about the insanity of "smart grids" , expecting to handle a large number of EVs without improving and enlarging the supply infrastructure, etc. But we know it's all smoke and mirrors, or at least just like the rest of the "wind generators" operating in D.C. All they are capable of is pushing a lot of hot air around.

    1. RegT - those currents they cited are already at 120VAC. This was an article looking at the impacts to the grid of EVs. The cars I've seen info on use higher voltage than 12V batteries, like you say.

      The Tesla was sucking 100A at 120V. The (much more common) smaller cars are OK with the size cables you saw because their current consumption is in line with those applications, 40A at 110, on peaks (fast charge).

      Personally, if I had $100,000 to throw away on a car, the Tesla roadster might be the one. The price is not out of line with cars in its class, and the torque curve on the electric motors is fantastic. But that's a very different question than practicality. How practical is a Bugati Veyron at almost $2,000,000 for the "bare bones" version?

  4. What amazes me is the fact that the guys who make the Tesla developed a worthwhile product that Government Motors and other companies seem to be incapable of emulating. If Tesla can produce torque, speed and decent mileage, why can't these other companies? If they shot for values that were half of what the Tesla provides, they ought to be able to do it for a whole lot less, yet still have something worth driving. I'd love to drive a quiet car. I'm not impressed by loud engines, exhaust noise, etc.

    Toyota supposedly produced a Rav that was all-electric some years back, but couldn't or wouldn't market it, even though it got pretty good reviews. Maybe it just didn't receive enough market share to continue producing?

  5. But..but...but...why do we need all those nasty power plants? They cost money we could use for universal health care, take up land that could be used for parks, and pollute Mother Earth.

    My electric car won't do that ... it doesn't need gasoline and doesn't have exhaust.

    Why do I need to worry about the power company putting in even more transformers? We all know that would just be an excuse to send us a bill that's already too high.

    Besides, I never need a power plant, I get all my electricity out of a plug in the wall. Why can't everybody else live that way too?

  6. Yeah - Q's comment is less like comment and more like documentary!

  7. I once had this discussion with my tech-geeky programmer-nerd friends out here in the PRC (People's Republic of California,) one of which had a first-gen Prius, and was salivating over the prospect of the forthcoming plug-in Prius.

    I asked: "How many new electrical generation plants have been built to serve California? What happens to the price of electricity when you and half your urban neighbors start plugging in their EVs?"

    The replies were mostly wishful thinking and pie-in-the-sky denialism. "Oh, don't worry, people will charge their cars during off-hours" was the only plausible response. I asked what they expected to happen when a limited-supply, non-free-market resource (electricity) would be consumed in far greater quantities. I pointed out that the current rate structure for household users was a 'progressive' rate: the more you use, the higher the per-unit rate. No reponse from the techies. They just thought this was all gonna be a peachy keen thing, best thing since sliced bread, etc.

    1. Why, they expect The Obamessiah to produce free, green electricity from unicorn farts!
      I thought *everybody* knew that!