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Whenever I get a shiny new copy of Electronic Design magazine, I eagerly read the section called Pease Porridge, at the very end of the magazine. This section is written by Bob Pease and typically contains whatever material Mr. Pease decides to include that month. In my view, this is the only page in the magazine that actually includes electronic designs and is in contrast with the rest of the magazine’s content (advertisements that look like written text).  Sometimes there are designs for circuits that detect dropping temperatures in boots, sometimes something on taxes, and sometimes the section contains responses to letter (or emails) that readers have sent in. This month’s porridge dealt with sent in letters and the first one, by Anonymous Engineer, has provoked some thought.

Hello Bob,

A note concerning electric cars and plugin hybrids: Consider that politics has little to do with engineering and/or science. It only pays lip service at those altars. So, somebody has to do serious planning for the immediate future.

I’ve been working on some serious battery-charger designs. One of our planners (an engineer) did some research in good old California. We learned that your utility companies have problems with metering even small numbers of plug-ins, nor can the California infrastructure absorb many cells of even 5000 plug-ins. You’re running at about 81% capacity, and without a smart meter and control, we would easily overload the electricity capacity on two peaks every day. That’s not politics. It’s business.

American, Japanese, and European manufacturers were contacted, and none of us can really do this without the cooperation of the utilities. Oh sure, we can sell a few and look green. The press wouldn’t even know who to blame when the grid broke. Some of our competitors have been doing that, but without that smart meter, it’s the wrong thing to do. They know it. But that’s business.

All of the automakers easily agreed on the meter and protocol. The utilities did not. They already have contracts on meters that aren’t smart. That’s business. The real greenies were there, too. They’re part of politics. They want California to be energy neutral in 10 years—sorry, no data on how to do it. Industry must be hiding it.

Back in the Midwest, we run about 1/2 the total power per person aggregate (at 740 W per person continuous) than you do out west, but that’s because of our low transport and air conditioning costs. Perhaps just targeting our levels would be a better starting point. There is no magic bullet in the next 10 years. So the utilities answer to the greenies and business, not to the engineers. Our charger is going to be great. We will get patents. It will be used all over, but not in volume in the west.

-An Anonymous Engineer

Prior to reading this, I have been all for plug-in electric vehicles, although I have never worked out the power load requirements to support such a population. Now thinking a of the power blackouts that crippled the North-Eastern United States a few years back, I am no longer sure that switching privately owned vehicles to plug-ins is the right thing to do right now due to obvious issues with the power infrastructure in the U.S. Although the need to address environmental issues related to automobiles is apparent, I doubt there will be a serious motivation behind it unless there are economic benefits involved. The switch over to electric (or hydrogen for that matter) vehicles should start with the sector that can be converted most efficiently which would allow for the highest return on investment.

In my mind, the public transportation system should make the switch first. I am mostly experienced with the Metro fleet in Washington D.C. and can note that all of the buses are made by Orion Bus Industries (owned by Daimler Trucking) and fall into two models (larger and smaller). Given that the buses operate on a pre-determined route and are equipped with GPS (to automate the current location display inside the bus), the energy demand per vehicle per day can be predicted with high accuracy. Furthermore, most of the vehicles are at the depot during the late night and early morning, when electricity is cheaper than the daytime, which would make for an ideal charging period.

Over all, this would lead to a very predictable off-peak energy demand that can be negotiated with the local power generation utility in advance to ensure that the power demand is met economically and without sacrificing the power grid’s integrity. An on-site generator may be employed to charge batteries in case of a power emergency where public transportation service is required. A more clever (and more difficult) design may involve modifying the buses to have a modular power system that can be swapped between conventional diesel and electric power-plants.

Again, most of this is mostly my intuition as I have not worked out most of the mathematics behind it, however, it seems that power demand predictability might be a mitigating economic factor for public transportation conversion. Unlike us, the bus driver rarely gets sleepy while reading at night and takes the bus out for a spin to the coffee shop.

 
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