Electronic Design

Bob's Mailbox

Hi Bob,

The plug-in hybrid seems like the best immediate transportation solution. (Yeah, but we ain’t got enough (a) cars, (b) batteries, or (c) power to recharge them all. /rap) My engineering solution for California is a smarter power meter that rations power to your charging car. (Yeah, but that meter does not yet exist. /rap)

If the power demand is high, your car will charge in proportion to how much stuff you turn off in the household. It is up to each power user to decide whether to charge the car or run the air conditioner. This would bring green reality to each household. (Yeah, but at my house, even if I turned off everything but one LED flashlight, I might not be able to get enough charge to get to work the next day. /rap)

Each home would get an equal ration of power. We could call it the Green Piece of Power. When the grid gets to full capacity, the brownout starts with the highest over-ration users. (That is a very fine concept, but it would need a very sophisticated meter—and I don’t think we know how to make that meter. And if we did, the electric companies and the customers might not agree to it. /rap)

After being the dark, hot house in the neighborhood a few times, increasing home power conservation will become a status symbol. (My “air conditioning” runs off the Pacific Ocean and requires no amperes at all. /rap)

Personally, I have over a foot of insulation in the attic, double-pane windows, and the biggest, most efficient air conditioning condenser in the neighborhood. During air conditioning season, we cook outside and limit inside power dissipation as much as possible. There is a connection between money conservation and being green. (Agreed. But sometimes it takes a lot of money to save money. Not everybody has that money. /rap)

Putting ethanol in gas tanks is a waste. My solution is to drink the ethanol and walk.

Tom Cater

That one, I like. Or, ride a bicycle. Best regards. –RAP

Hi Bob,

As a former electrical engineer from the 1950s and 1960s, I’ve been a long-time admirer. So I was surprised to see your letter in Electronic Design stating “Who is going to build the electrical generating and power transmission capacity for recharging a lot of cars?” California peak load during a normal summer day is about 43 GW. The max load is 50 GW. Nighttime summer load runs around 25 GW. (On a really hot night, the demand for electricity doesn’t taper off much. Here in San Francisco, it gets warm, but not warm enough to bother us. My air conditioning comes straight off the Pacific Ocean. It costs me zero amperes. /rap)

That leaves about 25 GW of off-peak capacity, which would power a maximum of 3.7 million cars in California. (Chargers pull about 6.7 kW.) (They can pull a lot more than that. And, there are a lot more cars than 3.7 million in California. If 10% of those cars were replaced by plug-in hybrids, the grid would go down on the first hot night. I think I will hold on to my Beetle just to be safe. I believe that Tom (above) is right, that we’d need chargers that are smart enough to charge per priorities. An electric car would be screwed if it couldn’t get much charge at night. A plug-in hybrid would just have to buy some gas. As I said in my column on this 12 years ago, the owner of an electric car could buy a gas engine as an accessory! /rap)

It also solves a big problem for the power-generating utilities who have to inefficiently throttle back their generators during off-peak. (A lot of places have pumped storage, such as Northfield Mt. in Massachusetts. Is there none of that in California? We got big hills and high reservoirs. I’ll have to look into this. /rap)

On the plus side, you sure got the hydrogen “boondoggle” right. The production, storage, and transportation of hydrogen is a nightmare under the best of circumstances, but the economics of generating hydrogen is so poor as to be laughable. I think the current cost is about $12 to $15/equivalent energy gallon. (And every time the price of gasoline rises, the price of hydrogen is thus ratcheted up, with that same brutal factor. Maybe we can get George to subsidize the cost of hydrogen. I’d love to, but I can’t afford the taxes. /rap)

All you need to do is look at the electrical energy required to electrolyze water and break the hydrogen bond. It takes four units of electrical energy to produce one unit of equal hydrogen energy. Talk about inefficiency! You may as well use the electrical energy to directly charge batteries. It’s four times as efficient. (Check. But those batteries are heavy to drag around. Maybe since George is so smart, he can figure out how to avoid that. Maybe he can invent the helium battery, even lighter than lithium. /rap)

Ditto for reforming hydrocarbons to make hydrogen. You would be better off using the gas directly. Either way, you’re generating the same pollutants, except you can scrub them easier in large central facilities. And, most people don’t know that oil refineries are the biggest users of electrical power in California. I’m not sure of the exact number, but I think it’s over 20%. That’s more electrical capacity that would be available if there was a reduction in gasoline production.

Malcolm Field

I doubt if we are going to worry about that very soon. Thanks for the comments and advice and good technical points. –RAP

P.S. I have heard that water pumps are the biggest users of electricity in California—pumping for farmers and pumping water to Los Angeles. That might be true. —RAP


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