Tuesday, September 22, 2009

The Electric Highway Part 1


I read an interesting article about running electric cars without batteries. Here is a quote.

The Korea Advanced Institute of Technology (KAIST) has developed a revolutionary electric vehicle that neatly side-steps the looming political/economic issue of scarcity of advanced battery materials, as well as the practical limitations imposed by battery weight and life, by dispensing with batteries altogether! The OLEV (On Line Electric Vehicle) draws power from cables buried in the road-bed, differing from existing electric train and bus technology in that the power is transferred by magnetic induction without physical contact of any kind. KAIST claims to achieve 80% efficiency of power-transfer across a 1cm gap, and 60% efficiency across a 12cm gap!

http://www.allcarselectric.com/blog/1034778_korean-ev-runs-without-batteries-by-induction-charging


It occurred to me that the two biggest limitations with Plug In Electric Vehicles are the limitations on range from current battery technology and the lack of stations to recharge their vehicles.

What if we made our whole freeway system into an electric road? Electric cars would only run off of batteries on surface streets. Once they got on the freeway, they would use power from the roads and recharge their battery at the same time. We could set up an e-pass like system at the entrance and exit ramps to read the vehicle ID and battery state and bill automatically for the electricity consumed. You could drive coast to coast and never use a KWh from your batteries.

My next thought is how do you build such a thing without it costing 10 trillion dollars? I started visualizing a large machine that would move down a lane on the freeway at a mile per hour and cut a slit a couple of inches deep in the pavement, lay the cable and seal the trench behind it. We probably need different machines for concrete or asphalt. Every five or ten miles you connect the road to the grid. If one section goes out, then cars only need to go five or ten miles on battery to get to the next section. If you operate the machine outside of rush hour you could run it 10 to 15 hours a day. On rural interstates you might be able to operate it close to 7/24.

How much would it cost?

The next part was doing a back of the envelope calculation about how much building such a grid would cost. I made a guess of 10,000 dollars an hour or 10,000 dollars per lane-mile to operate the machine. I figure double the number to account for grid connections, so I’m up to 20,000 per lane-mile. Next I check Wikipedia and it says we have 75,000 miles of freeway. Multiply by 4 and I’ve got 300,000 lane-miles. I know some freeways have more than 4 lanes, but I’m just trying for a ballpark number. That comes out to 6 billion to electrify all the freeways. This sounds low, but unless they use the same guys who did the Big Dig in Boston, it shouldn’t go over 24 billion. Once you figure in four lanes, then you end up with 320,000 dollars a mile. This actually seems plausible, if you contract the whole thing out at once, instead of piecemeal. Of course, every road construction company in the United States will scream bloody murder, but it doesn’t make much sense to do it any other way, since the construction machines will probably cost over 100 million per unit unless other countries jump on the band wagon and buy them. Also you hook all the lanes to the grid at the same time, which should reduce the cost.

How long would it take?

You would have a lot of development time up front. You have to design the whole infrastructure up front and make sure all EV makers design their cars to hook up to the system. You have to figure out a billing system that will work anywhere you can drive in the United States and the transponders it will need. You have to design the construction machines and build them. I’d say at least 10 years. I’ve got the total freeway system in the United States up to 300,000 lane-miles. I assume each construction machine handles 10 miles a day and I’ll assume we spend 1 billion dollars and buy 10 machines and electrify 100 lane-miles a day which would come out to 3000 days or 8.2 years.

Of course, it doesn’t actually happen this way, since the construction machines don’t all get built at the same time. Also it makes sense to build out the local area until you reach the critical mass where a lot of people want them. Keep in mind that electric motors are more efficient than internal combustion engines and if you don’t need a big battery pack, they may cost less to purchase as well as operate. The reason a Prius is expensive is that you are buying an electric motor and an internal combustion engine and stuffing them both under one hood. Once you have the local grid built out, then a lot of families will want an EV as their second car. Once the grid is totally built out, then they will want one as their first car.

Anyway , assume the first machine goes to Los Angeles and starts electrifying the Southern California freeway system and maybe they put several machines on the West Coast and work their way East and then put some more on the East Coast and work their way West. Unless, of course, it looks like a close election, and then Florida and Ohio get the machines. In any case, figure 15 years to build out on the whole freeway system.

So we are up to 2035 and the whole freeway system is electrified. Obviously we don’t quit at that point and we start electrifying the major surface streets. The E-pass doesn’t work for this, but by the time we need it, we can figure it out. Maybe we put meters in each car that keep track of where the car is and how much electricity it is using from the grid. Maybe we put sensors every 50 yards to figure when you enter and leave the grid. In either case, you might consider walking, if you plan on going anywhere where you don’t want your wife or the police to know about.

By now, we are up to 2045 and most of our cars are electric and the rest are running on Biodiesel from algae. Our electricity is from nuclear power, the carbon dioxide concentration in the atmosphere is going down. For Part II, I'll calculate how much power such a system would use.

References:

http://www.designboom.com/weblog/cat/16/view/7271/kaist-korean-electric-vehicle-project.html

http://www.kaist.edu/english/01_about/06_news_01.php?req_P=bv&req_BIDX=10&req_BNM=ed_news&req_VI=2056&req_PC=20&req_CG=&sCATE=&sCHAR=

3 comments:

  1. Nothing revolutionary about it. http://en.wikipedia.org/wiki/TrolleybusIt's been done for some time.

    Anyway I can see that it could serve a purpose. It would not be practical to provide this to everyone's doorstep, but for interstates, at some point, there may a good argument to use this with battery electric vehicles so that they can have basically unlimited range once on the freeway.

    I don't know that it would ever be worthwhile to electrify surface streets. I mean, lets consider that a battery electric car can pretty easily make outings of less than 50 miles and how often do you drive that far without using the highway at all?

    The thing that excites me more is automated cars that drive themselves. The technology has actually been there for some time, but the problem is standardization. Someone needs to decide how the cars will do things like communicate with each other. They'll need to be able to signal other cars to tell them they want to merge or something or to decide who has the right of way. The big problem is that if you mix human drivers and automated vehicles, they might not get along with eachother.

    Anyway, when it comes to electrifying the roads, I'd say it's premature to really think about doing that at this point. Once we start seeing a lot of electric cars, it will be simple to fit them with collectors and in terms of environmental concerns, switching how we generate power is priority one.

    IMHO, having a society where there are electric cars driving around on powered roads and the power is still coming mostly from coal burners is just idiotic.
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  2. What you say is sensible. I plan to explore some of them in the later parts of the series. The important thing is to do the calculations and figure out which options make economic sense and which don't. There is too much public policy driven by ideas that wouldn't survive even the simplest back of the envelope calculation.
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  3. Interesting> I am of the opinion that the way to get an automated, inexpensive, mass transit system is either by adapting the rail system or building overhead monorails, or more likely both integrated together. These seem to me to run less risk of unautometed drivers/pedestrians getting in the way & since they run on rails need less steering control. This method of power transmission would help roads more because it is more demonstrably short of a good, non-oil, power source but would be useful for them all.
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