Creating a New EV Paradigm
By Bill Moore
Posted: 18 Jul 2011
Recently Wayne Xing noted in the China Auto Review that what is needed in China -- and elsewhere -- is a new paradigm. He writes, "Maybe the electrification of transportation needs to be approached from a new and completely different paradigm in order to make it happen. It may be wrong and unnecessary for the industry and governments to try to realize individual mobility in the traditional sense of the word – driving a full-size sedan on expressways at high speed for an extended range of hundreds of miles. By moving away from the old paradigm we may suddenly find a practical solution to vehicle electrification and individual mobility."
Two recent developments brought this into focus for me personally. The first was Gordon Murray Design's recent announcement that the T.27 electric micro-mini car they developed is "the world's most efficient electric car." Now that's an easy boast to make. What evidence do they have to back up that claim? I did a bit of back-of-the-envelope guestimation to see if it could be substantiated based on the few details they provided about the little, three-seater.
The lithium ion battery pack in the 680kg runabout, whose top speed is 75 mph, is rated at 12kWh, half the size of that in the Nissan LEAF. Murray claims the car will do 100 to 130 miles per charge depending on which European driving cycle you use: the New European Drive Cycle or their urban drive cycle. Making some assumption about the battery buffer (5% at top and bottom) and battery-to-wheel efficiency, I figured the car might use 100 watts per mile in the NEDC test and an amazingly low 70 watts per mile in the urban test. Both numbers are phenomenal. Murray claims the T.27 is “36 percent more efficient than the Mitsubishi i-MiEV and 29 percent more than the Smart car.”
Why these numbers are important to the discussion of a "new paradigm" will become apparent shortly.
The second insight came when I started fooling around with the idea of mounting solar panels on street light poles. Again, I guestimated that about the maximum number of watts you might feasibly get out of such an arrangement for both wind load and aesthetic reasons would be between 800-1000 watts per fixture. Assuming the lower number and six hours of sunlight translates into 4,800 watt hours (4.8kWh) per day per fixture. Not a lot of energy, of course, but enough to certainly recharge our plug-in Prius, which, incidentally, uses about 4kWh a day for my wife's 11 mile commute to work and back. Assuming that a dedicated electric car like the LEAF gets about 3 miles per kilowatt hour, that equates to around 14 miles of electric driving range, so for many drivers whose commute is less than 30 miles a day, half of their journey could be powered by sunlight; a concept I really like.
But watch what happens when I plug in Gordon Murray's T.27. My wife's drive a mainly urban with top speeds of 40-45 mph. Divide 4,800 watt hours by 70 watt hours per mile and suddenly the distance you can drive jumps from less than 15 miles to nearly 70 miles, 68.5 to be more exact.
Now that IS a paradigm shift, but it gets even more interesting.
We know that the sun doesn't always shine with the same level of intensity day-in-day out. The shadow of passing clouds can dramatically impact electricity production. A rule of thumb I use is that about 40% of time in my region of America will be cloudy to one degree or another. So in my calculations I factor that in to come up with a estimate of potential power production. In the case of the 800 watt light pole idea, that comes out around 1,051,000 watt hours annually, or about 1MWh of electricity.
In practical terms that means that a car like the LEAF can drive almost 3,200 miles on sunlight. In dramatic contrast, the T.27 might be able go 15,014 miles! Or put another way, you can power five T.27s from the same 800 watt array, giving them each a range of 3,000 miles, close that of the single Nissan LEAF.
When we start thinking in those terms, instead of 'Can I drive 300 miles on a charge?' we begin to create that new paradigm. Imagine a totally pollution free -- other than during the actual manufacturing process -- personal mobility system that is powered by $3,000 worth of PV panels whose price is continuing to come down and will be good for at least 20 years of service. What's your cost-per-mile then? Literally a fraction of a fraction of a penny: $0.0099906!
Now that IS a paradigm shift, folks.
For more information on Gordon Murray's T.27 and iSTREAM® manufacturing process see Edition 11.29 of EV World's Insider newsletter.
Journal Entry Viewed 2775 Times
blog comments powered by Disqus