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Friday, September 17, 2004

Why conservation is mandatory

Here's a picture from Home Power magazine, showing a Volkswagen Rabbit which has been converted to run on electricity, and the solar panels which charge its batteries:

Note that that sizeable array of panels, which would cost about $12,000 at today's prices, is enough to give the "Voltsrabbit" a range of about 25 miles per day. Obviously, larger vehicles, like most vehicles currently in use in the US, would require correspondingly larger arrays. And most Americans are driving more than 25 miles per day. Just the amount of land needed to electrically power our current driving habits from solar panels would clearly be enormous, devouring land desperately needed for other purposes. And solar panels require specialized materials for their manufacture, some of which are relatively scarce. Most types of rechargeable batteries also use materials which are dangerous (lead-acid), use fairly exotic materials (cadmium, for example). Fuel cells might eventually compete with batteries for energy storage, but they also use scarce materials.

While the array in the picture is large enough to fully power my household electrical needs, even in a cloudy January, with plenty left over, it would only barely cover my driving needs, and wouldn't even come close if I drove as much as I used to. Pretty clearly, to me anyway, the only way that an automotive society like ours could run on solar power would be for the energy from hundreds or thousands of years to be gathered and stored in a compact, preferably liquid form. This was done for us, but within the course of probably less than 150 years we will have used up all of this stored energy that is accessible (that is, which can be extracted using less energy than it has in it). None of the available or potentially available renewable energy sources are likely to ever provide power fast enough even to fuel our current driving habits, and much less so if China, India, and other parts of the world try to emulate us. Long commutes, frivolous trips, and possibly personal motorized transportation itself are luxuries that the planet cannot afford much longer.