Let me most enthusiastically recommend this article in American Scientist on plug-in hybrids. It’s by an engineer named Andrew Frank that’s been working on hybrids in various incarnations since the early ’70s. You green techno-geeks will love it. It’s one of the most accessible pieces I’ve ever read on the history, technology, and challenges of plug-ins.

You really should read the whole thing, but meat of it, for me, is in these three paragraphs toward the end:

Indeed, one of the great advantages of plug-ins (and purely electric cars) is that they can directly use solar- and wind-generated electricity for transportation, a process that is three to four times more efficient than converting such renewable energy to hydrogen for vehicular use. Further, with solar panels or a small wind turbine generating a modest 1 to 2 kilowatts and with the appropriate power-handling electronics, the owner of a plug-in hybrid can have a reliable source of emergency power for his or her home, even when the sun is not shining and the wind is not blowing. In this way, a person can achieve a substantial degree of energy independence.

These features add value to owning a plug-in vehicle, making for an attractive product. The solar panels used to obviate the purchase of gasoline can be paid for with the money that is saved in about five to six years, whereas the panels themselves should last 30 years. This combination thus provides some 25 years of essentially free energy for transportation. Purchasing a plug-in hybrid and a renewable source of electrical energy to charge it thus buffers consumers from volatile energy prices. In addition, these cars could easily be made to burn biofuels (such as ethanol) when they need to run their engines. The widespread adoption of such vehicles would cut down on the net amount of carbon spewed into the air while providing considerable energy independence for the nation as a whole.

Still, car makers are understandably hesitant to bet on plug-in hybrids — or on any energy-conserving strategy for that matter — because a drop in fuel prices would cause demand for energy-thrifty cars to dry up. A national energy policy that ensured that fuel prices would undergo a steady, predictable increase would allow the automobile manufacturers to gauge the market with more certainty. But it seems unlikely that the United States would ever follow such a course. The politically likely alternative is to allow the price of energy to fluctuate drastically and to let the auto industry try to make the best guesses it can about what people will want to buy. Although this energy policy (or rather nonpolicy) can lead to poor business decisions, it should make plug-in hybrids attractive to some forward-looking consumers, who will seek energy independence wherever they can find it.

URGE2, baby.