Just in recent weeks, I’ve seen several stories about the unintended consequences of a switch to more energy-efficient technologies. For example, while U.S. drivers are switching to more fuel-efficient cars, many of their old, inefficient cars end up being resold in places like Mexico, where they continue to consume vast amounts of gas and spew out tons of carbon dioxide.

And then there’s the downside of compact fluorescent lightbulbs. Yes, they last longer and use up less energy, but they also contain mercury, which — when the CFLs break or are thrown away — can end up poisoning the environment.

It all gets very confusing, doesn’t it?

Switching to all new cars costs money, means that natural resources are used and pollutants created in the production of the new cars, and means that old cars end up in landfills.

Don’t get me wrong, I’m excited about advances like this and think they’re generally the right decision, I just feel that sometimes some of the costs in transitions like this get overlooked.

I’d be interested in seeing a comparison of additional costs to gas savings, though: at today’s prices (which I’m guessing will only go up), I’d bet the switch to hybrid vehicles would be worth it for cab drivers over the long term.