Some of his calculations are a bit dubious however such as the assumption that the battery in a hybrid only last five years. The idea that spending nearly $100K on a Tesla roadster will sacrifice the lives of fifty children is also questionable. After all, any new technology usually comes in at a high initial price that is necessary to seed a market. Where Rako's calculations make perhaps a little more sense is the solar cell example. Here he does some present value calculations to determine the net cost of installing PV panels, the savings and how much that money could make if invested elsewhere. It's a thought provoking piece that makes some interesting, if flawed, points.
[Source: Electronic Design News, thanks to Domenick for the tip]