The daddy of them all is missing from that list - the electric car. The first electric car was built in 1839 by a Scotsman named Robert Anderson, and we're still waiting for them to reach the mainstream.

Written in August

There's a good reason most of these things didn't make it. Many of them are borderline perpetual motion machines.

We've got all the technology we need. Just need to change our usage patterns a bit.

Battery cars are a long way off being "green" or cost effective, particularly if you look at all the battery costs. If the electricity is being generated from oil/coal then there's not much win over just burning gas in the car.

In a car, the energy efficiency is something like 15-20%. In an electric car it is something like 65% (90% motor efficiency x 75% storage efficiency). However in the case of the electric car the oil/coal to electricity efficiency is only around 40%, making the whole oil/coal-to-miles equation something like 40% x 90% x 75% = 27%

No huge gains... just fiddling with the numbers and hiding the impact elsewhere.

Whereas carpooling with one other person gives you an immediate 50% reduction.

Written in September