Plug-in hybrids make sense, though. My own commute is 12 miles each way - and I rarely drive anywhere else, so a tank of gas is in more danger of evaporating than being burned, if I only had a plug-in hybrid.

When I have the cash, I'll be converting to an all-electric plug-in vehicle - no gas at all. My old Nissan Maxima will still have the off-the-line performance I love after conversion, but I won't be a slave to Halliburton any more.

Inspired by the commenter above, my plan to save the environment is to make people work longer hours. If everyone just drove to work and back and rarely drove anywhere else or had any fun, we'd save billions of gallons of fuel annually and pump millions of tons less CO2 into the air. I think this is a plan that every environmentally conscious corporation could get behind!

Not a new idea, but still a very crap one!

So we're going to put power from the grid and into battery storage at night to extract during the day, following the numbers through -

Generation Efficiency = 35%

Transmission = 93%

AC > DC = 90%

Battery Charging = 70%

Battery Discharge = 60-80%

DC > AC = 90%

Transmission = 93%

Total process efficiency = 12%

So instead of a straight ~32.5% efficiency of generation and transmission we're going to accept a reduction of 2/3 in order to use PI-HEV's as some sort of electricity reservoir, and that's meant to be green? Are they completely mental?

Not to mention that its a completely unpredictable, unreliable and unmanageable solution to transient power demand during the day. Yes electricity at night is cheaper, but its not any greener now is it.

Plug in hybrids make sense in some global markets, but far from all - and feeding back in is sheer lunacy, it's pie in the sky shite like that which gives electric vehicles a laughable rep. No doubt David Milliband would think it was a great idea though.....

I agree as far as the electricity reservoir goes, that is terribly inefficient.

However 100+ MPG plug in hybrid for me makes sense, and it is a step in the right direction despite still being stuck on the petrol grid.

I drive 7 miles to work approx 24 miles each day. Like it or not batteries are the next step in transportation. Solar + battery = renewable. The compressed air vehicle makes sense too.

This is totally silcon valley yuppie type though, obviously not every market is going to use these, but it is a start. 30% solar is a start too. If you can't see any good in this, you need to remove the blinders.

I think you missed something from your calculations. The fuel has to be delivered to the cars to get your 32.5% figure. How about if you factor in the difference between supplying the power stations and ferrying the petrol to every garage in the land. I would not presume to put figures to this, but I reckon it swings the balance towards the hybrid.

You'd be surprised how efficient getting oil from the well to the pump as petrol actually is in terms of energy transfer (its about 90% depending where in the world the oil comes from) - it's a massively energy dense carrier and that's one of the principal reasons we're struggling to find a viable replacement that covers all requirements.

Not discounting the hybrid option at all - just the feed in aspect and to a certain degree the whole plug in idea. I work on fuel cell vehicles (30 years off reality currently) and hybrids are going to be the stepping stones towards hydrogen, the potential efficiency of diesel hybrids especially is phenomenal. I just wish the manufacturers would stop hybridising really ugly cars - people might actually buy more of them if they looked vaguely half decent - who except a tree hugging hippy (or media whore celeb/Scientologist/politician) wants to be seen dead in a Prius? It's the Ann Widecombe of cars...

Another aspect of using hybrid cars is that the pollution is displaced. It may sound selfish, but I'd prefer the power stations to produce more pollution and have the cars produce less. Improving the efficiency of power stations is relatively easier and less expensive than improving the efficiency of all the cars on the road, and 'green' cars means less pollution in suburbs and cities, where people are most exposed to it. Power stations are often in out-of-the-way places where the pollution has less effect on humans (and possibly the environment).

All they want is somewhere to charge up their Segways!!!

Hybrids are expensive as they have to be filled with batteries which use chemicals only found easily in some countries and need much work to use. If we switch to batterries for all cars we will quickly be in the War for Batteries instead of the War for Oil. We need a cheap solution and available solution to portable energy sotrage.

The next barrier as the PP said is the look. I think the best solution to this is to convert existing well loved cars to new energy sources, seperating the power train and the user interface in assesments.

If hydorgen isn't ready then compressed air should be strongly considered. It's far cheaper than batteries and doesn't require any exotic materials. Using an automated air tank exchange and slow charging of the tanks in the filling station it's very efficient too!

As for supply, we need to be using more renewables, not just wind (idiots complain about noise) and PV cells (too expensive and not enough kw/m). Stirling engines are simple, cheap and efficient and can be heated from geothermal or various configurations of mirrors. Fusion will come online soon enough too.

It would be a lot simpler and solve a lot of problems if governments just got over their religious hangups about free market ideology and offered free public transport to everyone in every major town and city. A bus can carry 40+ people. Heck even when it is half full, it will still have at least 20 people.

That would cut back a heck of a lot of driving, allow for big reductions in CO-2, save dwindling supplies of fossil fuels and lessen the need for potentially billions of hefty energy intensive, chemically nasty batteries.

This is something that could begin tomorrow morning unlike all the hand wringing over new technologies of every variety.

The simplest solutions are always the best.