The critiques I posted of the last two articles apply again here, since the assumptions and conclusions of those two feed into those of this one. I'm sure others will repeat themselves.

The analysis needs some comparative figures. For example,

• the cost of getting the same energy entirely from fossil fuels over the time period envisaged for the conversion to renewables
• the cost in disruptions to economy and society of simply letting the fossil fuels run short and replacing them with nothing

A lack of comparison is the most serious weakness of this paper. For example,

The figure quoted only represents the major energy production plant required. In parallel with this will be a similar cost associated with the changes made by energy users (i.e. electric vehicles, mining and manufacturing equipment, rail lines, power transmission, metal smelters etc. etc....)

You've not given a clear time period for the conversion to renewables. However, it seems fair to assume you're thinking of more than a generation (30 years). Even if coal fell like manna from the heavens and the Earth had a creamy nougat center of oil, over those 30 years much of our vehicles, mining and manufacturing equipment, rail lines, power transmission, metal smelters and the like would be replaced anyway.

So if we have a petrol-burning car now in 2009, and are going to have to replace it in 2020 at the latest, whether we're replacing it with a $10,000 petrol-burning car or a $10,000 electric car doesn't matter economically. It only matters if one is $10,000 and the other $15,000 or $5,000.

Your figures are absolute rather than relative. It's like someone saying to us, "buying your house will cost you $300,000 over 20 years!" Yes, it will. But if we didn't buy the house, we'd have to pay rent anyway, so the question must be what extra cost we have because of our choice.

Just as whether we own or rent, we're not going to let ourselves be homeless over the next 20 years, so too will we as a society not let ourselves be without electricity, transport and so on.

Whatever we do, we're going to spend shitloads of cash on building stuff. The only questions are:

• what will we build?
• how much more will it cost than building something else?
• is it worth it?

Your paper doesn't look at extra costs, only absolute costs. It thus vastly overstates the magnitude of the problem in economic terms. Presumably the aim is to raise the alarm. That's a good thing to do. But when you overstate the problem, people find excuses to dismiss what you say. Between crying wolf! and moderating everything into meaningless bland bureaucratese there's a sensible middle ground where you present the problem and its solutions in a reasonable and fair manner.

This ain't it.