Around four months. I had a team of about a dozen 'temps' to process the individual postcards, and there were about three of us who read all the substantial comments. I'd be happy to say a bit more off-list if you'd like to e-mail me. (I might be able to help with the common response to a minor extent as well)

I have just joined, and am an engineer. Both oil and gas depletion and climate change are expressed quantitatively. Therefore any worthwhile energy policy response must be expressed quantitatively. This ensures that proposals can be checked for validity (the assumptions and numbers are consistent with the relevant science and technology) and adequacy (the numbers add up to the objective).
I carried out such a study for the UK and submitted it for the 2003 Energy Review. Entitled 'Energy Solutions for 60% Carbon Reduction', it is at http://www.energypolicy.co.uk It is based on energy and carbon and found that ranges of solutions are available using current energy technologies (i.e. not nuclear or carbon sequestration). About half of the carbon reduction is achieved by energy saving - including increased energy efficiency - and the other half by biofuels (both home-grown and imported) and wind turbines (assumed offshore). I also examined the trade-offs between UK land used for growing biomass, the volume of imported biofuels, and the amount of electricity from wind turbines. The text includes reasons for choosing the particular energy technologies and - in Part II - a framework for delivery of the objective by Energy Service Companies subject to Carbon Emission Obligations.
The model is embodied in .xls spreadsheets and may be examined and run (using the 'Solver') on almost any PC. Moreover, it is generic and - with appropriate changes to the input data - could be applied to other countries or regions and carbon reductions. I welcome any comments and criticisms.