11-11-2010, 05:10 PM
Just to make sure that you didn't overlook my remark about non-negative variables: Re-reading you first posts, you mentioned that "For example, in my supply sector I have some negative emissions technologies. Therefore, emissions from the supply sector could be less than zero (say, -5 Mt)."
Does this mean that you have actually seen negative emissions in the results for the supply sector? If not, and your emission constraints are very stringent, I can well understand that your model might run out of options to reduce emissions at reasonable cost. In that case the light-duty vehicles might well become the marginal technologies, and your comments about the high costs of the LDVs might be quite relevant with respect to emission reduction, depending on your assumptions on the costs of e.g. electric cars. However, if you have enabled negative sectoral emissions by defining negative lower bounds for them, then I would not expect you to get such high marginal costs with a 80% reduction constraint.