Switch modeling from "% better than conventional" to absolute values

[denised]

In some parts of the model (particularly fuel consumption and emissions) the scenario inputs are in the form "how much more efficient is the solution than conventional technology?". The problem with this phrasing is that it couples the two together --- if someone updates the estimates of the conventional technology, the solution is automatically altered as well, which could be inappropriate. (Not the most important concern, but just something to think about.)