No, a widespread carbon price, when just applied to large final emitters, would apply to all energy use that involved fossil fuels, so we're not just talking about 50%. It's actually closer to 80% of the sectors that are putting out carbon dioxide.
Certain things aren't captured very well by carbon taxes, aren't affected very much by carbon taxes, and this is where I think there is a real need, at least in that case, for regulations for things like vehicle fuel efficiency, buildings, and much higher standards for efficiency for appliances, for example. We know how to make natural gas furnaces that are 96% efficient. Why do we have some on the market that are 78% efficient? It makes no sense, having regulations in various cases where the carbon price by itself won't incent the kind of behavioural change we need to reduce emissions to those levels.