I agree with the denotative message of your post (that we should let the energy market do its optimization unimpeded), but I'm guessing we disagree connotatively; most "green" solutions (especially wind, to a lesser degree solar) are only viable at all because of extreme distortions in the energy market induced by subsidies. Tariffs would of course also be distortionary, but it would be difficult for them to compete with the gross distortions that already exist! In the (loosely remembered) words of a friend who designs wind turbine blades and control systems: "we would build these things to be a lot more reliable if we weren't just trying to maximize subsidy revenue". I'm more immediately worried about these demand-side distortions than the hypothetical supply-side ones.