The tax would be proportional to the real cost of environmental damage. Zero for energy efficiency. Small for renewables. Highest of all for oil, coal, and nuclear. That may look like a tax, and it could substitute for other taxes, but it really is a fix of a market fault.
Carbon sequestration becomes economic everywhere and also solar and above all efficiency.
SUVs get 100 miles a gallon or run on hydrogen or both. A magic bullet in the economy helps all the technological bullets zero in on all the right targets.