This is a good point, and illustrates (1) the magnitude of what we are stealing from future generations and (2) that it would be economically disastrous to try

This is a good point, and illustrates (1) the magnitude of what we are stealing from future generations and (2) that it would be economically disastrous to try to make that difference up overnight via a 200% carbon tax. However, there is no need to make up the difference overnight, or really even to make up the entire difference. If coal power costs $0.1/kWh, and solar/wind/whatever costs $0.15/kWh, then you would only need a $0.05/kWh equivalent carbon tax to shift investment in research and infrastructure. Or really even just the promise of such a tax in five years. And it is fine for the tax to gradually approach $0.2/kWh equivalent, because by that point the only applications using coal would be specialized and could afford it without wrecking the economy.