Taxing emissions makes sense because emissions are a direct externality. But when you subsidies replacements you are essentially betting on the most efficient solution, not at all certain it would be the best, you also introduce new externalities for people to profit on unfairly.
I'm guessing it would be much more effective to tax emissions, do so aggressively, and then just pass back the money directly as a public dividend. This way the market has full freedom to pick a way forward, any way.