Limiting supply of fossil fuels doesn't spur green technology. Investment in R&D does. Why not stop subsidizing that fossil fuel power instead? See as it stand if you just ban new sources, while continuing to subsidize the power, you protect existing players form competition, while feeding them tax payer money, and simultaneously ensuring that they can transform their (now government mandated) monopoly in fossil fuels into a similar monopoly in the next energy source. This is just corporate welfare policy dressed up as environmentalism.