Comment by diffeomorphism

Not really. You don't need to get anywhere close to 100% to effectively make coal too expensive to be worth it. Even if he just convinces a few big ones that will make coal operations more expensive, hence less attractive also for other ones, hence more expensive... . Viscous cycle, virtuous cycle and all that. To win you only need the price to increase to a higher level than preferable alternatives and the market will do the rest.