> Once solar and wind, without any subsidies, are cheaper than coal, then societies will switch purely out of self interest. If coal prices included the negati

> Once solar and wind, without any subsidies, are cheaper than coal, then societies will switch purely out of self interest. If coal prices included the negative externalities costs - in other words, if we charged coal companies for dumping their trash into our collective air instead of subsidizing them by letting them do it for free - it would greatly change the price comparison. Then the market would likely do the rest.