Switching to cleaner energy sources is good for the economy. It will result in less pollution in the air, rivers and lakes. Study after study have shown that air pollution affects people's health in immeasurable ways. Kids require more medical treatment and do not perform as well in school. As they grow older, they will continue to require medical treatments. This may take them away from work, away from being a good parent or becoming a burden on the rest of society if they cannot afford their medical bills.
In a true capitalist energy market, we would not privatize profit and socialize the costs (i.e. pollution). If a private energy company cannot compete without socializing their costs, then they should not be in the market. Cleaner forms of energy are becoming cheaper, more reliable and are far better for the environment. Any initial costs in transitioning will be made up for in the long run through a cleaner environment which will save taxpayers money.