some of them like burning coal is very filty. of them like putting up a wind turbine are very clean. it used to be that coal was cheaper, 30 years ago. that is a very great 20th century strat he gee. but now wind and solar are much cheaper than coal. and so sensible businesses, sensible public utilities are busy replacing old, dirty things with new clean things. that's going to be the story of the 21s century. we are not 30 years from now going to be using the technology we use today. >> trevor: what happens to the people, though, that are in those jobs. because everyone says it's not about the coal, it's about the coal miners. >> if you go back to 1927 there were 800,000 coal miners, now there are 60,000. and it is not because of people using less coal, the production has gone up. it is because of technology. and what we have got to do is number one, stop using coal, but number two, find ways to retrain and create jobs for the people that get hurt. and in fact there are three organizations that bloomberg fill an thoppees is supp