That's kind of a tricky one in a capitalist society. Right now fossil fuel technologies are making some people a lot of money. It will take a lot of time, money and research before alternative energy technologies can compete with fossil fuels. We can either push it on the population and force development, or subsidize research/development with taxes. If we do neither, we will just have to wait until gas/oil is quite a bit more expensive than it is before the alternative energy technology becomes feasible for the private sector to develop and produce.