Renewable energy (I would say "green", but it reminds me too much of kale) is certainly a growing area within the energy sector. Albeit, it is not growing at nearly the rate espoused by the anti-oil/natural gas lobby; however, certain aspects will continue to slowly eat away at traditional energy's base.
There is a large choice that can be made if one desires exposure to this energy sub-sector, including pure stocks, yieldco's, and, lately closed-end funds. Some of the yieldco's have recently changed their branding to that of "sustainable infrastructure companies".
While I am only