The drop in fossil fuel prices does not make renewable energy companies less competitive -- or lesser investments, said David Richardson, managing director at environmentally focused Impax Asset Management.

"Oil is actually a transportation fuel rather than a generation fuel, so it does not have a high correlation where the investment opportunity is in renewable energy," said Richardson. "We also think there are strong growth opportunities in renewables that are not present in other areas of the markets."

Richardson added that another driver for renewable energy stocks is the "whole issue of climate change and the push towards lower fossil fuel emissions."

He is bullish on shares of American Water Works(AWK) - Get Report , which are up 25% in the past 12 months. The water utility operates in 16 northeastern states and pays a 2% dividend yield.

"Climate change is an issue that needs to be addresses by water companies because where it is raining now, it is raining more. And where it isn't raining, they need to create more facilities," said Richardson. "We see this infrastructure play as a long term theme."

He is also positive on Xylem(XYL) - Get Report , up over 14% in the past year, saying the water recycling specialist offers both an answer to the droughts in California, as well as the water crisis in Flint Michigan, where high levels of lead were poisoning citizens.

"Xylem is a company that is involved from the beginning of the water chain to the end of it," said Richardson. "They are in pumps, pipes, valves and will provide equipment to a lot of the infrastructure projects that will be need to address both drought and lead."

Finally, Richardson is a fan of LKQ(LKQ) - Get Report , up 25% in the past year, saying the auto parts replacement outfit offers a novel way to protect the environment.

"It's an environmentally interesting response and a profitable one for investors because it is cheaper to use existing materials then create them anew," said Richardson.