Wind exchange traded funds (ETFs) are generating enough interest and returns to be more than just hot air.

As oil prices are expected to stay high despite their retreat in recent weeks, investors have been considering renewable energy sources such as wind power as the next frontier.

Designers of the wind-industry indexes are building them around big, diversified companies along with smaller ones that focus on wind generation. The index builders say that over time the ETFs will be tweaked to be more of a pure play on the industry, reports Michael Pollack For The Wall Street Journal.

The first wind-energy ETF, First Trust ISE Global Wind Energy (FAN), was anticipated to draw $100 million in assets, and thus far, the ETF has net assets of $71 million since its June 16 inception. This ETF invests in Otter Tail Corp. which has wind-generation capacity, but also sells in markets ranging from medical diagnostic imaging systems to food.

PowerShares Global Wind Energy (PWND) has blown in $16 million since July 1, the first day of trading.

It’s important to look at the holdings and understand what you own, especially since the wind energy industry is still a fledgling one.

These funds are still so new, they don’t have 200-day moving averages yet. But keep an eye out – if oil does indeed stay high, sooner or later, we’re going to be forced to take alternative forms of energy a lot more seriously and it could benefit these funds.