There are numerous ways one can celebrate Earth Day: take out the recycling, turn off the lights, carpool to work or buy green exchange traded funds (ETFs).

After all, ETFs don’t emit anything, so you don’t even have to feel guilty about being a polluter.

While the sector has taken a hit along with the rest of the market in recent months, many experts encourage investors to take a long view when it comes to these funds. The United States is still in the early stages of solar energy development, and an interest in alternative fuels could increase if the cost of oil and gas keep up the way they have been.

Some experts accuse many companies of "greenwashing"; that is, making claims the make consumers think they’re more environmentally responsible than they actually are. Luckily, consumers are catching on, CNBC reports. In Britain and Australia, there are already hefty fines that come along with false claims.

The Federal Trade Commission (FTC) is currently reviewing its own environmental marketing standards. Terra Choice lists the six greenwashing sins.

There are a number of green ETFs to choose from, so take your pick. And remember to turn out the lights.

A few of them:

• PowerShares WilderHill Clean Energy (PBW), down 20.7% year-to-date
• PowerShares Global Clean Energy (PBD), down 12.2% year-to-date
• Market Vectors Global Alternative Energy (GEX), down 10.5% year-to-date
• First Trust NASDAQ Clean Edge US Liquid (QCLN), down 21.5% year-to-date
• PowerShares Cleantech Portfolio (PZD), down 5.8% year-to-date
• Claymore Global Solar Energy (TAN), up 4.4% since April 15 inception

Tags | gex, Green ETFs