Renewable energy ETFs were all the hype in the summer of 2008; crude oil prices topped $140 a barrel and investors searched for alternatives. The hype didn’t last, however. Crude prices crashed to the mid-$30s during the financial crisis later that year. The two largest green energy ETFs at the time, the PowerShares WilderHill Clean Energy ETF (NYSE Arca: PBW) and the Market Vectors Global Alternative Energy ETF (NYSE Arca: GEX), both plummeted over 70 percent in share price. PBW’s assets under management (AUM) also fell, from $1.5 billion to under $500 million, while GEX’s AUM fell from $300 million to under $32 million.