Renewable technologies offer more investment opportunities for corporations, governments, and individuals than ever, said Pernick, due to substantial progress in product efficiency and affordability, the addition of renewable energy divisions by large multi-national companies, and the prohibitive cost of fossil fuels.

"There's been a significant change since the beginning of the century. There's a confluence of forces that have aligned. It's very telling that, in terms of U.S. venture activity, clean energy and new energy tech investments have gone from less than 1% in 1999 to 4.2% in 2005. Most of the firms that were active in high-tech have now set up clean-tech divisions," Pernick said.

After years on the fringes of the energy sector, wind turbines, solar panels, biofuels and related technologies are moving into the mainstream.

Governmental intervention has also been a factor. After subsidizing gas, oil and coal producers well past the point of profitability, policymakers -- especially at the state and regional levels -- are starting to see the long-term wisdom of supporting renewable energy markets.

"What's happening now is that a number of different governments are waking up and saying, 'Do these large, established, mature industries need subsidies?' That's driving a shift in how governments are positioning their incentive and subsidy programs," said Pernick. Governments are also responding to the job growth and increased energy independence that comes with an expanding renewables market, Pernick said.

The status of incentive programs can have a dramatic effect on the investment environment. "Every two years the wind-production tax credit goes up for renewal. Six months before that date, development comes to a standstill. We need long-term, consistent policy. Hopefully, Washington, DC, is starting to understand that, especially when companies like GE are making $2 billion-plus a year on their wind division."

The NASDAQ Clean Edge Index tracks stock performance in five areas: renewable electricity generation, renewable fuels, energy storage and conversion, energy intelligence, and advanced energy-related materials. Listed companies must meet certain criteria.

"Working with NASDAQ, we've instituted a number of quantitative screens, including minimum market capitalization of $150 million and average daily trading volume of 100,000 shares," said Pernick. "That's one way of ensuring that we have established and emerging companies that meet key criteria."