NEW YORK ( TheStreet) -- Over the next two weeks the Copenhagen talks, coupled with initiatives stateside, will help to focus investor attention on green energy investments.

While the impact of global warming may still be up for scientific debate, regulation and legislation will reward "greener" companies in the upcoming months.

Investors looking to get ahead of the Copenhagen curve can invest in a number of ETFs that track companies involved in the green energy effort. Both the PowerShares Clean Energy ETF ( PBW) and Market Vectors Global Alternative Energy ETF ( GEX) track global companies that focus on renewable sources of energy and green technologies for cleaner energy.

As countries like the U.S. and China move to cap carbon emissions, companies that produce green-energy technology will be boosted by demand. Cree ( CREE), a top component in both GEX and PBW, has already seen a jump in sales of high-performance LED lighting in the wake of China's massive stimulus. New energy savings initiatives in the U.S. could help to sustain CREE's upward momentum well into 2010.

While both PBW and GEX track companies concerned with green technology, investors should consider important differences between the underlying portfolios before picking a fund.

PBW's underlying portfolio is comprised of 52 globally-based, U.S. traded firms, including top holdings like Trina Solar ( TSL), American Superconductor ( AMSC), Rubicon Technology ( RBCN) and Applied Materials ( AMAT). Launched in March of 2005, PBW has $760 million in assets and a three-month average daily trading volume of 430,000 shares. PBW's expense cap is 0.60%.

Market Vectors' more recent offering is smaller, with just 31 underlying holdings, and tracks international ordinaries rather than U.S.-traded receipts. GEX currently has $208 million in assets and a three-month average daily trading volume of 82,000 shares. GEX's net expense ratio is 0.62%.

An important difference between the two funds is the relative concentration of assets in top holdings. Nearly 51% of GEX's portfolio is allocated to the fund's top 10 components, while just 32% of PBW's underlying portfolio is dedicated to the fund's top 10 holdings. Vestas Wind Systems, GEX's top holding, makes up 9.12% of the underlying portfolio. PBW's top holding, TSL, makes up just 4.12% of the underlying portfolio.

When choosing between two narrowly focused funds, like GEX and PBW, portfolio concentration is key to determining risk suitability. PBW's larger, more balanced portfolio, will be less prone to security-specific risk than GEX' smaller, more concentrated portfolio.

Year to date, PBW's strategy has paid off. GEX is up 8% so far in 2009, while PBW is up 24%.

President Obama has emphasized that he prefers legislation ahead of regulation when it comes to cutting carbon emissions and promoting green energy. Either way, investors in green energy technology will be ahead of the curve in the upcoming months.

ETFs are a good way to gain exposure to the green energy sector without having to bet on the fortunes of any single green energy firm or technology. PBW is a large, liquid ETF with the portfolio and track record to succeed as attention shifts from the talks in Copenhagen to the practical business of implementing energy-saving technology.

-- Written by Don Dion in Williamstown, Mass.
At the time of publication, Dion has no positions in the equities mentioned.

Don Dion is president and founder of Dion Money Management, a fee-based investment advisory firm to affluent individuals, families and nonprofit organizations, where he is responsible for setting investment policy, creating custom portfolios and overseeing the performance of client accounts. Founded in 1996 and based in Williamstown, Mass., Dion Money Management manages assets for clients in 49 states and 11 countries. Dion is a licensed attorney in Massachusetts and Maine and has more than 25 years' experience working in the financial markets, having founded and run two publicly traded companies before establishing Dion Money Management.

Dion also is publisher of the Fidelity Independent Adviser family of newsletters, which provides to a broad range of investors his commentary on the financial markets, with a specific emphasis on mutual funds and exchange-traded funds. With more than 100,000 subscribers in the U.S. and 29 other countries, Fidelity Independent Adviser publishes six monthly newsletters and three weekly newsletters. Its flagship publication, Fidelity Independent Adviser, has been published monthly for 11 years and reaches 40,000 subscribers.