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%.