One of the main criticisms of wind and solar power is their nature as intermittent sources of energy. If the wind stops blowing on the plains of North Dakota, or clouds cover the desert in California, blackouts could occur across the country if these renewable energies were primary sources of power.
So the challenge for investors is finding who will supply the technology to smooth out those peaks and valleys. Some new technologies are now emerging that have the potential to play a big role in the future of renewables.
Inverter manufacturer Satcon Technology
The problem for battery storage is scale. Batteries may be able to charge quickly and release energy quickly, but right now they can't store mass amounts of energy for the grid -- something renewable power needs.
Store energy by pumping water uphill and release energy by capturing the energy of it running downhill. Simple, cost effective -- and so far, our best answer to energy storage. There are 21 GW of pumped hydro in the U.S. and 38 GW in Europe, but this isn't a solution for all problems. Wind-heavy areas like North Dakota and offshore aren't exactly conducive to this, nor are deserts where solar power is most effective.
Compressed air storage
Maybe the more immediate answer is compressed air storage. Think of this as a huge compressed air tank that is filled during off-peak hours and released as needed to provide electricity. There are two sites online in Alabama and Germany, with Pacific Gas and Electric
The PG&E site in Kern County is 300 MW so the potential size of compressed air energy storage is much larger than battery storage right now.
Energy storage roadblock that may decide how quickly renewable energy becomes adopted on a wider scale. With GW of projects in the works at solar leaders First Solar
There are no sure-fire solutions, but batteries are sure to play a role in smoothing out energy supply. It may not be on a GW scale, but even on a much smaller scale, A123 and Ener1 are working to play a role in making the grid both cleaner and smarter.
Fool contributor Travis Hoium owns shares of First Solar and SunPower. You can follow Travis on Twitter at @FlushDrawFool, check out his personal stock holdings or follow his CAPS picks at TMFFlushDraw.
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