On January 23, 2013 Duke Energy announced that it had completed the Notrees Battery Storage project in Texas which now represents the largest capacity battery facility in North America. Providing backup power for the Notrees Windpower project, this facility is able to produce 36 MW of power on demand whether or not the wind is blowing.

This announcement generated literally hundreds of articles and blogs claiming in essence that battery backup for wind generation facilities is now a reality. A particularly extreme example was a post by Tina Casey on www.cleantechnica.com site which stated that:

'the new storage facility blows a Texas-sized raspberry in the direction of renewable energy nay-sayers, whose complaints about the "unreliable" nature of wind power are now, well, blowing in the wind'

What this post and every other news article and blog about this facility fail to mention is just how long the 36 MW of power can be generated.

The answer is ... wait for it ... 15 minutes. After that the lights go out. All for the low low price of $44 million.

If you don't believe me then check out the government site that provided half the funding (http://www.energystorageexchange.org/projects/11).

This kind of facility is useful (as are the ones in Hawaii and Alaska) only as a bridge power source that can keep putting power into the grid for a few minutes until a truly reliable coal or natural gas-fired plant can ramp up when wind farm production drops to zero which happens on a regular basis.

What about the other storage technologies mentioned in Ms. Casey's blog? Flywheel technology is in its infancy and again has no ability to scale up to the kind of storage requirements needed to replace wind.

Pumped storage? Seriously? There are very few spots on earth where pumped storage can work (you need a large reservoir above the dam which is easy and a large reservoir below the dam which is almost impossible because hydro dams are typically constructed in very narrow river valleys).

I'll admit that if you throw enough money at battery technology it can provide a few minutes of storage which is useful as a bridge or to filter out some of the very extreme variability of renewable sources. For example, a single cloud passing over a large PV installation can drop its power out by 60% in 2 minutes. That kind of variability will cause chaos in any transmission system (and is starting to do so in places like Hawaii).

But to imply that battery storage can provide long-term (hours, not minutes) backup power to make up for rapid drops in wind generation is simply untrue.

Utility scale storage is not close and saying that it is will only make people complacent. We need a very serious international effort to commercialize storage solutions or else Ms. Casey's dream of a society powered by renewables, a dream that I share very passionately, will become a nightmare as soon as we have to actually rely on renewables. I have covered this scenario in detail in my blog at http://debarel.com/blog1/2013/01/01/2012-the-year-renwables-became-a-problem/

Test sites that demonstrate battery technology are essential and should be celebrated for what they are; baby steps on a long journey.