By David Wojick, Ph.D. ~
The use of big batteries to partially offset the intermittency of renewables is growing rapidly. Unfortunately some utilities have adopted a deceptive practice with the public, making these battery packs seem much more important then they are. It is all part of hyping the utility’s supposed greenness, which helps their stock price but not their customers.
A recent announcement by the giant Arizona Public Service is a perfect example of this deception. It is a little bit technical, so bear with me. It is all about the difference between megawatts and megawatt hours, which the public (including the average stock analyst) does not understand. APS is trading on this ignorance.
In simple terms, think of a battery as a box of electricity, or “juice.” The megawatt (MW) capacity is how fast you can pour out the juice. The megawatt hour (MWh) capacity is how much…
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