Saturday, June 13, 2015


Elon Musk, the owner of Tesla Motors and Space-X, has just announced his newest product, the Powerwall home battery. For US$3500, you get a lithium-ion battery pack you can mount on a wall at home that can store 10 kilowatt hours of electricity.

Why is this a big deal? Because the one thing the electric utilities have been wishing for is the ability to store energy. Let's break it down. Power plants fuelled by coal or gas produce a set amount of power regardless of how much of that power is being used from one minute to the next. Randomly available power sources like wind and solar only produce power when wind and sun are available, not when we need it. So, the utility is playing a constant game of guessing how much we need versus how much the fuelled and nature-driven power sources can produce. When wind and solar unexpectedly produces more, they can't just shut generators down, because the wind and solar could stop without warning. So wind and solar play a very minimal role in electricity, especially here.

If we had the ability to store excess power when it came available, this would create a very useful buffer of power both for when demand suddenly rose and when fuelled generation can't quite keep up. The other benefit to storage is the minute by minute cost changes of electricity, which changes based on demand versus supply. The generated capacity is being mostly used up during the day while factories and offices operate and especially when stoves and dryers come on at dinner time. But by 10 pm, demand has dropped off dramatically, yet the generated capacity is still high. This forces the utility to shunt a lot of power to ground unless generators are shut off or wind and solar supply drop off. In a more efficient system, homes, electric cars and commercial sites equipped with batteries would soak up as much cheap, plentiful power overnight as the system can provide. In the morning, there would be little need to crank up the system in anticipation of increasd demand because the battery capacity of the whole system would be able to provide a huge boost to capacity, even if each source was only supplying a little.

If I was a utility company, I would be chomping at the bit to get batteries established in as many sites as possible, thereby increasing whole system storage capacity as much as possible. This would not only allow for less fuel needing to be burned, but the variable wind and solar sources would be put to more practical use. I'd think it would be wise to pay for the battery and let the site owner, home or commercial, buy their own power sources. A solar panel or windmill could supplement the system enough to provide at least some of the site's needs, and be stored when it's not needed. This would make for a robust energy grid that would reduce the need for long distance power lines and make it completely realistic to eliminate coal fuelled plants.

Elon Musk has always been on the cutting edge of technological progress and I think this new product is one that has the potential to revolutionize the grid. Utilities would be wise to embrace this change, or witness the eventual and irreversible loss of energy customers once they figure out how to produce their own energy. This could come sooner than we think, since the cost of solar panels has dropped so much in the last 5 years, that we are at most months away from parity with coal on a cost per kilowatt-hour basis.

No comments: