

How Water Heaters Evolved into Grid-Scale Energy-Storage Devices (2014) - davesailer
http://www.esource.com/ES-WP-18/GIWHs

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snowwindwaves
This concept has been used in new zealand for decades.  The communications
channel is probably moving to radio and possibly integrated in to smart
meters.  It used to/still does work on a "ripple" signal where the utility
injects a higher frequency signal, such as 300 Hz, on to the power lines and
then relays at the customer's houses pick up the signals and operate on and
off. 

They cycle through groups of customers so nobody's hot water is off for very
long. 

here is an excellent resource with pictures of the ripple plant and the
evolution of the equipment
[http://www.oriongroup.co.nz/downloads/ripplesignalguide.pdf](http://www.oriongroup.co.nz/downloads/ripplesignalguide.pdf)

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smarks159
The legal issues with this technology have now been resolved and the first
units are being sold in the open market[1]. 

A 10-20x cheaper energy storage solution than current battery technologies and
it is available right now, and not years away from being implemented like
other technologies. 

[1][http://www.vaughncorp.com/downloads/press/grid-
enabled%20wat...](http://www.vaughncorp.com/downloads/press/grid-
enabled%20water%20heaters%20press%20release.pdf)

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cjbenedikt
"Sequentric’s technology has been tested by the Electric Power Research
Institute and is now being deployed by Hawaiian Electric, but we have yet to
see the results of these studies."  This technological approach is widely used
in private homes in Germany.  The energy savings are significant and customers
are extremely satisfied with every aspect of it. 

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dimitar
This reminds me of District heating - they do use the benefits of thermal
storage and economies of scale to cheaply create and store energy (for heating
homes). 

The issue with District heating is that in many places district heating
companies are abusive monopolists with awful service.  Here it is actually
cheaper to warm the water on demand with grid electricity! 

However, having the technology to allow individual households and businesses
to benefit from water heaters as grid storage is very different - this also
solves an economic/political issue. 

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anabis
I though heat pumps were generally more efficient. 

They still do use a lot of energy, so it can be used in a similar scheme, but
I wonder how it would change details.