Micro Grids Need Easy Energy Storage

The future Smart Grid will be a highly sophisticated and bi-directional network of electricity and information.  It isn’t one huge and monolithic grid, but rather a collection of networks that have some interconnection.  Homes, neighborhoods, and campuses can all be smaller Smart Grids “nested” within a larger utility network.      

What makes a home its own micro grid?  It takes the following (and presumes that the utility has smart meters and the complex systems in place to support a two-way flow of electricity and communication):

  • An alternative energy source of electricity production like solar panels on your roof
  • An energy storage capability – the home battery
  • Internal communicating technology that has contact with all appliances that use electricity – could be a wired or wireless technology
  • HEMS (home energy management system) software that manages home electricity use and communicates with the preferred utility in real-time about pricing and billing

Let’s talk about the micro grid’s home battery.  This is an energy storage device that doesn’t look like the batteries in a flashlight.  Based on today’s technologies, it will be much bigger – say the size of an average refrigerator – that will evolve over time into a more compact unit (remember the incredible shrinking cell phones?)  It can store the cheapest energy – whether you create that through your own generating capacity or buy electricity from the utility at the lowest price point.  It kicks into action based on the agreement you set up with the utility.  You might voluntarily disconnect from the utility grid when electricity is expensive to purchase or when your generating capacity can handle your home load.  The utility may ask you to disconnect when this type of demand response program eliminates the need to fire up a peaker plant, or to mitigate the loss of transmission or distribution capabilities due to planned or unplanned events (maintenance vs. accident).  Your home is its own “island”, which is a term used by utilities to describe this distributed generation concept.  How long your home remains islanded from the larger grid is based on your utility agreement as well as you home battery duration, your management of that stored energy, how much electricity you can continue to generate on your own, and the cessation of conditions that caused the utility to island your home.

I like this entire concept, but want to emphasize that the battery needs to be managed by the HEMS system.  I want the home battery management system integrated to my HEMS software so that I have one terminal (internet-enabled TV, computer, whatever) that tells me the health of my home battery, how much capacity it has for energy and power (its duration), how long it will take to fully recharge again, and recommend if I should buy power from the utility to recharge it (and at what cost) rather than use my own generating capacity.  Thus when it is nestled in a standard home utility closet or garage, it must be regularly updating its status with my HEMS software so I don’t discover that the battery isn’t working properly during a power outage.     

Energy storage is a key component of the smart grid whether we’re talking about utility-scale storage or home-based storage.  The simplicity by which any energy storage solution is managed is a key contributor to its adoption rate by homeowners – especially those of us who like plug and play instead of interpreting technical installation manuals. 

There is a lot of conversation about whether or not the home battery drives away every morning – is it an electric vehicle (EV) or plug-in hybrid electric vehicle (PHEV) instead of a stationary device.  That’s the topic of next week’s blog. 

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