Using buildings as batteries to accommodate more wind and solar | Hacker News Reader

Using buildings as batteries to accommodate more wind and solar

news.engin.umich.edu

9 pointsdnewms8 comments

The correct terms are "load shifting" or "peak shaving."

But, in a way, they are storing energy (thermally) in a similar way to batteries. One could imagine freezing water or condensing ammonia over night using surplus cheap wind energy, and then releasing that stored coldness during the day to cool the building.

I think the big objection to calling this a 'battery' is that nobody is suggesting using that stored thermal energy to generate electricity. It's just a way of shifting the electrical demands of the building to a time where there is surplus electricity.

The title isn't just clickbate, it is a lie. There is no way to construe this research as being a form of power storage.

It is commercial building-level demand-response, which already has been done at a residential level in California.

DR can also be provided by fast-responding storage systems like batteries and flywheels, which maybe explains the poorly chosen analogy to batteries.

I'm not surprised that it used more energy overall though because mechanical systems usually are most efficient when operating at a particular speed. Turning a huge HVAC system off and back on again quickly if it's not designed for that would probably reduce its operating efficiency.

> Turning a huge HVAC system off and back on again quickly if it's not designed for that would probably reduce its operating efficiency.

A lot of Rooftop Unit (RTU) controls typically take an on/off command from the Building Management System (BMS) and the BMS programming will have a deadband range (+/- 2°F) in which no action will occur to prevent the repeated cycling of RTUs.

Makes sense. IIRC smart thermostats also have this sort of feature to prevent excessive cycling of home HVAC.

Wouldn't it make more sense to use a water basin?

The headline is misleading. They aren't proposing using the buildings as batteries. They are proposing that a large number of commercial buildings would switch on/off their HVAC systems for short periods of grid surplus/shortfall to help balance grid demand.

The only "battery like" thing is that short durations of turning off/on a large building's HVAC shouldn't change the internal temperature much. And that's stretching "battery like".

It's a "battery" in the grid sense that it's an energy buffer which can be used to balance demand. If you can get over that stretch of terminology it's sort of interesting. I've seen proposals for shifting HVAC systems to create even larger buffers - increasing or insulating chiller fluid capacity (or even creating large ice masses) so that during excess/low-cost power one can build up a reserve, then cooling from that reserve during high-demand periods.

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