Storage ‘not fundamentally needed’ for future power grid, scientists say
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You have HVAC. Refrigeration. Your washer. Your dryer. And your dishwasher.
Each one of those things is inherently a form of energy storage, because you don't need any of those to start up or stop at the same milisecond where you flip the switch.
What's left?
Lighting. Entertainment. Communication.
All of these you do expect to consumer power on demand without any time slack. But the major loads I listed above can defer to the minor loads that demand that kind of priority.
So with a little TCP/IP to coordinate activities around your house, your need for power storage declines considerably.
I know that Nest has an option with some electric providers to integrate with their demand needs already for something like this; I have it enabled, but they've yet to utilize it.
I could totally see a dishwasher utilizing this, it makes the most sense, assuming I had enough extra dishes and space for the relatively small inconvenience it'd provide.
So the freezer can store energy by working extra hard bringing things down from -5C to -20C whenever it's expedient, and the equalizer keeps the fridge in its usual temperature range. Nothing spoils, and you don't even have to notice.
If you integrate washing machine and dryer into one mashine, the cost-savings from electricity would be even bigger with very little convenience lost.
Now, if all I had to do was dump all my dirty laundry in a hamper, and it automatically sorts it and folds it after it's done washing, now that's something I don't care about anymore and can just let a program decide when it wants to accomplish each step.
However, the heating element in your dryer doesn't have to be run like that. You start the dryer, and it starts tumbling your clothers with the motor, and blowing some air with the fan, but the heating element can turn on and off in coordination with the rest of your house, and you wouldn't even notice.
Also, most of us run a load just before going to bed, and shuffle it to the dryer in the morning.
Do you care if the washer takes a little while before starting up while you're sleeping? I sure don't.
Not if you care about the longevity of your clothing and mildew in your washer.
I don't know anyone who does this routinely on purpose.
Waiting days? Sure... random-internet-answer(s) seem to hover around 24-48 hours before mildew becomes an issue...
So, sitting over night and then maybe a few hours before the dryer starts (Assuming that, it too, would be on a timer) shouldn't be a major issue.
Also, if you have a front loader, they are extremely prone to growing mildew in the bottom of the rubber gasket. Leaving wet clothes inside makes that much more likely.
Further the once a year useage is going to be drawing a lot of batteries slightly lower at the cost of slightly shorter lifespans not a single bank that's only used once. Plus some emergency back up generators that flip on and use some minimal amount of fuel at hospitals and data centers etc.
PS: One interesting outgrowth from high wind solar production is likely to be fairly accurate models for electricity costs over the next few hours. So, you may be using power sooner if the prediction is a coming price increase.
Automate the washing, drying and folding of clothing.
Automate cooking. And shopping.
And so on. Like self-driving cars.
Then it can be done while you sleep :)
You need fingertips with lots of nerves, and probably thousands of very nuanced motor control paradigms.
Sleep pods (or smart beds as they'll be more likely to be called if invented any time soon) that repair your body and inject you with nutrients, making you feel as good as new when you wake up, to the point of not needing sleep again for a few days.
https://www.nih.gov/news-events/news-releases/brain-may-flus...
Considering this sophistication will probably not be easy to retrofit onto current devices, a combined, space/energy saving device is a given. As long as the clothes are dry and clean when I need them, I don't care at what time during the night the machine did its job.
With some extra cleverness, it could even negotiate very-short-term (hours) futures on energy prices based on current tendencies and knowledge of future house demand.
Why participate in the future market if one can simply choose to not partipate and get to consume any amount of energy you like at a constant price?
Effectively you'd have built a market with an unlimited option to buy at the monthly-average price. A market like that can't work...
I've never met anyone who does this and the only times it happens is on accident.
I live with hard water, so if I did this my clothes would be starchy and uncomfortable to wear. They have to immediately hit the dryer once the wash cycle finishes. Then - unless I want to wear crinkly clothes - straight to the hangers once the dryer finishes.
Have people told you that you smell funny or just acted weird when you are around?
Of course if washing, trying and ironing would be all integrated and automated then one could do that.
my goodness...
I don't do this, but perhaps more relevant, I have never discussed laundry habits with friends, so either a) I am unusually tight lipped about laundry, or b) I have no way to know what "most of us" do, though this seems not to be the norm in apartments I have lived in with shared laundry facilities.
Current safety advice is to not run washing machines when you're asleep.
I guess it's okay if you have very good, loud, fire alarms.
Yes, it's important o keep a fridge in certain temperature bands. But there;s a lot of timing leeway in those bands, and it's exploitable as a form of energy storage.
An electrical engineer I believe designed that part of the system...
I'm sure with enough IoT you could delay motor start +/-30s across a region to smooth the tip of a load spike, but it sounds very complicated. How would end users be compensated for such a tiny shift in load? Isn't instaneous power demand a martingale process?
It sounds like it would be easier and cheaper to have a few batteries.
Congratulation, you just re-invented the wheel. Do you really fridge builder are that dumb ?
I grew up in Switzerland and the cost incentive to running the dishwasher and washer/dryer at night was significant. Many families changed their behavior as a result.
You lost me. I don't understand how that connects.
And as a practical matter, busy parents with small children can't defer running the washer and dryer. It needs to finish in time to fold and put away the clothes, and you often need to run multiple loads.
A smart-ified clothes dryer is more attended to than a conventional one.
>And as a practical matter, busy parents with small children can't defer running the washer and dryer. It needs to finish in time to fold and put away the clothes, and you often need to run multiple loads
I'm one of them. I can't always defer, true enough. But I can often enough.
I don't care how smart your dryer is, if it catches on fire it's not going to do shit.
Lint does not catch fire at 140F.
This is how hay bales that are a little moist will catch fire, the digestive process (which is slow but exothermal) of the bacteria in the center of the slightly rotting bale of hay are so well insulated from the outside world by the rest of the hay that the temperature will at some point exceed the ignition temperature of the hay and then you have spontaneous combustion.
Something very similar can happy to driers if the exit ducts become more clogged than a certain percentage.
And let's not even talk about gas fired dryers (does anybody still use those other than dry cleaning services?).
That's why I said "more temperature sensors". It's possible to design a relatively-standard dryer where no part ever gets above boiling, even when the output is completely blocked, giving you a huge margin of error.
Heat in a dryer is all externally applied. It can't build up on its own.
No but sparks that can ignite lint are common risks around operating dryers (both wiring faults and static discharges are issues.)
"Task 4. Determine Characteristics Required for Lint Ignition
Lint that accumulates on the heater housing can easily ignite under conditions of a failed high-limit thermostat and a blocked exhaust vent. Lint accumulating near the heater intake can ignite before the high-limit thermostat switches the heater element off. Lint ingested by the heater and embers expelled from the heater outlet can easily ignite additional lint or fabric in the air stream, resulting in additional embers in the dryer system and exhaust vent."
But I can say for sure that those tested dryers are getting much hotter than necessary. Look at the designs on page 6 and 7. Small heater boxes with thin hot coils. If you redesigned it as a big block of heatsink fins with the heating element buried inside, you'd be a lot further away from causing ignition. It would cost more, but in a sub-$100 way.
So I'm unsure at this point. I don't have the resources to test exactly what temperatures are necessary and safe, and which one is higher.
It is extremely common to have smoke detectors integrated with the burglar alarm. I do not know how common monitored alarms are in private homes, however: I personally can only think of one person I know that has that.
Do you really watch over your dryer just
to make sure it doesn't catch on fire?
In my house, how it works is if an appliance in another room catches fire, I'm alerted by the smoke alarm and I can choose a correct response - such as a fire blanket, turning off the electricity, and/or calling the fire brigade.The purpose of me being in the building or nearby is to ensure a correct and timely response. If the fire brigade are called by a real person and asked to attend, they'll know it's not a false alarm.
But when I've seen the fire brigade called by automated systems? False alarms every time. And the police don't even bother to come out to a burglar alarm or car alarm going off - it's got to be confirmed as a genuine alarm by a neighbour or alarm monitoring service.
It's basically 100% detectable. If you are worried about failure of sensor, this is a field where they use sensors in ridiculously contaminated and abrasive environments (material handling, etc).
"Lint" is neither.
(compared to what else we use flexible tube to handle as a material)
So you can simply prevent the fire in the first place. Much more so than pretty much any other appliance.
I think this misses the elephant in the room. Large industrial machinery. Data centers. Manufacturing. Electrified transportation. At the place I work, we use more electricity in a single, 19 inch high density server rack than your entire neighborhood. We have rooms full of batteries like the Tesla Powerwall and would be lucky if they could operate for 10 minutes.
The good thing is these loads are relatively constant and predictable. One reasons electricity is expensive is the peak loads are much higher than a regular day - you need a power station (or storage) on standby for that hot day when everyone suddenly runs their AC continuously all afternoon.
>Electrified transportation
This is different and a good opportunity that the article talks about. Esp a plugin hybrid could charge on windy sunny days and not charge in the peak times as above.
https://flowcharts.llnl.gov/content/assets/images/energy/us/...
The mentality is the same as the California water crisis: ignore the big industrial uses like agriculture, instead pester people to run taps for a few seconds less.
https://en.wikipedia.org/wiki/District_heating In terms of efficiency, using excess heat, etc. electrical heating is utterly horrible.
- http://www.irdindia.in/journal_ijmer/pdf/vol4_iss1/9.pdf
- https://info.ornl.gov/sites/publications/files/pub31294.pdf
- https://www.acoustics.asn.au/conference_proceedings/AAS2009/papers/p28.pdfI think the progress made on electric cars is exciting to watch, but I have to laugh when they talk about "long-range".
http://insideevs.com/instrumented-test-of-chevrolet-bolt-190...
It is more about my personal situation than preference. I can't drive a Tesla from my house to a Supercharger station. I'd have take a slow charge somewhere - or a tow truck. I'm sure I'm not the only one in that situation. So for me and many others "long-range" continues to be an oxymoron. Someday range will increase and I'll have to decide if it makes sense for me or not - but it this point it isn't even a possibility. Until long-range means keeping up with an average gas/diesel car, it isn't long enough for many.
Tesla is much more likely to be able to sell me a power wall than a car. I could use one or two of those.
If you're located in the lower 48 states of the US, you're definitely one of a very, very small number of people in that situation - the map on https://www.tesla.com/supercharger claims they've pretty much got the map covered these days - though Hawaii and Alaska are out of luck. It looks like North Dakota might still be underserved right now, but pretty much everywhere is within a couple of hundred miles of a station.
Fact is, though, that a vanishingly small number of people are living in places that far from charging infrastructure, mechanics, or frankly, the places they need to drive to regularly.
Objectively speaking, long distance driving is a pain in the ass for an EV. I take a lot of Seattle -> BC trips. I drive to Whistler, Anmore, Kelowna, and Salmon Arm.
I can't do some of those trips on one charge - they are too far. That 238 mile range on the Bolt? You are not going to go 238 miles on the Coquihalla. It's all mountains, and in good weather, the speed of traffic is 80-90 mph. You'll be lucky if you get 150 miles.
And heaven forbid you have to turn around at the 100 mile mark. You'll be calling a tow truck, because you won't be getting back to civilization on a two-thirds drained battery.
Meanwhile, my Prius goes from Seattle to Salmon Arm on one tank of gas. But let's suppose it's winter, and I want to be safe, and I don't want to be sitting on the curb with my thumb in the air, praying that someone on the road has a full jerry can (The odds of which are pretty high) - so I'll stop for some.
When I stop for gas, my total time at the pump is 7 minutes - including pulling off the freeway, and back on.
With an EV? Well, if you want to top up at a super-charger... You're looking for a 40-50 minute wait. Every 2-3 hours of driving. Because the one thing that I'm looking forward to, on my long trips, is wasting more time on a 7 hour drive.
If you have kids or a dog, you may want that hour-long break. I don't, though.
There's a lot that can be said for EVs - I might own one, if I could charge it at my apartment. I wouldn't use it for road trips, though.
Using an appliance later is no more a form of energy storage than me "saving" air by holding my breath. Reduction in peak demand <> Storage.
On a hot summer day when I'm cooking in the house, running a load of dishes and trying to cool the house to a reasonable temperature - all before the guests arrive - Should the A/C wait for the dishwasher, which waits for refrigerator, which waits for the oven? Not in my house.
Storage - I'll gladly take some of that so my lighting and communication can be powered when the power is out. In that situation, the rest of those big loads can wait.
Loss - that should be one of the first clues that scheduling is not storage. Any electrical storage in my lifetime will have loss, I can accept that.
I'll give you scheduling as storage when it comes to a freezer or hot water heater. Why? Electricity was converted to something that can be stored. There is loss - a clue to real storage taking place, not pretend scheduling "storage". If I heat a tank of hot water and want to shower an 3 hours later after I've turned off the power to my house I'll have a hot shower (in the dark).
Try the same thing with an electric clothes dryer. Plan to run it in 3 hours and turn the power off and see how well it works. What? The dryer didn't store any electricity?
Storage, by definition, means you have something. When it comes to the grid, storage and scheduling can both reduce peak demand, bug scheduling is far from storage.
So the storage in your version is leaving it stored where it was. Great.
A 100 gallon (380 liter) hot water heater that raises water from 50 F to 120 F (40 C) can store 17.6 kWh, or just under 60% of daily household power use. Of course this was gonna be huge, and its a good opportunity, since in the mornings a house will use 40-80 gallons with the showers. I'm not sure how much of that is actionable, though. The water would have to stay hot all night.
The average newly built house in the US is 2600 sqft, which is 20,800 cubic feet with 8' ceilings. With a 45 F temperature change (25 C) the air in that alone is 5 kWh, which honestly surprised me with how big it is. You'll never want your house to be changing temperature that much during the day, of course. You'd get crazy condensation and whatnot. By the straight math this could cover 17% of daily usage- that could go up by several times due to the heat capacity of the objects and materials in the house, but down by 5 times since you wouldn't want your house changing that much in temperature.
Water/heat capacity would be a pretty decent way to store a large amount of electrical load, but I think it's gonna struggle to catch on. In northerly climates you could combine the hot water and home heating, but those places will struggle much more to get cheap solar power, which is 2.5-3x more expensive in the winter. Meanwhile southern climates will have solar power at 70% the price of the rest of the country, and it tracks the summer power demand increase well- but it's way harder to store your energy in cold water. Other than that it makes sense: while you're at work, the system cools down a large insulated tank of water, which it then circulates to a heat exchanger right before you come home. You can't use it for hot water though, and it'll be a lot bigger and more expensive than an AC.
Basically it would be good for load leveling, but not overnight storage or seasonal storage. There aren't many indications that load leveling is actually a real problem. It'll probably just be solved with a smarter grid.
If you are heating from room temperature to RT+50C the actual energy extractable (as electricity) from that heat is only about 15% of what you put in https://en.wikipedia.org/wiki/Thermal_efficiency.
If you used the energy purely for heating you would in theory get it all back but the low temperature differential would mean in practical terms it would not work fast enough.
You also need to factor in loss from conduction.
This is on top of the nuttiness I accrete after observing that foamed glass insulation that can put us up to terrific equivalent R-values (R-100+ pencils out if you intend the building structure to pass through several generations), and drop climate control operational energy costs 80-90% from current typical expenses, is a dead letter in the US residential market [2].
The amount of energy developed world practices and infrastructure throw away is mind boggling, once you view everything around you in energy flow terms.
But like others are discussing in this thread, industrial and commercial energy use overshadows residential [3], over 60%. The low-hanging fruit sits there, because the ROI is typically faster or more bearable in those business-oriented contexts. I'll still pursue saving for and building a highly-insulated and -instrumented shell on my property once my house is paid off in a few years, just to scratch those nutty itches.
[1] https://www.extremetech.com/extreme/130523-zeolite-thermal-s...
[2] http://www.greenbuildingadvisor.com/blogs/dept/green-buildin...
"But it's also two or three times as expensive as one of its chief rivals, extruded polystyrene (XPS), and its R-value per inch (R-3.4) is about 30% lower."
I don't know the true manufacturing costs of sheet and block form aerogel, but they're priced so high that even multi-generational payback periods didn't pencil out even close, even granting them a 30% premium. Current manufacturers simply aren't aiming those form factors at building insulation as far as I can tell, though I'd love to be shown wrong.
For the time being, when I need near-aerogel-like qualities insulation but without the volume penalty foamed glass incurs, but can't justify the cost of aerogel due to the required quantity, I look to vacuum insulated panels to cover the big expanses of area and volume, and aerogel to fill in the gaps.
I'm not a huge fan of plastics or styrofoams outside of very well-contained use cases since its breakdown in the outside into extremely small pellets is already easily detectable in our seawater-based salt supplies, and unabated, I'm not sanguine about our keeping it from pervasively entering our food supply. The actual plastic itself I'm not too happy about mainly because it represents energy waste to me, and at least those types that have phytoestrogenic effects are still debatable. The doped compounds attached to those plastics however, I'm not terribly enthusiastic about that stuff leaching out into our environment and letting the sun and weather eventually breaking them down before they materially damage our bodies.
I worked at a McDonald's in the 1980s that did that. All the heat from the ice maker and drink cooler condensors was captured in a "pre-heat" tank that fed into the water heater. The idea was that you'd need less electricity for heating water for the dishwasher.
It worked, but they removed it several years later so I guess it wasn't a net benefit.
In idle moments I've wondered if I could retrofit the multiple small compressors with a single large unit with multiplexed hoses and electronically-controlled relays that was designed to operate submerged in something like polyalkalene glycol (PAG fluid), insulate the heck out of that to minimize thermal conductivity to the surrounding air, then extract out the heat of the PAG fluid into the water heater. Would be a maintenance nightmare to be sure, but it would be a cool hack to play with exploring and measuring those boundaries of efficiency.
Also, hot days happen everywhere at once, so you can't even borrow power from other grids, because they are likely just as in need of power as you are.
Also, AC can be shifted. When power is cheap, use it to chill a tank of water or block of masonry, then use that coolness to reduce the AC load later. A tank of water can work just like a battery for HVAC.
Sort of. Away from the equator, days are longer in the summer, so one gets more total energy per day during the season when it's hottest. But hour-by-hour, the peak temperature usually happens later in the day (mid-afternoon) than the potential peak solar production (noon).
More pedantically, solar panels actually perform worse when they are hotter: https://www.thegreenage.co.uk/article/the-impact-of-temperat.... The ideal for solar power would be full sun and frigid cold. In the extreme (Andean mountain versus Australian outback) this difference in efficiency might be as large as 50% (+25% for the cold, -25% for the hot).
I agree with you that the "battery" doesn't necessarily need to store electricity, and that pre-cooling some large thermal mass might be better than a traditional battery.
There's been far lower-tech solutions for this stuff for a long time now:
https://en.wikipedia.org/wiki/Load_management#Ripple_control
Uhm. Maybe from a purely financial point of view. Physically they are energy consumers. They do not store energy in any sense that would be relevant here.
However, your question presupposes that it's only human behavior that can be influenced with price. Send a price signal and let technologists and entrepreneurs do what they do best...
I agree, a price signal might send some people finding solutions, but I'm afraid that a lot of the solutions would cost more than the savings, so that would reduce the field of what is possible. And mostly, I wanted to underline that simply sending a price signal is sometimes not enough for certain markets and does not scale too well by itself.
I think you might be on to something, but this needs to be presented to the consumer in a certain way. And I do not know how far you can get without support from the big players in the appliance market.
Cool to see you are working on this so concretely!
Also, at some point, can I get a discounted rate on my hyperloop ticket if I sell it energy during peak demand at an under-market rate?
Markets have their role to play but it's simply an enormously complex system quite unlike anything else.
Imagine if you had to run the street system but you couldn't ever have traffic jams.
* the currently running Brooklyn Microgrid [1]
* and Toronto Hydro is apparently currently assessing a similar one (the blockchain isn't mentioned in this summary, but Dr McGillivray mentioned its usage in his talk today) [2][3]
There is still so much to be worked out, I could hardly digest all of the details he spoke about. It does sound promising, though!
[0] http://www.ai-toronto.com/ [1] http://brooklynmicrogrid.com/ [2] https://www.sdtc.ca/en/portfolio/projects/transactive-energy... [3] http://awsassets.wwf.ca/downloads/wwf_dg_report_long_bookmar...
Change the price of electricity from moment to moment
This already happens. It is called the "Spot" price of electricity.It's not just supply though, the demand, ability of the infrastructure to carry the power, the relative costs of the power plants, etc are also factored into the price.
Note how gasoline prices vary on a daily basis. This matches supply with demand.
So let me just say that yes, you are right that gasoline prices better match price and demand.
Right. That's the policy issue. Government subsidies for batteries would be a huge giveaway to battery manufacturers. California [1] and Sweden [2] have already offered subsidies. That may not be a good thing.
[1] https://www.greentechmedia.com/articles/read/Will-California... [2] https://cleantechnica.com/2016/11/22/sweden-will-offer-60-su...
Users smart enough to change their electricity consumption eg night rates - they need more information to improve even more. Smart appliances will soon follow.
Unfortunately, many consumers live in older apartments and/or are more transient than most, so there's less incentive to invest in energy efficiency. The landlord is responsible for appliances/AC, but not the power, so there's no incentive to do anything except buy the minimally sufficient hardware for the occupant.
I think if we start to change some of the perverse incentives in the lessor/lessee relationship this will also have some significant effect on power consumption.
a) Households will have storage in the form of batteries b) We will replace the existing grid with a grid that advises devices of he cost of electricity. c) We will replace existing electricity using devices and systems and devices smart enough to turn themselves off when the cost of electiricity gets too high.
So, storage is actually needed and all we need to do is spend massive amounts on updating the grid and replacing devices to make this possible.
It annoys me that there are a lot of hand-waving articles like this but I have a lot of trouble finding solid analysis of the practicality of a renewables based energy system.
I am not convinced it will work at all, let alone at a reasonable cost.
There are obvious political problems with rate advertisement. Some are actually beneficial, such as being able to guarantee critical power supply on a more granular level. But what about ending up with a handful of backbone power providers with shady preferential practices and lackluster competitive spirit?
Self-regulating devices that turn themselves off during peak usage (back off packet sending...quiet broadcast radios...) seems extremely susceptible to bad actors. Perhaps I underestimate how bad current power infrastructure consistency is.
So storage still makes a lot of sense, because if I want to do anything about renewable energy, I unfortunately have to do it myself. Putting some sort of solar system on my house will cost ME money; either outright, leased, or through a home-improvement loan plan. Which is sad, but it is what it is (and kudos to what the government HAS done to bring down these costs). Since it's all on me to reduce my carbon footprint, that energy produced must be stored, and these home battery systems (Tesla or not, there's about 2 other choices though, it seems in my research with companies locally) are not all that expensive considering the cost and installation of a solar array, especially Tesla's pricier solar roof option. And that's giving you complete independence from the electric company.
I talked to a rep about a solar solution and he understood my concern for wanting to go "net zero" since it feels like locally, the power company is devaluing what you put back into the sub-system more and more. He explained that more and more people exploring their alternative energy solutions are interested in these battery/storage systems for the exact same reasons. With a minimum investment of about 30k or 40k for a whole-home solution, a lot of people don't trust that their power fed back into the grid won't be devalued over time (at least a rate higher than the natural decay of battery technology).
Here's a related article to what I'm talking about here, I think this is happening across the country though:
http://www.kansascity.com/news/business/technology/article38...
Specifically:
> Power companies argue that a solar house doesn’t pick up enough of the cost of all it takes to make energy available around the clock. If those solar homes don’t pay for upkeep, they contend, other customers eventually get stuck with higher bills.
Honestly, a solar house seems like it really is only beneficial to itself; it only has the capacity to produce power for itself, and maybe a fraction above. Nothing worth selling back "wholesale".
It will cost you regardless of how it's implemented. Through taxes, increased utility costs etc.
I'm okay with this.
Consumers storing electricity and load balancing it between devices in their house. Money in coming up with that technology and selling. In the mean time, you relieve the need to force companies to change for you. Instead they will move with the market.
You thereby help create the market. A much better tactic than trying to shut down market economics. Or making other people pay for what you want through threat of violence (taxation).
Power company cooperatives run the largest storage systems on the planet already, they built pumped storage because it was win-win for their cost structures (they use them to more efficiently operate baseload generators).
They also do things like run around buying old appliances to get green credits (a response to a negative cost imposed by regulators).
As far as selling power to the grid, the price should be fair for everyone, not just a big reward for having the upfront capital to install solar. Especially as the need to spur investment in solar tech goes away (because in more and more areas it is already cost competitive and an easy choice).
Now, new consumer products like Tesla’s grid-connected
home battery [...] are becoming more popular
I'm sure some people have home batteries - but isn't this a rather niche thing?I mean, I'm sure it's nice for people in the boonies where mains power is unreliable. Or if you're a survivalist/hippy that wants to be off-the-grid/completely-renewable and doesn't mind paying a big premium for it.
But what would a home battery offer me that I can't get from the grid already?
At least in the northern California PG&E service area, the credits are calculated month to month but trued up once a year, so your summer surplus generation does give you credit for your winter use. It's called net-metering [1]
[1] https://www.pge.com/en_US/residential/solar-and-vehicles/gre...
LA sees any competition to their utilities to be an existential threat. For a while, they forced me (and tens of thousands of others) to pay for trash pick up from a multi-family dwelling even though our landlord had hired a private service and had all of our city receptacles returned. They were recently smacked down in court, I received a class action settlement notification a few months back.
A major problem utilities face is the so-called duck-curve. As people come home at night and start turning on appliances, electricity demand surges. In solar-heavy places, this corresponds with the sun going down and all the solar capacity going offline. To meet this spike in demand, utilities need to fire up new power plants ("peaker plants").
Now, these are huge capital investments that stay idle for most of the day just to turn on to meet end-of-day requirements. Not ideal.
So in comes TOU pricing -- make electricity more expensive during these demand surges.
TOU pricing is already an option in a lot of places. It's popular if you have an electric car (you're going to use more electricity so tiered pricing is more expensive... instead, you can have an incentive to charge your car during the middle of the night at times of lowest demand). And TOU pricing is becoming more common in markets with heavy solar penetration (to combat the duck curve problem).
So, what would a home battery offer? Effectively allows you to load-shift around TOU pricing. Even if you don't have solar on your roof, if you live in an area with heavy solar penetration, TOU pricing makes electricity cheap during the day... charge your battery during cheap times and use it when you come home and electricity is expensive.
Whether the numbers makes sense depends on your market and consumption patterns, but as far as broad trends go, TOU is creating an incentive for batteries even on grid-connected houses.
Let's assume an extraterrestrial colony being established on the Moon, or Mars, or another planet.
Do you really want to spend time, effort and resources on building a traditional power grid in a hostile, unstable environment (or a planet whose natural terrain you want to affect as little as possible), or just provide each facility its own independent power supply?
Though I'm sure some analyst somewhere had similar words about air conditioners.
From the science side, it is solved. What's needed is implementation from industry to make it cost effective and have large enough scale.
This is already happening. Grid-scale lithium ion storage is cost effective enough to replace California peaker plants that run on natural gas.
In Arizona, the latest paired solar + storage project is selling electricity for $45/MWh.
And the cost curve is continuing to fall for lithium ion at a fast and steady rate. The market for storage has developed so quickly that there hasn't even been time to set up subsidies for storage, before it was economical to start using it in practice. Some states are now implementing storage subsidies, however, which will extend storage into more applications where it's not yet economical, and give the industry a further kickstart.
The question will be if demand response will be cheaper than storage, and if customers will put up with the hassle of demand response. As far as costs, not using electricity is hard to beat, investing in reducing consumption for identical work output, with efficiency measures, pay great dividends. Of course, for the common home owner, convincing them to spend $500 now, in order to save $1000 over the next 5 years, is a hard sell.