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Comment by ocschwar | Hacker News Reader

Take a look at the major power consumers in your house.

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.

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For household appliances to be used in this manner, they would have to be completely automated. Sure, I could choose to run my laundry cycle at 8pm rather than 5:30pm, but the convenience factor of doing it when I want to do it is going to trump the pennies they'd give me to wait, every single time.

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.

> Sure, I could choose to run my laundry cycle at 8pm rather than 5:30pm, but the convenience factor of doing it when I want to do it is going to trump the pennies they'd give me to wait, every single time.

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.

> Also, most of us run a load just before going to bed, and shuffle it to the dryer in the morning.

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.

Or one could just get a combo washer-dryer that washes and dries your clothes without any intervention.

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.

Energy futures on a "by the minute" basis are great in principle, but they are hampered for consumers by the fact that current billing is flat rate.

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...

If you embark in the floating price, you'll probably get better rates. The downside, you having to worry about it, is offset by the machines planning their own consumption within the criteria ("I want this dry in the morning") you set.

How much mildew is going to build up if it starts an hour or two later? Or sits in washer for a few hours after finish?

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.

In my personal experience, clothes start smelling funky and 'off' after about 3 hours wet after a wash, and the smell persists even after drying. Only solution is to rewash the entire load.

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.

Is it very warm where you are located? Here in the UK I can sometimes forget washing over night, or 24 hours in the machine (front loader) and not get a problem with smell, any longer and I likely will - and don't worry my wife tells me when it smells off! Never had a problem with mildew in the gasket either - maybe too cold here? Or maybe the weekly hot wash i do keeps the machine clean?

Same here in Melbourne (au), have forgotten clothes in front loader for 24 hours sometimes, and they've been fine. I guess it's either climate, or front loader, or appliance hygiene. Or a combination thereof

I find this depends a lot on where you are. In my house in California, I can leave the clothes in the washer a lot longer. In florida, the washer is already stinking most of the time. Even if I disinfect the washer occasionally with bleach, it still ends up stinking again. I put this down to the general humid environment.

Do you close the door on the washer? We have front loading washer and leave the door slightly ajar. When it's completely sealed the darkness and humidity are a breeding ground for mold.

Could be the water quality as well.

Florida water stinks like a swamp right out of the tap.

White vinegar in the prewash will kill the mildew smell.

White vinegar can also help when washing clothes that tend to bleed color (e.g. Just-bought dark blue jeans). Wash these once with white vinegar and the color should "stabilize".

I buy that stuff by the gallon. If you live in a high humidity area it has so many uses.

If a washing machine waits up to say 30 minutes unless you click the fast button, that's still quite a bit of time shifting in aggregate. Same for home heating/cooling, you might be willing to shift an extra 1-2 degrees if it will save a few dollars a month and you don't need to pay attention. However, if your willing to spend a few extra dollars a month that directly pays for grid storage.

Yes. This only matters for half an hour, once a year, when there isn't enough wind or sunlight to generate electricity. It's OK for a washer to just say no if you try to switch it on in that half hour, and maybe that makes more sense than buying a large battery that only gets used once a year. The timing can be forecast, and the news would warn you the night before.

The US grid already has a lot of storage in hydropower systems. So, I doubt a washing machine would ever need to say no.

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.

You need to bleach your washing machine if clothes are getting funky after three hours.

The solution is straightforward:

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 :)

Cooking and folding clothes aren't going to be automated for a long time. Fine motor control is a hard problem that has resisted automation for decades. GPUs and RNNs don't help.

You need fingertips with lots of nerves, and probably thousands of very nuanced motor control paradigms.

I'd be happy with just laying the clothes flat so they don't wrinkle. That way I can get to it whenever. Especially if they're pressed first.

Buy wrinkle resistant clothes - they can be washed without needing pressing.

No thanks, my current workflow works just fine.

There are demos of robots folding random laundry. They are slow and expensive, but that's the stuff that improves over time.

Sure, actual cooking won't be. However, taking a frozen entrée and heating it could very easily be automated.

Cooking has been automated for many people for a long time, all they need to do is open the microwave door.

Automate sleep too?

As in, the process in the brain? Because if I could turn on 'sleep mode' while maintaining enough consciousness to perform basic tasks/hobbies then several hours later turn off 'sleep mode' to regain full consciousness and feel fully rested then _YES_ sign me up for automated sleep.

Some people call that mode a meeting.

Or make sleep more efficient.

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.

Pretty sure you will always need sleep every day for optimal functioning. Unless you have nanobots cleaning things up maybe.

https://www.nih.gov/news-events/news-releases/brain-may-flus...

I could totally use the "making you feel as good as new when you wake up" part, though.

>Also, most of us run a load just before going to bed, and shuffle it to the dryer in the morning.

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.

>Also, most of us run a load just before going to bed, and shuffle it to the dryer in the morning.

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.

Not to mention the sour smell that clothes get when left wet for too long in the washing machine.

I routinely do this.

Knowing the kind of fire a malfunctioning dryer - and washing machine, though less likely - can cause, there is no way I leave either running without someone about and awake in the house.

Most of us put the last load in the dryer before going to bed, but that load has 6+ hours to dry before anyone notices, so your basic point, for dryers, is still reasonable.

>Also, most of us run a load just before going to bed

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.

This is a great example of how you should always understand your customer when creating product features.

so you don't iron or fold your clothing? you don't mind it smelling like mildew?

my goodness...

> Also, most of us run a load just before going to bed, and shuffle it to the dryer in the morning.

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.

> but the convenience factor of doing it when I want to do it is going to trump the pennies they'd give me to wait, every single time

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.

We already put our washing on a timer, when we come down in the morning it's ready to put on the line.

I agree. But at least heating/cooling could work this way. I don't mind whether my apartment or my fridge is a few degrees warmer or colder, but that difference could store a couple of kWh. If you use a water heater with a tank it too can be used in such a way.

Maybe you don't, but most people care---a lot---about the temperature of their dwelling (yes, to the resolution of a degree or so). And your friendly neighborhood microbiologist will be happy to discuss the implications of fridge temperature irregularity.

And your friendly neighborhood electrical engineer will insist on having that discussion before finalizing a design for a fridge controller.

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.

I have a five year old fridge whose defining features include a compressor that runs pretty much all the time at a lower current draw to reduce overall energy use (and keep it quieter).

An electrical engineer I believe designed that part of the system...

I don't think the microbiologist will object if the fridge is too cold for part of the day... it's not like we're storing the microbiologist's cell cultures.

We already waste a great deal of food. Having it too cold will damage food, as will too hot. Older fridges used a sawtooth cooling pattern (on/off) but newer ones, with fancier motors, have might tighter regulation. I'm sceptical of how much energy can be scavenged.

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.

I wasn't suggesting making it so cold as to damage food. I also wasn't arguing against batteries.

If you were suggesting a refrigerator to run the cooling in the night so much so that it'd be able to sustain a safe temperature for many hours while conserving energy in the day, then yes, you were suggesting making it so cold as to damage food - a few degrees difference isn't sufficient to achieve what you want, and if your temperature fluctuates more than 3-4 degrees then the food either gets unsafely warm or gets frozen/damaged.

I wasn't suggesting that, no.

I was just generally arguing against the parent proposition as well.

Well, if you're a skeptic as to how much can be saved, you might want to look at the many "smart grid" studies, because this has been a hot topic for a while and is already implemented to a small degree.

Both of these problems can be solved by shifting the energy storage into a medium other than air: refrigerant. Store the compressed refrigerant in an insulated tank and use as needed. It's no different in principle from storing hot water in an insulated tank. Shift the load off peak.

> Store the compressed refrigerant in an insulated tank and use as needed

Congratulation, you just re-invented the wheel. Do you really fridge builder are that dumb ?

A lot of the power that a fridge consumes is related to the defrost of coils. I don't care when my fridge heats up the coils, so that would be an easy load shift for a fridge that would not change the interior temp one bit.

Once I started renting and eventually owning a house, it always drove me a little nutty to observe that many of those power consumers you cited are variations of a heat pump of one kind or another. I've always wanted to co-locate the heat output from the compressor of the A/C+refrigerator+chest freezer, dryer, and dishwasher into the same equipment space as my water heater, which uses a heat pump to extract that heat and cool the space at the same time. Any "overflow" heat I'd like to put into zeolite balls [1], and release back when needed for the washer, dryer and dishwasher to use.

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...

[3] https://www.eia.gov/tools/faqs/faq.php?id=86&t=1

> I've always wanted to co-locate the heat output from the compressor of the A/C+refrigerator+chest freezer, dryer, and dishwasher into the same equipment space as my water heater

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.

Thanks for sharing that historical tidbit! My understanding is compressor manufacturers don't like to work on co-generation on a small scale. However, early attempts like you describe tended to use some kind of water jacket because heat pump technology back then was finicky and much more expensive than today. Using air to conduct heat is hugely inefficient, but we're dumping the waste heat into the air anyways and then later spending more kWh to cool down the air, so the current batch of heat pump-based water heaters are a possible starting point.

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.

Its also possible that labor/maintenance costs outweighed the cost savings. Or they couldnt buy the equipment any more :)

Speaking of everything being a heat pump, another interesting supplementary solution is https://en.m.wikipedia.org/wiki/New_York_City_steam_system

Um, your link is hardly an endorsement for foamed glass:

"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."

Thank you for pointing that out, I should have set out my qualifiers, it is definitely not for everyone nor every use case. I favor the extremely stable properties and far lower environmental impact over XPS. For my specific use case, I want an application where the lifetime of the building is measured in >100 years, without having to go in and replace the insulation during that period, and without significant deterioration from the ocassional penetration of water or dampness. I wanted the natural flame retardant properties without doping in chemicals that have to be extracted out later with solvents (yielding its own set of recovery, recycling and disposal challenges) during recycling like we currently have to employ with recycling XPS (if the recycling facility extracts it out at all). I really like the concept of building this insulation once, and being able to re-use it indefinitely until it is physically compromised, capturing the embedded energy to make the insulation in a one-and-done cycle.

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'm not sure if with foamglass they mean an aerogel made of glass. That stuff has wild thermal properties.

https://www.youtube.com/watch?v=kz95RnIG0NY

If Chinese factories figure out how to mass produce aerogel, with similar durability and environmental footprints to Corning Foamglas (or similar foamed glass blocks), then I'd be all over that. So far though, I can't get very good field reports of people using the much cheaper pellet-form factor aerogel products commonly coming out of China.

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.

Be careful retrofitting insulation to a house. It can cause damp issues.

Your house!?

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.

> Large industrial machinery. Data centers. Manufacturing

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.

Huge loads like Aluminium smelters are already "smart" and cooperate with the electricity providers, so there is not as much left to gain there.

Yes and no; you can't just switch off an aluminium smelter with destroying it; it takes quite a bit of time to ramp it down. I think that for forecast high demand they shut down production in a planned way.

In the United States, more electricity is used residentially than commercially or industrially (4.8, 4.6, and 3.2 quads respectively in 2016):

https://flowcharts.llnl.gov/content/assets/images/energy/us/...

This is not nearly upvoted enough.

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.

Running a clothes dryer unattended is not safe. Those appliances are among the more common causes of house fires.

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.

> Running a clothes dryer unattended is not safe. Those appliances are among the more common causes of house fires.

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.

> smart-ified

I don't care how smart your dryer is, if it catches on fire it's not going to do shit.

"I don't care how smart your dryer is, if it catches on fire it's not going to do shit." Basically all of these are caused blocked ducts, which is trivial to make smart by including a flow/pressure meter.

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.

You don't need smart to do that. A simple mechanical pressure switch can handle it. Also dryers have several high limit switches that will cut out if the temperature gets to high. None of this requires a silicon brain or internet connection.

I'm wondering how this works. Do you really watch over your dryer just to make sure it doesn't catch on fire? If that were really a problem, wouldn't a fire alarm do a better job than an easily distracted human?

  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.

This seems awfully paranoid. Dryers are responsible for less than 1% of house fires in the US. If my house is typical, then my odds of experiencing a dryer fire are maybe .002% per year. A substantial portion of these happen because people don't clean their lint, so you can cut the risk even more by just not being negligent.

I think this might just be disagreement over what "unattended" means. To me, being in the same house (and not in the same room) is closer to "unattended" and perfectly normal.

The context in this conversation is leaving the drier on while sleeping at night, though.

I see no significant difference between sleeping at night or watching TV in another room - in either case, I'd notice the dryer malfunction only by the sound of the fire alarm.

right, which means a fire alarm is a perfectly good method of alerting a nearby human of a problem.

Good point. Although I suppose you might still want to be home rather than running it while you're at work or otherwise away, to have a chance of grabbing the extinguisher and/or calling the fire department before your whole home is lost. I'm not sure how common it is to have smoke detectors automatically notify the fire department, and I expect there's issues there similar to burglar alarms, with false alarms being far more common than real ones, which affects response time.

I'm not sure how common it is to have smoke detectors automatically notify the fire department . . .

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.

The main cause of dryer fires is lint buildup resulting from poor maintenance, cleaning, or installation, from what I understand. Built up lint is an ideal material for starting a fire. I suppose if you added some sort of sensors, you could make a smart dryer that demands to be cleaned before running if it detects a significant buildup. Might be able to largely mitigate the risk, barring active user circumvention. I'm just spitballing, though.

Yeah, I would guess 'lint buildup would impact airflow through the lint screen, which would be easily monitored.

Well, if you equip it with a halon suppression system in a sealed and heavily sensored room, it might. Of course, now your dryer is your single most expensive possession by an order of magnitude. Which always seems to start being the problem when people propose "smart" solutions. "Well, first we need a class IV AI and on-demand local fusion energy, then everything gets easy..."

I mean, you could just put in a few more heat sensors.

But the dryer knowing that it, and most of your possessions, are about to cease to exist isn't really useful information. It doesn't remove the obligation that it be supervised. Dryer fires start quickly, often due to lint build-up, and can start when the dryer is operating in its normal temperature regime. Thus the sensors would often only be helpful in identifying that a fire has started, not in preventing it. Thus, unless the dryer has some way of intervening in the fire (like my admittedly sarcastic halon system), its "smart"ness isn't valuable for this failure mode.

> Dryer fires start quickly, often due to lint build-up, and can start when the dryer is operating in its normal temperature regime.

Lint does not catch fire at 140F.

You seem to have very strong opinions about this issue. I'm not convinced they are well-supported by either experience or data.

"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."

Source: https://www.cpsc.gov/PageFiles/117075/dryer.pdf

Oh, looks like the top result for dryer temperature was just wrong. And the various numbers I'm seeing for what temperatures are dangerous for lint are wildly inconsistent.

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.

Welcome to the science of fire. If you pump energy into a system faster than you are removing it then you are heating it up, if you pump energy out faster than you are adding it then you are cooling something down.

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?).

> Welcome to the science of fire. If you pump energy into a system faster than you are removing it then you are heating it up, if you pump energy out faster than you are adding it then you are cooling something down.

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.

I have had gas dryers whenever I've had a house with gas service. They dry faster and cost a lot less to operate.

> Lint does not catch fire at 140F.

No but sparks that can ignite lint are common risks around operating dryers (both wiring faults and static discharges are issues.)

"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."

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.

Load scheduling is precisely equivalent to energy storage. You store electrical energy with the intention of consuming it later. Load scheduling just makes this explicit. In fact one of the benefits of scheduling over storage is that there's no extra losses due to charging / discharging the battery.

"One of the benefits of scheduling over storage is that there's no extra losses due to charging / discharging the battery."

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.

I'll second that the issue is only semantics. Scheduling is not the same thing as storage, but it _has the same effect on the grid_.

We understand what you mean, but take issue with the semantics, because a dollar saved is a dollar earned presupposes the existence of that dollar, but your saving is fictive. Both versions are not invariant in load or time.

So the storage in your version is leaving it stored where it was. Great.

The most inefficient time to run your AC is when it is hottest, aka the time that most people are running their ACs and are unlikely to stop running their ACs. Peak usage isn't as flexible as you seem to think.

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.

When it's hottest corresponds to when the solar panels work best, so there's that.

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.

When it's hottest corresponds to when the solar panels work best, so there's that.

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.

It's hard to see how pre-cooling a thermal mass cannot help to be much more efficient than an electric battery.

Unfortunately, most solar panels point toward the equator for maximum overall power during the day. The highest demand for AC is in the afternoon; if panels faced West, they'd provide less overall power but more at peak times ( at least during summer)

It's almost like you've forgotten the original argument.

Don't forget "water heating". That could be done more dynamically than it is now... and water heating makes up 9% of household electricity usage:

https://www.eia.gov/tools/faqs/faq.php?id=96&t=3

It constantly surprises me how many places have electrical heating. I grew up in northern Europe where remotely heated water is the norm.

https://en.wikipedia.org/wiki/District_heating In terms of efficiency, using excess heat, etc. electrical heating is utterly horrible.

True. A water heater tank can keep the water hot for a full day with no power. Even two days will still get you a warm shower. I discovered this during power failures :-)

Solar heated water is probably much more efficient than solar generated electricity.

Good point, but I'm not always home to do the laundry at the most opportunistic time. Doesn't a refrigerator run most efficiently if it cools continuously? I'd hate for my milk to spoil.

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.

Refigerators commonly have a compressor to cool the freezer, and then a heat exchanger to equalize between the freezer and the fridge.

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.

It still isn't controlled by a timer or switch, though. That's the point I was opposing.

But there's no reason it can't be. So far there just wasn't a reason

Food safety dictates a minimum chilling temperature, we can't override that without sacrificing health. We can make fridges/freezers more efficient and insulated though. My deep freezer (according to Energy Star) takes $24 a year to freeze my food. That already seems extremely efficient.

Yes, but it's not going to be retrofitted onto existing fridges. You'd need to replace most of the fridges in the system.

Today's washing machines already have timers to start in X hours (at least mine has, and it's not exactly top of the line). Once consumer electricity prices reflect the actual electricity price at that moment new models would quickly contain internet-connected logic to start the washing cycle at the point in the next 24h with the lowest predicted electricity price.

If you integrate washing machine and dryer into one mashine, the cost-savings from electricity would be even bigger with very little convenience lost.

Absolutely, although I don't know how they handle wrinkles, though without an auto-fold/hang feature (that'd be so cool!).

Our drier tumbles the dry clothes for a second or two every five minutes or so for hours after the dry cycle has finished. This goes a long way to avoiding the clothes getting too wrinkled waiting for us to unload it.

...my dryer simply doesn't go long enough to keep them wrinkle-free.

A well designed refrigerator can hold temperatures without "turning on" for quite awhile if the door isn't opened and warmer food placed in it in that time period. The insulation is "passively storing" the temperature differential.

Yeah, "continuous" was a bad choice of word.

Back of the envelope math: Assuming a fridge has two cubic meters of air and twenty liters of water (the heat capacity of all the food and metal inside the fridge) and takes the temperature from 70 F to just above freezing (20 C difference), there's a heat storage of 472 watt-hours, or 1.6% of the average daily electricity consumption.

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.

> By the straight math this could cover 17% of daily usage

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.

> 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.

You lost me. I don't understand how that connects.

In a way a dishwasher is storing energy in the form of clean dishes. Now instead of storing electricity to run the dishwasher whenever, you simply run the dishwasher when there's an electricity surplus

In particular, when the dishwasher's in the drying phase. Do you really care if the heating element turns off here and there at that time? Probably not.

So you want priority queuing for power consumption. I understand it would be able to eliminate some spikes for my individual house but my overall usage doesn't go down. The article is really about the grid and not an individual house. If every house in my town had priority queuing would the hourly consumption really change? Maybe that last dryer or dishwasher load of the night could be time shifted but you can only delay refrigeration or clothes washing so long withing either spoilage or killing your throughput.

Yes, smart grids can really change hourly consumption. As an example, imagine a world where 1/3 of the cars are electric, and they're long-range cars like the Bolt or Tesla, which only need to be charged every couple of days, not all of the time. A system that looks at the solar/wind forecast and charges your car at the right time can make a huge improvement to the grid on a time-scale of days.

I still find "long-range" electric vehicles to be an oxymoron. A Bolt @ 75 mph can only make it 190 miles. I'm not sure that is enough to get me to a qualified mechanic and back and it sure doesn't compare to the nearly 500+ miles I get on fuel. I can't afford to drop $30,000 on a car that I can't take on a road trip.

I 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...

Even with superchargers, electric vehicles are an incredibly poor choice for road trips. Most driving is not road trips, though. In fact, the overwhelming majority of driving is not road trips.

So you're saying that people who think that EVs are a good choice for themselves because they own one and do road trips in one... are actually wrong?

People own all sorts of things that don't work well for them. Hell, that's pretty much the justification for the entire high-end audio industry.

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.

Huh. Well, I guess you know best, and Tesla owners who do long trips are all wrong.

You're getting off-topic, but, Tesla owners take road trips using the Supercharger network all of the time. Instead of focusing on your personal preferences, maybe you could also take a look at the actual behavior of early adopters?

I think the progress on EVs are amazing - I was poking fun at "long-range".

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.

Regarding "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."

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.

>with a little TCP/IP to coordinate activities around your house, your need for power storage declines considerably.

There's been far lower-tech solutions for this stuff for a long time now:

https://en.wikipedia.org/wiki/Load_management#Ripple_control

https://en.wikipedia.org/wiki/Radio_teleswitch

> Each one of those things is inherently a form of energy storage

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.

HVAC and refrigeration are critical. The first to heat your home when it's -30degC outside, and the second to preserve food.

Some, like Refrigeration, are also a form of storage. Your fridge stores coolness, and only runs when it gets too warm.

What about fridge heat harvesting btw ?

I had a crazy idea to relocate the compressor and coil from my fridge to the mechanical room in the basement directly below it. It would cut down on noise and should make the fridge more efficient because it wouldn't be dumping its heat under itself. Once the heat is dumped in the mechanical room, a heat exchanger around the pipe to the hot water heater would have to help a bit. Even in the summer water out of the ground is pretty cold and anything to take the chill off would be a bonus.

Basically what I thought. I googled and saw a few "fridge harvesting papers" I should read (or you ? .. ?)

  - 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.pdf

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