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.
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.
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.
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.
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.
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".
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.
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.
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.
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.
>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.
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.
> 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.
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.
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.
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.
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.
> 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.
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.
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.
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.
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.
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.
"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.
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.
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.
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..."
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.
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."
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.
"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.
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.
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)
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 :-)
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.
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.
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.
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.
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.
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.
> 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".
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.
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.
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.
> 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.
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.
The article doesn't mention a fundamental point. Change the price of electricity from moment to moment based on the supply. This will obviate much of the need for storage, since a lot of electricity usage is elastic (car battery charging, HVAC, etc.) and can be time-shifted.
On the other hand, the change in price from moment to moment is an arbitrage opportunity for anyone with a grid connected battery. As battery prices keep going down, more existing generators will be motivated to invest in them, which will gradually create an efficient time shifting of energy, which will gradually erode the existing price volatility.
I think that is a strictly good thing though; it is a flywheel solution (almost literally!) because the more people buy in and work with that model, the more successful it becomes. In a sense you gamify the electrical grid to train people to be more responsible consumers. If at the end of it we are paying the same price but the grid is more stable, I'm ok with that!
I heard a talk just today on this by Dr Dan McGillivray (Exec. Director of the Centre for Urban Energy @ Ryerson University, Toronto) at AI Toronto [0] who mentioned two projects, utilizing a mix of central power generation, decentralized power generation (via solar panels, etc), and the blockchain for transactions:
* 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!
This assumes automatic adjustment of consumption on the consumer end. I doubt individual residential consumers will look at the time and the consumption and plug their appliances according to the network for a few cents. I do not know if industrial usage is enough to move the needle here. Maybe someone can chime in with some data?
If every smart dishwasher does the same thing, the price will surge across a time period shorter than the minimum run time of your dishwasher. That stratagy only works if you're the only one doing it.
It could, but for it to work on a mass scale, everyone would need to replace all of their appliances, which will take at least a decade for the tipping point to occur.
Sure, but the same can be said for almost all change. Driverless cars, solar panels(renewable energy in general actually), even windows updates! I don't think saying "we shouldn't do it because it will take too long" should be a valid excuse
If (some) people drive five miles to save $0.10/gallon on gasoline, they'll run the dishwasher when power is less expensive.
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...
Some people doing that is not enough to assume significant shifts in market forces will happen. The question is will enough people do that?
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.
Gas prices vary daily. This works very well at matching supply with demand. I don't see any particular reason to believe that there's something different about electricity.
What is the cost of time-shifting usage versus paying peak pricing versus buying some storage to charge at lower rates? At the industrial scale this becomes a game of capital expenditures versus cash flow. At the consumer scale it's a game of convenience and cost. If energy can be made cheaper at the cost of informational overhead (or less convenience), then what is the role of storage (as it itself becomes cheaper) in managing that overhead? It doesn't seem far fetched that it will play a role.
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?
Hi, we are an energy company working on load shifting of EV charging. The customer will just set some preferences- the charging timing is then fully automated to shift load and smooth demand peaks. Pretty sure most modern demand response systems work this way.
How's your product going to far, and are you hiring? :P
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.
EV and heating/cooling. Sector coupling and electrification will bring in the needed flexibility. It's not really there now with all the washing machine and appliances talk.
Cool to see you are working on this so concretely!
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.
I know what the spot price is. My electric bill, however, has a fixed price 24/7. When the cost to deliver electricity varies significantly on an hourly basis, this is not an efficient way to match supply with demand.
Note how gasoline prices vary on a daily basis. This matches supply with demand.
The large electricity consumers, though, all are on spot prices; and in many countries you also have some split for residental users (e.g. two prices, peak/offpeak, for particular hours in the day) - adoption for this is mostly slowed down by the need to replace all the electricity meters with "smart meters" that can do the variable accounting instead of simply tracking a running total consumption.
Market-based solution? Incumbent interests object to this. Typical objections include 1) it will increase price volatility (which will hurt a) existing power generators or b) consumers), 2) it will reduce reliability. So, instead of market-based solutions, we get "energy policy" that subsidizes all incumbents and reduces innovation.
"The one question we will have to deal with as policymakers is do we want a subsidy regime for storage, or can it can be delivered by market forces alone."
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.
I agree storage is required if we continue to have flat rate power charges for users, but implementing variable power pricing for consumers it reduces the need for storage and is really over due. IE power should be cheaper on windier days with moderate temperatures. Expensive if it suddenly gets hot and cloudy. And users should know what the rates are.
Users smart enough to change their electricity consumption eg night rates - they need more information to improve even more. Smart appliances will soon follow.
FPL has started doing this based on the biggest load signal (time of day). We're charged peak rates and non-peak rates, and the peak rate is about 2x the non-peak.
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.
What would something like this look like? There's no incentive on the part of the inhabitant to conserve if the landlord covers electricity, so clearly it's not as simple on that.
Title of the article is misleading. The article title seems to imply that we just don't need storage. Really it is about needing to worry about on-demand output as we convert to more renewable (wind/solar) power generation. The only brief mention of what can take the place of storage in a renewable world is thermal and hydro generation.
The whole article is misleading. Hydro and geothermal are the only mentioned "flexible" substitutes for storage because this is a hit piece written by the old guard. "Flexible" is code for coal and gas plants that are currently fired up on demand already. C'mon now, use a little critical thinking and some follow the money. There isn't enough hydro and geothermal installed base to handle the load of the night time / non-windy day use cases.
They are saying that storage is not needed in the grid because
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.
Are you suggesting the grid will turn into an interconnected graph of power supply lines with a routers and a routing protocol to supply power dynamically based on usage? Sounds a lot like our favorite graph.
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.
In daydreaming what this article was about I thought it was going to be a transglobal power distribution where the folks receiving the sun were powering the folks in the evening the other hemisphere away. Pretty interesting thought but I'd doubt it would work uniformly. Probably a couple of pairs of partners like US and Japan or Australia or something could benefit from such an arrangement.
I only see this route going if the power companies themselves are responsible enough to make the transition to renewable energy (I'm not sure they are, at least in any relatively quick timeframe). So if the case comes that fossil fuels become more and more expensive, then and only then will they really make an effort to transition to mostly renewable energy. And it'll happen at a slow and crippling pace for all us tree-huggers out there.
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).
I would expect power companies to be extremely responsive to costs.
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).
Yes, I'm definitely not blaming them, I can see somewhere on my bill where my energy is coming from; but it's still mostly fossil (because obviously). They are making great strides in alternative and renewable energy. I would think their cost to go mostly with renewables are much more expensive to them than my cost to go mostly renewable. They're going to move slow on this.
> 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".
Unless you consider that peak electric demand correlates to daytime usage on the sunniest days of the year (for cooling purposes.) Electric companies are actively trying to discourage use during these times by offering a discount for interruptible power (they can remotely shut off power to your hot tub/water heater and other non-critical uses) or offering variable rates (proportional to overall grid demand.) Even if a solar installation merely reduces electric usage, it will almost always correlate to peak times making it immensely valuable to power companies. But I wouldn't expect their PR to confess to this.
Likewise. If you want to do something, why should you not pay for it?
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 should pay for it! Early adopters help everyone who come after.
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).
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?
There's a broad trend in the utility world towards so-called Time-Of-Use (TOU) pricing. Rather than a tiered rate (electricity gets more expensive the more you use it in a month), electricity has different prices at different times of day.
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.
The other thing it gets you is the full value of your rooftop solar generation. Many localities have protectionist regulations where the local utility doesn't have to pay for your electricity when your generation exceeds your consumption. The City of Los Angeles, for example, has that regulation. There's no "meter runs backward" after your bill for the grid drops to $0. And your generation credits are calculated month-to-month, so if you generate excess in the summer but not in the winter, you don't get credit for the summertime surplus when you need it.
> And your generation credits are calculated month-to-month, so if you generate excess in the summer but not in the winter, you don't get credit for the summertime surplus when you need it.
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]
That's pretty cool. But it varies from location to location.
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.
One thing it gets you is a discount from the power company for reducing the max consumption of your house. Many industrial users pay a fee for the near-guarantee that the power company gives that you can pull the max from the grid that your tie-in supports. That kind of charging is coming to residences in some places.
I think that it has already happened in some places. Essentially the electric company includes a charge for the peak load you drew that month - even if you only drew it for a few minutes.
How far in the "future" are we talking? Let's go all the way:
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?
So having failed to solve it, scientists say it never needed solving in the first place? Well it makes a change from "in conclusion, we need more funding" I guess...
This sort of biased cynicism is really uncalled for.
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.
Also, (large) batteries are not fundamentally needed in cars. With the upcoming self-driving technology, cars could feed themselves from power-lines embedded in roads.
What do power lines in the road have to do with self-driving? They could be used for existing cars as well. They aren't used because they are ridiculously expensive to build and maintain compared to normal roads.
He may well be, in which case he's demonstrating that he doesn't understand that those self-driving cars are only making money for their owner when the meter is running, and so the owner will be interested in whatever model needs as few recharges as possible.
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.