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The humble water heater could be the savior of our energy infrastructure woes
- ttyprintk 5y agoI think these water heaters in question are actually hybrid units. They cool the surrounding room to maintain a temperature set point. In some places, colder room air and thus more condensation is not appreciated. A less-sophisticated approach is to put your tank heater on a timer. Think carefully before you do this. Does your tank heater have the capacity to keep the water hot for a full shower, until you’re back under the non-peak schedule? If it doesn’t, you’ll be the first to hear about it.
- Retric 5y agoLarge insulated tanks of water are cheap. Sizing your house for a full week’s hot water is going to be cheaper than paying peak rates. That doesn’t help people today, but water heaters don’t last that long. Alternatively a tankless water heater provides both redundancy and instantly hot water.
- labster 5y agoLarge tanks are cheap, square feet of residential space are expensive. Tankless water heaters work well when powered by nat gas, but if you want electric it’s not great. I’ve been intending to do solar water heating, and convert from gas to electric, but the old heater gave out at the wrong time. So the current plan is build the solar and make a new place to move the electric tank into, then use the other tank for extra storage of the solar heated water. The good news about climate change is that I never have to worry about the pipes freezing any more.
- vl 5y ago> The good news about climate change is that I never have to worry about the pipes freezing any more. As they recently learned in Texas.
- labster 5y agoNah, I’m in coastal California. The last frost here was in the 1990s, last time it snowed was the 1930s. Think I’ll be okay.
- kube-system 5y agoClimate change is making weather more extreme, in both directions. “Global warming” is a good descriptor of global climate as a whole but a bad descriptor of the effects on local weather. Many places are seeing higher highs and lower lows. The only saving grace at the coasts is that you’re sitting beside a giant heatsink.
- seized 5y agoClimate change tends to mean more extremes, hot and cold (and windy). Southwest Canada is normally known for mild summers but it peaked over 110F last week. It was 95+F in my office. So maybe plan accordingly just in case....
- Retric 5y agoA family of 4 is normally fine with a 60 gallon water heater. Doubling that to 120 gallons takes up roughly 1 extra square foot of floor space assuming a 6’ tall tank. If you’re living in Manhattan at ~1,500$/sf might be worth it to avoid peak rates, but just about anywhere else it clearly is.
- deleted 5y ago[deleted]
- cartoonworld 5y ago>A less-sophisticated approach is to put your tank heater on a timer. Think carefully before you do this. Do not do this without understanding the lifecycle of legionella pneumophila, or you will face a dramatic decrease in your quality of life. https://en.wikipedia.org/wiki/Legionnaires'_disease https://en.wikipedia.org/wiki/Legionnaires'_disease
- toomuchtodo 5y agoYeah, timer or grid controlled water heaters are old and busted (especially with bacteria concerns due to a lack of in tank convection). New hotness are heat pump water heaters that are very efficient and can even add cool air to a conditioned spaces by their inherent operation. Electric vehicle charging orchestrated as large aggregate loads are what replaces “the humble water heater.” Tankless heaters are great if you’re burning gas, but electric versions are wildly inefficient versus a heat pump and require very large circuits and service entrances on the load center/breaker panel.
- ip26 5y agoHeat pump water heaters do seem promising... But many water heaters live in cold basements... Classic tanked electric is so cheap to make & operate, I have come to think they may always be with us. (Though certainly a heat pump water heater is an easy choice in the right climate)
- otterley 5y ago"Cold" basements rarely fall below 50 degrees Fahrenheit/10C. There's plenty of thermal headroom below that for heat pumps to work. Heat pumps already work outdoors at below freezing. I don't think there's anything to worry about.
- s0rce 5y agoMore of a problem is when your water heater is within your conditioned space envelope and in the cold months when you are heating your space the hot water heater takes that heat. Its not a huge issue but you do run the heater extra for the heat that's going into your hot water. If you've got an air source heat pump outside then its just an extra step.
- jethro_tell 5y agoI have a few servers that I have in a rack in my basement for various projects and work that I do. I ended up having to cool it in the summer so I made a small room around it to limit the amount I had to cool. When I replaced my water heater, I went with the hybrid model and dropped the AC. The room stays cool, my water heater uses less power on average and I don't have to fire up the ac unit at all.
- sokoloff 5y agoInherent in the cooling is (local) dehumidification.
- xupybd 5y ago"This approach can be deployed far faster than dam construction" Can we really manufacturer that many hot water tanks in less time than building a damn?
- kumarvvr 5y agoAbsolutely. DAM construction is essentially sequential. You can't build the top without completing the bottom. Manufacturing hot water tanks is trivial and highly parallelized. Thousands of manufacturers for parts, all of whom can contribute to the demand.
- nradov 5y agoIt looks trivial if you've never done it. If you actually try you'll see that manufacturing a safe, quality product at scale while turning a profit is extremely difficult.
- deleted 5y ago[deleted]
- splitstud 5y agoThankfully we have a large workforce with the experience to innovate in the manufacturing realm... oh wait.
- minikites 5y agoWe used to be world leaders and we collectively decided it was better for a handful of people to be wealthy instead. Excess wealth (>1 billion dollars is a nice start) should be used to improve society in ways like these and in many other ways. A society is great when it solves problems, not when people are wealthy.
- maxerickson 5y agoIt's explicitly addressed in the article. 10% of the water heaters purchased in a year would offset the dam. That 10% is 1 million out of 10 million. I guess the lead time on water heaters is short enough to hand wave a yes.
- s0rce 5y agoVirtual battery, there is an interesting project to do a similar thing with aluminum smelters where you heat them and operate at full capacity off-peak and then during peak electricity usage you run slower. Since a smelter consumes so much power this can significantly level the grid usage.
- Scoundreller 5y agoMy dream was that you would exchange a bin of bauxite for aluminum for your home smelter. All the "waste" heat goes into heating your home.
- perihelions 5y agoNot sure there's currently any sane way to put that into a house -- the industrial process involves a hydrogen fluoride loop. It's a interesting idea though. https://en.wikipedia.org/wiki/Hall%E2%80%93H%C3%A9roult_process https://en.wikipedia.org/wiki/Hall%E2%80%93H%C3%A9roult_proc...
- injidup 5y agoI have worked in an aluminium smelter, given the heart stopping magnetic fields, toxic fumes and potential for explosion when even a small amount of water gets in I can say I really don't want this under my house
- WhompingWindows 5y agoWould that be economical? Places with abundant geothermal power like Iceland are probably going to make much cheaper aluminum smelting than anywhere else.
- aaron695 5y agoIceland's power is hydro. (It's only ~26% geothermal) The Aluminum smelting is done on hydro not geothermal. Iceland is small compared to the USA or Indonesia for geothermal power. Large per capita, but Mexico has more geothermal power. https://www.thinkgeoenergy.com/the-top-10-geothermal-countries-2018-based-on-installed-generation-capacity-mwe/ https://www.thinkgeoenergy.com/the-top-10-geothermal-countri... (Iceland also has geothermal heating for housing which works well)
- temporallobe 5y agoI have a tankless hot water heater system in my new home that runs on a city natural gas line. It’s super efficient and thus my energy bills are very low compared to what I used to pay for the traditional electric hot water heater in my previous home, however it’s not a silver bullet. I find myself running the water for a ridiculously long time in order for the water to start getting hot, sometimes for more than a minute, depending on where I am in the house (obviously the farther you are from the heating unit, the more time it takes for the hot water to travel to its destination). Our water consumption is therefore quite a bit higher, thus I am not confident this is a good ecological or financial tradeoff. I have used similar systems in Europe and they seem to be a little quicker, but that could be from higher water pressure. They seem to suffer from the same problem though. Perhaps a good solution would be to have a small (4-5 gallon) booster tank that is periodically heated like a traditional tank-based system, so that when hot water is run, it can immediately be delivered while simultaneously engaging the on-demand system. Forgive my layman’s terminology, I’m not a plumber or HVAC engineer, but hopefully the idea is clear.
- vel0city 5y agoThere are electric instant hot water systems available. The sink at my office only has a cold water line plumbed to it and a small black box heats the water right there. I've seen some in kitchens for making things like soup or coffee real quick. Not sure why they're not more common, maybe reliability/flowrate/other cost issues?
- vorpalhex 5y agoThey need power and produce some noise. They take up space which may be at a premium. They require yearly-ish maintenance (running a cleaning solution through them with a small pump).
- maxerickson 5y agoThe problem is the cool water in the pipes. A typical solution is recirculating the water so that it stays hot. (I have a gas tank heater and the faucets far away take a bit to warm up, because of the water in the pipes)
- aaron695 5y agohttps://archive.is/NrQQC https://archive.is/NrQQC for those who don't want to support Salon with clicks. The article just wanders aimlessly between lies. Pumped Hydro dams are tiny compared to hydro-power or water dams and are beautiful, the same size as solar or wheat farms. A cool seawater based one in Japan - https://www.google.com/search?q=okinawa+pumped+storage+&tbm=isch&oq=okinawa+pumped+storage+&sclient=img https://www.google.com/search?q=okinawa+pumped+storage+&tbm=... A good example of a government doing something that worked is the Australian government which wanted to spend money fighting the global financial crisis so insulated homes. Unfortunately deaths from the scheme, which were at the same rate as normal but became larger in number stop people talking about it much. This tale of heat pump water heaters stopping a dam is rubbish. Where is the mathematics? Heat pumps are awesome however, go to Technology Connections, not this to learn about them - https://www.youtube.com/watch?v=7J52mDjZzto https://www.youtube.com/watch?v=7J52mDjZzto
- splitstud 5y agoIt's almost as if simple schemes can't solve systemic problems
- sidewndr46 5y agoThe one you reference is a very poor example of pumped hydro. It's nameplate capacity was only 30 MW, it was uneconomical to operate, and was dismantled in 2016.
- elil17 5y agoAnother type for thermal battery: ice thermal storage. Instead of running AC, it’s a freezer that makes ice during the night (using off-peak electricity and taking advantage of the cooler nighttime air) and then melts it during the day to cool large buildings. They’re a ridiculously good idea if you’re running a large enough HVAC system - they can even lower capital costs compared to traditional systems. Unfortunately, many building operators don’t use them because they’re unfamiliar with the technology or because they take up more building footprint. https://en.m.wikipedia.org/wiki/Ice_storage_air_conditioning https://en.m.wikipedia.org/wiki/Ice_storage_air_conditioning
- selectodude 5y agoThere is a large building in Chicago that basically contains a giant ice cube. https://www.enwave.com/locations/chicago.htm https://www.enwave.com/locations/chicago.htm
- nine_k 5y agoFrom their website I gleaned that they have 5 facilities, and several miles of piping that carries ice-cold water to their customers, large buildings around. It's the maximally outsourced air-conditioning solution I ever saw :)
- fy20 5y agoDistrict cooling (as opposed to district heating) is fairly common in Gulf countries.
- c_o_n_v_e_x 5y agoThey're around in the US as well. Worked on one in downtown Austin in a previous life.
- jfengel 5y agoI hadn't heard the term "district heating" before, but it makes sense. The name puts me in mind of a chain called District Taco, but unfortunately that doesn't mean a supply of tacos piped directly into your house. https://www.districttaco.com/ https://www.districttaco.com/ Not even slightly authentically Mexican, but nonetheless quite tasty.
- perihelions 5y agoCan you also store cold cheaply? For example, to run an A/C early in the morning, and put the cold in an insulated tank of a room-temperature phase change material [0]? [0] https://en.wikipedia.org/wiki/Phase-change_material#Common_PCMs https://en.wikipedia.org/wiki/Phase-change_material#Common_P...
- m463 5y agoA long time ago I read an article that made an impression on me. This guy had developed a house using logs that were basically phase change material. I think part of the design was to build almost a house within a house. An inside wall made of the logs containing pine sap that would change phase at a comfortable temperature. So with sun it would reach that temperature then start absorbing it and becoming more liquid, then later slowly solidify giving off heat. EDIT: it was the enertia house
- perihelions 5y agoOh thanks for that. Indeed it seems to be a phase change of resin in pine logs. https://enertia.com/about.html https://enertia.com/about.html
- nine_k 5y agoIndeed! The most abundant phase-change material with enormous specific heat of both the liquid phase and the transition to solid is water. Refrigerate water at night, use it during day heat. I see that many groceries use this technique; homes could, too.
- perihelions 5y agoTrue, but the much larger temperature difference makes the efficiency of the heat pump lower, which negates the advantage.
- fy20 5y agoThis is why old buildings in the Middle East and North Africa have thick stone walls. In these arid regions there is a large temperature difference between day and night, so the thermal inertia of the building can be used to store the 'cold'. Structures such as windcatchers help to naturally ventilate the building at night. https://en.m.wikipedia.org/wiki/Windcatcher https://en.m.wikipedia.org/wiki/Windcatcher
- phire 5y agoThis is old technology, I'm surprised the US hasn't already implemented it. They have been remote-controlling water heaters in New Zealand and Australia since the 50s. Just a simple relay installed in each house that responses to extra frequencies on the power lines in the 160-1600hz range. It's called ripple control, for obvious reasons. Each home gets assigned to one of several channels in each area so they can have more fine grained control of the load.
- ac29 5y agoAbout half of the US uses natural gas for water heating - its substantially more efficient than burning said gas (or coal) to generate electricity, then using the electricity to heat water.
- tacLog 5y agoIs it though? It might be cheaper in many area's but this source [1] says that the grid transmission loss is only 5%. Am I missing something that makes it a more substantial difference? Not to mention that piping all that natural gas out to each home has to result in a certain amount of leakage and energy cost in just the pumping itself. [1] https://www.eia.gov/tools/faqs/faq.php?id=105&t=3#:~:text=The%20U.S.%20Energy%20Information%20Administration,in%20the%20State%20Electricity%20Profiles https://www.eia.gov/tools/faqs/faq.php?id=105&t=3#:~:text=Th....
- simlan 5y agoGas to electricity efficiency is low so you loose more then half the energy when producing electricity from gas. Using a 90 percent efficiency furnace to heat water directly with gas is the better solution. Assuming your electricity comes from gas plants.
- ZeroGravitas 5y agoHeat pumps can have COPs above one so if your entire electrical grid was gas fired then youd need a COP of around 3 to break even which is doable. The grid is getting greener which means you win by even more if you electrify everything.
- DubiousPusher 5y ago> One flashy idea for storing energy goes something like this: dam a river, Incorrect. Or rather not necessarily correct. Pumped hydro does not necessarily require damning a river. > Making matters worse, about a quarter of the energy is cannibalized to do all that pumping. Pumped hydro is largely considered one of the most efficient forms of energy storage, beating most other methods by a fair amount. > This approach can be deployed far faster than dam construction, and free of protest (except perhaps from dam builders). We can't do both?
- manmal 5y agoMost newly built electric cars have a 50+ kWh battery. Imagine if smart meters could use _that_, regardless of where the car is currently parked and plugged in. 50kWh is in excess of what most households use in electricity on most days.
- adrianN 5y ago50kWh can cover about two to three weeks for me. Unless you use electricity for heating, you don't really need all that much.
- manmal 5y agoThat’s impressive. We don’t use electricity for heating (heating and warm water are powered by community heat), and need 11kWh per day on average, excluding the EV. The EV adds another 5.5kWh per day.
- adrianN 5y agoMy main consumers are probably the fridge and the oven. I made sure to buy an efficient fridge. Other than those I usually only have a laptop or two running. The washing machine only runs once or twice a week, most of the time only at 30°C.
- manmal 5y agoWell we are four people in the household. I guess that does increase consumption.
- choeger 5y agoThis will be the case in the next couple of years. Wall boxes are inherently smart (that is, controllable). So as a sink, the concept works somewhat already. But most cars won't be empty all the time. Also as source the 50kWh will only be usable as an emergency backup for the owner of the vehicle and only if they have the infrastructure to consume directed current. No one will let their own battery drain for the greater good. For public use cases people won't offer to unload more than maybe half of the capacity, realistically maybe 25% on average.
- cycomanic 5y agoIn Northern Europe heat pumps are now pretty much standard for new homes. They reduce heating bills quite dramatically compared to other technology. In particular if combined with solar power. One big advantage is that they can also be run in reverse so you could cool the house in summer (although you might need a special heat pump to do this, especially to separate from the hot water). In areas where it gets very cool, one can also use connect the heat pump to the ground as heat sink which improves efficiency even more.
- elric 5y ago> One big advantage is that they can also be run in reverse I don't get why this is an advantage. That's just plain old air conditioning, which is genreally considered to be a wasteful, energy guzzling luxury in colder climates. The heat pump hype is a bit puzzling to me. Here's a TreeHugger article which puts it better than I can: https://www.treehugger.com/why-are-there-so-many-fist-pumps-for-heat-pumps-these-days-5191393 https://www.treehugger.com/why-are-there-so-many-fist-pumps-...
- jcynix 5y agoGood heat pumps aren't of the air conditioner type. Our heat pump uses two 60m deep drilled holes. Thus heat exchange happens in the ground, which is always more or less 10 degrees Celsuis. Heat exchange in the house happens through floor heating. So during a hit summer, the reverse capability just pumps the cold water through our floors (controlled for the dew point) and the warm floor water into the ground. That, combined with controlled ventilation over a physical heat exchanger, keeps the warmth out. Or, during cool seasons, the warmth in. Our heat pump uses about 1 Kwh electricity (from ecological resources like water or wind only) to generatev3 to 4 Kwh of heating. Without producing carbon dioxide. Airflow based heat pumps are less efficient, and more noisy outside, of course.
- mprev 5y agoWhat sort of problems did you encounter drilling two 60m deep holes? How wide are they?
- nose 5y agoI'm able to turn my water heater off twice a week without a noticable difference in the water temperature. I wish there was an easier way other than flipping the circuit breaker.
- sbierwagen 5y agohttps://www.amazon.com/INTERMATIC-Electronic-Heater-Voltage-Channels/dp/B07J6RQRT1/ https://www.amazon.com/INTERMATIC-Electronic-Heater-Voltage-...
- elric 5y agoLots of good discussions about water heating in this thread. But it's such a tricky topic. Tankless water heaters are pretty efficient, but when you need hot water, you briefly use huge amounts of energy. It's for this reason that they almost always use natural gas. Electric tankless heaters are a great way to cause brownouts. They're roughly the size of a microwave oven, so they can fit in pretty much any kind of dwelling. Water heaters with tanks, on the other hand, take up huge amounts of space and require frequent (but lower) energy input. This can use heat from a variety of sources, including low quality/unrealiable heat sources like solar heat pipes. Then there's space heating. Unless you live in a Passivhaus, keeping a comfortable indoor temperature is challenging. Central heating using hot water and radiators is the most common approach where I live. But this again relies on burning hydrocarbons. Or, increasingly, on heat pumps, which require a lot of space, are noisy, and drop in efficiency as the temperature drops. As far as I can tell, there are no silver bullets in either space heating or water heating. If you have a really big house, a big tank is probably a good solution for hot water. But living in a really big house is horribly inefficient in its own way. So I'm guessing that's not the greener approach. Living in a smaller dwelling is more efficient. But it seems there are basically zero good ways to heat small living spaces and hot water for a family of 1-2 living in small houses.
- devwastaken 5y agoTankless are also useless if you don't have perfect water, and even if you do you have to descale them every year. The calcium, iron, and others in your water builds up in the small copper pipes, and an acidic cleaner is required to remove it. If youve ever used a Keurig it's similar. Propane water tanks are pretty bulletproof. Even with bad water they just truck, and require no electricity to operate, unlike some other gas appliances.
- dvdkhlng 5y agoWhere I live, tankless heaters are pretty wide-spread. They connect to 3-phase power supply, heating at a variable power level up to 24 kW [1]. They need almost no maintenance, nobody I know has ever descaled one. I think the better units directly run the heating wires through the water, so they do not calcify due to small surface area (or maybe the huge temperature gradient when operated breaks the calcification layer). Usually you operate them until they break (maybe around 10 years), then get a replacement heater for like 400 €. [1] https://www.stiebel-eltron.co.uk/en/products-solutions/dhw/instantaneous_waterheater/convenience_instantaneouswaterheater/dhb-e_lcd/dhb-e_18_21_24_lcdset.html https://www.stiebel-eltron.co.uk/en/products-solutions/dhw/i...
- stdgy 5y agoAm I the only one that find this article incredibly confusing? It starts off talking about wanting to move energy production to renewable sources. Great, I'm with you so far. A major issue with renewable energy (solar and wind) is that they're variable, not constant. This results in uneven power. The wind doesn't blow, it's cloudy or it's night time. So we need a way to convert this variable renewable energy into constant energy that's accessible around the clock. An obvious solution to the problem is to convert the renewable energy into stored potential energy. This is what pumped hydroelectric dams are all about. Use the variable energy to pump a bunch of water up behind a dam, then release it when you need a more constant supply of energy. Great, so we've got that much figured out. The world needs a way to convert renewable energy into constant energy. And the solution to this problem is... the distribution of more efficient water heaters. Wat How do more efficient water heaters in any way, shape or form help solve the renewable variable rate energy to constant energy problem? I feel like I must be missing something obvious. Are we able to somehow store energy in heat-pump based water heaters and then extract that energy to run other items in our homes? When you store energy in a heat-pump based water heater does it not need to run at night when renewable energy sources are lowest? Can anyone explain to me what the heck this article is talking about? I feel like I'm missing the larger picture, but I don't see how these two concepts (energy storage and appliance efficiency) are related.
- judge2020 5y agoMaybe this author has a stake in some up-and-coming smart water heater company whose sales pitch is that they only heat up the tanks when it would use only renewable energy?
- _ph_ 5y agoThe point is, that we can move demand around. The smart water-heaters with the ability to store heat are not only more efficient, they can be run when a lot of electricity is available and can be shut off, when there isn't. Yes, we also will need some amount of storage to produce electricity when demand exceeds production, moving the time of demand goes a long way on managing renewables.
- evandijk70 5y ago
- kwhitefoot 5y agoMeanwhile the EU is intending to ban hot water tanks in favour of instantaneous heaters.
- _ph_ 5y agoDo you have any source for that? Sounds difficult to believe for me as instantaneous heaters are known to be inefficient.
- kwhitefoot 5y agoI just vaguely remember reading it somewhere. Looking for it now it looks like either I misread something or the something I read was mistaken. Sorry.
- archi42 5y agoSource? For solar heating you'll want one to store excess heat collected during the day. With (grid sourced) electricity as the only energy source for the heat - and in absence of a "smart grid" - storing hot water adds losses, compared to heating the water just in time. So I can understand why they might think about some sort of ban. If they go for a ban, I'd expect them to add some conditions.
- WalterBright 5y agoI've proposed this (water heater as battery) innumerable times here on HN. Glad to see it finally catching on! You can do the same thing with the HVAC system. For example, when the sun is high and electricity is cheap, have the A/C cooling a large mass of stone or concrete. Then, blow air over it at night to keep the house cool.
- bluGill 5y agoYou are not the first to propose it, and won't be the last. It is obvious to any engineer who spends more than a few minutes thinking about the problem. It works in practice too, but the space needed means most people don't bother.
- WalterBright 5y ago> obvious You'd be surprised at the resistance to the idea it always engendered.
- dredmorbius 5y agoThe PassivHaus concept utilises a massive (5,000 gallon / 20k litre) insulated thermally stratified water tank as thermal storage mass, among other elements. It's used to create zero-net-energy homes in Fairbanks, Alaska. https://www.greenbuildingadvisor.com/article/a-passivhaus-design-for-alaskas-frigid-climate https://www.greenbuildingadvisor.com/article/a-passivhaus-de... http://www.esterlibrary.org/programs/lectures/chluppp4-20-2011.html http://www.esterlibrary.org/programs/lectures/chluppp4-20-20... (The videos are the best resource. They're very long, up to 2+ hours, but also incredibly detailed.)
- KaiserPro 5y agobangs head on table Energy efficiency/load redirection is not the same as energy storage. Heat pumps water heaters, with good insulation is about 3-3.8 times more efficient than straight electric heating. However keeping hot water hanging around isn't all that efficient.
- OliverJones 5y agoThis article contains two suggestions: 1. heat pumps rather than resistance heating: move the heat where you want it instead of creating it from scratch. 2. timeshifting electrical load. Figure out how to add and shed it on demand. The second one has a remarkable property. Load can be shed much more quickly than spinning up peak-load generators. That means grid operators can, in periods of overload, keep the grid's AC frequency (50 or 60Hz) from dropping. Without load shedding it's done with expensive and dirty peak-load generators. That's called "frequency control ancillary services" (FC/AS) in the grid biz, and it's economically important: regional grids don't work properly unless their local grids all run at the same frequency. Local grids don't want to be disconnected from regional grids in peak-load times because their generators slowed from 60Hz to 59.8Hz. Remotely switching off a mess of hot water heaters is a GREAT way to change the grid load quickly if that starts to happen. FC/AS is a major driver of the big Australian battery projects (built with parts from Tesla). https://www.greentechmedia.com/articles/read/australia-picks-massive-tesla-battery-to-ease-transmission-constraint https://www.greentechmedia.com/articles/read/australia-picks... Who is the Van Jacobson (TCP designer who dreamed up slow-start / exponential backoff) of smart grids? Is it somebody reading HN?
- pw262 5y agoWhat the enthusiasts for heap pump water heaters miss is the source of the heat they are pumping. In the summer they are removing heat from a hot house, great - free air conditioning. In the winter they are removing heat from a warm house, which then needs to be replaced by some other heating source to keep the house warm, great - you get to pay twice. I tried turning the heat pump element on my heater off during the winter. However, it is programmed to automatically turn on again after 5 days.
- jffry 5y ago> In the winter [...] you get to pay twice. That heat in the hot water is coming from somewhere, and you're paying for it regardless of where it came from. The question is _how much_ you're paying. The magic of heat pumps is that in many cases, they can move X joules of heat by expending less than X joules of electricity. As an extra bonus, in the winter, any "waste heat" from the heat pump doing its work is still inside your home and not wasted at all. So you could view a heat pump water heater as a way of converting one type of heating cost (the fuel/electricity used in a conventional tanked hot water heater) into another type of heating cost (the fuel/electricity used to heat your home). As long as the cost of the electricity used by the heat pump is not astronomically higher than the cost of whatever is heating your home, it should definitely be in the green. edit to add: Many state and local governments along with utilities are offering incentives/rebates/discounts to install heat-pump hot water heaters.
- giantg2 5y agoI looked at heat pump water heaters several years ago. They are massively expensive, have a little more risk of failure (potential for expensive repairs), and in many cases would only work for half of the year (basements are a common location and get relatively cold in the winter). I like the idea, the the ROI just wasn't there given the low cost of electricity, which green energy will continue to drive down. I don't like the idea of the grid or cloud controlling appliances in my home. If I could program the run options myself based on the power company's recommendation (like a programmable therostat), that would be better in my opinion.
- plater 5y agoNot sure what a cold basement has to do with it? You suck in air from outside, extract the energy, and blow out colder air. The warm water is stored in an isolated tank (sure if the basement is cold it might cool off slightly quicker, but you warm up the cold basement which is a good thing). It is then used for heating the house via radiators as well as for warm tap/shower water. We use it to warm a 240m2 house with four inhabitants. It works well down to -10 to -15C. During the night we pay only have the price per kWh to the utility company (as they have excess capacity during that period). It works great and it pays itself back quite fast. It's not controlled by any cloud. You can regulate on the control panel how and when you want it to run and it adapts with the weather too if you want.
- giantg2 5y ago"Not sure what a cold basement has to do with it? You suck in air from outside, extract the energy, and blow out colder air." The water heaters I saw were not running ducts to the outside, they use the room air. The point is that heat pump efficiency is tied to the ambient temperature. The hotter the air, the easier it is to collect the heat from it. So when it gets cold enough the "emergency" or "auxiliary" heating coil starts to be used (resistance based). This is very common in cold climates. My house heat pump auxiliary tends to kick in when the tempature gets below 40. This would also apply to water heaters if using outside air than the warmer basement air. Of course you are heating that basement air with another source, so that efficiency should be evaluated too (likely a heat pump because if you have a gas furnace, one would be likely to have a gas water heater too). "It's not controlled by any cloud. You can regulate on the control panel how and when you want it to run and it adapts with the weather too if you want." The proposal in the article is that smart water heaters could be controlled by the utility companies. "It is then used for heating the house via radiators as well as for warm tap/shower water." That is one type of system. The article is talking the US, in which the type of system you describe is relatively rare. The 10 million annual water heaters they reference are overwhelmingly used just for tap/shower water.
- PaulHoule 5y agoThat kind of thing is chronically overestimated. Amory Lovins does for that what the 1960s boosters of nuclear power did for the LWR. So much in the energy field is like a stopped clock.
- gdubs 5y agoI’m not sure if this is a stupid idea, but I think of all the energy people spend in places like LA to heat their pools even in the very warm months, while blasting AC inside. This seems like a pretty good opportunity for using a heat pump to take the cold pool water and use that as a heat sink for the hot indoor air. Or is there something about this setup I’m missing?
- opwieurposiu 5y agoI used to work at place that installed this exact system. You can get an extra 2-3 months a year use of your pool in warm climates. It does work but we sold way more geothermal systems then these pool based systems. Issues: Building inspectors do not like it because it is non-standard. Copper is attacked by wet chlorine so you have to use stainless heat exchangers and plastic pipe. Pool filter must be constantly maintained to ensure the AC does not get clogged. If the pool is small, it can become very warm in august, almost like a hot tub.
- gdubs 5y agoThis is great info, thanks!
- opwieurposiu 5y agoI have 1200w of solar panels hooked directly to the lower element of my hot water heater. I sized the element to match the source impedance of the panels in full sun. If you use a MPPT system you could get 50% more power in partial shade but panels were so cheap it was not worth the complexity. The top heating element is still on city power as backup but I rarely use it. The water will get up to 80c on a sunny day, so it can store enough heat to last a couple days without sun. There is a mixing valve so the water coming out of the tank is mixed with cold to stay below 50C for safety.
- jojohohanon 5y agoWhen hooked up to the grid, converting from electricity to heat for storage makes alot of sense (to me). But I'm curious about your case: why not use the old-fashioned solar water panels to create hot water directly?
- opwieurposiu 5y agoSolar hot water panels would make 4x the heat for the same area, but are too complex and expensive to install. They need pumps, expansion chamber, control system, antifreeze, new larger hot water tank. They are too heavy to get on the roof by yourself. My non-grid connected solar cost about $1200, and was easy to DIY. No $1000 permit needed since it is not connected to the grid. No moving parts and almost no electronics. House now uses only 8-12 kWh a day.
- kragen 5y agoSolar hot water heaters are cheap and can easily be 50% efficient, beating the heck out of 21%-efficient mass-market PV cells, often even if the PV cells are driving a heat pump. Thermosiphon-type solar hot-water heaters don't even need a pump, just a super-low-pressure check valve. Less efficient, but maybe even better, are safer passively-cooled solar hot water heaters, which can be made out of cheap materials like plastics and cement instead of stainless steel, and don't require a temperature-limiting valve to keep you from scalding yourself. However, even if hot-water heaters aren't where it's at, I think circadian thermal energy storage is a pretty big deal for demand response, and demand response is pretty important for the renewables transition—though not as essential as many claim. There's thermal-mass energy storage like the hot-water heater approach (and Trombe walls, and earth-berm walls, and several other possibilities), but phase-change storage like the ice-battery approach mentioned in https://news.ycombinator.com/item?id=27757018 https://news.ycombinator.com/item?id=27757018 allow an order of magnitude higher energy storage density and easier temperature control, and "thermochemical energy storage" (generally through reversible hydration of desiccants such as CaCl₂) potentially allows another order of magnitude density improvement over phase-change materials, as well as offering the possibility of thermally-driven air conditioning, humidification, and dehumidification, as well as greater controllability. I wrote extensive notes on this in https://dercuano.github.io/topics/thermodynamics.html https://dercuano.github.io/topics/thermodynamics.html (especially https://dercuano.github.io/notes/big-if-true.html#addtoc_8 https://dercuano.github.io/notes/big-if-true.html#addtoc_8 and https://dercuano.github.io/notes/household-thermal-stores.html https://dercuano.github.io/notes/household-thermal-stores.ht...) and also Derctuo and Dernocua.