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Hmm. One advantage of being able to connect homes without forcing them to disconnect from gas is that they can save the expense of a heat pump (for now) and can still gain benefits from preheating water. Could also incentivise lower temparature heating systems -- ceiling radiators could use 40c water directly, especially if the home is insulated. I think the system needs to be able to accept gradual improvements both on the user end and on the production end That would also allow it to perhaps be built for what homes with reasonable insulation would require, rather than current demand -- people who don't insulate will just have to make up the loss with their gas boilers I guess.
What sort of heat transfer rate are we looking at, for a given temperature difference? Obviously its going to take time for 30c water to heat a 25c borehole...
One thing we could do with geothermal heat is to circulate it during the summer to heat the entire borehole rather than just the bottom. Then draw the heat out during the winter. Improved capacity factor.
As for car park heat collection, there are four sizeable car parks in central Carnforth, the three supermarkets and the railway station. Looks like they could be enough for the centre?
Hmm at some point it might end up being cheaper and easier to just keep drilling. Go a couple of kilometres down and tap 30-40c temperatures. But if solar thermal is used, I don't think 100m is necessary as an insulation layer. IIRC when I looked at this last 10m would suffice to achieve quite small heat losses.
For a network serving the central part of the town where almost all the terraced housing it, it could wrap around running along Grosvenor then down Haws Hill, back up Hawk Street, down to the canal and returning via the marina. Then presumable supply pipes would run across town between these, probably through the back alleys. Another advantage of the alleys being that the switchover can be more gradual -- if people want to keep their ridiculous gas line they can, no need to switch everyone over at once to minimise disruption. Political palatability is quite important as well. Though I'm not averse to compulsory purchasing easements through people's back gardens to run the service lines...
There are maybe 600 to 800 homes in that central area (I think closer to 600). Almost all terraced, so heat demand should be on the low end for houses. Unfortunately subject to some historic conservation order. Which may actually make a heat network one of the few acceptable ways to decarbonise heating...
Well, we're not allowed to have houses there in case they want to mine gravel for 22nd century motorway construction, might as well make use of it for something that benefits the town...
What I have in mind though are smaller such schemes. Admittedly greenfield solar collectors will probably be cheaper than over car parks and roofs, even flat ones. But the space for boreholes is certainly not hard to find. I suppose the solar thermal collectors would be angled for summer?
The other issue is that running the mains along the road means digging up the roaad. Unfortunately there's a gas main under the townpath until I think the canal turn, but if there's room it would be far less disruptive. But past the canal turn (next to where the town gas was made, hence the gas lines) I think it is clear and would not be a bad place to run a hot water mains if so. Certainly they dont trim the trees the way they're supposed to near gas lines in that section.
Hmm I could do this in QGIS... going to be getting a lot of experience with that over the next few months of my dissertation...
Back alleys form an almost complete loop around the central triangle of A6-Haws Hill-Market Street. I expect it would be the second easiest location to build a heat network in, after the A6-North Road-Kellet Road one I've mentioned before.
There should be maps of the gas network available; you have to sign up, but the maps are free because they don't want people rupturing gas lines whilst repaving driveways (gas is probably the craziest infrastructure ever built -- at least high voltage power lines carry versatile electricity and are unlikely to cause explosions if damaged...).
As an alternative to district heating for houses with front gardens, perhaps the costs of an individual borehole could be brought down significantly by doing the entire street in one go?
EDIT: the street map is already available online? https://explore.osmaps.com/?lat=54.1272 … rd&type=2d Scanning and printing seems a little overcomplicated.
Taking the UK as a case study, most UK towns are densely populated. The majority of houses are either terraced or semi-detached. Gardens are typically small. If district heating can work anywhere it will work here. I suggest we resurect our previous case study (Carnforth) and produce a concept design that accounts for local resource and limitations.
I'd suggest the locations to look for are (1) large heat users that are (2) located next to open spaces for ease of borehole drilling and which (3) can be connected to domestic customers relatively easily (no long stretches that involve shutting down roads to install pipes).
In the case of Carnforth, I can see 2/3 -- the triangle I've mentioned before (primary school field, hotel and civic hall and school and church located around the edge, terraced houses also along it); the high school (large playing field, school and swimming pool adjacent); and possibly the area next to the train station (car park for boreholes, station hotel as anchor customer, terraced homes with alleys for running piping). Aside from that, there are various school fields and parks and car parks throughout the Victorian centre of town, an area that benefits from alley access (the cold water supply presently runs under these also).
If there's a mass buildout, we could manufacture pre insulated pipes? I know a cold system doesn't necessarily require much, but I'd like to futureproof it so we can do things like seasonal heat storage and supply heat at 25c instead of 10c...
EDIT: One problem that occured to me in cases where there are no convenient alleys -- gas pipes are routed under streets. Any attempt to run pipes under the pavements would have to deal with the connections to the houses every 5-10m. Obviously not a problem if the entire street switches over at once, but that is likely to take a level of coercion that will be difficult to achieve. Perhaps we could compulsory purchase easements right down the middle of the block and make an alley...
Re. boreholes, the cost per borehole goes down the more you drill, but the figures I've seen are for systems with only three to five. I can't find anything solid for how much it would cost to drill one hundred in under say a school playing field, as would be used in a district heating system.
One advantage of having a centralised heatpump I suppose is that upgrading the electricity supply to it to benefit from strong wind generation might be easier than upgrading it for multiple neighbourhoods and homes.
From 2013 -- Cost analysis of district heating
Their estimated costs for installation were around €2000 per house in prebuilt areas. It shouldn't be an especially expensive infrastructure to construct -- £2-400/m? -- because it's "just" trenching and piping, no messing around with high pressure gas. If it cost £2500 per house to put the pipes in, about £75 billion for all the homes in the country. Several years of gas bills, not a particularly large amount relative to other plans for a clean energy transition, and would be largely privately funded. And of course, costs will depend on the type of housing -- terraced houses with alleyways to run the pipes without disruption could be a lot cheaper to supply, whilst being the biggest beneficiaries due to limited space for more individual systems.
EDIT: I didn't realise how small the domestic distribution system would need to be. A litre of water cooled through 10c (say, 35 to 25 Celsius) would give up 40kJ of heat. A house might only need to tap 0.1L/s then, so a street of forty houses needs to provide 4L/s at peak. At 0.1m/s flow, that's a pipe ~25cm wide. We can easily fit that in alleys or under pavements.
Should also be noted that it's fairly straightforward to use shower drain heat to preheat cold water, reducing the quantity needed from the tank. I think off the shelf heat exchangers can recover about 2/3? With showers being the primary hot water use, this shrinks both storage needs and energy consumption.
And, of courses, one major benefit of external insulation is that the heavy thermal massing is within it. The house itself can store a large amount of heat, once it has warmed up. Perhaps there is a way we can speed the heat transfer along, helping to cool in summer and store heat in winter? A mid terrace might have 25cm of stone/brich on either party walls (the one I grew up in is 50cm narrower on the inside -- those walls are thick, whatever Max Brooks thinks in his zombie stories). At about 7m long by 6m tall, that's ~20 cubic metres. At 1.6MJ (~0.5kWh) per cubic metre, cooling down by 2 degrees would put 20kWh of heat into the house from just the party walls. It will take time for the house to cool. Which means also that once the walls are warm, heating energy will not be taken by them, only by the air and furniture.
Ventilation is important, and at 100L/s air exchange (good ventilation, rarely achieved) and freezing temperatures outside we're talking ~2kW of heating needed. I'd suggest shrinking our windows slightly to make it easy to put in vents... raising the ground floor window of a terrace by 20cm isn't going to screw it up super badly from an aesthetic standpoint, and means we can run pipes and cables into the house without needing any hatchet jobs. Recovering 75% of the heat would make it a far more manageable 500W heating. Or none, if there are 4 or 5 people in the house.
Huh. Three of the most power hungry devices on that list are literally heating hot water. Then there's the hob, which for the most part is used to heat hot water. And the dryer, which heat hot air...
Three hours of TV a day is quite a lot though. A lot of people watch stuff on their tablets and laptops now.
I don't think the heating demand in even a somewhat more insulated house would be anywhere near that amount. British houses are really poorly insulated; even a few centimetres of cork board on the inside would improve things a lot. We let the perfect be the enemy of the good and then don't insulate. A lot of (most) houses here can't be brought up the passivhaus standards, so we just don't do anything, and older ones need breathable insulation to avoid damage instead of a lot of modern synthetic options. But there's still a lot that can be done.
Still find it crazy how much electricity we use...
I have made a new topic in home improvements to talk about home thermal storage -- https://newmars.com/forums/viewtopic.ph … 38#p225338
I feel this needs its own topic
A typical washer uses 0.79kWh per cycle and is used 200x per year.
https://checkappliance.co.uk/how-much-e … chine-use/This UK company manufactures a hot fill washing machine that they claim reduces electric energy consumption by 64%. This reduces the electrical energy consumption to 288Wh per cycle or 158Wh per day (average).
https://ebac.com/washing-machines/e-care-8kg-hot-fillA dryer uses somewhat more power. But it isn't difficult to dry clothes on a line. My wife and I use a combination of outside drying on a line and an indoor airer.
A typical fridge uses 166kWh/year in the UK. That is 454Wh/day.
https://www.homebuilding.co.uk/advice/h … fridge-useA 40W-equivalent LED bulb uses about 5W of power. Some 5 of these bulbs, running 8h aday, will use 200Wh of energy per day.
Total = 812Wh. If we can take the fridge off of baseload by including thermal storage, the total is reduced to 358Wh.
It definitely seems to be feasible without needing much modification of off the shelf products. I'd suggest a chest freezer be considered also, due to its advantages in retaining cold air when opened and the space to produce ice. Also a spin dryer would add very little to the demand whilst removing quite a bit of the water.
Extractor fans should be considered, especially if drying on an indoor rack.
We should build up a list of COTS products that would be useful in achieving this.
Hot water tanks are standard in a lot of houses. It's an oversized one that's the non standard part here. Phase change thermal storage is available for use with heat pumps.
For fridges and freezers, adding in water should not be a particularly difficult thing to do. And hot water dispensors are off the shelf too, though probably need some better insulation.
More excited about this kind of energy storage than others because of this. It's not a massive leap from what is already there, and multi-tariff deals from energy suppliers that provide cheap off peak energy, especially if flexible (so you can buy wind energy when it's basically being dumped onto the grid) should provide a strong incentive to install it.
Are you sure it's 2kW, or 2kWh? 2kW is a ridiculous amount of power consumpton for a fridge. Literally would put the national grid at capacity if that's how much power it required. 2kWh *per day* is pretty typical on the lower end.
But in the case of refridgeration, you could just use ice instead to store cold. Far cheaper than any kind of power storage, be it compressed air, batteries, or pumped hydro.
Calliban,
Washers and (tumble) dryers primarily use heat also. There's no good reason to use electricity to heat the water over simply plumbing it in to the hot water tank. I think its 400W for just the spinning? So a load might take 200Whr. Likewise, kitchens should not require much storage microwave and oven aside, since near boiling water can be stored and only requires a small amount of power to keep it hot (or phase change materials?). The baseload electricity demand for a house that's optimised heat storage would be significantly lower than it is now. Maybe we could get away with about a kWh a day...
Compressed air takes time to cool. How does this affect its use for transmission? Could a series of windmills directly pump air into a chamber that is then tapped for steady power? Thinking about underwater air pipelines here.
Kind of hard to attend when you start the meeting at 1AM.
In another thread, Calliban mentioned hydraulic accumulators:
Interesting DOE project for small scale (building scale) pumped storage.
https://www.osti.gov/biblio/1817438The device that they are describing is a hydraulic accumulator. Energy is stored by compressing a fixed mass of gas within a steel bottle, by pumping a liquid into the bottle under pressure. The hydraulic fluid compresses the gas as its level rises within the bottle. It works as a liquid piston. Energy is stored in the enthalpy change of the gas. Its pressure rises and its temperature increases. Ordinary low alloy steels lose negligible strength up to 400°C, but strength declines rapidly with increasing temperature thereafter. At 550°C, tensile strength is down by 50%.
https://www.engineeringtoolbox.com/meta … _1353.htmlInterestingly, we have mineral oils that are used as lube oils and heat transfer fluids that remain stable at temperatures up to 400°C. A hydraulic accumulator can retain most of the compression heat that results when its internal gas reservoir heats up. When it expands, the thermal energy of the gas is converted back into work. This makes hydraulic accumulators a very efficient way of storing mechanical energy. How much energy can be stored? Let us assume a vessel 1m3 in volume, filled with nitrogen at 283K and compressed from 1 bar(a) to 30 bar (a). I am going to use an online calculator because I am lazy. But energy stored is given by the formula: E = P1V1 x ln(P2/P1). This assumes isothermal compression and expansion.
https://www.omnicalculator.com/physics/ … -processesEnergy stored is 411.2KJ/m3. Final volume is 0.088m3 and temperature is 748K. We would want to store some of the heat in the oil I think, so our pressure vessel temperature doesn't exceed 673K. A steel vessel with volume 4m2 could store 0.5kWh of mechanical energy.
I am a little confused by the temperature rise here. If water were used, then a 1 deg. change in temperature would store 4kWh of sensible heat. Surely the heat of compression would end up being lost to the hydraulic fluid, if there is no insulation between them?
But also, the compression is taking place within the tank. Does this offer opportunities to better capture the heat of compression, given the greater surface area available vs. a compressor?
Think of how efficient the grid could be if we did that with home appliances too.
I now have a goal of converting a camper van once I have a drivers license and some money lol Seems to be the best way to go about a testbed for the Neo-dymaxion house. At least, one that could be affordable to me within a couple of years...
Kitchens are the biggest use of domestic electricity, especially if the washing machine is located in it. Almost all of this electricity, bar the motor in a washing machine or dryer or pump in a dishwasher, is used to produce heat for boiling water or cooking food, and as we have discussed many times, storing heat is far simpler and cheaper than storing energy in a form easily converted back to electrity. So if we are to run a kitchen on intermittent electricity it is worth seeing what can make use of stored heat instead of batteries.
It can be taken as a given that hot water for washing will be from the homes hot water tank, and that refridgeration uses insulation and ice for buffering. What about near boiling water? There are countertop insulate water boilers available that could be heated during times of high electricity production. The one in the link uses 2W to maintain the temperature; a larger boiler will use more, but less per litre, and perhaps we can improve the insulation to reduce these losses further. Between cups of tea, coffee, and cooking, a household might use perhaps 4-5L of boiling water day per person, requiring ~500Wh to boil. Storing enough for a couple of days should be doable.
For cooking, obligatory Low Tech Magazine article on insulated cookpots. Most of the heat used in cooking is wasted rather than going into the food. For convenience items such as air fryers and microwaves, I think this is an acceptable cost, and would simply install storage to run them. But for stovetops, perhaps we can achieve sufficient heat from hot water stores and insulate the pots. It would also be an option to look at phase change materials to achieve consistent high temperatures. A slow cooker with an inbuilt paraffin wax heat store?
But the single biggest win, as always, is probably in hot water. Especially if the grid is unreliable. Having a big tank of near boiling water and a supply of tea, instant hot chocolate, and meals that can be made with it would make blackouts less miserable.
IDK how much research has already been done on this, but a small tank could be jacketed with paraffin or some other phase change material? It may require fins to be installed in the tank itself to provide fast enough heat transfer. If we can get away without having to add intercoolers and a separate heat store, the system will be considerably simpler and should be cheaper. The ohase change material may have to be installed within the tank itself to achieve this. Or for that matter at the opening... hmm.
IIRC Calliban proposed somewhere to combine windmills with pumped energy storage, where the windmills would be used directly to raise water to the upper pond and the generator set up would be hydroelectrical? Now that we're allowed onshore wind again, this is worth considering.
1000m^3 -- a 10x10x10 cube -- of water can store 250kWh of energy if raised to a height of 100m. Britain has an abundance of hills, such heights are plentiful, and its on these hills that onshore wind turbines are built. If one hectare ponds 5m deep were built at the top and bottom of a 100m difference, they could store 12.5MWhr of energy. Enough to even out the flow of a small wind farm. This would be able to power my hometown for 4-5hrs. The lower "pond" could even be the sea.
The ponds would not have to be open. We may prefer to use buried concrete tanks and restore the farmland on top of them. I do not know what the ecological impacts of doing this in peatland will be; whilst we would replace the peat on top, I do not know what the disturbance would do to it.
How much weight can concrete withstand?
Wondering if old quarries could be a good place for this. Quite a few holes in the ground that need filling in. Though I suppose in that case they normally get fillled in by water. Build an artificial lake bed to store air before that happens?
Basically a manmade version of the caverns that are used by a lot of systems today.
Finding large numbers of planets with life would not be reassuring if you're worried about the "Great Filter". If Earth turns out to be an incredibly rare type of world, that's good news from a Fermi "Paradox" perspective.
Metaphysically I believe us to be alone. Our job is to no longer be alone. "Now no shrub of the field was yet on the earth, and no plant of the field had yet sprouted, for the LORD God had not sent rain upon the earth, and there was no man to cultivate the ground."