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Large-scale ‘sand battery’ goes online in Finland

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Re: Large-scale ‘sand battery’ goes online in Finland

#221

Post by pretdl »

vkou wrote: post #16
pavon wrote: post #8

As an American it completely breaks my expectations that district heating not only works can be more efficient that decentralized heating. The amount of heat lost just moving water from the water heater on one side of the house to the shower on the other is ridiculously high in houses here. The idea that you can insulate well enough to efficiently move heat across a city is amazing to me.

> The idea that you can insulate well enough to efficiently move heat across a city is amazing to me. It only works well when heating is 'free' - such as when you're using waste heat from a nuclear power plant, or from overproducing solar/wind plants.

No post body was provided.

Re: Large-scale ‘sand battery’ goes online in Finland

#222

Post by adrianN »

ethagknight wrote: post #66
pavon wrote: post #8

As an American it completely breaks my expectations that district heating not only works can be more efficient that decentralized heating. The amount of heat lost just moving water from the water heater on one side of the house to the shower on the other is ridiculously high in houses here. The idea that you can insulate well enough to efficiently move heat across a city is amazing to me.

For USA, district heating made sense in the coal power era. Today, why burn natural gas at a central plant and then have to manage a complex steam distribution network with associated losses when you can simply distribute natural gas instead and get 98% AFUE at the point of use? Even better is a heat pump with gas backup at point of use. Triumph of technology. Also, You dont really insulate the steam distribution pip…

If you burn the gas in a power plant you turn something like 40% into electricity. You can deliver something like half of the remaining Joules as heat to homes, raising the overall efficiency to 60% or so. You can then use the 40% you have as electricity to run heat pumps, which put out something like 2-5 Joules of heat per Joule of electricity. In total this gives you a lot more Joules of heat per unit of gas than just burning the gas in the homes directly.

Re: Large-scale ‘sand battery’ goes online in Finland

#223

Post by bbarn »

kitd wrote: post #146
pavon wrote: post #8

As an American it completely breaks my expectations that district heating not only works can be more efficient that decentralized heating. The amount of heat lost just moving water from the water heater on one side of the house to the shower on the other is ridiculously high in houses here. The idea that you can insulate well enough to efficiently move heat across a city is amazing to me.

I once visited a geothermal plant about 20km outside Reykjavik that supplies hot water for heating the city. Even in the depths of Icelandic winter, the temperature only drops 1 deg C between the plant and the city. A lot of Rockwool around the pipe IIRC.

I live on a small island in Iceland, too far across the sea to pipe Geothermal water to, so the town heats water electrically and pipes it to homes instead. It's not very efficient, and it is rather expensive. It's kind of interesting because there just aren't hot water heaters for sale here, and Icelandic homes are built with that assumption.

I'm on the far side of the island from the plant, and in winter you can absolutely tell the difference in water temperature. In summer months there's an anti-scald unit in every home that's necessary to prevent it being too hot, but in winter sometimes you end up with rather lackluster showers.

Re: Large-scale ‘sand battery’ goes online in Finland

#224

Post by soco »

Gasp0de wrote: post #204
killerpopiller wrote: post #185

Earlier quoted context omitted.

that can't be true. In Germany it is quite a trend now, but they are installed for many years. What I can read in the boards is not that discouraging. Where does this 10 year number come from?

The internet tells me that split-ac systems (basically small heat pumps) have a life expectancy of 10-20 years. That's not too bad, for example an oil-based heating system (as we have in our german basement) also only has a life expectancy of 20 years and has way less moving parts.

My oil based system is 45 years old but no part in it is the original one anymore, so with a certain maintenance cost spread over the years you keep it living indefinitely. Does the ship of Theseus concept apply also for heat pumps, or there you have to throw it away after 10 years?

Re: Large-scale ‘sand battery’ goes online in Finland

#225

Post by sawjet »

unethical_ban wrote: post #134
gamegoblin wrote: post #14

Earlier quoted context omitted.

Many American universities use district heating for the whole campus. Also, as made famous by the many steam vents in NYC movie shots: https://en.wikipedia.org/wiki/New_York_City_steam_system . More info: https://en.wikipedia.org/wiki/District_heating#United_States

Texas tech in Lubbock does it. Blew my mind then and now.

Yet anytime it snows/freezes somehow the school shuts down. There is no drainage for runoff to accumulate so it just sits on the roads. Alum from 2012

Re: Large-scale ‘sand battery’ goes online in Finland

#226

Post by krageon »

mulmen wrote: post #211
krageon wrote: post #209

Earlier quoted context omitted.

When the sidewalks are melted, it becomes waste heat. The rest of the year, it is waste heat. No matter how cold it is, if you accidentally leak heat it is wasteful - even if the side effect is something you may otherwise want.

Idaho summers are very hot. The district heat only runs part time. It is all waste heat from the power plant. There’s ample hydroelectric and wind power in the region as well. I’m not sure if the plant does demand shifting over the course of seasons but it could only run in winter because it runs on biomass and employs students. Many campus facilities are essentially jobs programs for students. The mission is experie…

That sounds pretty cool

Re: Large-scale ‘sand battery’ goes online in Finland

#227

Post by dwighttk »

vesinisa wrote: post #157
dwighttk wrote: post #50

Earlier quoted context omitted.

As the first dorm on the loop my freshman year, I’d get back from crew practice, go into the bathroom, turn on all three showers, and flush the three toilets about three times each to flush all of the hot water out of the cold water line so that I wouldn’t burn myself when taking a shower. I never heard if anyone got hurt when I took a day off and slept in.

This is most unfortunate but in proper district heating systems the scalding hot district circulation water never touches your house's heating / warm water. A heat exchanger is employed to insulate the different circulation systems. For example, my house has district heating and the warm water side is capped at +65C to protect against burns. It's still pretty damn hot of course but I've never had any problems like yo…

I’m not positive I would have been scalded if I didn’t do that, but I do know that just turning on the cold line would yield at least uncomfortably hot water.

Re: Large-scale ‘sand battery’ goes online in Finland

#228

Post by 2Gkashmiri »

galfarragem wrote: post #183
2Gkashmiri wrote: post #170

Earlier quoted context omitted.

i have been thinking about getting a solar water heater>heat pump>radiator to warm up my home but the costs just dont make sense because of the heat pump. i am told the life expectancy of a good heatpump is like 10 years, that amount divided by only 10 winters it is expected to see is more than what we currently pay for electricity in winters, accepting that we don't currently have whole house heating, (we rely on pe…

My father works in that field. In his opinion heat pumps (with today prices and optimizations) are way overrated. The initial investment and the energy spent (it’s way more than advertised) doesn’t make sense for the average family.

i dont mind the energy spent on a day to day basis because i already have a 5.5kwh solar off grid array. i generate around 30 kwh during a good summer month and a fraction during winters but it gets offset from the grid also.

the grand scheme as i wrote above does not seem cost effective only because of the heat pump. if it were cheaper, i would definitely buy it because radiators/solar water/solar panels are low/no maintenance while heat pump does have it.

Re: Large-scale ‘sand battery’ goes online in Finland

#229

Post by rosetremiere »

trenchgun wrote: post #181
konschubert wrote: post #15

Earlier quoted context omitted.

As a German living in a city with mandatory district heating... the end result is to be that people seem pay more for heating than they would with a decentralised system. I think that's mostly due to the high upkeep costs of the system, though, the transmission loss is quite manageable, I think. Of course there are arguments to be made that when accounting for the cost of installing a heating system, and the space it…

Wood burning ovens for heating in city area should not be allowed, that is just idiotic. The amount of deaths and health issues that is going to cause is really nasty.

Is your claim still true when air filters are installed in the chimney?

Re: Large-scale ‘sand battery’ goes online in Finland

#230

Post by mulmen »

krageon wrote: post #226
mulmen wrote: post #211

Earlier quoted context omitted.

Idaho summers are very hot. The district heat only runs part time. It is all waste heat from the power plant. There’s ample hydroelectric and wind power in the region as well. I’m not sure if the plant does demand shifting over the course of seasons but it could only run in winter because it runs on biomass and employs students. Many campus facilities are essentially jobs programs for students. The mission is experie…

That sounds pretty cool

It was actually a great experience. It’s a land grant university that does a lot of really good research and has solid mechanical engineering, business, law, and architecture schools. I worked several on-campus jobs like janitor and IT support. They set me up with good internships over summers and decent mentors. I wouldn’t be where I am in life without the University of Idaho.
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