What are these “heat pumps” ? Is that like a heater or an AC?
this post was submitted on 25 Sep 2024
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It's a reverse-cycle AC if you've heard the term. Basically, an AC that can can run in reverse, heating the room.
It's the most efficient form of heating and cooling that we have, since it doesn't create energy, but instead moves it (so its efficiency is greater than 100%).
It takes less energy to move heat than it does to produce it. A heat pump basically runs an air conditioner backwards, so rather than moving heat from inside a structure to outside, it moves heat from outside to in. With the right units, this works even in cold weather for the same reason a freezer gets warm on the outside - it's moving heat from inside the (freezing) unit out.
Geothermal energy takes this concept a step further by putting the outside unit underground. Underground temperatures are more stable and moderate, so it's easier (more efficient) to expel/collect heat, but also much more involved to install.
It's what different parts of the world call a reverse cycle, split system air conditioner.
On individual scale, precisely that - a split type AC with one half indoors (or in a water tank) and the other half in an outdoor environement (air, water or ground).
If you're extracting heat from the environment, the machine lets the working fluid evaporate into the outdoor heat exchanger and compresses it back into the indoor heat exchanger. If you're cooling your premises - reverse that.
However, on a city scale, it's like "you've got a lot of sewage at 30 C" -> "your heat pump is a large building" -> "your sewage outflow is now at 10 C, but your underground heat reservoir gets charged to 140 C (stays liquid because of water column pressure), and you spend much less energy pumping the heat than you would spend heating the water directly".
Air conditioners are exactly a heat pump. As are refrigerators. The only difference is that it's turned around so the hot side is inside.
The typical heat pump setup (in the US) is not reversible. That means you would also have the AC heat pump next to it, capable of moving heat in the other direction.
Heat pumps are quite common in the warmer US states. They are great at cooling in summer and good enough at heating in the winter.
Yeah, I'm always a little mystified by these stories. Not sure I've lived anywhere without a heat pump in the last 20-years. Why are we trying to promote these things when they seem like a no-brainer in the first place?
Yep, but district heating and cooling is rare; it exists in a few major cities and a few university and corporate campuses.
In Netherlands the fixed cost for city based heating is paid by the people who make use of it. That seems fair, but practically it means that it'll be cheaper for people to arrange their own heating system and rely on electric heating. This because the fixed cost is high. However, if everyone switches to using electricity the city based heating would overall be much cheaper solution than relying on electricity. This as currently loads use a gas solution and there's a huge cost involved to upgrade the electricity network.
The city based heating variable price is connected to the gas price. So even if city based heating per kWh equivalent would be cheaper, people wouldn't notice or get the advantage.
As a result, city based heating is very unpopular. Planned projects to switch entire neighbourhoods have been cancelled. Again, logical because people were really upset to pay significantly more despite insulating their entire home.
Seems that in Netherlands they'll ignore the problem and have the country be less cost effective and upgrade the electricity network for significantly more money.
The Dutch Financial Times did a few articles on above in the last 12 months or so.
I've been looking into getting a heat pump in the northern US and for heating it doesn't seem to be worth it quite yet. The problem where I'm at is that it gets very cold and natural gas is pretty cheap but electricity is expensive. I hope this changes soon. It would be a no brainer if I were replacing a resistive heater though.
Not to discount your experience, but heat pumps are remarkably efficient. It would actually use less gas to convert it to electricity at an industrial scale, and then use that to locally power (recent) heat pumps, than it would be to burn the gas inside your home for all of its heat.
It sounds like your area has some politics in play that are either subsidizing gas or surcharging electric. It's not necessarily a bad thing, but it does put a thumb on the scale.
Stockholm decommissioned its last coal-fired plant in 2020, and its giant heat pumps are a major supplier of heat to the city, along with power plants that burn waste and scrap wood from Sweden’s forestry industry that would otherwise be left to rot. Levihn contends that generating heat and electricity from incinerated waste is more efficient than dumping it in a landfill, although these plants still emit carbon dioxide. Stockholm Exergi is working to install carbon-capture technology in the plants in hopes of making the system net carbon negative, he told me.
"We don't use coal, we just burn waste rather than turning the wood scrap into something useful." Greenwashing at its finest. I suppose the angle is it's "almost" recycling carbon rather than releasing old buried carbon into the atmosphere?
What an odd guilt-laden non-article. It's non-trivial to install underground piping systems in neighborhoods, they then also need a source/sink of heat to power the mechanism, not every neighborhood would have that, not all topographies would support that. Cities already have centralized heating systems that have been around for decades in some building groupings.
Seems it'd make more sense to just install a house-grade heat pump on each home the next time the AC needs to be replaced and some grid-scale solar and/or wind and/or hydro and Bob's your uncle. Toss in some base-load nuclear for good measure. Build out the energy infra enough that resistance or baseboard resistance electric heat can be used for when it's too cold to use a heat pump in the meantime, and then sunset gas furnaces the next time those need to be replaced.
This avoids polluting with big diggers tearing up streets, moving dirt around, possibly destroying gas (causing methane leaks), water, power, Internet infra, and laying new asphalt. No carbon creation by building the piping systems/energy plant and avoids trucking those parts around.