District heating systems: The greenest energy is the energy we don't use
March 19, 2023 6:54 AM   Subscribe

Oil Frackers Hold a Crucial Piece of the Net Zero Puzzle [ungated] - "Technology used to produce bad old fossil fuels is now being turned to clean renewable purposes. What matters is how companies manage the risks."
Knowledge gained forcing oil and gas from deep rocks over the past few decades may provide a crucial piece of the puzzle to build zero-carbon grids, by turning geothermal energy from a niche industry into a powerhouse...

The industries have a surprising amount in common. Both drill holes deep in the ground and hope to extract energy by forcing fluids to the surface. Both originated in the middle of the 20th century but remained small-scale for decades, with technology and economics barring wider deployment. Both suffer decline rates: Oil gets harder to extract as crude is pumped out and underground pressures fall, while geothermal reservoirs can gradually get cooler over time and lose their ability to force steam to the surface. Some of the most crucial information needed for working out the ideal locations for geothermal reservoirs is locked in the vast database of sedimentary rock basins that the petroleum industry has assembled over the past century.

There’s already signs that spillovers are happening. The US government has developed a fluid to fracture impermeable rocks to open up more geothermal reservoirs, a process identical to the one that frackers use in petroleum deposits. Start-up Eavor Technologies Inc. plans to use the horizontal drilling pioneered by the unconventional oil and gas industry to build radiator-like networks of pipes in areas that would otherwise be unsuitable for development.

Shell Plc set up a geothermal division in 2018 that’s been exploring the potential of the technology to provide heat for buildings and industry in the Netherlands. Baker Hughes Co., the former oilfield services division of General Electric Co., has developed deep, high-temperature drilling technologies to tap reservoirs that can produce heat more efficiently than conventional ones.
Pumping Heat a Mile Underground Is Helping One City Cut Carbon [ungated] - "Hamburg, Germany, is building an experimental system—called aquifer thermal energy storage—that keeps hot water underground until it can warm homes during winter."

also btw...
Residential Heat Pumps Could Cut U.S. Energy Consumption In Half - "Heat pumps are a promising and cost-effective way to reduce greenhouse gas emissions and energy consumption through improved energy efficiency."
posted by kliuless (21 comments total) 12 users marked this as a favorite
 
I thought this was going to be about plugging wells. There are hundreds of thousands of uneconomic oil and gas wells out there. there are likely to be tens of thousands just putting methane into the atmosphere, do de do.

Oil companies have laid everyone off, right when we need the workers to clean up the old mess.

We will need oil workers forever, as, even when the wells are plugged with cement, the cement cracks over time.
posted by eustatic at 7:38 AM on March 19, 2023 [6 favorites]


When I was in Iceland, I went to the geothermal plant outside Reykjavík for a tour. They are doing really awesome things with geothermal! My understanding is the system allows the geothermal liquid to heat-exchange with potable water, and then that potable hot water is piped directly to people's homes (along with your usual cold water pipe).

Because the winters are severe and hot water is almost free, they've also got some heated sidewalks and streets in the busiest parts of downtown. By embedding hot water pipes under the pavement, they're able to melt ice and snow and keep the paths clear.

Reykjavík's got the advantage of quite a bit of geothermal energy close to the surface, and it's on a mountain (volcano?) to boot so they can utilize gravity flow pipes to bring the water to the city rather than pumping it, which is part of what makes this system work so well.

Maybe it's my solarpunk fantasies talking, but I have to believe that there are more clever opportunities like this to make our build environment both more ecologically sustainable *and* more pleasant to live in!
posted by cnidaria at 11:04 AM on March 19, 2023 [13 favorites]




They are doing really awesome things with geothermal! My understanding is the system allows the geothermal liquid to heat-exchange with potable water, and then that potable hot water is piped directly to people's homes (along with your usual cold water pipe).

Basically, if the water comes out of the ground above about 150C then they use it for electrical generation. Once it is below 150C (or if it comes up below 150) then its used for hot water delivery. As you say, the thing with Iceland is that you can get water above 150 at depths of 1000m in Iceland, due to the volcanic activity. Elsewhere you have to go much deeper, making getting to the resource more expensive in most places. That's not to say geothermal isn't useful elsewhere (the US and Italy have more installed capacity), but Iceland isn't easily replicable. My own part of the world is looking at getting hot water at 5000m, which is really challenging.

I think the stat is that about 1% of Iceland's energy goes to underfloor outdoor heating.
posted by biffa at 12:01 PM on March 19, 2023 [3 favorites]


This is interesting from a technology perspective, but we don't need new tech; we have everything we need to get carbon out of the energy cycle but the will to do it.
posted by Ickster at 12:20 PM on March 19, 2023 [7 favorites]


I think the stat is that about 1% of Iceland's energy goes to underfloor outdoor heating.

Iceland is powered by 100% renewable energy. Saves using salt everywhere to keep the footpaths clear in the city which reduces the amount of salty runoff infiltrating the groundwater, Iceland's only water source.
posted by Your Childhood Pet Rock at 12:22 PM on March 19, 2023 [6 favorites]


We definitely have nearby volcanoes here in Seattle; I'm not sure if what qualifies as nearby *enough*, though.
posted by cnidaria at 1:15 PM on March 19, 2023


District heating doesn't have to source from geothermal, that's just one of the cleanest ways. Every power plant has huge cooling towers to dump heat that could be used for district heating.
posted by Mitheral at 1:22 PM on March 19, 2023 [11 favorites]


Came here to post the Sabine Hossenfelder take that flabdabbet beat me to.

As an aside, these fracking fluids are not benign and the minerals brought up include radioactive materials (the reason earths interior has stayed warm all these billions of years post formation.

Plus, can't wait to see the effects if any of altering the thermal flow of energy through the earths crust and simultaneously weakening its structural integrity. Also, the ground water we permanently contaminate is usually worth more than the one time or short term energy extracted.

We really will try anything but reducing our footprint and redistributing materials and finances to the poor.
posted by anecdotal_grand_theory at 1:28 PM on March 19, 2023 [6 favorites]


Just to be clear, ground sourced heat pumps do not use the type of geothermal heat discussed in the article and do not require nearly that depth of drilling. They just very efficiently use the normal heat in the ground (which is always the same year round for a given location, somewhere between 45°F (7°C) and 75°F (21°C) depending on where you live) to heat and cool buildings. That has nothing to do with the sort of high temperature geothermal power in, e.g., Iceland, and can be installed anywhere in the world right now, no new technology needed. If you're in the US, Rewiring America can help you learn how the Inflation Reduction Act can help pay for your heat pump
posted by hydropsyche at 1:30 PM on March 19, 2023 [8 favorites]


Yep, my company has designed ground-sourced heat pumps in Michigan with not-ridiculous drilling depths. Like a lot of sustainable building strategies, there's a higher initial cost but much lower operational cost.

Also in Michigan, the entire downtown of Holland has a snowmelt system under its sidewalks. Quite a few buildings have their own smaller systems just for their entries or other paved areas.
posted by LionIndex at 1:55 PM on March 19, 2023 [5 favorites]


Came in to make the same distinction as hydropsyche here:

Ground Source Heat Pumps (regulary called geothermal, as confusing as it is) are just like the air-source heat pumps everyone is installing right now, but in colder climates they have no need for a backup system as they maintain their excellent efficiency regardless of the outside temperature. Even in milder climates their efficiency is just way better than (the already very good) air source efficiency. If you live in NY state, you can try contacting Dandelion Energy to switch off your bad dumb fossil fuels. They even offer financing directly. Older ground source heat pump systems tended to be giant horizontal fields, mostly seen in rural areas... but even in denser housing you can just drill 100m straight down and get enough heat for the whole winter. Pretty much anywhere! You only need about 10m spacing between boreholes. Up here in Canada we are going to have to go this direction in a big way I suspect.

Geothermal Energy drills waaaaay deeper down to get much, much, much hotter temperatures directly. We will see how widely applicable this is, but wherever you can do it, you should (imo) be generating electricity with it first, and using the low-grade rejected heat after the fact for district heating.
posted by molecicco at 3:11 PM on March 19, 2023 [2 favorites]


I do not work for Dandelion, nor have I ever, and I do not know anyone at the company. Just excited to see people pushing for GSHP. LionIndex --> which company is that?
posted by molecicco at 3:13 PM on March 19, 2023


Frankly, if a fracking operator told me it was raining I'd get a second opinion, a lawyer, and a guard dog. There's an extensive history of unethical practice, regulatory failure, and promises never kept by frackers around the world that make me highly sceptical of this 'development'...
posted by prismatic7 at 4:58 PM on March 19, 2023 [7 favorites]


Ground Source Heat Pumps (regulary called geothermal, as confusing as it is) are just like the air-source heat pumps everyone is installing right now, but in colder climates they have no need for a backup system as they maintain their excellent efficiency regardless of the outside temperature. Even in milder climates their efficiency is just way better than (the already very good) air source efficiency.

This is largely because once you get more than about five metres down, any heat you apply to the ground is mostly going to stay there unless the temperature difference to the surrounding ground gets really high. It's hard to find more thermal mass than a great big chunk of earth.

As your GSHP cools your dwelling in summer, all the thermal energy it's sucking out of the building goes into the earth and basically stays there. The thermal mass of the earth around your GSHP's waste-side radiator/absorber pipe is big enough that dumping an entire summer's worth of waste heat into it still won't raise its temperature to anything like that of the air on a hot summer's day, so even with all that added heat building up on its warm side the GSHP is going to have less work to do than an air sourced heat pump with the same indoor temperature regulation capacity would.

So when winter rolls around and you start needing to warm your building, the GSHP will be starting out with a season's worth of heat in its underground reservoir. In any snowy winter climate that's going to make the GSHP's cold side way warmer than the outside air and keep it that way for the entire season.

A heat pump's coefficient of performance (CoP) is the ratio between the amount of heat energy it either supplies to or removes from the target side and the amount of electrical energy required to do that. The lower the temperature difference between its cold side and its hot side, the higher the CoP is going to be, simply because it takes less work to push any given quantity of heat up a less steep temperature hill. And the higher the CoP, the less the machine costs to run.

You'd need to run the numbers for the place where you live, but in many places there is a good chance that a GSHP would save you enough money in energy costs over its service life, compared to a similarly capable ASHP, to pay back the additional drilling and plumbing costs several times over.

And if you've got a neighbourhood's worth of dwellings all running GSHPs, the ground under the entire neighbourhood becomes a shared thermal mass that loses even less energy per dwelling across seasons.

I don't know if anybody's done any studies into the economics of providing neighbourhood-scale seasonal thermal mass as a utility, perhaps integrating it into the existing water supply system via two-way-per-dwelling water connections and neighbourhood-scale loop circulation pumps, but it doesn't strike me as an entirely stupid idea. Basically, district heating without the district heater.
posted by flabdablet at 10:33 PM on March 19, 2023 [2 favorites]


if a fracking operator told me it was raining I'd get a second opinion, a lawyer, and a guard dog

You'd want a decent kennel for that guard dog, because who knows what's going to be dissolved in that rain.
posted by flabdablet at 10:39 PM on March 19, 2023 [4 favorites]


As an aside, these fracking fluids are not benign and the minerals brought up include radioactive materials (the reason earths interior has stayed warm all these billions of years post formation.

Whether or not the fluids are benign is irrelevant - one of the operators in Texas did a well as a stunt using food grade ingredients they ordered from a catering catalogue as a stunt and it worked perfectly well - it's that second point: just because something is naturally in the ground doesn't mean it's benign to connect it up to all the other layers of the earth with a borehole.

For one thing, at the very least the fossil fuels themselves, but also mercury, sulphur compounds, arsenic in many cases. All this stuff is just fine where it is, not so great when a clumsily completed well leaks them into an aquifer that people are also using. Shallow tight formation wells have short production lives of only a few years so you have to drill loads of them i.e. inevitably some of them will be clumsy.

I've looked into the applicability of hydraulic fracturing technology for geothermal heat and power production for an investment a client was considering making and I'm not so positive on it.

The main reason is that the kind of horizontal drilled, fractured formation drilling that people refer to when they say "frac'ing" (actually almost all oil and gas wells are hydraulically fractured but we all know the kind that's meant) is generally shallow, low temperature drilling. The best heat sources are at high depth and high (obvs) temperature which is much more similar to the technology developed for offshore drilling in extreme conditions like the Brazilian pre-salt.

Shell Plc set up a geothermal division in 2018 that’s been exploring the potential of the technology to provide heat for buildings and industry in the Netherlands. Baker Hughes Co., the former oilfield services division of General Electric Co., has developed deep, high-temperature drilling technologies to tap reservoirs that can produce heat more efficiently than conventional ones.

i.e. this is helpful tech but it is not really related to hydraulic fracturing.

I have worked on a number of Dutch geothermal projects (including ATES which is what Hamburg is doing) and the technology used there is pretty conventional. Conventional closed loop systems are the opposite of fractured, you don't want your water leaking out.

I don't know if anybody's done any studies into the economics of providing neighbourhood-scale seasonal thermal mass as a utility, perhaps integrating it into the existing water supply system via two-way-per-dwelling water connections and neighbourhood-scale loop circulation pumps, but it doesn't strike me as an entirely stupid idea. Basically, district heating without the district heater.

This is an ambient or fourth gen district heating network. I've worked with a developer who wanted to put a Kensa system in which basically does this. This is for the UK so heat pumps are outputting to water which goes into radiators here rather than to air like in a ducted system. Unfortunately that does mean you can't use it for cooling (using radiators for cooling is inefficient and leads to condensation problems). So these are basically shoe-box sized water/water heat pumps. If you want to boost system efficiency you run the loop a little hotter than ambient in the heating system (potentially using another HP to inject heating energy) and a little cooler in the cooling season (again you need to withdraw the heat from the loop somewhere).

They are almost preposterously efficient.
posted by atrazine at 7:40 AM on March 20, 2023 [1 favorite]


What kind of CoP figures are you seeing out of those?

What are the chances of somebody commercialising split system heat pumps with indoor units identical to those already in use today and water-sourced outdoor units designed to be plumbed into an ambient district heating network?
posted by flabdablet at 8:21 AM on March 20, 2023


5+ seasonally averaged.

I think the problem is getting the ambient systems off the ground (same problem as with typical DH networks) in non-new-build situations. It costs a lot of money to put the pipes in and then you have no way of compelling people to connect to them. If ambient networks were common, it would not be hard to manufacture and commercialise a system like that at all. Especially in high density urban cores where building owners worry about where to but central chillers / heaters and energy costs.

I had a flat which was attached to a district cooling system in Dubai which worked exceptionally well.

What I'd really like is a residential VRF system (this is a split system which allows you to heat with some units and cool with others at the same time) so that a single external air source system could provide supply for mini-splits in some rooms to provide air heating and cooling, warm domestic hot water, warm water for underfloor heating, and transitionally hot water for radiators. That would be a sort of domestic retrofit master solution but I am sure that nobody will build such a complex and potentially inefficient system.
posted by atrazine at 8:49 AM on March 20, 2023 [1 favorite]


With the proliferation of heat pumps for home heating / cooling, I wonder if we'll ever start laying new pipe to circulate antifreeze to every home. That could as much as double heating / cooling efficiency compared to air-source heat pumps, especially if the central heat sink is a nice deep well, lake or ocean.

[edit] - or what flabdabblet said.
posted by Popular Ethics at 1:05 PM on March 20, 2023


What's going on with geothermal? - "A conversation with Jamie Beard, founder of Project InnerSpace."
posted by kliuless at 11:42 PM on April 6, 2023


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