A visionary solution to America's aging, leaking natural gas infrastructure: replace it! In place of pipes carrying gas, lay pipes carrying water warmed by the Earth. Two Massachusetts activists explain how it would work.
I have a friend who's been talking up district thermal networks for months. This episode made it clear. Thanks. What I really like is bringing along the utilities as an ally rather than an opponent. Here in NYC, with Local Law 97 requiring emissions reductions, this can be a win-win. Lower cost plus lower emissions.
I really hope this succeeds. For northern US climates and moderately dense neighborhoods it seems to have multiple advantages over individual air-source HPs. I believe the areas selected have a fair bit of multi-family housing in 3-plex walkups, etc. Some of these buildings probably have boiler heat. I'd be interested to hear what the systems are being selected to replace these. I understand actual construction starts this summer. There are many other permutations on this concept. Other HVAC geeks might be interested in these free webinars subsidized by NY state: https://www.ashrae.org/professional-development/chp-webinars/ashrae-nyserda-community-heat-pump-systems-webinar-series
In the EU, boilers in district heat systems are being replaced by heat pumps, many water-source, often using ammonia as the working fluid so the district heating HW can be supplied at 180F. That's covered in #13 in that series.
David it is good you are tuning in to low carbon district energy. There are many, many existing low carbon DE projects around the world using a wide range of energy sources. Europe, in particular, has much greater market penetration for district heating than North America and most DE utilities in Europe are working on transitioning their systems to lower carbon resources. This is an interesting initiative and I look forward to listening.
I was listening for mention of other thermal resources and their cost/value to the new thermal grid: water heaters, refrigerators... and of course, pools and hot tubs. And for rural and semi-rural landowners, unused water (and oil and gas) wells may become new thermal assets. Municipal water tanks and ponds are designed and managed to avoid freezing; now they can also become thermal assets.
Another interesting area for fresh thought is efficiency. As part of the Transition, we still need to strongly incentivize improvement in building efficiency. Consumer cost is going to become dependent on insulation if the cost is based on consumption. (BTW: COP is proportional to the efficiency of the machine that moves the mass that contains the heat and inversely proportional to the "distance" (temperature) you move it. The less different the two temperatures are of the source and sink, the higher the COP.)
Still another resource is solar thermal. Where a bit more energy is needed, solar thermal can be installed near the need. Solar thermal could finally "arrive" in America.
Thermal resources need to become the center of new thinking for many needs. For example, dehumidification.
Sewers and other sources of wastewater should also be exploited in addressing the need for heating and cooling. Sewer water can be both a source and sink for thermal energy.
In many large residential buildings, water heating is often as much as 20% or more of their total heating energy requirement, however, most of that heat is simply dumped down the drain. Ideally, we would use heat exchangers and heat pumps to extract heat from that wastewater and recycle it back into water or space heating systems. (Sharc Energy, https://www.sharcenergy.com/, and Huber, https://www.huber-technology.com/solutions/heating-and-cooling-with-wastewater.html, are among those who offer such systems.)
There are also passive systems for drainwater heat recovery (DWHR). For instance, one can install a heat exchanger in a shower drain to transfer heat from the drainwater to the shower's cold water input and thus reduce the quantity of hot water needed to achieve the desired temperature. (California offers a number of resources on passive drainwater heat recovery systems: https://title24stakeholders.com/measures/cycle-2019/drain-water-heat-recovery/ )
For a recent survey of heat recovery from wastewater in components (like showers), buildings, sewers, or waste-water treatment plants , see: https://www.mdpi.com/2073-4441/13/9/1274
@David, Check this out: Smith College, in Northampton, MA, is converting their entire campus-wide heating and cooling system to geothermal heat pumps! That's 90% of their current carbon footprint. Would make a great use-case podcast: https://www.smith.edu/news/modeling-carbon-neutrality
Really enjoyed the listen, but I felt that the cost implications on the customer's side of this weren't fully expressed. The customer still needs a way to transfer that thermal energy in the water to the air of their forced air heating/cooling system. It’s certainly doable, but a higher capital expense than most customers are usually willing to swallow, and it’d be hard for the utility to own that piece. Not to mention the finances become a complete train wreck if they’re using a radiator heating system. Don’t get me wrong, I’m still all for this, but the retrofitting costs are not to be taken lightly. It is not simply “plug and play.”
This idea would make heat pumps more efficient; but rather than go to all the cost and labor to get a higher COP, we could just install more cheaply - more solar modules to make up for the COP efficiency gains from ground- based heat pumps.
Can't listen yet, but this strikes me as counterproductive to the push to electrify everything. For city/communal/apartment systems I could see it be useful at scale. For more suburban settings, seems like a water main break problem that now also means you have no heat, since invariably they'd be mostly co-located in the infrastructure routing.
Keep in mind that this is still an electric heat pump-based solution - just at network scale. The question is whether it can offer lower costs or greater benefits than building-scale heat pump solutions.
Your observation does raise a question - If we think our objective should be that all energy services are met via discrete pieces of electrically driven equipment located in each separate building then OK, don't pay any attention to ideas like this. If we think our objective should be decarbonization at low cost (with due regard for other considerations) then it is worth considering alternate configurations and technologies.
Re: water main break - district energy pipe networks are physically separate from potable water mains. Water utilities generally prefer for other infrastructure to be well set back from their lines, and that includes DE.
for large buildings, city centers and other dense situations, I agree it seems like an interesting option.
To complete with individual building setups, you have to take in to account the entire infrastructure build vs what is already basically covered in current HVAC systems. i.e. Heat Pumps are just AC running backwards. As Dave says HVAC is 95% of a heat pump solution already there.
I wonder about just pure power generation from geothermal. Don't know if it's capable of scaling to significant power potential though w/o uber deep drilling.
The jargon with geo, in particular, is very confusing. The solution discussed here is what is usually called geoexchange (at least in my experience). It is distinct from "geothermal" which usually refers to high temperature resources which are suitable for power generation. To date most geothermal power installations have been in places like Iceland, Hawaii (only the Big Island), and other areas where very high temperature heat is at relatively shallow depths. Apart from those locations, yes power generation requires extremely deep drilling (which some people are working on).
There is also another heating configuration usually referred to in English as "deep geo" - there are district energy systems in Munich and Paris using this approach. They are doing deeper wells, on the order of 1+km, to reach high temp aquifers which provide water at around 60C or higher. Not hot enough for power generation but plenty hot for buildings. I believe they are still doing some polishing with heat pumps to meet the needs of their infrastructure but the COPs are very favorable with a resource that hot. Unfortunately not possible everywhere as it requires the right type of aquifer.
Regarding this proposed concept - yes in general DE has been deployed in higher density settings and it is very difficult to make it cost effective in a suburban setting. Personally I am trying to be open minded but this infrastructure is not cheap. Agreed that we need to compare against building scale systems but I'll also note that is true in all cases, regardless of scale.
I have a friend who's been talking up district thermal networks for months. This episode made it clear. Thanks. What I really like is bringing along the utilities as an ally rather than an opponent. Here in NYC, with Local Law 97 requiring emissions reductions, this can be a win-win. Lower cost plus lower emissions.
I really hope this succeeds. For northern US climates and moderately dense neighborhoods it seems to have multiple advantages over individual air-source HPs. I believe the areas selected have a fair bit of multi-family housing in 3-plex walkups, etc. Some of these buildings probably have boiler heat. I'd be interested to hear what the systems are being selected to replace these. I understand actual construction starts this summer. There are many other permutations on this concept. Other HVAC geeks might be interested in these free webinars subsidized by NY state: https://www.ashrae.org/professional-development/chp-webinars/ashrae-nyserda-community-heat-pump-systems-webinar-series
In the EU, boilers in district heat systems are being replaced by heat pumps, many water-source, often using ammonia as the working fluid so the district heating HW can be supplied at 180F. That's covered in #13 in that series.
This is already such a hopeful series, I love it. What a cool idea.
David it is good you are tuning in to low carbon district energy. There are many, many existing low carbon DE projects around the world using a wide range of energy sources. Europe, in particular, has much greater market penetration for district heating than North America and most DE utilities in Europe are working on transitioning their systems to lower carbon resources. This is an interesting initiative and I look forward to listening.
Great podcast. Thank you.
I was listening for mention of other thermal resources and their cost/value to the new thermal grid: water heaters, refrigerators... and of course, pools and hot tubs. And for rural and semi-rural landowners, unused water (and oil and gas) wells may become new thermal assets. Municipal water tanks and ponds are designed and managed to avoid freezing; now they can also become thermal assets.
Another interesting area for fresh thought is efficiency. As part of the Transition, we still need to strongly incentivize improvement in building efficiency. Consumer cost is going to become dependent on insulation if the cost is based on consumption. (BTW: COP is proportional to the efficiency of the machine that moves the mass that contains the heat and inversely proportional to the "distance" (temperature) you move it. The less different the two temperatures are of the source and sink, the higher the COP.)
Still another resource is solar thermal. Where a bit more energy is needed, solar thermal can be installed near the need. Solar thermal could finally "arrive" in America.
Thermal resources need to become the center of new thinking for many needs. For example, dehumidification.
Sewers and other sources of wastewater should also be exploited in addressing the need for heating and cooling. Sewer water can be both a source and sink for thermal energy.
In many large residential buildings, water heating is often as much as 20% or more of their total heating energy requirement, however, most of that heat is simply dumped down the drain. Ideally, we would use heat exchangers and heat pumps to extract heat from that wastewater and recycle it back into water or space heating systems. (Sharc Energy, https://www.sharcenergy.com/, and Huber, https://www.huber-technology.com/solutions/heating-and-cooling-with-wastewater.html, are among those who offer such systems.)
There are also passive systems for drainwater heat recovery (DWHR). For instance, one can install a heat exchanger in a shower drain to transfer heat from the drainwater to the shower's cold water input and thus reduce the quantity of hot water needed to achieve the desired temperature. (California offers a number of resources on passive drainwater heat recovery systems: https://title24stakeholders.com/measures/cycle-2019/drain-water-heat-recovery/ )
For a recent survey of heat recovery from wastewater in components (like showers), buildings, sewers, or waste-water treatment plants , see: https://www.mdpi.com/2073-4441/13/9/1274
Thank you for this inspiring discussion.
@David, Check this out: Smith College, in Northampton, MA, is converting their entire campus-wide heating and cooling system to geothermal heat pumps! That's 90% of their current carbon footprint. Would make a great use-case podcast: https://www.smith.edu/news/modeling-carbon-neutrality
Really enjoyed the listen, but I felt that the cost implications on the customer's side of this weren't fully expressed. The customer still needs a way to transfer that thermal energy in the water to the air of their forced air heating/cooling system. It’s certainly doable, but a higher capital expense than most customers are usually willing to swallow, and it’d be hard for the utility to own that piece. Not to mention the finances become a complete train wreck if they’re using a radiator heating system. Don’t get me wrong, I’m still all for this, but the retrofitting costs are not to be taken lightly. It is not simply “plug and play.”
This idea would make heat pumps more efficient; but rather than go to all the cost and labor to get a higher COP, we could just install more cheaply - more solar modules to make up for the COP efficiency gains from ground- based heat pumps.
Can't listen yet, but this strikes me as counterproductive to the push to electrify everything. For city/communal/apartment systems I could see it be useful at scale. For more suburban settings, seems like a water main break problem that now also means you have no heat, since invariably they'd be mostly co-located in the infrastructure routing.
Keep in mind that this is still an electric heat pump-based solution - just at network scale. The question is whether it can offer lower costs or greater benefits than building-scale heat pump solutions.
Your observation does raise a question - If we think our objective should be that all energy services are met via discrete pieces of electrically driven equipment located in each separate building then OK, don't pay any attention to ideas like this. If we think our objective should be decarbonization at low cost (with due regard for other considerations) then it is worth considering alternate configurations and technologies.
Re: water main break - district energy pipe networks are physically separate from potable water mains. Water utilities generally prefer for other infrastructure to be well set back from their lines, and that includes DE.
for large buildings, city centers and other dense situations, I agree it seems like an interesting option.
To complete with individual building setups, you have to take in to account the entire infrastructure build vs what is already basically covered in current HVAC systems. i.e. Heat Pumps are just AC running backwards. As Dave says HVAC is 95% of a heat pump solution already there.
I wonder about just pure power generation from geothermal. Don't know if it's capable of scaling to significant power potential though w/o uber deep drilling.
The jargon with geo, in particular, is very confusing. The solution discussed here is what is usually called geoexchange (at least in my experience). It is distinct from "geothermal" which usually refers to high temperature resources which are suitable for power generation. To date most geothermal power installations have been in places like Iceland, Hawaii (only the Big Island), and other areas where very high temperature heat is at relatively shallow depths. Apart from those locations, yes power generation requires extremely deep drilling (which some people are working on).
There is also another heating configuration usually referred to in English as "deep geo" - there are district energy systems in Munich and Paris using this approach. They are doing deeper wells, on the order of 1+km, to reach high temp aquifers which provide water at around 60C or higher. Not hot enough for power generation but plenty hot for buildings. I believe they are still doing some polishing with heat pumps to meet the needs of their infrastructure but the COPs are very favorable with a resource that hot. Unfortunately not possible everywhere as it requires the right type of aquifer.
Regarding this proposed concept - yes in general DE has been deployed in higher density settings and it is very difficult to make it cost effective in a suburban setting. Personally I am trying to be open minded but this infrastructure is not cheap. Agreed that we need to compare against building scale systems but I'll also note that is true in all cases, regardless of scale.
For anyone who is interested - below is some info on the Paris system.
https://www.thinkgeoenergy.com/geothermal-greater-paris-area-making-better-and-better-use-of-enormous-potential/