2021 Webinar Series - 18 Next Generation Thermal Infrastructure

Since regional climate goals are slowing the expansion of natural gas infrastructure, a strong dialog has developed around the next generation of thermal infrastructure.  A very promising concept is using networks of geothermal ground loops in various combinations connected to buildings with water-source heat pump equipment for extremely efficient heating and cooling.  This panel will outline some of the regional initiatives and point out some of the key attributes and challenges to the mass deployment of such a concept. 


  • Audrey Schulman / HEET
  • Owen Brady / National Grid
  • Brian Urlaub / MEP Geothermal







  1. What is the minimum size of a demo system? How can this be done in a new suburban development, especially on Long Island, where Nat Grid sells gas but not electricity - thus no profit from selling renewable electricity to the power system?
    1. For National Grid, we generally think of a demo for a networked geothermal system being 10 or more buildings. We want to ensure there is sufficient size to demonstrate the diversity. However, if there were a potential demo that involved <10 buildings but had unique characteristics, it could be considered.
    2. Regarding the gas/electric coordination, this is why we are working closely with electric utilities. If they can capture a value stream, that should be able to be incorporated into the project economics. Over time, policy and legislative changes may affect this as well.
  2. Could we have contact info for Audrey please?
    1. Audrey.Schulman@HEET.org
  3. How can you securitize gas assets if the number of gas ratepayers declines over time? Will future non-gas ratepayers or taxpayers be required to pay the financing costs for those securities
    1. I am assuming a single ratebase for the gas/geo hybrid system, one where the gas part of the system decreases every year.  Imagine a tree where more and more of its branches are replaced over time with geo branches.  The grafting happens first off wherever gas infrastructure upgrades are needed, This would reduce the investment in future stranded assets since the geoblock installations can be continued to be used and useful past 2050. Over the next 30 years, more and more gas infrastructure gets replaced, dramatically decreasing the future assets that would be stranded.  My hope is the energy bill savings from the geo system would reduce/stop the fleeing customer base allowing the stranded costs to get paid back. - Audrey
  4. If you merely "limit depreciation after 2050," but don't switch from "straight-line" to "units of production" depreciation, the fixed-cost per therm of gas will grow in proportion to the decline in gas usage. Are you also addressing the issue of how deprecation is done, not just the average service life?
    1. Bob - anyway you want to help us run some calculations on this?  I'd love to compare the results of the units of production depreciation with a single gas/geo hybrid rate base with the potential of not allowing deprecation of gas infrastructure past 2050 with that single gas/geo rate base. - Audrey
    2. Audrey: For perspective on straight-line v UoP depreciation, see pages 5-8 in the doc linked to here: https://twitter.com/bobwyman/status/1445214161642868738
    3. Bob - I’ve looked at straight line v UoP depreciation before. It’s a great concept.  Let’s model out the comparison.
  5. ​​I hope you are selling this concept to the Hub development in Nassau County - its mixed building occupancy is a good mix for large loop community geothermal. Also new multi-hundred home development in Woodmere area in Nassau County.
    1. Great suggestion, Peter. We are certainly looking at all developments in LI and trying to ascertain if this sort of solution would work, both for us and for the developer. We also need to figure out how we would invest in a project like this. The Non-Pipeline Alternative framework may facilitate that as it matures.
    2. Another excellent suggestion! Please see my answer regarding the Hub.
  6. What do you think are the number of projects or data points needed to understand whether design parameters can be reduced to be closer to that 80% of capacity? How long will they have to run for the data to be reliable?
    1. Excellent question, Tim. I think this will be a question that will need to be jointly discussed with regulators/legislators. They will likely be the ones that will perform the prudency review so we need to ensure they feel comfortable with the data as well. Each new project is helpful to increase confidence in these sorts of systems.
    2. Regarding how long they must operate, it may not be a function only of time. We need to ensure that the system can demonstrate its ability to perform during the temperature ranges in which it will be expected to perform over its lifetime. If we have a few mild winters/summers, that may be insufficient to demonstrate that it can perform during peak conditions.
    3. We are trying to share as much data as we can so that the concept can be advanced as quickly as possible.
  7. What is the plan for M&V of performance for this expanded set of installations similar to Riverhead?
  8. ​​Besides its modularity, do you see any advantage of this concept compared to conventional low temperature water district heating? Why wouldn't you prefer DH as a carbon neutral solution ?
    1. As the planet warms we will need more cooling.  Ambient temperature water means A) you can deliver cooling and heating as needed, B) you can move excess thermal energy (either heating or cooling) to next building that needs it, radically increasing efficiency, C) you don’t need any energy to create the temperature since all of it is sourced either from the temperature in the earth or from the buildings (with the exception of any supplemental backup heating or cooling system for thermal management.  Managed well, this use of supplemental backup thermal management would be minimal or nonexistent, depending on the site). - Audrey
  9. Question to Owen: Most private contracts establish, up-front, the costs that will be incurred over time. But, utilities change their rates every few years via rate cases. Why would customers prefer unpredictable utility pricing over more predictable firm contracts with non-utility shared loop providers?
    1. We are not seeking an exclusive authorization to install geothermal systems. Unlike the natural gas and electric grids, a networked system and a non-networked system could be installed in the same community without adversely impacting each other. Therefore, if a customer prefers the offering from a given contractor, they would be able to select that option.
  10. Are you assessing the thermal capacity of the boreholes before drilling and if so, how?  If there's rock is that good or bad?
    1. Test boreholes are drilled to assess thermal capacity.  The research team would also install fiber optic sensors to continue to monitor the capacity and storage of the system.  Bedrock has great thermal storage so it is good. - Audrey
  11. Audrey: If gas-geo ratepayers must pay the cost of stranded gas assets, they will pay more for GeoBlock installed by the utility than one installed by someone who isn't a gas utility. Thus, gas-geo systems will be disadvantaged in the market. Will you prohibit competition with the utilities in order to protect them from the impact of competition?
    1. Good lord, I'd never want to prohibit competition with utilities. Competition keeps us all doing our best. - Audrey
    2. Gas infrastructure being stranded would be radically reduced by stopping new or replacement gas installations now.  I believe given the lower geo customer bill, the result energy bill for the gas/geo hybrid customer base would be competitive with air source heat pumps and most other options.  If you wanted to help us run that calculation, that would be great. -Audrey
  12. Is any thought being given at this stage to the inclusion of a future generation of water source appliances such as refrigerators and DHW heaters that might also be piped into district geo heating & cooling?
    1. This was answered live.  Including such appliances in the system would be fabulous and can help with thermal management.  An internet of things could help with active predictive management of the system, i.e. before a cold snap, storing extra heat in water heaters, etc.. 
  13. Audrey: For perspective on straight-line v UoP depreciation, see pages 5-8 in the doc linked to here: https://twitter.com/bobwyman/status/1445214161642868738
    1. Answered above.
  14. Could individual homeowners who are now selecting to install their own GSHP systems with an eye toward becoming a pod in a neighborhood system, decide on a "community loop-ready" system?
    1. Yes they could join the community system, however it is possible that the ground loop HX they paid for and installed would not be used.  It would depend on how the community system is structured from a utility standpoint and also from a design standpoint.
  15. To all - How do we address neighborhoods where everyone does not want to convert immediately?  Is there a minimum percentage of buildings that need to buy in to make a neighborhood conversion possible?
    1. Answered live. We don’t want to find ourselves in a situation where we make it harder for people. Under our obligation to serve, we aren’t able to remove service from customers. One idea is to co-locate geothermal systems with natural gas systems so customers could choose. We will seek input on this question.
  16. Are you getting superb cooperation from PSEG-LI and LIPA?
  17. Can the customer use a heat pump system using community geothermal which would provide heat through their existing baseboard heating system?
    1. No, baseboard heating (assuming you are referring to hot water baseboard) typically operates at high temperature (180F) and geothermal heat pumps do not have the capability to produce that high of a water temperature.  However, if more baseboard or a different type (low temperature) baseboard was installed it is possible to retrofit that system.  Geothermal systems typically operate at 120F or lower for hot water heating.  A few innovative products are now able to achieve 140F water, but that market is limited.
  18. Recent Washington Post aticle about Audrey that folks might want to read  https://www.washingtonpost.com/climate-solutions/interactive/2021/change-natural-gas-audrey-schulman/
  19. Is there enough diversity in single family homes to make it worthwhile for the district or do you need to loop in commercial or other building types?
    1. The system grows more efficient, the larger it is and the more mixed heating and cooling uses it has.  Ideally it is started in an area with mixed heating and cooling, since that makes thermal management easier.  However if necessary it would radically reduce emissions (and fuel costs) even to start with a group of single family homes with supplemental back up heating/cooling as necessary, then interconnect and grow the GeoGrid as quickly as possible to reduce the need for the supplemental backup . - Audrey
    2. Also, if domestic hot water is included, there is more diversity with that added to the load profile due to different schedules of showering, laundry, etc.
  20. Will GeoBlocks pay providers of what would otherwise be waste heat? Can a supermarket or ice skating rink "sell" the heat that is exhausted from their refrigeration units? Could a manufacturing plant "sell" heat to the GeoBlock? Can we make a market for excess heat and/or cooling capacity?
    1. Yes.  This is exactly what I want.  A single skating rink could heat 50 homes with its wasted heat, and a data center could heat many many more. Start with sites like this (“seed site”) and grow a GeoGrid out from there.  Offer to provide the cooling to the seed site for half cost and you pay for the infrastructure.  Who would say no? Meanwhile you’ve just built your “power plant” for the neighborhood, providing renewable energy at a low cost to all. - Audrey
  21. What is the speaker's contact info?
  22. How can we find the link to the geo designer course please to the moderator....thanks i am interested
    1. Please go to www.igspha.org for the geothermal designers course info.
  23. How about using the existing natural gas pipes for this new purpose?
    1. With the exception of a few large diameter cast iron pipes, most gas pipes could not be repurposed for this.