District energy -- in which a group of buildings share a common source of heating & cooling -- dates back at least to the Roman Empire, but the clean-energy transition has brought this extremely clean & efficient arrangement to the forefront. I talk with an expert about how it works & where to find it.
One major miss: Remind listeners, for climate reasons NO new or retrofit energy system can include natural gas. IEA: “no new fossil fuel infrastructure.” This includes district energy systems - no matter how “efficient,” natural gas is high GHG emissions. The 2021 WA Commerce Energy Strategy envisions all-electric heat pump building heat statewide for that reason. Where sewer, wastewater or industrial heat is very abundant, heat recovery can enhance groundwater heat pumps for district heat. An engineer will help clients determine the best system choices. A caution: Before I retired, I tracked energy use of state buildings in Washington state. Our district energy systems were the biggest energy hogs and highest GHG emissions per square foot of building space (colleges, universities). Regarding sharing heat between buildings (except for data centers), the buildings all call for heat or cooling about the same time, so sharing heat/ cooling benefit between buildings is not that great, and there are losses in pipes between buildings. Heat/cooling sharing to meet variable demand within each building is more efficient using VRF. I’ll believe the district energy efficiency hype when I see it. Our most energy efficient buildings tended to have good tight envelope and use simple air to air heat pumps. Ground source heat pumps planned for later last I heard, and some may serve multiple buildings. (Water as a time-of-use battery could be valuable to shave peaks if electricity provider given control -- large tanks required.) Remember, NO new or retrofit natural gas, for climate reasons.
This is a question not related to the this particular podcast, but what are the "lyrics" to the theme song? I thought it spelled out V-O-L-T-S, but I really can't make that out. This is not very important, but a bit vexing to me! 🙃 Thanks David!
It's too bad so much of this time was spent discussing cooling. But the US is "exceptional."
Most existing district heating systems here still use steam. It's basically impossible to make steam with a heat pump utilizing river, lake or bay water or geo-exchange. Most DH systems in the EU were converted from steam to 140F HW years ago. They have a rating system for generations of DH, which get higher as the temps get lower. The lowest temp DH systems sometimes require boosting by a local heat pump.
As part of the Princeton system geo-exchange HP district heat system cited, they first are converting or have converted a steam system to 140F HW. That's a big project right there. Most radiators and AHU coils need to be replaced. To minimize that work, first they are insulating and triple glazing where possible. So then the awesome heat pumps and heat recovery chillers can work together and with the geo-boreholes to produce HW and CHW. Stanford's done something similar, but was able to get to 75% of htg. load met w/o even using boreholes, because they recover so much heat from winter cooling of data rooms, bio-freezer rooms, etc. And it's not really the same winter in Palo Alto.
There are a few steam systems switching to electric resistance heat during hours with cheap renewables. A very few doing it with storage, and more for industrial steam I think. It's a pretty local thing along the Baltic right now. Typically, there isn't extra solar during winter. For these surplus renewables for heating, the rest of us will need to wait for the wind industry to regroup, and it's not clear that the GOP will allow that again in the US.
Some thermal energy news in NYC https://www.coned.com/en/our-energy-future/our-energy-vision/where-we-are-going/thermal-energy-networks
King County just announced a new system that transfers heat from sewers in Seattle too. https://kingcounty.gov/en/dept/dnrp/about-king-county/about-dnrp/newsroom/2023-news-releases/10-19-sewer-heat-recovery
'Cheap' fossil energy has, and continues to, place the US so far behind other economies in all non-fossil forms of energy that with every 'innovation' examined, one soon finds that it has been in use somewhere else for ages. It's embarrassing!
Wow. On a webinar now hosted by Rob Thornton on Denver sewer heat recovery. Then will listen to Volts. Timing. Thanks.