What's the deal with district energy?
District energy refers to a system in which a shared central plant distributes steam, hot water, and/or chilled water to multiple buildings via underground pipes. In this episode, Rob Thornton of the International District Energy Association shares about district energy’s newfound popularity and the role it could play in the clean energy transition.
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David Roberts
District energy is one of the oldest concepts in all of energy, dating back at least to the ancient Romans. It simply refers to connecting multiple buildings to a common source of heating and cooling — a furnace, heat pump, geothermal well, or what have you — and distributing the heat via water or steam flowing through underground pipes. There are hundreds of district energy systems in operation, in every country in the world. (Virtually all of the buildings in Iceland, which I visited recently, are heated by district energy systems running on geothermal.)
However, fossil fuel heat has been so cheap for so long that district energy has never quite become the default — it’s just been too easy to stick a natural gas furnace in every building. There hasn’t been much pressure to share heat.
But with the climate crisis and the clean energy transition, that’s changing. These days, lots of people are looking for cleaner sources of heat and more efficient ways to share it, so district energy is becoming sexy again. Among other things, it’s a great way for cities to meet their carbon goals without overburdening their electrical grids.
With all that in mind, I contacted Rob Thornton, the head of the International District Energy Association, to chat about the clever new sources district energy systems are drawing on (everything from sewage to deepwater lakes), the infrastructure they can integrate with, and the other services they can provide.
All right, then. With no further ado, Rob Thornton of the International District Energy Association. Welcome to Volts. Thanks so much for coming.
Rob Thornton
Thanks for having me, David. Pleasure to be here.
David Roberts
I am super into district heat, so I was delighted when you all reached out to me. I've been meaning to do something on it, but I think it's, at least in the US, not particularly familiar or well understood to most people. It's relatively rare in the US, which we will discuss later. So, let's start with a definition. What is district heating?
Rob Thornton
So, we call it district energy because it's both heating and cooling in cities, campuses, communities. Essentially, it's a central plant that's providing steam, hot water, and/or chilled water to an underground thermal piping network to provide heating and cooling to buildings in a city central business district, campus, airport, hospital, healthcare, et cetera. So, it really is the aggregation of multiple users of heat or cool provided by a central plant. So, each individual building doesn't need to dedicate space or equipment, right, to boilers, chillers, et cetera. So, yeah, that's the simple definition.
David Roberts
Could not be more simple. It's using one source, a single source of heating and cooling for multiple buildings, which you think seems like an obvious thing to do. What, in terms of existing district energy systems in the world, what is that central source? Typically, empirically, what's the most common current central source?
Rob Thornton
I'd say at the moment, still natural gas.
David Roberts
Just a big boiler?
Rob Thornton
Well, often large boilers, sometimes gas turbines, recovering the heat, making additional electricity. So, combined heat and power. But that's shifting with the energy transition appetite for lower carbon solutions. There's a l
