Rob Thornton is President and CEO of the International District Energy Association (IDEA). In this feature interview with The Energy Mix publisher Mitchell Beer, he talked about where district heating and cooling can make a difference around the world as an antidote to a deadly “hidden epidemic” that kills 1,700 people per day, more than gun violence.

This interview has been edited for length, and to reflect the final number of countries signing IDEA’s global memorandum of understanding.

The Energy Mix: How have you seen district energy evolve over the last couple or few years, and do you think the pace of activity is meeting the full potential?

Rob Thornton: The district energy industry is really surging right now, both public and private investment globally. In North America, particularly in Canada, there’s been a great deal of engagement and innovation. We see new systems being designed, planned, and implemented.

We see existing systems growing organically and market share continues to ramp up dramatically, and not only in traditional hot climates like Dubai or Abu Dhabi or Doha. Now, because of extended heat waves and, frankly, public health and mortality issues, we’re seeing a lot more interest in northern cities like London, Brussels, Berlin. Seattle.

The Mix: Chicago, Vancouver, Victoria.

Thornton: Chicago already has a very significant district cooling system downtown in the loop. It serves 120 buildings, with five plants interconnected…

I was on a call with the UN Environment Programme, and one of the participants said that daily in the globe, more people die from heat exhaustion, 1,700 people per day, than are killed by gun violence. [World Health Organization data put the annual death toll from extreme heat at 489,000, or about 1,340 per day, between 2010 and 2019.] So it’s a hidden epidemic. You may recall some years back in Paris, there was an extended heat wave and 800 or 900 people died, mostly pensioners who were limited to their downtown apartments without air conditioning. As a result, there is a vast district cooling system in downtown Paris, and the mayor has pledged to double its size by 2030.

That is actually happening, and it’s very innovative. They recover waste heat from a waste-to-energy plant. They use that to produce cooling. They use the Seine River as a condenser loop. And in the wintertime, when the Seine is cold enough, that becomes the primary source of cooling. So district energy becomes a quiver of technologies. It isn’t a single plant serving a little district. It’s an aggregation of assets that really results in more resilience, higher efficiency, lower fuel consumption, reduced emissions, but the most important benefit is better public health and safety.

For our members that operate district cooling systems in cities like Dubai, where they now have 91 plant rooms, it’s not a luxury. It’s life safety. And because they use thermal storage, they can also dramatically change their electricity use profile so that not all these buildings are drawing electricity to run their own air conditioners at very low efficiency, then all just rejecting heat into the street onto their neighbour.

The Mix: So this also helps green the grid by reducing the basic demand that the grid needs to meet.

Thornton: Absolutely. It’s dramatic.

The Mix: So how do these insights help accelerate what district energy can deliver? You mentioned mostly communities in Europe and North America. Then you mentioned Dubai and Doha and Abu Dhabi. Now, let’s take ourselves to India, where the heat waves this summer have already been brutal and deadly—we saw five figures for the number of people killed over a period of days. What will it take to mainstream these technologies to the max in all of those different settings and economies?

Thornton: There is a good deal of activity in India. The challenge for district cooling, frankly, is adequate density, whether there are enough users with enough consumption within a district or cluster to enable the investment in a district cooling plant and network.

India is somewhat unique. There often isn’t uniform zoning, so you could have a 50-story tower next to smaller housing. There are certainly clusters where a hospital or a university is there as an anchor, where a large user can account for 30 or 40% of the initial investment. That’s typically how these things get started, where the business risk of building these networks or assets has at least some coverage initially, and then you build a plant. You look at the consumption patterns and the mix of uses and buildings, because different uses have different cooling requirements, and that tells you what sort of cooling revenue there will be. Then you assess the return you can generate on a $50-million investment over 30 years…

The Mix: So you need an anchor client in that scenario, but if the 50-story building had the right load profile, would that be your ticket to make this available to a community that wouldn’t otherwise have access?

Thornton: Potentially. Then the other considerations are, what are the other uses nearby? Does the scale of district cooling fit that use? Density matters, and use per trench-foot of pipe is an important criterion. So even if you had a 50-story building and the next five blocks were, say, two-story residential, that may not match. Even though you could cover a portion of the plant on that anchor, the distribution network would still need an amortization process.

But we’re getting very good as an industry at doing area-based planning. We try to solve these problems holistically, not one building at a time.

In Canada, the federal government recently modernized the four district energy plants that serve 80 buildings in the Parliament Hill district. They’ve gone from steam to hot and chilled water. And they’ve really modernized the source of energy, as well. They’re now combining natural gas and electricity, and the electricity is coming across the river from Hydro-Québec, arguably one of the greenest grids anywhere.

They’ve really reduced their emissions per kilowatt-hour of thermal energy, and now they also have tremendous flexibility. They can determine, based on either price or carbon intensity, which source to use. And they’ll be using the Ottawa River for their condenser water, and for cool and chilled water in the winter. This was an initial public-private investment of $1.2 billion with a 30-year concession agreement.

And Ottawa isn’t alone. We’re seeing electrification of steam in Boston, Cambridge, San Francisco, Vancouver, using low-carbon electricity with first-stage electric boilers, large electric boilers, then large industrial heat pumps, integrated with thermal storage.

The Mix: What is the pathway for district energy to get off gas? Because notwithstanding the gas industry’s reflexive greenwashing, we know that gas is still a methane bomb, and that methane is still 84 times more potent a greenhouse gas than carbon dioxide. So where’s the moment when district energy can largely or eventually completely electrify?

Thornton: District energy providers are aggressively decarbonizing their assets by integrating other sources like     wind or solar. However, depending on the uses, the customer cluster, many of them are also serving mission-critical assets in health care or research. And as I’m sure you’re aware, the price of electricity is rising at almost double the inflation rate. So…

The Mix: But that’s not because of renewables. If you look at the recent LT2 procurement in Ontario, they invited bids for both energy and capacity. The thumb was on the scale for gas, and yet the energy procurement led to [originally] 14 contracts, 12 solar and two wind. Then they announced their capacity results. Three projects, 640 megawatts over a business day, all batteries. So if you’re looking for cost-effective, you’ve come to the right place.

Thornton: I’m not saying renewables are the culprit here. But when you’re serving 30 million square feet of customer space and five million are health care, two million are research, and they maybe have decades of Petri dishes, there’s a resiliency requirement. And it’s really helpful to have gas-fired generation onboard, even a small portion.

The Mix: It’s funny, we’ve been hearing that argument for a long time. The example we’ve been seeing more recently is a facility running a 100- or 200-day experiment where it doesn’t even take a power outage. If the power frequency fluctuates, it sends the experiment back to Day One. We’re hearing that the solution begins with behind-the-meter renewables and storage. That gas might be reliable, but it’s not reliable enough for some of those very exacting applications.

Thornton: Again, it depends on scale. When Superstorm Sandy hit here in the U.S. in 2012, it touched 21 states and left eight million people without power—except for Princeton University, New York University, Co-op City, Fairfield University that had combined heat and power (CHP) on campus. They maintained heating, cooling, and power and became an area of refuge.

The Mix: So the argument is that in that emergency, you needed something that didn’t depend on centralized delivery. I think we’re both saying the question is what’s most affordable, what’s most reliable, what’s hyper-reliable when necessary, what’s quickest to scale, all of those standard questions.

Thornton: In 2012, lithium-ion batteries were really not available at any scale.

The Mix: Right, in 2012. But it’s 2026.

Thornton: And many of our universities are continuing to operate CHP behind the meter. They’re not selling power into the grid. They’re basically backing off the grid. Princeton University has 25 million square feet of invaluable research on campus. We’re talking ice cores that go back 100,000 years. They cannot lose power. They cannot go dark. MIT cannot go dark. But at Princeton, over the last 20 years, they’ve put on 16 megawatts of rooftop solar. They have 16 megawatts of natural gas turbine generation.

Their load on a summer day would be 27 megawatts. But guess what happens when that peak day comes around in June? It’s the hottest, most humid day of the year. Princeton diminishes its load to make sure their chilled water storage is plentiful and flowing. They may run their turbine. It’s usually a sunny day because it’s hot, so the photovoltaic unit is doing its job. And they appear to the grid on that day under one megawatt.

The Mix: So this really speaks for the value of distributed, decentralized, behind-the-meter generation. Not as 100% of the solution—we still need the grid connecting us all—but as a much bigger part than it’s been. How is district energy positioned to be a part of that, and to lead?

Thornton: We already are. What Princeton does, so does Harvard, so does MIT, as do a lot of our member systems. Not only do they monitor the price of power coming into their plant and whether they can make the power, heat, and cooling more affordably. Even if they burn natural gas, they’re reducing consumption dramatically because they’re making three products with it. The carbon they consume is actually producing 80, 85% of their needs, not just 30%, not just electricity. So these are incrementally lower-carbon solutions. The same thing happens in New York City with the district steam system because they’re using natural gas to make heat and power.

But here’s the thing. In addition to price, our member systems get a carbon signal from the grid. So on a certain day, sun’s really bright, lots of solar inrush, wind turbines are pumping, the carbon intensity of the grid is down, they buy more power. And you know what else they might do? They might store that power in their thermal systems, which happens all the time in Europe. They buy today’s power for tomorrow’s heat, and district energy becomes a grid resource.

The Mix: I’ve had the impression that North America is quite a ways behind Europe in this kind of technique. Correct me?

Thornton: No, no, not really. There are distinctions.

In the large cities in Europe—Helsinki, Copenhagen, Berlin, Paris—they’re largely hot water networks. Hot water is more easily stored, whereas steam is a gas and needs to be produced almost instantaneously. But with our high-temperature heat pumps, we produce high enough levels of heat and use electricity to make steam.

So in Boston, they have a 42-megawatt electric boiler that can cover 30 million square feet of floor space. It basically looks like a railroad car standing on its nose, very big, very heavy. If either the price of power or the carbon intensity on the grid drops, they can start that electric boiler almost instantaneously. Then at night when the demand for electricity is low, but the supply is still there because offshore wind is working and there are plenty of clean electrons, they can consume.

So when we aggregate these thermal loads and assets at scale, they make economic sense. We can do it because we’re serving a few 100, sometimes 1,000 buildings. One building can’t do that on its own. But district energy is surging because people are beginning to realize that if we approach this holistically as a community, or as a cluster, or a city, we can have access to these types of tools. We can use local energy, improve our circular economy, recover waste heat, collect from data centres, use a river or lake.

The Mix: Inurban planning, there’s a distinction between “tall and sprawl” and “missing middle” development or gentle density. Does that give you enough density that district energy can be a part of the solution?

Thornton: I think so. But it has to be available. A builder is really under time pressure to construct these assets, sell them, and get them occupied. But it is occurring.

The Mix: I guess False Creek in Vancouver is an example?

Thornton: Exactly. So it’s possible. It does require cohesion, though, and sometimes maybe a friendly nudge from the city. We’re seeing it in British Columbia, in cities like Surrey and Richmond and Vancouver. They don’t require district energy, but they’ve been involved in helping it deploy. So an informed local government, whether it’s through zoning or development, is the key to getting it done.

We had 19 countries sign a global memorandum of understanding at our annual conference in Ottawa in mid-June, and it’s really about best practices, advocacy, education for local governments, and progressive policy at the national and subnational levels.

The Mix: Did Canada sign on?

Thornton: Canada signed on, yes.