Why electrifying industrial heat is such a big deal

A full quarter of global energy use goes toward heat that powers industrial processes. To provide clean industrial heat but avoid the variability often associated with renewable energy, a company called Rondo makes a thermal battery, storing renewable-energy heat in bricks. In this episode, Rondo CEO John O’Donnell talks about this breakthrough technology and the opportunities that thermal storage promises to open.

(PDF transcript)

(Active transcript)

Text transcript:

David Roberts

Electricity gets the bulk of the attention in clean-energy discourse (this newsletter is, after all, called Volts) but half of global final energy consumption comes in the form not of electricity, but of heat. When it comes to reaching net zero emissions, heat is half the problem.

Roughly half of heat is used for space and water heating, which I have covered on other pods. The other half — a quarter of all energy humans use — is found in high-temperature industrial processes, everything from manufacturing dog food to making steel or cement.

The vast bulk of industrial heat today is provided by fossil fuels, usually natural gas or specialized forms of coal. Conventional wisdom has had it that these sectors are “difficult to decarbonize” because alternatives are either more expensive or nowhere to be found. Indeed, when I covered an exhaustive report on industrial heat back in 2019, the conclusion was that the cheapest decarbonization option was probably CCS, capturing carbon post-combustion and burying it.

A lot has changed in the last few years. Most notably, renewable energy has gotten extremely cheap, which makes it an attractive source of heat. However, it is variable, while industrial processes cannot afford to start and stop. Enter the thermal battery, a way to store clean electricity as heat until it is needed.

A new class of battery — “rocks in a box” — stores renewable energy as heat in a variety of different materials from sand to graphite, delivering a steady supply to various end uses. One of the more promising companies in this area is Rondo, which makes a battery that stores heat in bricks.

I talked with Rondo CEO John O'Donnell about the importance of heat in the clean-energy discussion, the technological changes that have made thermal storage viable, and the enormous future opportunities for clean heat and a renewables-based grid to grow together.

All right, John O'Donnell of Rondo. Welcome to Volts. Thank you for coming.

John O'Donnell

Thank you. It's a great pleasure.

David Roberts

I am so excited to talk to you. I've been geeking out about thermal storage for over a year now, just wanting to do something on it, and there's so much there. And I find that unlike a lot of electricity topics which I cover, there's just not a lot of baseline familiarity out there among, let's say, normal people. So there's a ton to cover from the ground up. So I want to start at the highest possible level, which is to say, let's just talk about heat. Like in the clean energy world, electrical power gets a lot of attention, a lot of discussion, a lot of technological development.

Everybody's got their favorites, everybody knows what's going on. But then there's also heat, which is the sort of weirdly ignored not so much anymore, but up till pretty recently ignored. So maybe just start with an explanation of why heat is important if you care about clean energy, why you should care about heat?

John O'Donnell

Thank you. Sure. That's a great question. And that context you just provided is, of course, dead on. There's a really simple answer. Heat. Industrial heat is 26% of total world final energy consumption. Whether you are making baby food, or fuel, or cement, or steel, the manufacturing processes vastly predominantly use energy in the form of heat, not electricity. Globally, it's three quarters of all the energy used by industry is in the form of heat. Again, whether you're pasteurizing milk or melting steel. And the DOE has just created a new office focused on this topic. We're thrilled about it.

Their assessment is that industrial heat is 11%, I think, of all total US CO2 I'm in California. Here in California, we burn more natural gas for industrial process heat than we do for electric power generation. And to a first approximation, as you just mentioned, no one knows that.

David Roberts

Right. So heat is a huge portion of final energy consumption. It's a huge portion of global CO2 emissions. So maybe give a sense of like, what percentage of total heat final consumption is industry, like how's the total heat-pie divided up.

John O'Donnell

So when I said 26% of world — that's industrial heat, right. So that's not buildings, that's not other heating sources.

David Roberts

Right. Heat is a bigger category than that.

John O'Donnell

I mean, if you take actually heat for buildings and heat for industry, together they're like 60% of all the natural gas used in Europe. But within industrial heat, people sort it out by a couple of different things. One of them is the temperature. There's a lot of heat in cooking processes. That's around 150°C in the form of steam all the way up to the highest temperature heat in making cement, that's around 1800°C. About 95% of total heat is used in processes that need it below 1500°C, about maybe half to two thirds of industrial heat is below about 400°C.

There's a fairly steep curve. About half of all industrial heat, something like that, is delivered as steam.

David Roberts

Right. Steam is the lower end of the temperature spectrum. I recall looking at these charts of sort of what industries use, what levels of heat. Up at the super high heat, you have pretty singular industries, like steel's up there and concrete's up there. But down in the lower heat registers, where you're using just steam, there's a bunch of little industries clustered up there. Most of the industries are using that.

John O'Donnell

That's right. All of these have been things that people say are hard to decarbonize because across many of these industries, they're making commodities, whether it's steel or tomato paste that are relatively low margin and for which the cost of heat is a very significant portion of the total cost of production. So this is a sector where all these processes use heat in somewhat different ways. The cost of that energy is really critical to the competitiveness of that industry and what commodities cost consumers. And there have not been great solutions until recently that could provide decarbonized heat at the same or lower cost.

David Roberts

So the situation is there's a huge chunk of our energy that goes toward heat, a huge chunk of that goes toward industrial heat. And there's been comparatively little work on finding zero carbon versions of that heat. That's the problem we discussed the last time we talked, probably three or four, five years ago. Everything pre-pandemic is a haze. But I think it was around five years ago I covered this big comprehensive report on industrial heat options, like