Process Heating: A Key Step in Industrial Electrification (CEP)

Published in the July 2023 print issue of Chemical Engineering Progress (CEP), the flagship publication of the American Institute of Chemical Engineers.

This 1,500-feature is a trend piece about the electrification of the process industries.

The chemical process industries are deeply rooted in fossil-fuel powered operations, especially when it comes to process heating. Today, though, innovations in electrification are on the cusp of transforming the process industries. Just as electric cars are becoming more widespread, electric heat sources are starting to replace fossil fuel combustion in plants and factories. 

Process heating — for drying, melting, and cracking processes — accounts for 45% of energy consumption in industry, contributing a significant portion of greenhouse gas emissions from the industrial sector (1). In the critical effort to reach net-zero emissions by 2050, companies of a variety of sizes, from startups to corporate giants, are researching and developing new technologies and solutions that could decarbonize industrial heat. 

This transition is in part enabled by dropping prices in renewable electricity, which makes electrification not only an opportunity for businesses to reduce emissions, but save costs. 

“Roughly a third of overall global energy demand comes from industrial manufacturing and 80–90% of it is currently supplied through fossil fuels,” says Monica Heredia, Shell’s Theme Lead in the Electrification of Demand Technology Program. “Electrifying industrial heat demand is paramount to achieving net-zero emissions in the energy system.” 

Steam cracking without emissions

Steam cracking, the process of breaking down hydrocarbon feedstocks into the building blocks used to make plastics and chemicals, is one of the most carbon-intensive aspects of petrochemical manufacturing. Its furnaces produce roughly 270 million tons of CO2 per year—equivalent to about 10% of global CO2 emissions. 

In a move toward sustainability, industry giants Shell and Dow, together responsible for nearly 10% of the global ethylene market, have formed a collaborative development agreement to accelerate technology for electrifying steam cracking furnaces. The collaboration, which began in 2021, is part of both companies’ commitments to becoming a net-zero-emissions businesses by 2050. 

The program aims to reinvent steam cracker design to use electricity rather than fossil fuel combustion for heat, paving the way for what will be known as an e-furnace. “While theoretically possible, e-furnace has never been proven on an industrial scale,” says Leslie Fan, Dow’s External Technology – Government Program Collaboration Manager. “This is a genuinely groundbreaking technology that could cut our cracker emissions by 90% and, if taken together with clean energy, by 100%.”

In July 2022, Shell and Dow’s experimental e-cracking furnace was successfully started up on Shell’s Energy Transition Campus Amsterdam in The Netherlands. The unit is being used to test and validate critical process hardware that will be required for retrofitting today’s gas-fired steam cracker furnaces. Data generated from the experimental unit will inform the engineering design and scale-up of a larger pilot e-furnace, which is planned to start up in 2025, subject to investment.

Scaling electric heating will also depend on another factor: the availability of clean energy. For electric applications to be considered carbon-neutral, they must use electricity generated via renewables as opposed to coal-fired or natural gas power plants. However, renewable energy currently constitutes less than one-third of the global electricity mix, and key infrastructure is missing to fully decarbonize electric grids. 

“We believe government plays a significant role in accelerating the development and deployment of all forms of clean energy technologies such as nuclear, battery technologies, and modernization of the transmission grid,” says Fan. Provided that clean, cost-effective electricity is readily available, industrial-scale e-furnace technology should one day be possible. 

“Any pathway to net-zero emissions will require deeper electrification of the U.S. economy, with most of that electricity generated from renewable sources. In Shell’s scenario analysis, more than 60% of final energy demand will need to be electrified by 2050, compared to about 22% now,” says Heredia.

Decarbonizing heat and grids with long-duration energy storage

One solution to providing a more stable and reliable clean energy system — thus enabling wider solutions for industrial electrification — is long-duration energy storage (LDES). LDES technologies, which can store energy from 10 hours up to days or weeks, address the intermittent nature of renewables like solar and wind.

RedoxBlox, a company specializing in thermochemical energy storage systems, is aiming to use their innovative energy storage modules to decarbonize two areas: industrial heat and power grids. “Our goal is to use a combination of electrification and energy storage to compete directly with natural gas,” says James Klausner, RedoxBlox Chairman and Founder. “We can be a drop-in replacement anywhere you have a natural gas budget.” For example, RedoxBlox modules can effectively replace gas turbines, calciners, steam boilers, metal-melting furnaces, and so on — but this heat source is zero-carbon. 

The company is already working with a number of industrial customers to implement their modules as heat sources in process facilities. Deploying the modules on a grid-scale, however, is a longer-term vision that may rely on government funding, Klausner says. 

The RedoxBlox module design features a steel vessel filled with a proprietary metal oxide material in pelletized form. To charge it, renewable electricity from the grid is used to heat the metal oxide pellets to 1,000–1,500°C, triggering an endothermic reaction that releases oxygen and stores heat in the form of chemical energy. Later, when the stored energy is needed, passing air through the system causes the metal oxide pellets to consume the oxygen, reverse the reaction, and release heat to the oxygen-depleted air. Hot air from the RedoxBlox module can then deliver heat to an array of industrial processes, or it can be delivered to a gas turbine to generate electricity. 

Still, convincing companies to electrify comes down to cost, and natural gas is typically cheaper than electricity. RedoxBlox’s strategy here is to purchase renewable electricity at times of curtailment, or when supply exceeds demand on the grid. “We grab those electrons when they’re available at low cost, store the energy, and then we can deliver 24/7,” says Klausner.

The other challenge is scaling. RedoxBlox modules have demonstrated an energy capacity of 100 kilowatt-hours (kWh). The next demonstration will be 2 megawatt-hours (MWh). However, tackling the big carbon emitters in the industry, such as steam cracking for ethylene production, will require hundreds of megawatts of power. “It’s going to be a few years until we get to that scale,” Klausner says. “Our strategy is to tackle small-scale industrial heat markets first, and then gradually scale to get to that large-scale industrial heat market.” 

Thinking even bigger picture, RedoxBlox also wants to use its technology to put renewable electricity back on the grid. The company envisions retrofitting its modules with existing combined cycle power plants, where stored heat could be converted back into electrical power. This could seamlessly transform existing natural gas power plants into renewable energy storage facilities, a huge step toward net-zero goals. 

Re-designing industrial heat from the ground up

Decarbonizing commercial-scale industrial plants presents immense challenges. For example, bringing in enough electric current to support electric heating technologies could require complex infrastructure changes at the plant-level. But certain electric heating companies are making headway with small-scale manufacturers; and their solutions may inspire new, more sustainable plants and processes.

IFS, a North Carolina company that develops industrial heating equipment, is working to make process heating for fluids more precise, with less energy. “Heating of a fluid is one of the most difficult areas to decarbonize because everyone's process is a little bit different,” says Francesco Aimone, the company’s CEO and cofounder. “One manufacturer’s orange juice is not like the next chemical company’s monomer.” 

IFS aims to provide custom heating solutions to a wide range of industries, from food to fuel, enabled by its innovative FluxCore technology. The approach wields all the advantages of induction — rapid heating, high energy efficiency, and precision temperature control — with an added benefit. Typical industrial practices heat fluids from the outside in: a product runs through a tube, which is surrounded by hot steam from a boiler. But IFS equipment heats fluids directly from the “middle out,” explains Aimone. This relies on a special insert, called a FluxCore, which runs through the center of a process tube. Surrounding the tube, a coil energizes the FluxCore using electromagnetic energy, heating the flowing fluid. Currently, IFS systems can operate at temperatures up to 300°C. 

Although originally developed for pasteurizing and sterilizing food products, IFS technology is starting to find new applications in the chemical and petrochemical sectors. The company’s FluxCore design makes it effective at fast yet gentle heating of viscous liquids, a challenge that traditional steam-based systems often face. On top of that, the system has precision temperature control to 0.1°C. These capabilities make FluxCore heating particularly suited to delicate processes in the specialty chemical industries, where maintaining the integrity of highly specialized molecular structures is critical. 

In San Francisco, Malachite Technologies, an engineering service provider, is developing a heating technology using another familiar system: microwave. For decades, process industries, such as food, textiles, and ceramics, have used microwave technologies for heating and drying applications, according to Alex Welsh, a material scientist and Malachite cofounder. “But the chemical industry never really took that on, likely because of scale and cost. Now… microwave is having a bit of a resurgence.”

Malachite has engineered a continuous flow microwave reactor that’s currently in the pilot testing phase. But the system isn’t like the microwave in your kitchen. Whereas your kitchen microwave is multimode, meaning multiple electromagnetic waves bounce throughout the microwave cavity, the new technology is monomode, meaning a single, steady wave of energy is directed at an exact location in the reactor. This offers better control, a higher electric field, and higher heating rates, claims Welsh. 

In the Malachite lab, the company used their microwave system to demonstrate ammonia synthesis. Currently, as a proof concept, they are able to produce 1 kg of ammonia per day. Looking ahead, this electrified heat source could perhaps even change ammonia’s production model, transitioning it from a centralized approach to a distributed one, says Welsh. “We're hoping that with a microwave-assisted technique, you can reduce the temperature, you can reduce the pressure, and you can have it operate economically at a smaller scale, in a distributed and deployable model,” he says.

This is just one area where microwave heating could replace burning carbon. Many companies are developing new microwave-assisted technologies, including for hydrogen production, methane conversion, recycling plastics, or creating biofuels. “There's lots of applications being developed,” says Welsh. “The sky's the limit.”