FULL STEAM AHEAD
Most large commercial buildings and factories still rely on industrial boilers for heating, but nearly all use oil or natural gas to generate steam—and emissions. But the next clean industrial revolution could be just around the corner.
Written by Addison Stark
STEAM PLAYS A CRUCIAL ROLE in a wide range of industrial processes. In sectors such as food and beverage, pharmaceuticals, pulp and paper, and chemicals, steam is used to transfer heat, sterilize equipment, concentrate solutions, and drive endothermic reactions. These processes demand high reliability, consistent pressure, and controllable temperatures—attributes that steam systems are uniquely positioned to deliver. As a result, steam remains the thermal backbone of many production facilities across the country and around the world. According to the American Council for an Energy-Efficient Economy (ACEEE), approximately 37 percent of fossil fuel consumed by industry in the U.S. is used to produce steam, and its global primary energy consumption is equivalent to that used for steel production.
Beyond industrial applications, steam is also used in district energy systems that provide heat to entire neighborhoods, campuses, and cities. In urban environments like New York City and on college campuses across the United States, centralized steam plants distribute heat through underground pipe networks to buildings, reducing the need for individual boilers and improving energy efficiency. While these systems have the advantage of scale, they also rely heavily on fossil fuels and aging infrastructure. In Manhattan, for example, Con Edison operates the world’s largest steam network with 105 miles of steam mains that is responsible for heating 1.8 billion square feet of residential, 700 million square feet of commercial, and 90 million square feet of industrial floorspace.
In larger buildings—particularly older apartment complexes, hospitals, and government facilities—steam remains the dominant source of space heating and hot water. These systems were often installed in the early to mid-20th century and continue to operate today, offering a reliable though carbon-intensive heating solution.
Upgrading these legacy systems with modern, electrified steam alternatives represents a major opportunity to cut emissions while maintaining the performance characteristics upon which building operators and residents depend.
The steam boiler—one of the foundational technologies of the Industrial Revolution—has remained remarkably unchanged for more than 150 years.
A portrait of George Babcock
Photo: Keen Collection
ANCIENT ORIGINS
The steam boiler—one of the foundational technologies of the Industrial Revolution—has remained remarkably unchanged for over 150 years. In 1867, Babcock & Wilcox introduced the mass-produced “safety boiler,” standardizing industrial steam generation and ushering in a new era of scalable manufacturing and economic growth.
But the journey of the steam boiler began long before that. The concept of steam as a medium for transporting heat and power dates to the 1st century AD, with Heron of Alexandria’s aeolipile—a simple device that demonstrated the principles of steam propulsion. While it was more a curio than a workhorse, it planted the seeds for centuries of innovation.
In the 17th century, inventors like Denis Papin advanced the field by developing the steam digester, a precursor to the pressure cooker and early steam engines. By the early 18th century, Thomas Savery and Thomas Newcomen built some of the first practical steam engines for pumping water, laying the groundwork for more advanced applications.
James Watt’s improvements to the steam engine in the late 1700s, including the separate condenser and rotary motion, accelerated the adoption of steam power in industry. By the mid-19th century, steam boilers were essential to delivering heat for locomotion, manufacturing, and power generation. Yet, they were also prone to catastrophic explosions.
In response to the mounting toll of boiler accidents, the American Society of Mechanical Engineers (ASME) was founded in 1880 to improve the safety and standardization of boiler design. This move catalyzed the formal regulation and certification of boiler systems in the United States.
Steam remains just as vital today, and it continues to be predominantly produced by burning fossil fuels to boil water. Its generation delivers more than 50 percent of all industrial heat and accounts for approximately 8 percent of global energy use. This makes steam generation one of the most overlooked yet high-potential levers for industrial decarbonization. Fossil-fueled boilers alone are responsible for 2.25 gigatons of global greenhouse gas emissions annually, putting them on par with the emissions from steel or cement production.
A model of Babcock & Wilcox’s mass-produced “Safety Boiler”
Photo: National Museum of American History
Babcock & Wilcox’s “Safety Boiler” from the 1913 book, Heat Engines, by William Ripper.
GREENING STEAM
So why hasn’t this critical technology evolved? In short, economics. Conventional boilers are inexpensive, reliable, and easy to manufacture and maintain. While numerous low-carbon alternatives—including electric boilers, renewable natural gas, biomass combustion, and industrial heat pumps—have been developed, no solution has yet been proven cost-competitive at scale.
Fuel switching, for instance, can reduce carbon intensity by replacing natural gas with biomass or renewable natural gas. But in most cases, operating costs increase two- to tenfold or more, unless facilities already produce waste biomass onsite (as in pulp and paper mills). Similarly, electric boilers—from smaller resistive units to large electrode-based systems—are gaining traction due to their simplicity and plug-and-play nature. Yet with one unit of electricity yielding one unit of steam heat, their operating costs can be two to three times higher than those of fossil-fueled systems.
Industrial Thermal Energy Consumption by Heat Temperature
Credit: Renewable Thermal Collaborative
Thermal energy storage (TES) is another interesting solution for decarbonizing industrial steam by enabling the use of intermittent renewable electricity to produce and store heat for on-demand use. Systems like Rondo Energy’s brick-based batteries convert off-peak electricity into high-temperature heat, which can later be discharged. This approach addresses a core challenge for many industrial sites: How to maintain consistent steam output amid fluctuating renewable energy supply. By charging with off-peak power or on-site generated power and discharging as needed, TES can deliver low carbon heat at a competitive price.
These technologies are also well suited for integration into existing industrial operations. TES systems can be deployed modularly and operate at temperatures compatible with conventional boilers. Their ability to time-shift renewable energy and provide firm steam supply enhances energy resilience and reduces exposure to fuel price volatility. As more pilot projects come online and manufacturing scales, thermal storage is similarly poised to become a viable option for industrial steam decarbonization—providing a reliable, flexible, and emissions-free alternative to fossil-fueled heat—where low-cost renewable electricity is available.
Heat Pump Capacity in Buildings by Country and Region, 2021-2030
Pictured: Industrial heat pumps in a boiler room
Photo: Visoot Uthairam/Getty
Industrial heat pumps offer a more efficient path toward electrification. By moving and upgrading heat to generate high-temperature steam rather than converting chemical energy through combustion, they can deliver the same output with a fraction of the fuel input. But to date, they’ve been deployed only in custom, site-specific installations, relying on waste heat integration. These bespoke designs drive up capital costs, engineering complexity, and plant downtime. If the waste heat source goes offline, so does the steam supply. Until this point, the industrial heat pump industry has lacked a standardized, mass-manufactured, steam generation solution.
The development of industrial heat pumps dates back to the mid-20th century when early prototypes were used in niche applications like food processing and district heating in Europe. While residential heat pumps gained traction in buildings due to standardized equipment and favorable policy incentives, industrial-scale systems remained custom-engineered and limited to demonstration projects. These early systems often focused on recovering waste heat with limited temperature lift capabilities and were poorly suited to replace combustion boilers for high-temperature steam.
In recent decades, advances in compressor technology, refrigerants, and thermodynamic cycle design have significantly expanded the temperature range and efficiency of industrial heat pumps. Research institutions and companies across Europe and Asia have demonstrated steam-generating systems capable of exceeding 120 °C. Yet challenges associated with waste-heat integration complexity, cost, and reliability have kept them from scaling widely.
The next leap in potential comes not just from performance gains, but from standardizing these systems into modular products that can directly replace fossil-fired boilers across a broad set of industries, something that can be deployed across industries and geographies without complex retrofits or custom engineering.
Thermal storage and industrial heat pumps are complementary electrification technologies, each suited to different segments of industrial heat demand. Heat pumps offer high electrical efficiency, thus reducing grid interconnect requirements, and are effective for applications up to 200 °C. Thermal storage, by contrast, excels in high-temperature applications (>250 °C) and in bridging the gap between intermittent power supply and continuous heat demand. Together, they could provide a versatile toolkit for industrial decarbonization, expanding the range of processes that can be electrified and enabling deep emissions reductions across diverse sectors.
Above: An image of Boiler 2.0 by AtmosZero Left: “How Boiler 2.0 Works” Credit: AtmosZero
A SUSTAINABLE FUTURE
Like solar panels, batteries, and residential heat pumps before them, for industrial steam electrification solutions to be successful, the solutions must enter the market as modular, factory-built products designed for scale.
The U.S. has long been a leader in energy innovation—from the silicon breakthroughs that enabled solar photovoltaics to the lithium-ion batteries powering electric vehicles. But industrial decarbonization, particularly in process heat, has lagged. Despite growing pressure on manufacturers to cut emissions, deployment of next-generation heating systems remains limited to pilot projects and niche applications. What’s missing is the transition from custom projects to scalable products.
At AtmosZero, where I serve as CEO and co-founder, we saw the steam boiler as a tremendous opportunity. By applying the lessons from other technologies that have successfully scaled to industrial heat pumps, we’re working to commercialize a fully standardized and productized steam heat pump, which we call Boiler 2.0, designed to be a true drop-in replacement for fossil-fueled boilers. It delivers high-temperature steam from ambient air using a standardized, modular design that requires no waste heat, no custom engineering, and minimal site downtime.
Unlike conventional industrial heat pumps that rely on upgrading waste heat from adjacent processes, Boiler 2.0 operates independently, extracting low-grade heat from the environment and upgrading it to produce saturated steam at temperatures up to 150 °C. This is enabled by a novel system architecture that integrates a high-efficiency vapor compression cycle, optimized working fluids, and advanced control algorithms to maintain stable performance across varying ambient conditions. The result is a fully electrified, drop-in replacement for fossil-fired boilers that expands the applicability of industrial heat pumps to a broader range of facilities without requiring process redesign or waste heat availability.
Boiler 2.0 is among the first commercial systems to match or beat the operating cost of combustion boilers while eliminating emissions of carbon dioxide, nitrogen oxides, and particulate matter.
To avoid the cost and complexity of waste heat integration, we are working to lower both capital and operational barriers to adoption. By being factory-built, we hope to minimize project lead times and accelerate deployment across food and beverage, pharmaceuticals, chemicals, building heating, and more. In the same way that Babcock and Wilcox made the combustion boiler highly scalable, we’re working to make steam electrification a product, not a project.
As we saw in electric vehicles, solar cells, and the original steam boiler, scaling disruptive hardware requires three ingredients: a breakthrough product, mass manufacturing, and market pull. Industrial electrification now stands on the cusp of that trifecta.
Replacing fossil-fueled boilers with a productized air-sourced steam heat pump offers a pathway not just to decarbonization, but to modernization. These innovations can revitalize American manufacturing, strengthen energy security, and catalyze export-driven growth.
More than a century after Babcock & Wilcox changed the world with their safety boiler, Boiler 2.0 and other electrification approaches for higher temperature heat like thermal storage could spark the next industrial revolution. Built in America, deployed globally, and powered by clean electricity, they offer the rare promise of doing well by doing good—cutting costs, cutting emissions, and unleashing the full potential of steam for the 21st century.
Addison Stark is CEO and co-founder of AtmosZero, an industrial steam heat pump startup. He was previously a fellow at the Department of Energy’s ARPA-E division and was honored in the 2024 Mechanical Engineering Watch List.
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