Decarbonizing heavy industry with thermal batteries
Whether you manufacture cement, steel, chemicals or paper, you need a large amount of heat. Almost without exception, manufacturers around the world create that heat by burning fossil fuels.
In an effort to clean up the industrial sector, some startups are changing production processes for specific materials. Some even change the materials themselves. Daniel Stack SM ’17, PhD ’21 aims to address industrial emissions across the board by replacing the heat source.
Since joining MIT in 2014, Stack has worked to develop thermal batteries that use electricity to heat a conductive version of ceramic firebricks, which have been used as heat stores and insulators for centuries. In 2021, Stack co-founded Electrified Thermal Solutions, which has since demonstrated that its refractory bricks can efficiently store heat for hours and dissipate it by heating air or gas to 3,272 degrees Fahrenheit – hot enough to power the most demanding industrial applications .
Reaching temperatures above 3,000 F represents a breakthrough for the electric heating industry, as it allows some of the world’s hardest-to-decarbonize sectors to use renewable energy for the first time. It also unlocks a new, low-cost model for using electricity when it is cheapest and cleanest.
“We have a global perspective at Electrified Thermal, but in the US we have seen an incredible opportunity emerge in energy prices over the past five years that drives flexible electricity purchasing,” says Stack. “Across the country, especially in the wind zone, electricity prices are negative in many places for more than 20 percent of the year, and the trend toward declining off-peak electricity prices is a nationwide phenomenon. Technologies like ours The Joule Hive Thermal Battery will allow us to access this cheap, clean electricity and compete with fossil fuels in terms of price for industrial heating needs, without even taking into account the positive impact on the climate.
A new approach to an old technology
Stack’s research plans changed quickly when he joined MIT’s Department of Nuclear Science and Engineering as a graduate student in 2014.
“I went to MIT excited to work on the next generation of nuclear reactors, but what I focused on from day one was how to heat rocks,” says Stack. “It wasn’t what I expected, but when I spoke to my advisor, [Principal Research Scientist] Charles Forsberg, on energy storage and why it was valuable, not just for nuclear power, but for the entire energy transition, I realized there was no project I would rather work on.”
Refractory bricks are ubiquitous, inexpensive bricks that have been used in fireplaces and ovens for thousands of years. In 2017, Forsberg and Stack co-authored a paper demonstrating the potential of refractory bricks to store heat from renewable sources, but the system still used electric resistance heaters – like the metal coils in toasters and space heaters – that limited the temperature output.
For his doctoral work, Stack worked with Forsberg to create refractory bricks that were electrically conductive, replacing the resistance heaters so that the bricks produced the heat directly.
“Electric heaters are your biggest limitation: they burn out too quickly, they break, they don’t get hot enough,” Stack explains. “The idea was to ditch the heaters because flints themselves are very cheap, plentiful materials that can reach flame-like temperatures and linger there for days.”
Forsberg and Stacks were able to create conductive refractory bricks by modifying the chemical composition of traditional refractory bricks. Electrified Thermal bricks are 98 percent similar to existing refractory bricks and are produced using the same processes, allowing existing manufacturers to make them cheaply.
Towards the end of his PhD program, Stack realized that the invention could be commercialized. He started taking classes at the MIT Sloan School of Management and spent time at the Martin Trust Center for MIT Entrepreneurship. He also participated in the StartMIT program and the I-Corps program and received support from the U.S. Department of Energy and MIT’s Venture Mentoring Service (VMS).
“Through the Boston ecosystem, the MIT ecosystem, and with help from the Department of Energy, we were able to launch this from the MIT lab,” Stack says. “What we spun out was an electrically conductive flint, or what we call an e-Brick.”
Electrified Thermal contains the refractory bricks in insulated, ready-to-use metal boxes. While the system is highly configurable depending on end use, the company’s standard system can collect and release approximately 5 megawatts of energy and store approximately 25 megawatt hours.
The company has demonstrated its system’s ability to produce high temperatures and has deployed its system at its headquarters in Medford, Massachusetts. That work has earned Electrified Thermal a combined $40 million from various Department of Energy offices to scale up the technology and work with manufacturers.
“Compared to other electric heaters, we can run hotter and last longer than any other solution on the market,” says Stack. “That means replacing fossil fuels at many industrial sites that could not otherwise be decarbonized.”
Scaling up to solve a global problem
Electrified Thermal works with hundreds of industrial companies, including manufacturers of cement, steel, glass, basic and specialty chemicals, food and beverages, and pulp and paper.
“The industrial heating challenge affects everyone under the sun,” says Stack. “They all have fundamentally the same problem: getting their heat in a way that is affordable and carbon-free for the energy transition.”
The company is currently building a commercial version of its megawatt-scale system, which is expected to be operational within the next seven months.
“Next year will be a huge proving ground for the industry,” says Stack. “We will be using the commercial system to show a variety of operating points that customers need to see, and we hope to have systems running at customer locations by the end of the year. It will be a huge achievement and a first for electric heating, as no other solution on the market can produce the kind of temperatures we can produce.”
By working with manufacturers to produce its refractory bricks and casings, Electrified Thermal hopes to deploy its systems quickly and at low cost across a vast industry.
“From the very beginning, we designed these e-bricks to be rapidly scalable and rapidly producible within existing supply chains and manufacturing processes,” says Stack. “If you want to decarbonize heavy industry, there is no cheaper way than converting electricity into heat from carbon-free electricity sources. We want to be the leading technology that unlocks these possibilities, with double digits of global energy flowing through the system. our system as we achieve the energy transition.”