Tech Briefs: What inspired your research?
Jonathan Fan: This research was inspired by the urgent need to decarbonize industrial chemical processes that rely on high-grade heat traditionally produced through the combustion of fossil fuels. Our goal was to harness green electricity to efficiently drive thermochemical reactions, offering a sustainable alternative to fossil fuels. Our goal is to push reactor performance to new heights, enabling energy-efficient processes and scalability for industry.
Tech Briefs: What got you thinking about inductive heating?
Fan: Inductive heating caught our attention because of its inherent advantages, such as high efficiency, wireless contact, and scalability. Unlike traditional heating methods, inductive heating allows for direct and volumetric energy transfer without requiring physical contact. This leads to uniform power densities and reduces parasitic heat losses.
Tech Briefs: Has inductive heating been previously used for industrial processes?
Fan: While induction heating has been used in industrial applications before, it was often implemented without a rigorous co-design of the power electronics and the materials. This meant that earlier investigations didn't fully explore the potential for highly efficient volumetric heating. Our approach uniquely integrates two aspects, electronics and materials, to unlock new levels of efficiency and performance.
Tech Briefs: What are some types of industrial processes that thermochemical reactors are used for?
Fan: Thermochemical reactors are critical to a wide range of industrial processes that require high-grade heat to drive chemical reactions. These include the production of fuels, hydrogen, and other chemicals, through steam methane reforming, and ammonia synthesis. They are also used to produce materials like cement and steel.
We have used our reactor to power a chemical reaction, called the reverse water-gas shift (RWGS) reaction, which converts CO2 and H2 into CO and water. This reaction is crucial for CO2 utilization, as both H2 and CO are building blocks for synthesizing sustainable fuels and chemicals.
Tech Briefs: What new applications do you foresee?
Fan: Electrified thermochemical reactors are a viable and near-term solution to decarbonizing many heavy industry processes, which currently contribute significantly to global carbon emissions. Decarbonization solutions based on thermochemistry have advantages in scaling. That is very important when considering the decarbonization of commodity chemicals and materials and where the economics of the processes must be accounted for.
Tech Briefs: How would it be used in cement manufacturing?
Fan: Conventional cement manufacturing is a significant source of greenhouse gases due to the high-temperature requirements of the calcination process. By utilizing thermochemical reactors with our inductive heating systems, we can heat the raw materials, or a specially designed mixture baffle that is in close contact with the materials, providing efficient volumetric heating. This approach increases energy efficiency and reduces reliance on fossil fuels. In fact, this is an on-going research project in our lab.
Tech Briefs: You’ve written: “As we make these reactors even larger or operate them at even higher temperatures, they just get more efficient.” Could you explain why?
Fan: The efficiency gains as we scale up the size or increase operating temperatures in these reactors because of multiple factors, such as heat transfer, power dissipation, reaction kinetics, and reactor design. As reactor size increases, the energy losses from thermal conduction and coil power dissipation (parasitic losses) scale more slowly than the energy utilized for chemical reactions and gas heating (useful energy). In addition, at higher operating temperatures, reaction kinetics are enhanced, which leads to better conversion rates and reduced energy requirements. These electrical and thermodynamic factors enable us to push the reactor’s performance toward its physical limits, making it more efficient as it scales.
Tech Briefs: How much electrical power will be required?
Fan: The electrical power required for these reactors depends on several factors, including the reactor size, operating temperatures, chemical reactions, and the design of the power electronics. In our lab-scale demonstrations, the reactors operated in the 100 W range. However, as we grow the system to industrial scales, we expect the power requirements to increase significantly, reaching the kilowatt (kW) to megawatt (MW) range. Power electronics will also need to be co-designed to handle these large power demands as the reactor scales.
Tech Briefs: Could you tell me about your prototype?
Fan: Our reactor is powered by a custom power amplifier that drives the AC magnetic field and operates in the 100 W range at a frequency of 6.78 MHz. The amplifier is specially designed using wide bandgap semiconductor switches that can efficiently convert DC power to megahertz frequencies at high efficiencies. Our choice to perform magnetic induction at such a high frequency is based on detailed co-design of the power electronics with the reactor baffle, where we found that high frequency induction together with a properly designed three-dimensional baffle was required to enable highly efficient volumetric heating.
Tech Briefs: How does the efficiency of your reactor compare to conventional ones?
Fan: In contrast to conventional fossil fuel-based reactors, our reactors are decarbonized and have the potential to be much smaller and less costly because they do not require infrastructure such as external boilers and heat exchanger infrastructure. They can support process intensification — a reduction in reactor size due to enhancements of heat transfer within the reactor.
Regarding alternative electrified thermochemical reactors, our reactor concept has efficiencies approaching direct Joule heating and it uniquely supports a route to scaling such that it can readily apply to both modular and large-scale reactor form factors.
Tech Briefs: Do you have any thoughts about the timeline for commercialization? Would this be used only in new installations, or could it be retrofitted?
Fan: The intent of this research is to develop a new systems-level concept that integrates existing materials and power electronics in new ways, so it has a much lower barrier to commercialization compared to alternative concepts.
There are still important areas of development that need to be tackled, such as adapting our concept to pressurized environments, which we are currently working on. Looking ahead, we anticipate that the initial use case for these reactor systems will be new modular installations built in the vicinity of sustainable feedstocks and green electricity. They can also be used as retrofit solutions in some existing chemical manufacturing facilities.
Tech Briefs: Is there anything you would like to add?
Fan: Decarbonizing the chemicals industry is an urgent action item for the world. While there is no obvious solution yet, electrification will play a major role. Our goal is to provide a practical, economic, and scalable electrification solution as one such answer to this challenge. We hope our work helps to catalyze new efforts at the intersection of electrification and thermochemistry. We are enthusiastic about our initial analysis and results, but there is still much to be done to translate these concepts to the real world.
