Dryers account for more than 75 percent of energy use in paper mills. Orien Energy is commercializing a low-cost energy and water harvesting device to retrofit dryers in paper mills, aimed at significantly reducing energy waste.
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Yajing Zhao
Yajing Zhao is the founder and CEO of Orien Energy, which seeks to enhance energy-efficiency via surface innovations. She holds a Ph.D. in mechanical engineering from the Massachusetts Institute of Technology. She is passionate about clean energy and has spent two years of research in power plant thermo-economic analysis and six years of research in condensation heat transfer. Zhao advocates for women’s empowerment and served as the executive co-chair of the MIT Mechanical Engineering Graduate Association of Women.
TECHNOLOGY
Critical Need
Roughly a third of global primary energy demand and emissions are attributed by the industrial sector. As much as 20% to 50% of industrial energy consumption is ultimately discharged as waste heat. Drying, one of the most energy-intensive industrial processes, leads to enormous amounts of low-temperature waste heat, typically in the form of warm moisture. Existing technologies of waste heat recovery (e.g., Organic Rankine Cycle) focus on medium and high temperatures (T>200°C), but do not address waste heat dissipated at low temperatures. Turning low-temperature waste heat into useful heat is challenging and industrial end-users are looking for viable solutions to do that.
Technology Vision
Orien Energy is developing an innovative sorption heat pump to recover waste heat in dryer exhaust. Sorption heat pumps have existed for decades, with great potential for recovery of low-temperature waste heat. Unlike mechanical heat pumps that are driven by electricity, sorption heat pumps use heat as the driving force for temperature lift. When electricity prices are high or there is abundant waste heat, sorption pumps become advantageous. However, commercialization of sorption-heat pumps has not been widespread, with limited use cases primarily in the chiller space. The common barriers for them to be adopted include: system complexity and the associated high capital expenses (CapEx); use of high-temperature heat sources for the regeneration of sorption materials; use of corrosive materials (i.e., liquid desiccants) or requirement for high vacuum (in the case of solid desiccants); low coefficient of performance (COP). Orien Energy aims to address customers’ needs by developing a simple, cost-effective, and energy-efficient heat pump that can be easily retrofitted to existing facilities, with a potential to cut energy consumption in the drying process by over 40%.
Potential for Impact
Orien Energy is developing a disruptive sorption heat pump to recover and upgrade the waste heat in the dryer exhaust. The recovered energy in the format of steam can be directly used in industrial processes. Such a technology is of utmost interest to industries where premium process heat is wasted as moisture, for example, paper and food industries. The paper industry, as an example, spends over 60% of its total energy consumption in drying. Assuming a steam cost of $6/MMBTU and a 40% of energy consumption reduction in paper drying, Orien Energy can save over 1 quads of energy per year for the global paper industry alone, translating to a $8B market.