The future of PET recycling: Harnessing bacteria and waste heat from data centers
Think of an artist who uses everyday objects to create stunning sculptures. Instead of seeing a pile of scrap metal, they envision a beautiful piece of art and bring it to life. That’s the kind of innovative thinking process engineers at AECOM are applying. They are looking at data centers from a different perspective. In the next few years, there will be a significant increase in the number of data centers built in the U.S. While many engineers focus on maximizing computing power, our process engineers are turning their attention to the often-overlooked byproduct: waste heat.
One fascinating opportunity they’ve identified is using this waste heat to assist in the production of PET (polyethylene terephthalate), a type of plastic commonly used in packaging. This forward-thinking approach exemplifies how we are pushing the boundaries of conventional engineering.
PET plastic is ubiquitous in everyday life. From water bottles to food containers, PET is one of the most widely produced plastics, with around 70 million metric tons produced annually. Despite its prevalence, only about 29 percent of all disposed PET was recycled in 2022. Traditional recycling methods often degrade the quality of PET, limiting the applications for recycled PET.
A breakthrough in PET recycling
In 2016, scientists made a remarkable discovery in a bottle recycling facility: a strain of bacteria known as ideonella sakaiensis. This bacterium produces two enzymes capable of breaking down the ester bonds in PET, reducing it to its monomer components. These monomers can then be reused to produce PET goods of the same quality as those made from virgin plastic.
Since this discovery, researchers have made significant advancements, developing more active and stable strains of ideonella sakaiensis. Under optimal conditions, these bacteria can break down 90 percent of PET in just 10 hours. To thrive, ideonella sakaiensis requires a steady heat source, ideally around 50°C.
Innovative use of waste heat
Data centers produce large amounts of low-quality heat at temperatures of 30-40°C. While the low temperature presents challenges for traditional recovery and reuse of this waste heat, PET recycling presents a unique opportunity due to its low ideal temperature for growth. By collocating a data center with an ideonella sakaiensis recycling plant, the waste heat from the data center could be used to reduce the heating load on the reaction vessel. While additional heating is still required, this innovative approach could lead to potential energy savings.
This approach highlights our innovative thinking in tackling key data center challenges by leveraging our process expertise and thinking outside the box to find effective solutions.
The fluctuating nature of the waste heat supply means that cost savings can vary, ranging from $23,700 to $76,800 annually for a 47,000-square-foot data center. This not only makes use of a waste stream from the data centers to reduce heating load, but also contributes to a more sustainable and eco-friendly solution.
Conclusion
The combination of ideonella sakaiensis bacteria and the innovative use of waste heat from data centers offers a promising, more economical, and sustainable future for PET recycling. By enhancing the quality of recycled PET and reducing operational costs, this approach could significantly improve the sustainability of PET production and recycling.
Our process department exemplifies innovation and creativity in the engineering field. By reimagining the role of data centers and harnessing the untapped potential of waste heat, they are pioneering new ways to enhance energy efficiency and sustainability. This inventive approach not only sets AECOM apart but also demonstrates their commitment to pushing the boundaries of conventional engineering.
What are your thoughts on this innovative approach to recycling?