New method to converts plastic trash into clean hydrogen fuel

Scientists from Nanyang Technological University, Singapore (NTU Singapore) have developed a new method for plastic waste to be converted into hydrogen based on pyrolysis, a high temperature chemical process. Unlike PET plastic bottles which can be recycled easily, plastic litter containing contaminated food packaging, styrofoam and plastic bags, is challenging to recycle. They are currently incinerated or buried in landfills, leading to both water and ground pollution.

Using pyrolysis, plastic litter can then be converted into two main products: hydrogen and a form of solid carbon called carbon nanotubes. Hydrogen is useful for generating electricity and powering fuel cells like those found in electric vehicles, with clean water as its only by-product.

To further refine the new conversion method and to assess its commercial feasibility, the research team is test-bedding it on the NTU Smart Campus to treat local plastic waste, in partnership with Bluefield Renewable Energy, a local environmental firm that specialises in mobile waste to resources technologies. The multimillion-dollar research joint project, supported by the Industry Alignment Fund-Industry Collaboration Projects (IAF-ICP) administered by Singapore’s Agency for Science, Technology and Research (A*STAR), aims to develop feasible solutions to economically scale up the conversion of waste plastics to hydrogen over the next three years. 

The project will also explore the potential of other emerging technologies for decentralised waste management. The conversion of challenging waste streams into energy and valuable resources, such as syngas, biochar, activated carbon and carbon nanotubes will be investigated.  

With 832 million kilogrammes of unrecycled plastic waste generated in Singapore annually, the converted energy could potentially power up to 1,000 five-room apartments for a year.

Led by Associate Professor Grzegorz Lisak from NTU’s Nanyang Environment and Water Research Institute (NEWRI), the research project used marine litter collected from local waters in collaboration with the Ocean Purpose Project, a non-governmental organisation and social enterprise based in Singapore. 

With 269 million kilogrammes of plastic waste currently floating in the oceans, the NTU team estimates that if converted into energy the waste could power an electric vehicle for 20 to 40 million kilometres – 500 to 1000 times the Earth’s circumference. 

“As part of NTU’s sustainability drive, in developing new ways to turn trash to treasure, we  are looking to convert waste plastics that cannot be recycled into high-value chemicals and resources, such as hydrogen fuel, synthetic fuel that could replace petrol, and carbon nanotubes used for many industrial applications,” explained co-inventor Associate Professor Lisak, Director of the Residues, Resource and Reclamation Centre  (R3C) at NEWRI, who is  also a faculty at the School of Civil and Environmental Engineering.

Last November, NEWRI researchers participated in Race for Oceans Singapore, a kayak race organised by the Ocean Purpose Project, to collect plastic waste along the shores of Singapore. The purpose was two-fold – to clean up marine litter through sports as community mobilisation and to use these litter as research materials for developing an efficient plastic waste-to-hydrogen process. 

Ms. Mathilda D’silva, CEO and Founder, Ocean Purpose Project, said: “Our collaboration with NTU NEWRI comes at a critical time when we need to rethink how plastics are recycled in Asia. As evident in our recent collaboration for the Ending Plastic Pollution Innovation challenge (EPICC) United Nations Development Programme, where NTU NEWRI showcased how plastics in Lombok, Indonesia could be converted into hydrogen, it is clear that there is an untapped and highly available resource of ocean plastic that can be converted into the fuel of the future: hydrogen, which will prove a gamechanger in removing ocean pollution at scale.

“The cutting-edge research, innovation and dynamism of the NTU NEWRI team is a dream collaboration for NGOs like us in ocean conservation, who have to move beyond awareness campaigns and beach clean ups towards completely disrupting our ideas of how plastic waste should be handled. We are proud as plastic-to-resources influencers to promote our Singapore-based research that will forge a new future for plastic recovery, potentially cleaning thousands of coastlines in Asia.”

Mr. Craig Gavin, CTO, Bluefield Renewable Energy (BRE), added that during the pandemic, there has been increased plastic usage due to food delivery and more grocery shopping. Current practices and efforts to recycle them have been challenging and require disposals in landfills and/or incineration plants leading to environmental contamination issues. BRE prices itself for its ability to convert wastes into resources based on its flexi-pyrolysis system.  Its collaborating  with  NTU  NEWRI  has  allowed  BRE to  utilise  these  environmentally unfriendly  plastic  waste  stream  as  a  feedstock  and  convert  them  into  valuable resources.  

The research team says the solid carbon from their new conversion process is much easier to store as compared to gaseous CO2 emissions from plastic waste incineration. Furthermore, the solid carbon can be easily sold as a manufacturing feedstock for speciality chemicals or biofuels.  For instance, it is a greener source of carbon for making carbon nanotubes, which is useful for many applications such as for batteries and composite manufacturing, says NEWRI Senior Research Fellow Dr Andrei Veksha, the co-inventor of the process who is piloting the technology.

Plastic waste-to-hydrogen is a two-stage process: plastic waste is first decomposed upon  heating  into  gases  that  contain  low  concentrations  of  hydrogen  molecules. During the second stage, when the gases enter a reactor filled with a catalyst, the technology  enables  the  release  of  hydrogen  fuel  and  the  formation  of  carbon nanotubes.

If the initiative is successful, it will help Singapore reduce the amount of total waste disposed and prolong the lifespan of Singapore’s only landfill, Semakau Landfill, which is estimated to run out of space by 2035.  This  research  collaboration  is  also  part  of  NTU’s  commitment  to  sustainability, unveiled  in  its  Sustainability  Manifesto  earlier  last  year,  where  the  University  has pledged to reduce its waste, water and energy consumption by 50% by 2026, as compared to the levels of 2011, and to achieve carbon neutrality as well as a 50% reduction in carbon emissions. 

- This article also appears in the International Plastics News for Asia - June issue. To read the e-zine, click here.