Applications of Solar Thermal Technology for Plastic Waste Management in Developing Communities

Abstract: As the plastic industry continues to grow globally, with plastic materials contained in a vast quantity of consumer products, the management of the resultant waste has become one of the greatest challenges of our time. Greater than 8 million metric tons of plastics were estimated to enter the world’s oceans as of 2010, with an even larger amount remaining on land. The associated ecological and health effects of plastic waste disposal are many, and existing solutions can only tackle small portions of the waste.China and Indonesia top the current list of contributors to ocean contamination with plastic waste, which is dominated by Asian countries. China in particular is positioned as the world’s leader in plastic production. The waste management scenarios of these countries and associated energy outlooks are discussed, where the plastic waste of the islands of Indonesia is mostly a result of residential, not industrial activities. These calculations are projected to 2025 with recent values of population growth, as an update to previous literature, with Vietnam now expected to supersede both Indonesia and the Philippines. Given the available solar resource in the top coastal plastic waste producing nations, many of which lie within close proximity to the equator, the feasibility of applying solar thermal power for the melting of plastic waste is examined. Melting points of common plastics are typically below 200°C, and thus lie within the range of low-temperature parabolic solar thermal systems.A prototype non-evacuated tube parabolic trough was constructed following methodologies for accessible technologies for the developing world. Tests in Stockholm, Sweden demonstrated its ability to partially melt waste ABS from a 3D printer. Internal temperatures up to 211°C were recorded in further tests in Ioannina, Greece, where HDPE, LDPE, and PP were successfully melted along with waste household items. Heat loss was calculated as well as associated internal dynamics, examining the interaction of ambient conditions with the chosen design parameters. Additional testing is needed to constrain surface heat loss for higher temperature applications such as plastics like PET that melt above the exhibited range. Future refinements to the design are discussed as well as the role micro-projects have in the reduction of plastic waste at its source within developing countries.