The research team, led by Kwame Ankomah with David Azanu and Mwema Felix Mwema, followed the internationally recognized ISO 14040 and ISO 14044 standards for life cycle assessment. Rather than examining a single factory or a single pollutant, the method traces every input and output associated with a defined unit of production. In this case, the functional unit was 100,000 polyethylene carrier bags manufactured per year, weighing 750 kilograms in total. That figure reflects the scale of small and medium-sized recycling operations that have sprung up across Ghana, where plastic waste collection and reprocessing have become both an environmental necessity and a source of livelihood.

The system boundary of the analysis covered the manufacturing phase along with the upstream burdens of the materials and energy that feed it. Electricity consumption, sodium nitrate, and carbon black production were all included, with background data drawn from the Ecoinvent 3.11 database, one of the most widely used life cycle inventory resources in the world. The impact assessment was carried out in SimaPro 10.2.0.3 using the ReCiPe 2016 Midpoint (H) methodology for a world-scale characterization, which allowed the team to quantify eighteen separate impact categories, ranging from global warming and fossil resource depletion to human toxicity, freshwater ecotoxicity, and particulate matter formation.

The headline finding is stark: electricity is the dominant contributor to most of the impact categories examined. Ghana’s national grid currently relies on thermal generation for 66.4 percent of its supply, hydropower for 32.9 percent, and renewables for a mere 0.7 percent. That mix means every kilowatt-hour consumed by an extruder or a pelletizer carries a substantial fossil signature. For the annual production of 100,000 recycled bags, electricity alone accounted for 288.9 kilograms of carbon dioxide equivalent out of a total global warming potential of 353.53 kilograms. In other words, more than four-fifths of the climate impact of making recycled carrier bags in Ghana comes from the power they consume during manufacturing.

The pattern repeats across other environmental dimensions. Electricity was responsible for 137.2 kilograms of 1,4-dichlorobenzene equivalent in terrestrial ecotoxicity, out of a total of 264.5 kilograms, and for 106.3 kilograms of oil equivalent in fossil resource scarcity, out of a total of 131.3 kilograms. These numbers matter because they reframe the debate about recycling in developing economies. The recycled feedstock itself avoids the virgin polymer production that would otherwise dominate a conventional life cycle, yet the downstream processing can erode those gains if the energy supply remains carbon-intensive.

Chemical additives emerged as a second, more subtle tier of environmental burden. Sodium hydroxide, used in wastewater treatment at the recycling facility, was the second-largest contributor to global warming, adding 26.0 kilograms of carbon dioxide equivalent. Carbon black, the pigment that gives many carrier bags their familiar dark color, ranked second for fossil resource scarcity at 13.7 kilograms of oil equivalent. Meanwhile, sodium hydroxide and polyaluminium chloride, both employed to treat process wastewater, were significant contributors to toxicity categories. These chemicals are often overlooked in public discussions of plastic recycling, which tend to focus on collection rates and sorting efficiency, yet they represent a meaningful share of the total footprint and a clear target for optimization.

To test how sensitive the results were to the energy assumption, the researchers ran a sensitivity analysis comparing Ghana’s actual grid with a solar tower energy scenario. The difference was dramatic. Switching to concentrated solar power reduced the global warming potential of the annual bag production by approximately 74 percent, from 353.5 kilograms of carbon dioxide equivalent down to 92.0 kilograms. Reductions of similar magnitude appeared across most of the other impact categories, since fossil combustion is implicated not only in climate change but also in particulate formation, acidification, and resource depletion. The result demonstrates that the environmental performance of recycling operations is not fixed by the recycling process itself but by the energy system in which it is embedded.

The implications extend well beyond Ghana. Many sub-Saharan African countries share a similar profile: growing plastic waste streams, emerging recycling industries, and electricity grids dominated by thermal generation. In such contexts, the environmental case for recycling depends heavily on parallel investments in clean energy. A recycling plant connected to a decarbonized grid can deliver genuine circular economy benefits, diverting waste from open dumps and waterways while avoiding the emissions of virgin plastic production. The same plant connected to a coal- or gas-heavy grid may deliver far smaller net gains than policymakers assume.

The study also highlights the practical value of life cycle assessment as a decision-making tool for emerging industries. By quantifying eighteen impact categories at the midpoint level, the analysis gives plant operators and regulators a granular map of where environmental burdens arise. The findings point to two concrete levers: energy decarbonization, whether through grid greening or on-site renewable generation, and additive optimization, including reducing chemical inputs in wastewater treatment and reconsidering pigment choices such as carbon black. Neither lever requires rethinking the fundamental recycling process, which makes them attractive targets for near-term improvement.

As plastic production continues to rise globally and developing economies grapple with mounting waste, studies like this one provide a necessary corrective to simplistic narratives. Recycling is essential, but its benefits are contingent. In Ghana, the path to genuinely sustainable plastic recycling runs directly through the national grid, and the faster that grid sheds its fossil intensity, the closer the country’s circular economy ambitions come to delivering the environmental dividends they promise.

Subject of Research: Life cycle assessment of recycled polyethylene carrier bag manufacturing in Ghana

Article Title: Life cycle assessment of polyethylene carrier bags manufactured from recycled plastics in Ghana: Environmental impacts of chemical additives and a fossil-intensive electricity grid

Article References: Ankomah, K., Azanu, D., & Mwema, M. F. (2026). Life cycle assessment of polyethylene carrier bags manufactured from recycled plastics in Ghana: Environmental impacts of chemical additives and a fossil-intensive electricity grid. PLOS Sustainability and Transformation, 5(8), e0000259. https://doi.org/10.1371/journal.pstr.0000259

Image Credits: AI Generated

DOI: 10.1371/journal.pstr.0000259

Keywords: life cycle assessment, plastic recycling, polyethylene carrier bags, Ghana, electricity grid, carbon footprint, solar power, carbon black, sodium hydroxide, circular economy, ReCiPe 2016, sub-Saharan Africa