Research Papers

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    Managing automotive end-of-life NiMH and Li-ion batteries in Mongolia: a Material Flow Analysis to assess challenges and opportunities for circular batteries in the Global South
    (Frontiers Media S.A., 2026-02-12) Gantuya Ganbat; Daniel Karthe
    Introduction: Mongolia’s transition to electric mobility presents environmental opportunities to mitigate air pollution and potentially reduce greenhouse gas emissions but also generates complex waste streams such as end-of-life (EoL) Nickel Metal Hydride (NiMH) and Lithium-Ion Batteries (LIB). This study investigates the status of Mongolia’s waste management system and how it can be optimized to enhance the circularity of such waste streams. Methods: Original data was collected through field research at collection, repair, storage, and disposal sites, and complemented by stakeholder interviews and an analysis of the country’s waste management legislation. Official vehicle fleet statistics (2010–2023) were used to forecast the quantity of EoL NiMH and LIB until 2050 and conduct a Material Flow Analysis for 10 different scenarios. The dataset comprises both qualitative data, describing the current waste management scenario, and quantitative data on vehicle imports, fleet composition, and battery specifications, with assumptions for missing values based on market trends. Results: Results reveal that Mongolia lacks infrastructure and policy for safe and sustainable EoL battery management. EoL battery outflows were estimated using a two-parameter Weibull distribution model; forecast reliability was assessed via out-of-sample backcasting of the vehicle-fleet projection against historical fleet statistics (2019–2023 hold-out: MAPE = 4.71%). The results of the EoL battery quantities are scenario- and parameter-dependent projections for the lifetime and battery-specification assumptions. The results show that cumulatively (from 2023 to 2050), in the Current Scenario, 10,302 tons of EoL NiMH and 38,650 tons of EoL LIB are expected to be generated. In contrast, for the Climate Focus Scenario, 10,455 tons of EoL NiMH and 102,586 tons of EoL LIB are expected. Discussion: The lower values of NiMH in 2050 are due to the expected transition from NiMH to LIB in HEV. Recommendations to enhance EoL battery management’s circularity include focusing on improving EoL battery collection, implementing Extended Producer Responsibility, integrating the existing informal sector, enhancing regional and international cooperation, and improving data acquisition and management. In summary, a combined approach involving local and international cooperation and socio- and technological development is essential for improving the circularity of EoL battery management in Mongolia. 1 Introduction
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    Spatiotemporal Variability of Near-Surface Temperature Inversion over Ulaanbaatar City, Mongolia
    (MDPI, 2026-08-14) Gantuya Ganbat
    Near-surface temperature inversions are prevalent during the cold months in Ulaanbaatar city, Mongolia, and significantly degrade urban air quality by trapping hazardous pollutants within a shallow atmospheric boundary layer. This study investigates spatiotemporal variability, physical mechanisms, and long-term evolution of near-surface temperature inversions over Ulaanbaatar by integrating 25 years (2000–2024) of ground-based meteorological and radiosonde observations, with high-resolution Weather Research and Forecasting (WRF) model simulations for 2012–2023. Our results demonstrate the fourdimensional data assimilation (FDDA) grid nudging effectively captures localized topographic influences in the WRF simulations, showing a strong agreement with radiosonde observations (R2 = 0.783, p < 0.000). Near-surface temperature inversions are strongly controlled by the Siberian High, with the highest frequency occurring from December to February, when up to 67% of morning observations exhibit inversion conditions. A pronounced diurnal cycle was identified, with inversion intensity peaking at 5.6–6.8 ◦C during the early morning hours (02:00–08:00 LST) before reaching a minimum around 14:00 LST. Spatially, the strongest inversions occur along the low-lying Tuul River valley, where the planetary boundary layer is compressed to below 350 m and wind speeds decrease to less than 2.4 m·s−1, creating persistent atmospheric stagnation. Despite these favorable conditions for inversion formation, long-term observations indicate that regional warming (+2.0 ◦C) and the urban heat island effects have reduced inversion frequency by 31%, inversion thickness by 170 m, and inversion intensity by 0.9 ◦C over the past 25 years. These findings demonstrate the strong coupling between regional complex terrain, and boundary layer thermodynamics, highlighting the need to incorporate urban ventilation corridors and topography-informed planning into climate adaptation and winter air-quality management strategies.