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Maintaining crop outputs to feed its large population with limited resources while simultaneously mitigating carbon emissions are great challenges for China. Improving the efficiency of resource use in crop production is important in reducing carbon emissions. This paper constructs a methodological framework combining emergy-based indicator accounting and a nonseparable undesirable output slack-based measurement (SBM) data envelopment analysis (DEA) model. This framework is used to explore the efficiency of inputs and outputs and the greenhouse gas (GHG) emissions reduction potential for crop production systems, using Zhejiang province, China, as a case study. It is found that an emergy synthesis and a nonseparable undesirable output SBM-DEA framework is compatible with the case study. Crop production in Zhejiang province has relied heavily on an increase in agrochemical inputs to maintain agricultural output. Energy and chemical fertilizer use are determined as the province’s major carbon emissions sources. Although carbon emissions per unit of monetary output has decreased sharply, the carbon emissions per unit emergy output has increased, demonstrating a high carbon intensity reality. The DEA highlighted the differences in crop production efficiency, resource factor redundancy and carbon mitigation potential in the different prefectures of the province. To conclude this research, policies to support low carbon agriculture development, including subsidizing low carbon agriculture technology development and expansion and the cancellation of subsidies to high carbon production factors, such as chemical fertilizer production and sales, are discussed to conclude the research. [ABSTRACT FROM AUTHOR]

Hydrogen fuel cell vehicle (HFCV) is regarded as one of the most promising technical paths towards transportation sector's carbon neutrality in China, to assess the environmental and economic performances of HFCV is of great significance for emission reduction policies construction. This study carries out a fuel-cycle analysis of HFCV in 2020 and 2030 using the GREET model. 19 fuel paths are generated by combining mainstream patterns of HFCV's hydrogen production, storage and transportation, and filling processes. The results show a contradiction at present that, hydrogen production from electrolytic water with renewable energy has the lowest air pollutants and carbon emissions, while the traditional hydrogen production from natural gas, coke oven gas and coal, etc., have better economic performances. However, the decreasing trends of both pollution emissions and costs of HFCVs are expected towards 2030. Specifically, the CO 2 , VOC, NO x , PM 2.5 and SO 2 emissions would decrease by 21.58%, 16.55%, 22.35%, 22.49%, and 18.76%, respectively. The total cost of fuel path with the participation of renewable energy decreases rapidly, which is mainly benefit from its lower environmental externality costs. This study puts forward policy suggestion of improving the hydrogenation infrastructure construction, accelerating the large-scale and low-cost renewable energy hydrogen production. • Fuel-cycle analysis of hydrogen fuel cell vehicle using localized GREET model. • Environmental and economic assessment of 19 fuel paths in 2020 and 2030. • Electrolytic water with renewable energy paths show great pollution reduction effect. • Material and environmental cost of hydrogen fuel cell vehicle drop significantly in 2030. [ABSTRACT FROM AUTHOR]