All Publications

  • Resampling and data augmentation for short-term PV output prediction based on an imbalanced sky images dataset using convolutional neural networks Solar Energy Nie, Y. 2021; 224
  • PV power output prediction from sky images using convolutional neural network: The comparison of sky-condition-specific sub-models and an end-to-end model JOURNAL OF RENEWABLE AND SUSTAINABLE ENERGY Nie, Y., Sun, Y., Chen, Y., Orsini, R., Brandt, A. 2020; 12 (4)

    View details for DOI 10.1063/5.0014016

    View details for Web of Science ID 000562468800001

  • Greenhouse-gas emissions of Canadian liquefied natural gas for use in China: Comparison and synthesis of three independent life cycle assessments JOURNAL OF CLEANER PRODUCTION Nie, Y., Zhang, S., Liu, R., Roda-Stuart, D., Ravikumar, A. P., Bradley, A., Masnadi, M. S., Brandt, A. R., Bergerson, J., Bi, X. 2020; 258
  • Techno-economic assessment of transportation biofuels from hydrothermal liquefaction of forest residues in British Columbia ENERGY Nie, Y., Bi, X. T. 2018; 153: 464–75
  • Life-cycle assessment of transportation biofuels from hydrothermal liquefaction of forest residues in British Columbia BIOTECHNOLOGY FOR BIOFUELS Nie, Y., Bi, X. 2018; 11: 23


    Biofuels from hydrothermal liquefaction (HTL) of abundantly available forest residues in British Columbia (BC) can potentially make great contributions to reduce the greenhouse gas (GHG) emissions from the transportation sector. A life-cycle assessment was conducted to quantify the GHG emissions of a hypothetic 100 million liters per year HTL biofuel system in the Coast Region of BC. Three scenarios were defined and investigated, namely, supply of bulky forest residues for conversion in a central integrated refinery (Fr-CIR), HTL of forest residues to bio-oil in distributed biorefineries and subsequent upgrading in a central oil refinery (Bo-DBR), and densification of forest residues in distributed pellet plants and conversion in a central integrated refinery (Wp-CIR).The life-cycle GHG emissions of HTL biofuels is 20.5, 17.0, and 19.5 g CO2-eq/MJ for Fr-CIR, Bo-DBR, and Wp-CIR scenarios, respectively, corresponding to 78-82% reduction compared with petroleum fuels. The conversion stage dominates the total GHG emissions, making up more than 50%. The process emitting most GHGs over the life cycle of HTL biofuels is HTL buffer production. Transportation emission, accounting for 25% of Fr-CIR, can be lowered by 83% if forest residues are converted to bio-oil before transportation. When the credit from biochar applied for soil amendment is considered, a further reduction of 6.8 g CO2-eq/MJ can be achieved.Converting forest residues to bio-oil and wood pellets before transportation can significantly lower the transportation emission and contribute to a considerable reduction of the life-cycle GHG emissions. Process performance parameters (e.g., HTL energy requirement and biofuel yield) and the location specific parameter (e.g., electricity mix) have significant influence on the GHG emissions of HTL biofuels. Besides, the recycling of the HTL buffer needs to be investigated to further improve the environmental performance of HTL biofuels.

    View details for DOI 10.1186/s13068-018-1019-x

    View details for Web of Science ID 000424353200001

    View details for PubMedID 29434666

    View details for PubMedCentralID PMC5797420

  • Greenhouse Gas Emissions of Western Canadian Natural Gas: Proposed Emissions Tracking for Life Cycle Modeling. Environmental science & technology Liu, R. E., Ravikumar, A. P., Bi, X. T., Zhang, S., Nie, Y., Brandt, A., Bergerson, J. A. 2021


    Natural gas (NG) produced in Western Canada is a major and growing source of Canada's energy and greenhouse gas (GHG) emissions portfolio. Despite recent progress, there is still only limited understanding of the sources and drivers of Western Canadian greenhouse gas (GHG) emissions. We conduct a case study of a production facility based on Seven Generation Energy Ltd.'s Western Canadian operations and an upstream NG emissions intensity model. The case study upstream emissions intensity is estimated to be 3.1-4.0 gCO2e/MJ NG compared to current best estimates of British Columbia (BC) emissions intensities of 6.2-12 gCO2e/MJ NG and a US average estimate of 15 gCO2e/MJ. The analysis reveals that compared to US studies, public GHG emissions data for Western Canada is insufficient as current public data satisfies only 50% of typical LCA model inputs. Company provided data closes most of these gaps (80% of the model inputs). We recommend more detailed data collection and presentation of government reported data such as a breakdown of vented and fugitive methane emissions by source. We propose a data collection template to facilitate improved GHG emissions intensity estimates and insight about potential mitigation strategies.

    View details for DOI 10.1021/acs.est.0c06353

    View details for PubMedID 34254796

  • Repeated leak detection and repair surveys reduce methane emissions over scale of years ENVIRONMENTAL RESEARCH LETTERS Ravikumar, A. P., Roda-Stuart, D., Liu, R., Bradley, A., Bergerson, J., Nie, Y., Zhang, S., Bi, X., Brandt, A. R. 2020; 15 (3)
  • Analysis of wind turbine Gearbox's environmental impact considering its reliability JOURNAL OF CLEANER PRODUCTION Jiang, L., Xiang, D., Tan, Y. F., Nie, Y. H., Cao, H. J., Wei, Y. Z., Zeng, D., Shen, Y. H., Shen, G. 2018; 180: 846–57