Browsing by Author "Shen, Cheng"

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    Evaluation and projection of the changes in near-surface wind speed: implication for wind energy potential
    (2024-08-10) Shen, Cheng
    Understanding variations in near-surface wind speed (NSWS) is scientifically challenging and crucial for the optimal utilization of wind energy and air quality. Changes in NSWS are linked to variations in atmospheric and surface conditions, such as large-scale atmospheric circulations, land use/cover changes, and anthropogenic aerosols. However, the influences of other factors, such as volcanic eruptions, and anthropogenic greenhouse gases (GHGs), remain largely unexplored. This thesis aims to investigate the impact of volcanic eruptions on the changes in NSWS in the past, and to reliably project the future changes concerning onshore and offshore wind energy potential under global warming, induced by GHGs. Specifically, the thesis addresses the following scientific questions: (1) what is the performance of global climate models in reproducing the past NSWS over land, and how to get reliable future projections? (2) how past volcanic eruptions affect global NSWS? (3) To what extent is wind energy generation affected by the changes in NSWS? Results indicate that most global climate models significantly underestimate the observed NSWS trends over land. The projection uncertainty can be expected to be reduced by selecting the model with the most historical fidelity, which can reasonably reproduce past trends. Additionally, this thesis provides evidence of a robust two-year reduction in global NSWS following tropical volcanic eruptions, exemplified by up to ~9.2% decrease in global wind power density after the 1815 Tambora eruption. This reduction is linked to the weakening of subtropical descending air corresponding with a decrease in downward momentum flux, triggered by volcanic aerosol forcing. Finally, this thesis projects future global offshore NSWS and wind potential density under different scenarios, with an example focus on China. After performing a correction method, global offshore wind power density is expected to increase in future, with an anticipated rise of 4-18% under four emission scenarios by the end of the 21st century. The findings in this thesis improve our understanding of the changes in NSWS and the implication to wind energy production. Specifically, this thesis highlights the potential risk of wind energy deficits associated with atmospheric aerosol injections from large volcanic eruptions, also highlights the growing importance of offshore wind in our energy mix and underscores the need for improved modeling to guide investments and policies.