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Innovation and development of renewable energy devices are crucial for reaching a sustainable and environmentally conscious future. This work focuses on the development of a new type of renewable energy devices in the context of Smart Garden at the Chinese University of Hong Kong, which aims to design a bladeless wind turbine for urban areas, addressing the pressing need for clean energy locally and globally. Traditional wind turbines have been widely adopted in recent decades, while bladeless wind turbines have also displayed their advantages and uniqueness in urban areas. A Vortex Bladeless Wind Turbine (VBWT) is modeled by using Fusion 360 to optimize wind energy generation in urban settings with limited space and buildings-dominated landscape. Optimal parameters of the VBWT were obtained by comparing the results of drag force, lift force and deflection, via the simulations in Ansys. Hardware of proposed bladeless wind turbine has been assembled and developed by 3-dimensional printing. Additional tests and adjustments on hardware further improve the performance of the developed wind turbine. The outcomes of this work have the potential to contribute to future renewable energy initiatives and devote the sustainability efforts in urban energy systems., Comment: 6 pages, 9 figures

The increasing electric vehicle (EV) adoption challenges the energy management of charging stations (CSs) due to the large number of EVs and the underlying uncertainties. Moreover, the carbon footprint of CSs is growing significantly due to the rising charging power demand. This makes it important for CSs to properly manage their energy usage and ensure their carbon footprint stay within their carbon emission quotas. This paper proposes a two-stage online algorithm for this purpose, considering the different time scales of energy management and carbon trading. In the first stage, the CS characterizes the real-time aggregate EV power flexibility, in terms of upper and lower bounds on the total charging power, by a Lyapunov optimization-based online algorithm. In the second stage, the CS co-optimizes energy management and carbon trading, with EV charging power chosen within the aggregate flexibility region provided by the first stage. A generalized battery model is proposed to capture the dynamic carbon footprint changes and carbon trading. A virtual carbon queue is designed to develop an online algorithm for the second stage, which can ensure the carbon footprint of CS be within its carbon emission quota and its total operation cost is nearly offline optimal. Case studies validate the effectiveness and advantages of the proposed algorithm., Comment: 12 pages, 13 figures

With the rapid growth of electric vehicles (EVs), EV aggregators have been playing a increasingly vital role in power systems by not merely providing charging management but also participating in wholesale electricity markets. This work studies the optimal real-time bidding strategy for an EV aggregator. Since the charging process of EVs is time-coupled, it is necessary for EV aggregators to consider future operational conditions (e.g., future EV arrivals) when deciding the current bidding strategy. However, accurately forecasting future operational conditions is challenging under the inherent uncertainties. Hence, there demands a real-time bidding strategy based solely on the up-to-date information, which is the main goal of this work. We start by developing an online optimal EV charging management algorithm for the EV aggregator via Lyapunov optimization. Based on this, an optimal real-time bidding strategy (bidding cost curve and bounds) for the aggregator is derived. Then, an efficient yet practical algorithm is proposed to obtain the bidding strategy. It shows that with the proposed bidding strategy, the aggregator's profit is nearly offline optimal. Moreover, the wholesale electricity market clearing result aligns with the individual aggregator's optimal charging strategy given the prices. Case studies against several benchmarks are conducted to evaluate the performance of the proposed method., Comment: 13 pages, 6 figures

Regional data center clusters have flourished in recent years to serve customers in a major city with low latency. The optimal coordination of data centers in a regional cluster has become a pressing issue because of its rising energy consumption. In this paper, a Lyapunov optimization-based online algorithm is developed for the combined computing workload and energy coordination of data centers in a regional cluster. The proposed online algorithm is prediction-free and easy to implement. We prove that the workload queues and battery energy level will be within their physical limits, though their related time-coupling constraints are not considered explicitly in the proposed algorithm. The previous online algorithms do not have such a guarantee. A theoretical upper bound on the optimality gap between the online and offline results is derived to provide a performance guarantee for the proposed algorithm. To enable distributed implementation, an accelerated ADMM algorithm is developed with iteration truncation and follow-up well-designed adjustments, whereby a nearly optimal solution is attained with much enhanced computational efficiency. Case studies show the effectiveness of the proposed method and its advantages over the existing methods., Comment: 27 pages, 10 figures

As an essential measure to combat global warming, electric vehicles (EVs) have witnessed rapid growth. Flexible EVs can enhance power systems' ability to handle renewable generation uncertainties. How EV flexibility can be utilized in power grid operation has captured great attention. However, the direct control of individual EVs is challenging due to their small capacity and large number. Hence, it is the aggregator that interacts with the grid on behalf of the EVs by characterizing their aggregate flexibility. In this paper, we focus on the aggregate EV power flexibility characterization problem. First, an offline model is built to obtain the lower and upper bounds of the aggregate EV power flexibility region. It ensures that any trajectory within the region is feasible. Then, considering that parameters such as real-time electricity prices and EV arrival/departure times are not known in advance, an online algorithm is developed based on Lyapunov optimization techniques. We provide a theoretical bound for the maximum charging delay under the proposed online algorithm. Furthermore, real-time feedback is designed and integrated into the proposed online algorithm to better unlock EV power flexibility. Comprehensive performance comparisons are carried out to demonstrate the advantages of the proposed method., Comment: 16 pages, 21 figures