「電動公車至電網」營運模式成本有效性分析：以台北市公車為例

隨著近年來越來越多再生能源加入電網，電力產業需要儲能設備平衡電網供需，以維持電力系統的穩定度。電力產業除了建置電池儲能系統，可以選擇電動公車的電池作為儲能設備之替代方案。電動公車可以藉由車輛至電網(Vehicle-to-grid, V2G)的技術，當不作為交通用途使用時，可以藉由整合大規模數量電動公車的電池，提供儲存量能，對於電力公司可以節省建置儲能設備之成本，公車業者可以在電動公車參與B2G(Bus-to-grid)之營運模式中，獲取業外收益。本研究分析台灣電動公車參與B2G之營運模式下，相對於傳統柴油公車之成本有效性分析。本研究首先比較電動公車與柴油公車之差異，釐清電動公車所需考慮之成本項目與收益項目，及其如何估算；接著說明電動公車與B2G的營運模式，探討B2G營運模式之興起，而電動公車如何從其營運模式中獲取收益；最後說明B2G的概念，為電動公車參與B2G營運模式提供相關技術背景與架構。本研究的研究方法是成本效益分析中的成本有效性分析法，分別計算傳統柴油公車與電動公車之使用成本，對於公車業者與整體社會之影響，並考量免除電動公車牌照稅以及電動公車參與B2G營運模式對於使用成本的改變。本研究結果顯示，從使用者情境的角度，公車業者購置電動公車，且免除牌照稅，並同時申請政府補助的情況下，12輛電動公車之淨現值約為90百萬元。相較於電動公車，考量12輛柴油公車之固定成本、變動成本與稅額成本，其淨現值約為63百萬元。因此，在使用者情境中，電動公車係具有成本有效性。從整體社會情境的角度，12輛傳統柴油公車之總成本現值約為-88萬元。相較於柴油公車，考量公車業者購置電動公車不會以參與輔助服務為主要營業目的，在此情況下，12輛電動公車之總成本現值約為-104百萬元。因此，在整體社會情境中，柴油公車係具有成本有效性。

關鍵字

電動公車；成本有效性分析；車至電網；再生能源；電池儲能

並列摘要

With renewable energies increasingly being incorporated into power grids, the power industry requires energy storage equipment to balance the supply and demand in power grids and thus maintain the stability of the power system. As an alternative to establishing battery energy storage systems, electric bus batteries can also be used as energy storage equipment by the power industry. With vehicle-to-grid technology, the batteries of the large amount of electric buses when not in use for transportation purposes can be integrated to store energy. This practice reduces power companies’ costs in constructing energy storage systems and helps bus operators, through engagement of their electric buses in the bus-to-grid (B2G) business model, to gain nonoperating income. This study conducted a cost-effectiveness analysis of electric buses under the B2G business model in comparison with conventional diesel buses in Taiwan. The study compares electric and diesel buses, clarifies cost and revenue items concerning the operation of electric buses and their estimations, explores electric bus and B2G business models, and describes the rise of the B2G business model and how electric buses are a source of revenue in the model. The B2G concept is elaborated, and relevant technical background and framework for electric buses’ engagement in the B2G business model is provided. The study employs the cost-effectiveness analysis, a type of cost–benefit analysis, to separately evaluate the influence of the costs of conventional diesel and electric buses on bus operators and society and investigate the changes in costs given that vehicle license tax is not levied on electric buses and that the electric buses are engaged in the B2G business model. The results revealed that, in a user scenario, the net present value of 12 electric buses under the circumstance of the vehicle license tax exemption and receipt of government subsidies was approximately 90 million NTD when bus operators purchased electric buses. By contrast, the net present value of 12 diesel buses was approximately 63 million NTD after considering the fixed costs, variable costs, and tax costs. Hence, electric buses are cost effective in a user scenario. In a social scenario, the present value of the total cost of 12 conventional diesel buses was approximately −880 thousand NTD, whereas that of 12 electric buses was approximately −104 million NTD, given that bus operators are unlikely to purchase electric buses mainly to provide ancillary services. Therefore, diesel buses are cost effective in a social scenario.