再生能源及水資源之聯合運用模型與離岸風力技術發展分析

Abstract

在我國2025年再生能源規劃目標中，離岸風力與太陽能可視為兩大主力技術，然而再生能源在大量開發後，其間歇特性將對現有的電網穩定與電力調度產生重大影響；即使目前運行中相對穩定的慣常水力發電，雖然全台灣已有將近2.1 GW的裝置容量，但受限於水況與供水調度需求，水力機組在許多尖峰用電的時間可能無法全力輸出因應。此外，在全球氣候變遷的影響下，即使台灣年降雨量並不少，然而隨著降雨強度增強但降雨日數減少的趨勢顯現，加上受到地形限制、雨量集中夏季等自然因素影響，造成供水短缺之議題不時浮現。為了同步解決上述議題，本論文建立了一套整合水資源與再生能源之聯合運用模型，模型中包含了大甲溪之慣常水力機組、新增之抽蓄發電廠與海水淡化廠，並考量了政府未來可能推行之大安大甲溪聯合運用機制以及大量的再生能源裝置目標。模型之運轉策略為利用海水淡化廠與抽蓄電廠來提高德基水庫的供水彈性、大甲溪電廠尖峰負載運轉能力與儲能之能力，以降低再生能源間歇性對電網的衝擊，並且一併解決供水短缺與海水淡化成本過高等問題。經利用2031年台中地區的用水需求，以及2011年至2015年的德基水庫入流量、鯉魚潭水庫運轉曲線、全國用電曲線，搭配所模擬的太陽能與風力發電曲線作為輸入條件進行分析，其結果顯示所考量的各種情境均可在滿足供水的前提下大幅提高水力機組分攤尖峰用電之能力。藉由更新既有老舊機組以及增加102 MW水力機組，本研究模型之水力機組可有效替代參考情境中853 MW的尖載用燃氣機組增建需求，並節省每年1403百萬元之尖峰發電成本；藉由增設1099 MW之抽蓄電廠，除了可進一步增加尖峰負載之分攤能力外，其能源儲存成本相較於成本高昂之電池儲能系統，每年可進一步節省5155百萬元之儲能成本。至於模型中設置的日產31.2萬噸海淡水規模的海水淡化廠，由於其成本仍高，因此相較於參考情境中新增水庫之方案，每年仍多出近1265 百萬元之成本。然而，若以整體效益而言，本研究之模型除了每年可以節省5292 百萬元之產水產電綜合成本外，亦提高了供水的安全性。 在前述模型考量的再生能源中，無論是太陽能或是水力，其技術不僅成熟且發展已久。相比之下，離岸風力在台灣僅屬初步發展階段，為了瞭解離岸風力技術之發展趨勢並對政府之發展策略提出建議，本論文除了研究前述的能源模型外，另以專利分析之觀點針對離岸風力技術之發展策略進行探討。本研究利用美國與歐盟在2015年6月以前核准之專利建立了離岸風力技術之專利地圖。根據分析結果顯示，離岸風力主要的專利技術發展方向並非風力機本體，佔比較高者反而是著重在施工船舶、浮動式基礎、風機安裝、跨領域技術整合、塔架與錨定系統，其相關的專利佔所分析的專利高達59%。在技術所欲達成的功效方面，降低成本、改善運輸、改善安裝為最普遍的目標，具有此功效相關的專利在美國與歐盟專利中分別佔了45%及50%。在所分析的施工船舶與風機安裝相關專利中，有一個特別的趨勢在於設計特殊的運輸機構與系統，來將整架已組裝好的風機運輸與安裝至施工地點。另有不少專利著重在離岸風機平台上整合各種領域的再生能源技術，希望能藉此降低風機平台的製造與安裝成本。雖然自2007年以來，浮動式基礎專利持續的增加，然而分析結果顯示對於浮動式基礎的形式與錨定方式目前仍未有特定的形式偏好。自2013年起，美國專利與歐盟專利的重疊性越來越明顯，因此相關專利技術與所欲達成的功效也越來越相近。本論文另根據所觀察的技術領先國家專利配置狀況，對於遠東地區相關國家在發展離岸風力技術之策略上提出了相對應的建議。

Offshore wind power and solar power are the most important targets for the ambitious development plan of renewable energy in Taiwan by 2025. However, the intermittency of renewables could cause serious impacts on the existing power grid; even the traditional hydropower, which has 2.1 GW installed capacity in Taiwan, shows a relatively stable power supply among the existing installed renewables, its capability of supporting peak-power demand is largely limited by the water demand and dispatch. Under the global climate changes, the strength of rainfall increases but the frequency of raining decreases in Taiwan. This factor and the disadvantageous topography for the storage of rainfall combined together make the water shortage issues become worst. To solve the aforementioned issues related to the renewables and water resources once and for all, a simulation model related to the integrated operation of renewables and water resources has been proposed in this dissertation. In this model, not only hydropower of Dajia river, newly proposed pumped-storage hydropower and desalination plants are included but also the project “Water Resources Conjunctive Use in the Taan and Tachia River” and the ambitious renewable development target planned by government are also considered. The basic ideas of the model are to enhance the flexibility of Techi reservoir and the capability of peak-power supporting from its downstream traditional hydropower; the input data include the water demand in Taichung city by 2031, the inflow curve of Techi reservoir through 2011 to 2015, the operation curve of Liyutan reservoir, the power demand curve, and the simulated solar power curve and wind power curve. With the retrofit of existing old units and the addition of 102 MW new units, the hydropower units of the proposed model can eliminate the requirement of 853 MW gas-fired power plants during peak-loading in the reference case, and the cost of power generation can be saved by 1403 Million-NTD per year. With the addition of 1099 MW pumped-storage hydropower units, the proposed model further enhances the peak-loading supporting and the cost for energy storage can be saved by 5155 Million-NTD per year when comparing with the battery storage system in the reference case. As for the desalination plant in the proposed model, the water production cost is still higher than the planned reservoir in the reference case due to its higher operation cost. However, when considering the total benefits from water and energy sector, the extra expenses of 1265 Million-NTD per year for desalination can be easily compensated and the proposed model can save more cost (5292 Million-NTD per year) than the reference case. Besides, the proposed model also enhances the security of water supply through the implementation of the desalination plant. Among the renewables considered in the aforementioned model, solar power and hydro power are all mature technologies and have been commercialized for many years; by contrast, the offshore wind power is still on its initial stage of development in Taiwan. To understand the trend of its development of technology and propose practical suggestions on the development strategy, we explored the development of offshore wind technology through the evaluation of patents granted by the United States Patent and Trademark Office and the European Patent Office before June 31, 2015. On establishing the landscape of offshore wind patents, the key trends of technical development were identified from the leading countries. Rather than a wind turbine itself, technologies related to engineering vessels, floating foundations, turbine installations, integration of multiple technologies, towers and mooring systems have been identified as the top priorities for the development; they occupied around 59 % of granted patents selected from USPTO and EPO. The cost decrease, improvement of equipment transport and improvement of installation are the most common targets to be achieved; they occupied 45 % and 50 % of the granted patents selected from USPTO and EPO, respectively. The trends of installing a wholly assembled wind turbine with specially designed support and transport systems have been observed in sectors of vessels and turbine installations; there are many patents of which the aim was to integrate other renewable technologies within an offshore wind-turbine platform to share the costs of production and construction. Although, since 2007, there are increasing numbers of patents related to floating foundations, no obvious tendency of a specific type of floating foundation and mooring system has been observed. With an increase number of overlapping patents between USPTO and EPO after 2013, the functions of those technologies mentioned above become similar. Based on the observation from the portfolio of patents from the leading countries and the current status of development in far-east countries, specialized development strategies for far-east countries are proposed in this research.