劍橋市攜手MN8能源：場外採購清潔能源，打造可持續發展新模式

劍橋市近日與可再生能源開發商MN8能源簽署了一項具有里程碑意義的虛擬購電協議（Virtual Power Purchase Agreement, VPPA），從伊利諾伊州的135兆瓦草原太陽能項目（Prairie Solar Project）購買清潔能源。據交易撮合方Sustainability Roundtable介紹，這是美國城市簽署的規模最大的VPPA，也是全美首次有城市利用VPPA抵消住宅碳排放的嘗試。此舉不僅彰顯了劍橋市在氣候行動領域的領導力，也為其他城市實現可持續發展提供了新模式。

The City of Cambridge recently signed a landmark Virtual Power Purchase Agreement (VPPA) with renewable energy developer MN8 Energy to purchase clean energy from the 135-MW Prairie Solar Project in Illinois. According to Sustainability Roundtable, the dealmaker, this is the largest VPPA signed by a U.S. city and the first time a city in the United States has attempted to use a VPPA to offset residential carbon emissions. This move not only demonstrates Cambridge’s leadership in climate action, but also provides a new model for other cities to achieve sustainable development.

劍橋市的創新舉措：應對高密度城市能源挑戰

Innovative initiatives in Cambridge: addressing high-density urban energy challenges

Cambridge has a population of about 120,000 and an area of only 6.5 square miles. It has high urban density and strong electricity demand. It is impossible to rely solely on renewable energy in the city to meet the electricity needs of residents and businesses. In order to solve this problem, the City of Cambridge chose to support clean energy projects through off-site procurement to promote the reduction of carbon emissions in the city.

劍橋市人口約12萬，面積僅6.5平方英里，城市密度高，電力需求旺盛，無法僅依靠市內可再生能源滿足居民和企業的用電需求。為了解決這一難題，劍橋市選擇通過場外採購的方式支持清潔能源項目，推動市內碳排放的減少。

劍橋市首席氣候官朱莉·沃姆瑟（Julie Wormser）指出：“這是一個具有里程碑意義的協議，展現了劍橋市在應對氣候變化方面的領導力。通過這項協議，我們不僅能有效減少市內碳排放，還能為其他城市提供一個可複製的模式，推動更多地區共同參與可持續發展。”

Julie Wormser, chief climate officer of the City of Cambridge, said: "This is a landmark agreement that demonstrates the leadership of the City of Cambridge in addressing climate change. Through this agreement, we can not only effectively reduce carbon emissions in the city, but also provide a replicable model for other cities and promote more regions to participate in sustainable development."

根據協議，草原太陽能項目每年將產生約113,000兆瓦時的清潔能源，足以滿足超過25,000戶劍橋家庭的年度能源需求，占全市家庭總數的近一半。劍橋市將從交易中獲得可再生能源憑證（RECs），這些憑證可以用於抵消市內的碳排放，而伊利諾伊州香檳縣的居民則將直接受益於草原太陽能項目產生的清潔電力。

提升減排效益：選擇碳強度更高的地區進行採購

大衛·奧斯本（David Osborn），Sustainability Roundtable的首席財務官表示：“由於伊利諾伊州的電力碳強度高於馬薩諸塞州，這筆交易在減排效益上具有額外的優勢。根據我們的估算，劍橋市通過該項目實現的減排效果將是其在本州採購的2.6倍。”

Under the agreement, the Prairie Solar Project will generate approximately 113,000 megawatt hours of clean energy annually, enough to meet the annual energy needs of more than 25,000 Cambridge households, accounting for nearly half of the city’s total households. The City of Cambridge will receive Renewable Energy Certificates (RECs) from the transaction, which can be used to offset the city’s carbon emissions, while residents of Champaign County, Illinois, will directly benefit from the clean electricity generated by the Prairie Solar project.

Improve emission reduction benefits: choose regions with higher carbon intensity for procurement

David Osborn, chief financial officer of Sustainability Roundtable, said: “Because Illinois’ electricity carbon intensity is higher than that of Massachusetts, this deal has the added advantage of emission reduction benefits. Based on our estimates, the emission reductions achieved by the City of Cambridge through this project will be 2.6 times greater than its in-state purchases.”

MISO（中部獨立系統運營商）區域的電網在2023年僅有32%的電力來自低碳能源，這使得這一地區在清潔能源開發和減排方面具有巨大潛力。劍橋市的選擇不僅促進了該地區的可再生能源發展，也展現了其在全國氣候行動中的戰略性思維。

為其他城市樹立榜樣：VPPA的可持續性價值

奧斯本指出，這一VPPA協議為其他城市提供了一個具有示範意義的解決方案，特別是對於那些同樣面臨土地和能源資源限制的高密度城市。他建議，城市之間可以通過合作形式，聯合採用VPPA 2.0模式進行清潔能源採購。這種“反向拍賣”方式讓多個城市聯合起來，以更高的議價能力從開發商那裡獲得最具性價比的清潔能源項目，尤其對用電需求較低的城市尤為有效。

The grid in the MISO (Midlands Independent System Operator) region will generate only 32% of its electricity from low-carbon energy sources in 2023, giving this region huge potential for clean energy development and emissions reduction. The City of Cambridge’s choice not only promotes renewable energy development in the region, but also demonstrates strategic thinking in climate action across the country.

Setting an example for other cities: VPPA’s sustainability value

Osborne noted that this VPPA agreement provides a model solution for other cities, especially those high-density cities that also face land and energy resource constraints. He suggested that cities can jointly adopt the VPPA 2.0 model for clean energy procurement through cooperation. This "reverse auction" method allows multiple cities to join forces to obtain the most cost-effective clean energy projects from developers with higher bargaining power. It is especially effective for cities with low electricity demand.

沃姆瑟補充道：“這一協議不僅是一個財務上的成功案例，也是一種實現全市可持續發展目標的創新方式。隨著更多城市效仿這一模式，我們將看到場外清潔能源採購成為全國脫碳戰略的重要工具。”

Wurmser added: "This agreement is not only a financial success story, but also an innovative way to achieve city-wide sustainability goals. As more cities follow this model, we will see off-site clean energy procurement become an important tool in the national decarbonization strategy."

未來展望：引領全美城市能源轉型

Looking Ahead: Leading the Energy Transformation of U.S. Cities

劍橋市的這一協議不僅為本地居民帶來了切實的減排效益，也向全國展示了密集型城市如何克服能源挑戰、實現清潔能源轉型的新路徑。隨著草原太陽能項目的投入運行，這一協議將對劍橋市和伊利諾伊州的環境和經濟帶來雙重影響，並為其他希望加速減排的城市提供寶貴的參考。

This agreement in Cambridge not only brings tangible emission reduction benefits to local residents, but also shows the country how dense cities can overcome energy challenges and achieve a new path to clean energy transition. With the Prairie Solar project now operational, this agreement will have a dual impact on the environment and economy of Cambridge and the state of Illinois, and provide a valuable reference for other cities looking to accelerate emissions reductions.