以區域CGE模型評估建築廢棄物循環利用對溫室氣體排放及經濟之影響

Abstract

循環經濟被認為是重要的減碳策略，能以此減緩氣候變遷。而都市地區人口集中，並消耗大量的自然資源，因此都市地區的循環經濟潛力相當大。由於各個區域的社會文化背景、環境問題存在著相當大的差異，因地制宜的管理方式可能相對有效。因此以都市為主體的區域性循環經濟策略近年來日益受到重視。然而，都市制定的循環經濟策略對於經濟方面的影響以及減碳的效果，充滿著不確定性。因此政策評估模型的角色就顯得相當重要，透過政策評估模型的輔助，可事先評估政策的效果，以確保政策的有效性。然而，目前可用於都市層級循環經濟政策的政策評估模型卻寥寥無幾。 因此，本研究以區域可計算一般均衡模型(區域CGE模型)，搭配碳盤查模型，建立區域性循環經濟政策評估模型。將全國劃分成七個區域，分別是六個直轄市，以及六都以外的其他地區。並以建築廢棄物為例，進行地方層級的循環經濟政策評估，以供決策者作為制定政策時之參考。 研究結果顯示，對於台北而言，實施補貼再生建築材料業之政策以及實施補貼再生建築材料業並向污染整治業課徵環境特別公課之政策能有效促進建築廢棄物的資源循環，且前者為最佳之循環經濟促進政策。然而台北實施補貼再生建築材料業之政策時，會因為再生建築材料業的擴張而帶動台北地區其他產業的發展，導致台北的溫室氣體排放量上升，無法實現循環經濟預期的減碳效果。但是對於整個國家而言，台北實施補貼再生建築材料業之政策卻能使全國的溫室氣體排放總量減少，且GDP增加，達成最理想的脫鉤情況。因此循環經濟的推動並不一定只會造成減碳的效果，也有可能反而會使碳排增加。而政策效果究竟如何，需仰賴區域性循環經濟政策評估模型來評估。 本研究建立之區域性循環經濟政策評估模型，最大的優點在於其將評估的對象從國家層級擴展到地方層級，可模擬區域性的政策、評估地方層級的影響效果、呈現各個區域的個別產業受政策影響之情形。此為多數政策評估模型所無法評估之項目。

The circular economy is regarded as an important carbon reduction strategy, and it has recently been applied for climate change mitigation. For the circular economy, urban areas are high potential because of their high-density population and consumption of many natural resources. Effective urban managements have to suit the city’s measures to local conditions according to the sociocultural context and environmental issues. Hence, circular economy strategies at the city level have received more and more attention in recent years. However, the effect of the circular economy strategy, which is developed by the city to reduce greenhouse gas and improve the economy, is unexpected. Ensuring the effectiveness of the policy can be projected by models in advance to decrease the cost and mistakes when implementing policy. However, few policy evaluation models are currently available for circular economy policies at the city level. Therefore, this study establishes a regional circular economy policy evaluation model consisting of a regional computable general equilibrium model and carbon inventory model to assess the effectiveness of circular economy policies at the city level. Taking construction and demolition waste recycling as an example, subsidizing the recycled building materials industry and levying special common levies for the environment on pollution control industries are applied for promoting the reuse of construction and demolition waste only in Taipei. As a result, subsidizing the recycled building materials industry can promote not only the development of the recycled building materials industry but also the decoupling indicator for Taipei. Conversely, subsidizing the recycled building materials industry will increase greenhouse gas emissions in Taipei due to repercussions between industries. But for the whole of Taiwan, the action in Taipei can reduce the national greenhouse gas emissions and increase the GDP, which achieves the ideal decoupling situation. The effectiveness of the circular economy may be unexpected in decreasing or increasing greenhouse gas emissions; hence the effect of the policy needs to be assessed through a regional circular economy policy evaluation model. The most significant advantage of the regional circular economy policy evaluation model established in this study is that this model increase resolution from the national level to the city level. High resolution can simulate regional policies, assess impacts at the city level, and present the effect of individual industries in each region affected by the policy, which most policy evaluation models are not available.