能源足跡情境分析架構之研提與應用

A SCENARIO ANALYSIS FRAMEWORK FOR ENERGY FOOTPRINT

生態足跡（ecological footprint）指標由Wackemagel and Rees於1996年提出，以土地及水域面積量度一特定地區居民之消費型態與水準對生態環境的依賴，例如：資源的提供以及廢棄物的承納與淨化。由於生態足跡分析至今仍只用於量度已發生的狀態，因而有學者質疑將生態足跡當做一項永續發展指標的適當性，尤其是有關其中的能源足跡（energy footprint）其估算方式未能考量能源替代方案的情形，更是備受評論。特別關注能源足跡估算，主要是因在個案研究中生態赤字多導因於能源足跡過於龐大，而能源足跡又以淨化燃燒化石燃料的CO2釋出量所需之森林面積為主，因此若降低最終能源消費量、或調整初級能源轉變投入結構，均有助於大幅降低生態赤字。由於Wackemagel等人估算能源足跡的方式是直接利用初級能源使用量的統計數字，完全忽略驅動初級能源需求的主要因素是為了提供生產活動所需能源以製造出滿足一地區居民消費的物品與服務，以致於估算的結果是反映出支持一地區經濟活動的初級能源量，而非生態足跡指標概念所欲估算之滿足一地區居民消費所利用的初級能源。在缺少這些關係的考量以及估算基礎的偏差，若以原先的估算方式進行情境分析，確有困難之處。基此，本文研提一個能進行能源足跡情境分析的估算架構，並以台灣地區1996年的資料為例進行個案估算。在情境分析架構中，本研究建議有關一地區居民最終需求因應相關政策，例如：CO2減量之市場機制，所造成的變動結果，可利用「可計算一般均衡模型」進行概估，並利用投入產出分析推估滿足這些居民最終需求直接與間接所需之各部門產品，再計算各產業部門的能源投入係數，推估最終能源消費量，接著應用最終能源消費與初級能源需求轉換的關係矩障，估計不同類別初級能源使用量，再利用相關文獻採用之能源－－土地轉換率，估計台灣地區基期與模擬方案的能源足跡與能源地赤字。

Wackernagel and Rees proposed the ecological footprint, the area of land and water required for resource provision and environment assimilation in order to support the final consumption of a defined human population, as an index of sustainability in 1996. The purpose of footprint calculations is to provide an evaluation regarding the dependence of humanity on the ecosystem and then to justify whether the human population survives within the carrying capacity of the earth. So far, the major component of ecological footprints in most case studies is the energy footprint, which represents the area required for assimilating C02 from burning fossil fuels, for buffering the radiation from nuclear power, and for building dams to generate hydrological electricity. The dominant role of energy footprints has been criticized as not able to reflect the possibility that an significant reduction in energy footprints can be achieved by changing energy structure or decreasing final energy consumption. The original calculation method of energy footprints fails to conducting policy simulation because the calculation is based on the statistics of the primary energy consumption and thus lacks of the relationship linkages between final consumption of goods and services, energy final consumption, and the primary energy use. However, it is these linkages that provide the possibilities for policy simulation. This paper proposes a calculation framework that comprehends the concerned linkages for energy footprint assimilation and then applies the calculation to Taiwan. In the proposed framework, this paper suggests to combine two policy simulation models: a computable general equilibrium model and primary energy transformation matrix. The first one simulates the change of domestic final demand resulting from imposing a new tax; and the second one takes into account the relationship between final energy consumption and primary energy demands of different types that have influences on the size of energy footprint.