企業低碳轉型：結合線性規劃與分治法決定內部碳定價策略

Abstract

內部碳定價（Internal Carbon Pricing, ICP）是企業自發採取減碳策略的一種。藉由對企業內部營運單位收取排放溫室氣體的成本，從而達到以經濟誘因將外部成本內部化、激勵內部減碳行為、整合永續發展與策略決策等目標。然而，針對如何制定內部碳定價策略，目前卻未有定論。多數現行的定價策略，皆未能整合企業本身營運概況、減量目標等因素，故而無法反映出企業排放溫室氣體的真實成本；內部碳定價的價格水準普遍被低估。此種狀況除了使定價策略無法發揮最大減碳效益之外，也使得企業在擬訂內部碳定價時無從下手、面臨決策難題。本研究由資源分配的角度出發，以線性規劃（Linear Programming, LP）結合分治法（Divide-and-Conquer）計算企業排放溫室氣體的邊際價值，並以此作為內部碳定價的設定依據。除此以外，本研究針對企業如何運用內部碳定價引導低碳轉型計畫進行規劃，並以灰色規劃（Grey Programming）保留低碳轉型方案高度不確定（uncertainty）的特性，預留決策彈性。規劃結果顯示，內部碳定價對於引導企業投入於較長期的減量方案，確實有所助益。本研究協助企業決策者計算內部碳定價的適合價格，以在制定決策時能夠有更明確、具體的定價方向，並期望藉此支持內部碳定價在企業溫室氣體管理策略的執行現況，助益於全球淨零排放（net zero emissions）目標與減緩（mitigation）氣候變遷的願景，實現企業的低碳轉型及永續發展。

Internal Carbon Pricing (ICP) is one of the corporate mitigation strategies. By imposing an emission fee on the operational unit, ICP can help the organization internalize the external emission cost, promote low-carbon behaviors, and integrate business strategies and sustainable governance. What comes to the problem is the methodology to design the pricing level. Although the CDP had already published “How to Guide to Internal Carbon Pricing” in 2017, which is a guideline for decision-makers to form their ICP strategies, there is still a lack of clear, specific steps to make the decision. Because of the difficulty around the pricing approach, the ICP level is often under-evaluated. Therefore, this study proposes a methodology based on Linear Programming (LP) to calculate the marginal value of emissions, which set as the pricing level of ICP. Moreover, we introduce the Divide-and-Conquer strategy to ensure the efficiency of optimization. Afterward, the decided ICP is applied to the decision process of the low-carbon transition with Grey Programming, which consider the uncertainty of transition plans. As a result, we find that the ICP strategy can great support the long-term transition decisions. With our model, the corporate decision-makers can decide the ICP strategy more clearly and directly, thus contribute to global net zero vision.