排放交易、廠商最適投資決策及經濟成長

Emission Trading, Investments and Economic Growth

本文修正傳統文獻中排放許可證無限效期的假設，納入廠商「完全預期」之排放交易價格動態調整方程式之觀念，以分析廠商投資決策之問題。排放交易價格的成長率小於時間偏好率僅為廠商不從事防制性資本投資的必要條件，而非充分條件；利率對防制性投資的影響也不像對生產性投資的影響那般確定，這與未考慮價格預期時的結論大有不同，這也顯示主管機關擬以低利貸款來獎勵防制性投資的誘因效果將不如預期中的有效。此外，本文首度指出，在某些情況下，期初配額從寬可能具有誘導廠商增加污染染防制投資的效果，這可為grandfathering rule提供另類的理性基礎。

Taking into account the firm's expectation about the permit price dynamics, we examine the firm's investment decision of production and abatement under a tradable emission permit system. That the growth rate of the permit price must be lower than the interest rate is found only being a necessary condition rather than a sufficient one. The impact of interest rate on the abatement investment is indeterminate, implying the limited effect of low interest loan on inducing more abatement investment. Contradictory to the environmentalist's argument, we find that under certain circumstances the lenient allocation of permits at the beginning of the trading program may not only induce more abatement investment, but also generate a low permit price that eventually will increase to a steady-state level.