The impact of the energy efficiency design index on very large crude carrier design and CO_2 emissions

摘要

This paper studies the impact of the energy efficiency design index (EEDI) on very large crude carriers' (VLCCs) CO_2 emissions. In competitive sectors such as the VLCC market, this analysis must be performed over a market cycle adjusting a ship's steaming speed to the market rate and bunker cost. Our numbers indicated that, over a market cycle, imposition of EEDI will result in a slight increase in VLCC CO_2 emissions, relative to no regulation at all. The problem is two-fold: (1) For VLCCs, EEDI effectively limits installed power. But at current and expected Bunker Fuel Oil prices, a non-EEDI VLCC owner uses all his installed power only in a full boom. For the great bulk of her life, a non-EEDI VLCC uses little or no more power than an EEDI-compliant ship. (2) In limiting installed power, EEDI induces owners to use smaller bore, higher revolutions-per-minute engines. These engines have a higher specific fuel consumption and, more importantly, require a smaller and less efficient propeller. This means the EEDI-compliant VLCC consumes more fuel when the market is not in boom, which is 90% of the time. In contrast, we find that a $50 per ton CO_2 bunker tax will reduce VLCC CO_2 emissions by more than 6% over a market cycle. Moreover, it will do so without forcing the world to devote 30% more resources to a greatly expanded, under-powered, overdriven VLCC fleet.