地域間高速旅客輸送機関の二酸化炭素排出からみた優位性評価手法

抄録

Objective. The focus of carbon dioxide (CO₂) emissions reduction policies for the inter-regional passenger transport system depends on two factors: 1) the aviation sector is the slowest to eliminate use of carbon fuels; and 2) aviation is expected to contribute more to greenhouse gas emissions than other transport modes. Therefore, the purpose of this study is to explore the possible changes in each indicator of Life Cycle CO₂ (LC-CO₂) per passenger-km and eco-efficiency considering travel speed as a result of a shift from aviation to the high speed railway system (Shinkansen). CO₂ emissions both for aviation and Shinkansen were estimated by applying the Life Cycle Assessment (LCA) method and taking into account same important parameters such as passenger demand.
Results and Discussion. CO₂ exhausted from aviation and Shinkansen during normal operation and the additional LC-CO₂ from new infrastructure provision were compared. The first analyzed the sensitivity with regard to the number of passengers for a 500km long corridor. The results indicate the following: 1) CO₂ per passenger-km generated from aviation hardly vary with the number of passengers; 2) LC-CO₂ per passenger-km for Shinkansen is inversely proportional to the number of passengers; 3) LC-CO₂ per passenger-km for Shinkansen is lower than that for aviation for the passenger volume of approximately 1,200 or more passengers per day; and 4) for eco-efficiency, the break-even point is more than around 2,000 passengers per day. The second considers the distance and travel demand for both aviation and Shinkansen. A possible shift from the current demand for aviation to Shinkansen was compared for each inter-prefectural Origin-Destination (OD) pair. Shinkansen was found to be superior for OD pairs with higher demand and shorter distances.
Conclusions. This paper proposed a methodology for identifying an inter-regional transport system with lower CO₂ emissions. An application to the inter-prefectural ODs for existing airlines in Japan shows the conditions that provide an advantage of lower CO₂ emissions for aviation or Shinkansen.