6. Conclusions
The South Korean government announced its aim to reduce by 2020 its national GHG emissions by 30%, relative to the BAU sce- nario; in achieving this target, the transportation sector will bear the highest rate of reduction (34.3%) [4,9]. The current study investigated the effectiveness of policies that the South Korean government has imposed on the transportation sector, and ana- lyzed the ripple effect it will have on energy and environmental aspects if the policies are maintained until 2050.
This study considered five policies, in terms of scenarios: fuel efficiency improvements (IFE), the distribution of green cars (GC and CGC), an expansion in public transportation shift (PTS), and the reinforcement of modal shift (MS). To distinguish the effects of var- ious vehicle models, the green car scenario was subdivided into two scenarios: clean diesel/hybrid cars were the focus of the GC scenario, and the CGC scenario centered on hydrogen fuel cell/electric vehicles. Among the five alternative scenarios, the improved fuel efficiency policy for vehicles resulted in the largest reduction of energy con- sumption and GHG emissions. The sector-based shares of total energy demand in 2011 were as follows: the ground transportation sector, 80.6%; the railway sector, 0.9%; the maritime transportation sector, 9.1%; and the air transportation sector, 9.4%. Analysis of the sector-based shares of GHG emissions garnered the following results: the ground transportation sector, 79.3%; the railway sector, 1.3%; the maritime transportation sector, 9.5%; and the air transportation sector, 9.8%. Since the ground transportation sector accounted for approximately 80% of the total transportation sector from energy and environmental perspectives, the ripple effect resulting from improved fuel efficiency was found to be much greater than that of
the others, proving it to be the most effective policy.
Analysis of the green car distribution scenario indicated that its effect on energy consumption and GHG reduction was lower than expected, considering that the analysis was conducted on the ambitious premise that green cars would account for 43% of the transportation sector in 2020 and 90% in 2050. The cause of these lower-than-expected results seems to be the overwhelming market share of clean diesel vehicles in the hybrid/clean diesel vehicle- centered GC scenario and the electric/hydrogen fuel cell-centered