Analysis of CO2 emissions for island ferry services

• CO2 emissions are compared for small ferries on short and long routes.
• CO2 emissions are also compared for land transport connections.
• For small ferries, optimal solution is to select shortest possible sea route.
• Power, speed and payload of small ferries requires careful analysis.
• Transport authorities should compare ferry CO2 emissions.

In this study CO2 emissions are calculated for ferries operating on both short and long range sea routes between mainland Scotland and the Orkney Isles. CO2 emissions for land transport options connecting with the respective ferry services are also analysed. In particular the study offers a comparison of transport CO2 emissions for long-range ferry services between Aberdeen and the Orkney Islands and short-range ferry services across the Pentland Firth. The latter involve a longer road journey for vehicles than the former. The results indicate significantly greater CO2 emissions for long-range ferry services, despite shorter road connections. Existing public policy in this regard specifies and subsidises higher CO2 emission ferry services operating on longer sea routes, to the disadvantage of non-subsidised short crossing services, the latter offering much lower CO2 emission impacts (inclusive of connecting land transport CO2 emissions). This suggests that policymakers need to focus on assessing CO2 emission impacts when considering future tenders for subsidised ferry services. Findings also suggest that, for modest sized ferries serving islands, the optimal solution may be to use/specify the shortest possible sea routes in order to reduce CO2 emissions from transport.