Use of oil tanker return/ballast space for the transportation of freshwater
MetadataShow full item record
- Institutt for marin teknikk 
This report analyzes the concept of using oil tankers’ free cargo space and/or segregated ballast tanks to transport freshwater on the return leg, i.e. from oil unloading port back to oil loading port – also called freshwater backhauling (FWBH). The hypothesis considered is that by shipping freshwater this way to arid, oil exporting regions one can achieve a low cost and low GHG emission water supply system. The report analyzes the concept in a holistic manner, considering technical issues, transport and infrastructure costs, environmental impacts and contractual and legal issues. Technically FWBH is feasible as the technical modifications and new infrastructure to be developed for FWBH can be integrated with the present oil tanker and trade infrastructure. Costs are estimated both on a general and scenario specific level. It is found that freshwater could be shipped by way of backhauling by oil tankers to Saudi Arabia from Japan at a cost of between 0.83 and 1.16 USD/ton, including all infrastructure except distribution systems and excluding modifications to the tankers themselves. This cost level makes FWBH to a certain degree competitive with the chief water supply technology in the Middle East, desalination. Deducing sustainability by comparing FWBH with desalination has been done by calculating CO2 emissions for unit volume transportation/production of freshwater (kgs/m3) and harmful marine discharges. It is found that FWBH is not conclusively better than desalination in terms of GHG emissions. Emission level of FWBH is found to vary strongly with operational parameters. On the other hand FWBH can be a simple and potent solution to the seawater ballast water problem for regions with sufficient freshwater resources. Viability of FWBH is found to be very dependent on oil market conditions, so to preserve some stability in water supply it is advised that handling of the water trade at a contractual level is done by public authorities. Accordingly, long term contracts can be considered more suitable for the purpose of FWBH than short term or spot contracts. Feasibility of the FWBH concept is complex, and the question depends on mode of operation, location of ports and terminals, oil market conditions, ship type and several other factors. It is clear, however, that in many cases FWBH is the superior option compared to desalination, especially when including environmental aspects. Still, no FWBH project or scheme has ever been carried out. We conclude that the reason for this lies with authorities in both potential water importing and water exporting nations. Questions regarding the status of freshwater as an economic good has to be resolved on an international level, and oil exporting nations (especially Middle East countries) has to be convinced about the benefits of considering alternatives to desalination.