The Case for OPS
The environmental profile of electricity generated by power plants on land versus ships’ diesel electric generators running on bunker fuels, is one of the main advantages of OPS technology. In land-based power plants, electricity can be generated at high energy efficiency in large efficient power plants with the use of either clean fuel or exhaust gas cleaning systems. Also, electricity is generally generated in remote areas beyond population centres with minimal air quality impact on population centres. On the contrary, ship-board generation is not as energy efficient as land-based plants and also any exhaust emissions from engines directly pollutes the port and surrounding areas. The reason that shipboard generation is less efficient is due to smaller engines used (with an MCR of up to 2,000 kW) as well as part-load operation (engine load factors at berth barely go beyond 50% for most of the time). OPS will substantially but not completely reduce SOX emissions as the steam generated by the on-board boiler is still needed for some ship’s operation at berth. Nevertheless, OPS have been widely used as a viable way to reduce ship-based local polluting emissions. The use of OPS thus could be seen primarily as a green port initiative in order to improve the port air quality. For ports, the ability to supply power to ships at berth enables them to establish a more efficient overall electrical supply and also act as a utility, i.e. as an organization that sells electricity to ships. For the port and ship staff closely linked to ships while at berth, there is an additional benefit of reduced noise and vibration in harbour areas. For ship staff, when the system is fully operational, more time will be available to deal with maintenance and other aspects of port-related activities (MariEMS 2017).