Marine Emissions Control
The technology is there, costs are high and then there are the logistics of the systems. Note : Photo courtesy of Hamworthy
We now see the debate from the marine side. The elemental form of exhaust scrubbing has been in use for many years in the form of inert gas plants aboard tankers. Exhaust effluent was scrubbed and cooled with sea water in a simple pass through system. Little was said about the effects of the effluent even though many scrubbers were used with HFO burning steam boilers using heavy fuel. Inert gas plants aboard motor ships on the other hand were a bit more forgiving with respect to the effluent as they generally burned distillate fuel in the IG generator.
The stumbling blocks to acceptance by the ship operating community?
Any system will require a monitoring element and the associated maintenance and training.
From an engineering standpoint the obvious choice with respect to simplicity and logistical support is the open loop scrubber. Other than maintenance of the internals of the spray chamber and salt water pump and associated piping we see significant reductions in the common pollutants including particulate matter. What we are lacking here is definitive data on the contaminant level and effects of the wash effluent as well as development of an internationally accepted limit for such effluent which will help a ship operator to make a cost effective conclusion and selection of such a system. Scrubbing is applicable to the large majority of plants in the handy sector with current limits of application being plants up to 20mW. When we look at the large, high power plants of container ships scrubbing might not be possible due to the size and weight of such systems as well as the large water volumes, if from one point alone the stability question.
Next we see closed loop scrubbers, much the same as open loop however, now we have an effluent treatment system and the logistics of supplies and disposal of both solid waste and contaminants from the wash system. One more point? The human element and the added maintenance requirement of control systems.
Next we see the sophisticated systems such as Selective Catalytic Reduction and Particulate Filtration. While every operator should strive to keep his/her plant in line with it's design operating parameters we all know this is something that is unfortunately subjective and not always the case. The basic nature of these more sophisticated systems require "controlled and efficient engine operations" at all times or one will face extensive problems maintaining both the emissions control equipment as well compliance. This was well documented in the early days of catalytic systems in the automotive world. Factor in again the maintenance and logistics of supply, exchange and disposal of elements of the system and we see this option may be costly as well as inconvenient. Of course, should distillate fuel operation in all types of plants and operating areas be mandated, these systems might be the best choice.
How are we going to get this issue off center and move forward with environmental protection? We need less debate on the issues of the effects of emissions on the environment, we all know what these are and increased efforts to document the pros and cons of the available technology that is available to enable an operator to make a cost effective decision for refit or incorporation in new building projects.
Let's not put the cart before the horse and implement legislation which impedes commerce when we must first place the costs and logistics issues versus efficiency in pollutant reduction in a simple and easy to read format so operators can move forward and get these systems in place.