In-depth | PAINTS The illusion of fuel savings
A vessel’s fuel consumption throughout its docking cycle depends on several variables; however, most observers believe that fuel consumption increases throughout the docking cycle – even with the best available hull performance solutions (HPS). Why, then, do we talk about fuel savings in the same sentence as hull coatings? Asks Bjørn Wallentin, global sales director, HPS, Jotun Coatings.
T
he answer to the above is as simple as it is complex – “fuel savings” sends positive buying signals
while “reduced loss in performance” will easily be perceived as negative. In this article we will try to offer some insight as to what some of these approaches actually mean in real performance terms. The environment and how all our
actions influence the planet we inhabit are all around us every day. We meet it in newspapers, on television, on signboards and also from our children as they teach us how not to waste water while brushing our teeth for example. We are faced with lack of agreement/
action from the United Nations (UN) Copenhagen summit in 2009 and Cancun in 2010 for global environmental improvements, while individual countries and local authorities take a much tougher approach to reduce their environmental impact and “carbon footprint”. This is the situation and we cannot
as individuals avoid being influenced by this massive amount of information and pressure. The global focus on the negative effects of increasing emissions of greenhouse gases (GHG) is one of the key issues on the agenda for the marine environment protection committee (MEPC) and other organisations within the marine industry. In 2007, shipping was estimated
to have emitted 3.3% of global CO2 emissions,
to which international
shipping contributed 2.7%, or 870 million tonnes [1]. Vessel owners and operators do take responsibility and many have clear environmental policies well
communicated this focus, through their
organisation. As a positive consequence, of
chain has been developing solutions that aim to reduce emissions.
16 the whole marine value
vessels. Tis is a fleet that in actual terms may run more efficiently and with less emissions than a new vessel of the same size. Te marine coating industry has adapted to this time zero perspective by offering new biocide free hull coatings that are initially very smooth, thus contributing to a higher initial vessel speed (vref.). However, it is our experience that there is an additional long term fuel penalty as a result of a more dense slime fouling and also animal fouling on the biocide free technologies compared to the high quality biocide containing products. Observing the above simplified formula
Bjørn Wallentin global sales director hull performance solutions at Jotun.
Tis covers the whole range of products
from new vessel designs and use of other types of fuels, through to more efficient coating systems for the underwater hull. Tere actually seems to be an unlimited number of fuel saving devises, that if they all worked as promised, would combined, allow the vessels to operate with no emissions what so ever. Obviously something must be wrong. Some of these technologies cannot possibly perform as promised – but how to select the ones that do? Instead of developing a performance
index that reflects the actual vessel’s performance, tools have been developed to compare how vessels could theoretically perform with the basis in vessel data from new build. An example of this would be the Energy Efficiency Design Index2 (EEDI) developed to put focus on improving the performance of new buildings. We consider this to be a good example of
a typical time zero (initial/perfect condition and not representative to actual long term performance) perspective that offers little or no advantages for the existing fleet of
), propelled by a small engine (installed power) running on LNG (Ccarbon
for calculation of EEDI we can easily conclude that an increase in vref will contribute to a lower, and improved, EEDI. Te above equation promotes a smooth hull (vref
). This
seems however, sadly to have little relevance with regards to the vessel performance and fuel consumption beyond the sea trials at the new-building stage. Te most efficient way to reduce the emissions is to maintain a clean and smooth hull in service between the dockings. How then can statements of huge fuel savings in the range of 5-10% be made by the paint makers?
The illusion Jotun’s conclusion is that the answer to why these 5-10% fuel savings statements are made lies within the reference used, or lack of such. As a result attention should be drawn to the conditions under which most of the biocide free systems are sold and applied. Biocide free hull paint systems are
normally perceived as quite expensive and to apply these on top of an aging primer system does not make sense with the long lifetime they are designed to last. For that reason most, if not all, hulls/sections are fully blasted down to steel.
The Naval Architect July/August 2011
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