Transportation's Role in Reducing U.S. Greenhouse Gas Emissions ...

Transportations Role in Reducing U.S. Greenhouse Gas Emissions: Volume 2
tested and optimized in a towing tank and currently is being piloted on a 250-foot
multipurpose vessel (Technology Denmark, 2007).
In general, the vessel design technologies discussed in this section are commercially
available. While hull designs can only be introduced on new vessels, interceptor planes,
ducktails, and air injectors can be added as retrofits, though these changes can be made
more cost-effectively during new vessel construction. Their application has been limited
by the cost for retrofits; for example, interceptor plates with ducktails can cost millions of
dollars to install (IMO, 2009).
Magnitude and Timing of GHG Reduction
Use of larger containerships, tankers, and bulk carriers allows for more efficient
movement of cargo. Generally a 10 percent increase in ship volume can improve fuel
efficiency by 4 to 5 percent in terms of gallons of fuel needed per ton-mile transported
(Wartsila, 2008). However, this can vary depending upon the vessel type and operation.
Reducing vessel displacement by increasing the hull width by only 0.25 meters allows for
a reduction of 3,000 tons of ballast, reducing propulsion energy requirements by
8.5 percent (Wartsila, 2008). Use of interceptor or trim planes can improve fuel
consumption by 1 to 4 percent, or up to 10 percent if the interceptor or trim plane is used
in conjunction with a ducktail (Wartsila, 2008; Hansen, 2008; Jaap, 2005). Air lubrication
systems can improve fuel efficiency from 3.5 percent for ferry operations to 15 percent for
large tankers (Wartsila, 2008; Technology Demark, 2007; Frey and Kuo, 2007; Katsui,
2003).
Given that the lifespan of large commercial vessels is over 35 years, fleet turnover is slow,
roughly 2 percent of the fleet per year (EPA, 2002). Accordingly it will take nearly half a
century to incorporate current new hull designs into the global fleet.
Estimates of potential fuel savings and emission reductions are provided in Table 3.6A.
Information on the efficiency benefits of different technologies is quite limited and can
vary significantly depending upon the characteristics of the specific vessel being modified
(i.e., long-haul operations such as tankers and containerships, versus vessels whose
operations can change frequently such as cruise ships and tugs). As a result, a
considerable variation in the range of potential benefits is shown in Table 3.6A. These
estimates assume that identified technologies currently are used in a very limited capacity
or not at all, but will achieve full market penetration by 2050 if programs to encourage the
application of these technologies are put in place in the near future. Combined benefits
could potentially range from 1.0 to 18 mmt CO2e. With a 25- to 40-year turnover cycle
typical for marine vessels, benefits in 2030 could be in the range of half to three-quarters of
the 2050 benefits, or up to 12 mmt CO2e assuming a two-thirds turnover. 2030 benefits
could potentially be higher if policies and/or market forces lead to accelerated fleet
replacement.
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