Environmental Engineering Reference
In-Depth Information
10 000
10 000
1 000
100
10
1
Road
Shipping
Aviation
Rail
US freight
EU 25 freight
Seaborne trade
Note:
Global mode-share estimates include seaborne trade. Like estimates for truck and rail, neither US
nor EU-25 data include ocean shipping or air freight outside their domains.
Figure 2.2
Comparison of freight-mode shares (tonne-km) for the USA and Europe
pollution related to ocean shipping is not directly from the ships, but from e
ff
orts to serve the
ocean shipping sector through port infrastructure maintenance and
eet modernization.
Episodic pollution discharges are among those best understood by the commercial
industry and policy-makers, as evidenced by the international conventions and national
regulations addressing them. The dominant mitigation approach is to prohibit pollution
episodes from occurring (as in ocean dumping), to design systems that are safer (as in
double hulls to prevent oil spills or tra
fl
c separation schemes to avoid collisions), to
con
ne activities that produce untreated discharges to safer times or locations (e.g. envi-
ronmental windows for dredging), to require onboard treatment before discharge (e.g. oily
water separators), and/or to provide segregated holding and transfer to reception facili-
ties at port (as in sewage handling).
Routine pollution releases are di
fi
erent than episodic discharges because they represent
activities necessary for the safe operation of the vessel, whether at sea or in port.
Regulation of routine releases has lagged policy action to address episodic discharges,
partly because these impacts were not so well understood in the past, and partly because
operational behavior must change and/or new technology is required.
ff
Freight energy and emissions
Energy use by mode is generally proportional to the work done (cargo tkm) by each
freight mode, with intermodal adjustments for di
ff
erences in energy intensities. Energy
