1 2 Motivation Ships are strong sources of greenhouse gases and air pollutants 3 of global CO 2 emissions 13 of global NO x emissions 520 12 of global SO 2 emissions ID: 796024
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Slide1
Slide2Press release from ERL: 2 readings
1.
2
.
Slide3MotivationShips are strong sources of greenhouse gases and air pollutants:
3% of global CO2 emissions±13% of global
NOx emissions (5-20%)±12% of global SO2
emissions
IMO, 2014
Slide4MotivationShipping sector shows a degree of awareness
Claims to be a relatively clean mode of transportationReduce emissions by speed reductions and other measures
Ship CO
2
efficiencies
Slide5MotivationLegal framework to reduce ship emissions slow in makingIMO initiatives to implement NECA and SECA
I
mplemented in US waters in 2016
2000
2011
Slide6Very few measurements on open sea OMI overpass time: 13:40 hrs
Slide7Estimating NOx
emissions from NO2 observations
Lifetime of NO
2 at noon is generally short (few hours)Close relationship between NOx emissions and local NO2 columnsS
imple mass balance approach (Martin et al. [2003]):
Practical difficulties:
Standard CTM chemistry
not appropriate for
plumes
Emissions may be misplaced (
E
apriori
)
E
apriori
:
N
CTM
varies in time and space (non-linear local chemistry)
Smearing, weak signal (poster
Huan
Yu)
NO
2
column measured by OMI
NO
2
column simulated by CTM
Emission inventory used in CTM
Slide81. Account for plume chemistry in GEOS-Chem
GEOS-
Chem
plume-in-grid approach for ship emissions
Higher OH in early stages of the plume
Improved simulations with plume-in-grid show 50% lower
NO
x
concentrations than instant dilution!
Vinken
et al., ACP, 2011
OH
NO2
t
Slide92. Detecting
emission patterns with OMI
OMI shows that EMEP emissions are misplaced
(2.5 Tg NO
2
)
(3.7 Tg NO
2
)
Slide103. Account for non-linear chemistry in providing constraints on emissions
Satellite
Model
3
4
1
2
3
4
1
2
β describes local, monthly mean clear-sky sensitivity of NO
2
columns to (changes in)
NO
x
emissions
(
Lamsal
)
For clear-sky European Seas:
β = 0.5-1.0 (0.7)
Slide114. Avoid smearing
Select days
without clouds
and
without outflow
of continental pollution
Slide12NO
x emission estimates
ships in Europe: 2005
before
OMI top down inventory
(0.9
Tg
N/
yr
)
Slide13Changes in 2005-2012 ship
NOx emissions over European Seas (in
TgN yr-1
)4 lanes represent 30% of European shipping NOx emissions
Estimates mostly based on Spring & Summer observations
Increase from 2005-2008, then decrease in 2009
Slide14NOx pollution from ships increasing in relevance
Annual changes in
NO
x emissions (2005-2008)Changes inferred from OMI by Curier et al. [2014]
Changes inferred from OMI in this work
Slide15Comparison to changes in economic indicators
No net change in European ship
NOx emissions between 2005 and 2012Increase in share of shipping sector to NOx emissions from 1 in 9 to 1 in 7
Slide16Slow steaming?
Economic recession in Autumn 2008; shipping sector responded
Cutting costs by saving on fuelReducing overcapacity (less demand)
Slow steaming:Reducing vessel speed from 20-25 knots to 16-19 knotsThis would reduce CO2 and NOx
emissions
Slide17Slow steaming observed from space1. Long-term data set (1992-2012) of ship presence detected by satellite altimeter instruments
2
. Registration of the number of ships passing the Suez Canal
Slide18Slow steaming from space:
Mediterranean Sea
Slide19Slow steaming from space
N
umber of ships through the Suez Canal relatively constant
Number of ships detected over Mediterranean increasesIndication for a longer residence time in the MediterraneanRatio Suez : altimeter ~ ship speed
Ratio OMI
NOx
: altimeter ~
per ship emission factor
Normal
(20-25 knots;
37 – 46
km/
hr
)
Slow
steaming
(14-
20 knots;
25 – 37 km
/
hr
)
Slide20Slide21SummaryOMI allows detection of ship emissions on open sea
European ship NOx emissions increased from 2005-2008Back at their 2005 levels in 2012 (in line with trade)
Because land-based emissions decreased by 25%, ship emissions now make up a larger fraction (1 in 7) of European NOx emissions
Direct evidence of slow steaming from altimeter in combination with Suez Canal passagesShip speeds reduced by 30% in the MediterraneanAccompanied by large NOx emission reductions
21
st
century
ECA’s will be enforced in 2016
Demand will increase
Oil will still be used as fuel