Estimate baseline NOx mass, SCR removal, urea-solution
consumption, tank capacity, catalyst and utility cost,
post-SCR NOx intensity and cost per tonne of NOx removed.
Advanced mode builds the calculation from multiple engine
operating segments with different loads, hours, baseline
NOx factors, SCR-active shares and removal efficiencies.
NOx Load
Engine energy × entered baseline NOx factor
Urea Demand
NOx removed × entered stoichiometric and solution assumptions
SCR Cost
Urea, auxiliary fuel, catalyst, service and other OPEX
Engine & NOx Load
Use the engine's certified, measured or project-specific
NOx factor where possible. The calculator does not
hard-code a regulatory Tier limit.
kW
%
hours
g/kWh
%
g/kWh
Set to 0 to disable the target check.
Urea Dosing Assumptions
kg/kg NOx
Editable planning assumption. Use vendor dosing
data when available.
% by mass
%
kg/L
Cost, Utilities & Storage
$
/MT solution
kW
g/kWh
$
/MT
$
$
$
tCO2/MT fuel
$
/tCO2
days
%
m³
Set to 0 to disable storage-capacity checking.
Engine Operating Segments
Build the NOx inventory from separate operating segments.
SCR-active share represents the portion of each segment
when the SCR system is actually dosing and available.
Segment
Power kW
Load %
Hours
NOx g/kWh
SCR Active %
Removal %
Urea Chemistry & Dosing
kg/kg NOx
% by mass
%
kg/L
g/kWh
Cost & Auxiliary Power
$
/MT solution
kW active
g/kWh
$
/MT
$
$
$
tCO2/MT fuel
$
/tCO2
Urea Storage Planning
days
%
m³
SCR Urea & NOx Results
Simple SCR operating-cost estimate
Enter SCR data
Enter engine power, load, operating hours and NOx
assumptions to calculate SCR urea consumption and NOx cost.
Urea Solution Consumption
N/A
Total aqueous urea solution required for the modeled NOx reduction
Total SCR Operating Cost
N/A
Urea, auxiliary fuel, catalyst, service, carbon and other entered OPEX
SCR Cost Breakdown
NOx & Urea Summary
Operating Segment Results
Advanced mode
Segment
Energy MWh
Baseline NOx
NOx Removed
Post-SCR NOx
Active Hours
SCR Cost Sensitivity
Baseline NOx load vs urea price
NOx Load \ Urea Price
-20%
Base
+20%
Model approach:
baseline NOx mass = engine energy × entered NOx factor.
NOx removed = baseline NOx × SCR-active share × entered
removal efficiency. Pure urea demand = NOx removed ×
entered stoichiometric ratio ÷ dosing utilization.
Urea-solution mass then divides pure urea demand by entered
solution concentration. Auxiliary electrical demand is
converted to generator fuel using the entered SFOC. This
is a planning model and does not determine regulatory
certification or engine/SCR approval.
Planning estimate only.
Actual SCR dosing depends on exhaust flow, NO/NO2 ratio,
exhaust temperature, sulfur level, catalyst formulation and
age, mixing quality, control strategy, ammonia-slip limits,
engine load, transient operation and maker-specific dosing
maps. Urea solution properties also vary with concentration
and temperature. This calculator does not determine IMO Tier
compliance, ECA compliance, technical-file conformity,
certification, ammonia slip or safe storage requirements.
Use the certified engine/SCR technical file, maker data,
supplier specifications and applicable vessel requirements
for operational decisions.
