Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-1 ENVIRON

3 Emission Source Description

In this section of the permit application, we describe the emissions calculation basis for each 

emissions unit proposed for the Developer and Discoverer Americas. As previously discussed, 

Statoil is requesting flexibility to use either the Developer or Discoverer Americas to perform 

exploration activities in its Desoto Canyon lease blocks. The Developer is presented as 

Operating Scenario 1, and the Discoverer Americas is presented as Operating Scenario 2. 

Whether using the Developer or Discoverer Americas, the potential annual emissions proposed 

with this permit application are based on approximately 180 days per calendar year of 

exploration activities. However, when Statoil begins the exploration activities proposed with this 

permit application, the actual daily average operating rates of the emissions units associated 

with the specific drilling vessel may not be as high as the daily average operating rates 

corresponding to the 180 days per year potential emissions basis for the vessel. Therefore,

Statoil is requesting the establishment of annual operating rate and emission rate permit limits, 

not a limit on the annual number of days of exploration activities. For example, Statoil proposes 

the following annual fuel usage limits for the Developer engines and its associated OSV and 

crew boat engines rather than a 180 day per year limit.

• Developer engines – 2,652,180 gallons of diesel per year

• Developer OSV engines – 796,086 gallons of diesel per year when within 25 miles of 

and servicing the Developer

• Developer crew boat engines – 252,195 gallons of diesel per year when within 25 miles 

of and servicing the Developer

Alternatively, Statoil proposes the following annual fuel usage limits for the Discoverer Americas

engines and its associated OSV and crew boat engines rather than a 180 day per year limit.

• Discoverer Americas engines – 2,182,414 gallons of diesel per year

• Discoverer Americas OSV engines – 796,086 gallons of diesel per year when within 25 

miles of and servicing the Developer

• Discoverer Americas crew boat engines – 252,195 gallons of diesel per year when within 

25 miles of and servicing the Developer

This section is organized as follows. In Section 3.1, we describe general emissions basis 

information that applies globally to the drilling and exploration activities proposed with this 

permit application. Section 3.2 presents the emission calculation basis for each of the 

emissions units associated with the Developer, and Section 3.3 presents the same information 

for the Discoverer Americas. Lastly, Section 3.4 describes emergency operations that could 

occur for the two drilling vessels and the emissions to the atmosphere that would likely be 

related with these emergency operations. Please see Appendix B of this permit application for 

the detailed potential emissions calculations discussed in this section.
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Emission Source Description 3-2 ENVIRON

3.1 General Emissions Basis Information

In this section, we describe general emissions basis information that applies globally to the 

drilling and exploration activities proposed with this permit application.

3.1.1 Emission Factor Basis Development

The emissions calculations included in this permit application are based on the most current 

EPA approved emissions estimating procedures, industry standard methods, best professional 

judgment, and the most accurate emissions estimating data believed to be available after 

reasonable inquiry. Below we describe the emission factors used to estimate emissions from 

the diesel engines aboard the Developer and Discoverer Americas and associated support fleet.

Emission factors serve as the basis of emission rate estimates for all diesel-fired engines. 

Emission factors represent a quantity of emissions per unit of fuel consumed or unit of power 

produced. The emission factors that have been utilized to estimate emissions were derived 

from multiple sources as documented herein.

Vendor Supplied Data – The emission factor was supplied by the owner, operator, or 

manufacturer of the emissions unit. For engines, the basis for vendor supplied data is typically 

engine test data, either in a test laboratory or during actual use.

Certification Level – For an engine, this emission factor would have been obtained from 

documentation provided by the engine manufacturer that certifies the engine emissions comply 

with a regulatory emissions limitation or standard.

Mass Balance – The emission factor used to estimate sulfur dioxide (SO2) emissions from the 

combustion of diesel in the engines located on the drilling vessels was calculated using a mass 

balance approach. The factor was based on the sulfur content (0.0015 percent by weight) of 

the diesel fuel proposed to be combusted in the engines and an assumption that 100 percent of 

the sulfur contained in the diesel will be oxidized to SO2. The noted sulfur content represents 

the specification required for ultra low sulfur diesel, which is the grade of diesel to be combusted 

in the engines.

AP-42 – The emission factor was obtained from EPA published AP-42 documents. Specifically, 

factors for large engines (>600 hp) were obtained from Section 3.4, Large Stationary Diesel and 

All Stationary Dual-fuel Engines, October 1996. Similarly, the emission factors for small 

engines (≤600 hp) were obtained from Section 3.3, Gasoline and Diesel Industrial Engines, 

October 1996. In some cases particulate matter (PM) size distribution information from AP-42 

was applied to certification level PM data to calculate PM less than 10 microns (PM10) and PM 

less than 2.5 microns (PM2.5) emission factors. These cases are noted in this section with the 

following reference, “Certification & AP-42.”

EPA – The emission factor was obtained from an EPA published document other than AP-42. 

Emission factors for carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) resulting 

from the combustion of diesel were obtained from Tables C-1 and C-2 of 40 CFR part 98, 

subpart C. These greenhouse gas (GHG) emissions were converted to carbon dioxide 
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Emission Source Description 3-3 ENVIRON

equivalent (CO2e) based on the respective global warming potential identified for each of the 

pollutants in Table A-1 of 40 CFR part 98, subpart A. Additionally, the emission factor for lead 

resulting from the combustion of diesel was obtained from the following EPA document:

Locating and Estimating Air Emissions from Sources of Lead and Lead Compounds (454-R-98-

006), May 1998. Finally, the following EPA document was used as a reference to consider 

emissions of sulfuric acid mist and total reduced in association with the combustion of diesel: 

Draft Regulatory Impact Analysis: Control of Emissions from Nonroad Diesel Engines (420-R03-008), April 2003.

3.1.2 Sulfur Compound Emissions

As discussed above, we have calculated SO2 emissions from diesel-fired engines on the basis 

that 100 percent of the sulfur compounds in the diesel will be oxidized to SO2. The sulfur 

compounds in diesel fuel do not include hydrogen sulfide (H2S).1

 Because H2S is not a normal 

constituent of diesel fuel and is not expected to be formed during combustion, H2S emissions

from the combustion of diesel are considered negligible.2

In association with the determination of PSD applicability, we have calculated sulfuric acid mist 

(H2SO4) and total reduced sulfur (TRS)3 emissions from diesel-fired engines. As previously

discussed, when estimating potential SO2 emissions from the diesel-fired engines proposed in 

this permit application, we have assumed that 100 percent of the sulfur compounds in the diesel 

are oxidized to SO2. However, out of an abundance of caution, we have calculated potential 

H2SO4 and TRS emissions from diesel-fired engines using information contained in the 

following draft EPA document: Draft Regulatory Impact Analysis: Control of Emissions from 

Nonroad Diesel Engines (420-R-03-008), April 2003.

Potential H2SO4 emissions from diesel-fired engines were estimated on the basis that 2.247 

percent by weight of the sulfur in the diesel is converted to SO4, which is then converted to 

sulfuric acid. Similarly, potential TRS emissions were calculated on the basis that 1 percent by 

weight of the sulfur in the diesel is emitted as TRS rather than being oxidized to SO2. Note that 

the 1 percent sulfur could be converted to TRS or reduced sulfur compounds (RSC).

4

 With 

either designation, the potential emissions are considerably less than the relevant PSD 

significant level of 10 tpy. Please see Appendix B for the potential emissions calculations.

3.1.3 Fluoride Emissions

Based on a literature review and internet search, no information was identified indicating there is 

the potential for fluoride emissions from the combustion of diesel fuel in internal combustion 

engines. Consistent with this concept, fluorine-containing compounds are not identified in the 

speciation profile of Distillate Fuel Oil No. 2 (diesel) included in the EPA TANKS 4.09d program, 

 1 According to the speciation profile of Distillate Fuel Oil No. 2 (diesel) from the EPA TANKS 4.09d Program, 

hydrogen sulfide is not a component of diesel. 2 Based on AP-42, Chapter 3.4, Large Stationary Diesel and All Stationary Dual-fuel Engines, (10/1996), hydrogen 

sulfide is not a speciated component of diesel combustion emissions. Furthermore, based on information provided in 

this section of AP-42, all sulfur in the fuel is expected to be oxidized to SO2.

3 TRS compounds comprise hydrogen sulfide, methyl mercaptan, dimethyl sulfide, and dimethyl disulfide.

4 RSC compounds comprise hydrogen sulfide, carbonyl sulfide, and carbon disulfide.
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Emission Source Description 3-4 ENVIRON

and no literature review or internet search indicated that fluorine-containing compounds would 

be present in diesel fuel. As a result of these findings, fluoride emissions resulting from the 

combustion of diesel are considered negligible.

5

3.1.4 Startup, Shutdown, and Maintenance Emissions

Emissions associated with the start-up and shutdown of the engines located on the Developer

and Discoverer Americas are accounted for in the potential emissions proposed for the engines. 

Additionally, maintenance will be performed on the diesel engines on a periodic basis in 

accordance with the procedures recommended by the particular engine manufacturer. 

However, emissions associated with such maintenance activities are accounted for in the 

potential emissions proposed for the engines. In summary, the proposed potential emissions for 

the Developer and Discoverer Americas emissions units are intended to cover start-up,

shutdown, and maintenance emissions.

3.2 Developer Emission Calculation Basis

As previously discussed, the use of the Developer is Operating Scenario 1. The Developer will 

be supported by various support vessels operating within 25 miles its location. The support 

vessels will transport personnel and supplies to and from the drilling vessel. The Developer

does not require towing or anchoring vessels because the vessel is self-powered for transport 

and dynamically positioned when operating at the drilling location.

The following table summarizes the emissions units that are proposed for the Developer.

Table 3.2-1

Developer Emissions Units

Emissions Unit ID Source Description Quantity

GEN-1 thru GEN-8 Main Generator Engines 8

EGEN Emergency Generator Engine 1

CMU-1 and CMU-2 Cement Unit Engines 2

LB Lifeboat Engines 4

MOB Fast Rescue Boat Engine 1

FO ST Fuel Oil Storage Tanks 4

FO SER ST Fuel Oil Service Tanks 2

FO SET ST Fuel Oil Settling Tanks 2

FO E GEN ST Emergency Generator Fuel Oil Tank 1

FO CMV ST Cement Unit Fuel Oil Tank 1

FO LB ST Lifeboat Fuel Tanks 1 per lifeboat

FO MOB ST Fast Rescue Boat Fuel Tank 1

AV ST Aviation Fuel Tanks 3

 

5 Based on AP-42, Chapter 3.4, Large Stationary Diesel and All Stationary Dual-fuel Engines, (10/1996), fluoride is 

not a speciated component of diesel combustion emissions. 
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Emission Source Description 3-5 ENVIRON

Emissions Unit ID Source Description Quantity

WO ST Waste Oil Tanks 2

FUG Fugitive Component Emissions -

OSV Offshore Support Vessels Multiple

CREW Crew Boats Multiple

Note that the wireline units (also referred to as “logging units”) located on the Developer will be 

electric powered. Therefore, the units will not be directly powered by an internal combustion 

engine.

In the sections below, we discuss in detail the proposed potential emissions basis for each of 

the emissions units identified in the above table.

3.2.1 Main Generator Engines

The main generator engines located on the Developer represent the “main” electric power 

generating engines on the drilling vessel. There are eight identical 6,651 hp (4,960 kW) main 

generator engines on the Developer, and these engines were manufactured by Wärtsilä 

Corporation. The following summarizes the proposed operating basis for the main generator 

engines on the vessel.

• “Normal Operations” Basis – The “Normal Operations” basis consists of operating 

three engines at 60% load while the remaining five engines are on standby at 0% 

load. Note that the proposed allowable annual emissions will apply to all of the 

engines as a group, which provides flexibility to operate any combination of the 

engines.

• Maximum Hourly Emissions Basis – The maximum hourly emissions basis consists

of operating five engines at 60% load while the three remaining engines are on 

standby at 0% load. This scenario accounts for the most engines running during any 

given hour of operation at their highest power rating. Note that the proposed 

allowable maximum hourly emission rate limits will apply to all of the engines as a 

group, which provides flexibility to operate any combination of the engines.

The table below summarizes key operating parameters that are the basis of the emission 

calculations for the main generator engines.

Table 3.2.1-1

Main Generator Engine Operating Parameters

Emissions

Unit ID

Maximum Power

Rating

(kW)

Normal Operation 

Power Rating

(kW)

Normal Operation 

Annual Hours

(hr/yr)

Maximum Hourly

Power Rating

(kW)

GEN-1 4,960 2,976 4,320 2,976

GEN-2 4,960 2,976 4,320 2,976
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Emission Source Description 3-6 ENVIRON

Emissions 

Unit ID

Maximum Power 

Rating

(kW)

Normal Operation 

Power Rating

(kW)

Normal Operation 

Annual Hours

(hr/yr)

Maximum Hourly

Power Rating

(kW)

GEN-3 4,960 2,976 4,320 2,976

GEN-4 4,960 0 4,320 2,976

GEN-5 4,960 0 4,320 2,976

GEN-6 4,960 0 4,320 0

GEN-7 4,960 0 4,320 0

GEN-8 4,960 0 4,320 0

Below is a summary of the emission factors used to calculate annual and maximum hourly 

emissions for the main generator engines installed on the Developer.

Table 3.2.1-2

Main Generator Engine Emission Factors

Pollutant

Emission Factor

(g/kW-hr) Emission Factor Basis

Total VOC 0.43 AP-42

NOx 8.16 Vendor Supplied Data

SO2 0.007 Mass Balance

CO 0.39 Vendor Supplied Data

PM 0.15 Vendor Supplied Data

PM10 0.15 Vendor Supplied Data

PM2.5 0.15 Vendor Supplied Data

CO2e 696.6 EPA

Lead 1.23E-04 EPA

Benzene 3.30E-03 AP-42

Toluene 1.20E-03 AP-42

Xylenes 8.22E-04 AP-42

Formaldehyde 3.36E-04 AP-42

Acetaldehyde 1.07E-04 AP-42

Acrolein 3.36E-05 AP-42

Naphthalene 5.54E-04 AP-42

3.2.2 Cement Unit Engines

The Developer is equipped with two cementing units that produce cement that is pumped 

around the outside of the casing during the drilling process to stabilize the casing. Each 

cementing unit is equipped with a 500 hp (373 kW) diesel-fired engine. The table below 

summarizes the key operating parameters that are the basis of the potential emission 

calculations for the cement unit engines. The maximum hourly emissions for each engine are 

based on running the engine at 100% capacity for an entire hour.
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Emission Source Description 3-7 ENVIRON

Table 3.2.2-1

Cement Unit Engine Operating Summary

Emissions Unit 

ID Source Description

Maximum Power 

Rating (kW)

Run Time

(hr/yr)

CMU-1 Cement Unit Engine #1 373 60

CMU-2 Cement Unit Engine #2 373 60

Below is a summary of the emission factors used to calculate annual and maximum hourly 

emissions for the cement unit engines installed on the Developer.

Table 3.2.2-2

Cement Unit Engine Emission Factors

Pollutant

Emission Factor

(g/kW-hr) Emission Factor Basis

Total VOC 1.53 AP-42

NOx 7.2 Certification

SO2 0.007 Mass Balance

CO 5.00 Certification

PM 0.20 Certification

PM10 0.16 Certification & AP-42

PM2.5 0.16 Certification & AP-42

CO2e 696.60 EPA

Lead 1.23E-04 EPA

Benzene 3.97E-03 AP-42

Toluene 1.74E-03 AP-42

Xylenes 1.21E-03 AP-42

Formaldehyde 5.02E-03 AP-42

Acetaldehyde 3.27E-03 AP-42

Acrolein 3.94E-04 AP-42

Naphthalene 3.61E-04 AP-42

1,3-Butadiene 1.66E-04 AP-42

3.2.3 Emergency Generator Engines

The Developer is equipped with an emergency generator driven by a 2,551 hp (1,902 kW) 

diesel engine. The emergency generator engine is operated during maintenance checks or in 

the event of an emergency. The engine is planned to be operated for 6.7 hours per month, with 

one-half of this time for normal engine testing and maintenance hours and the other half for 

expected emergency use of the engine based on past operations. The table below summarizes 

the key operating parameters that are the basis of the potential emissions calculations for the 

emergency generator engine. The maximum hourly emissions for the engine are based on 

running the engine at 100% capacity for an entire hour.
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Emission Source Description 3-8 ENVIRON

Table 3.2.3-1

Emergency Generator Engine Operating Summary

Emissions 

Unit ID Source Description

Maximum 

Power Rating

(kW)

Run Time

hr/month hr/yr

EGEN Emergency Generator Engine 1,902 6.7 39

Below is a summary of the emission factors used to calculate annual and maximum hourly 

emissions for the emergency generator engine installed on the Developer.

Table 3.2.3-2

Emergency Generator Emission Factors

Pollutant

Emission Factor

(g/kW-hr) Emission Factor Basis

Total VOC 0.43 AP-42

NOx 9.2 Certification

SO2 0.007 Mass Balance

CO 3.35 AP-42

PM 0.30 AP-42

PM10 0.244 AP-42

PM2.5 0.237 AP-42

CO2e 696.60 EPA

Lead 1.23E-04 EPA

Benzene 3.30E-03 AP-42

Toluene 1.20E-03 AP-42

Xylenes 8.22E-04 AP-42

Formaldehyde 3.36E-04 AP-42

Acetaldehyde 1.07E-04 AP-42

Acrolein 3.36E-05 AP-42

Naphthalene 5.54E-04 AP-42

3.2.4 Lifeboat Engines

The Developer is equipped with four lifeboats. Each lifeboat is equipped with a 29 hp (22 kW) 

engine that is operated during maintenance checks, safety exercises, or in the event of an 

emergency. The planned operating time for maintenance of the engines is one hour per month, 

which we have doubled to account for safety exercises. Since the potential emissions of 

regulated air pollutants are less than 2 tpy, and HAP emissions are less than 1,000 lb/yr, the 

emission levels from the lifeboat engines are considered insignificant per 40 CFR 71.5(c)(11)(ii) 

and will be included as such in the permit application forms. The table below summarizes the 

key operating parameters that are the basis of the potential emissions calculations for the 

lifeboat engines.
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Emission Source Description 3-9 ENVIRON

Table 3.2.4-1

Lifeboat Engine Operating Summary

Emissions Unit 

ID Source Description

Maximum 

Power Rating

(kW)

Run Time

hr/month hr/yr

LB-1 Lifeboat No. 1 Engine 22 2 12

LB-2 Lifeboat No. 2 Engine 22 2 12

LB-3 Lifeboat No. 3 Engine 22 2 12

LB-4 Lifeboat No. 4 Engine 22 2 12

Furthermore, below is a summary of the emission factors used to calculate annual and 

maximum hourly emissions for the Developer lifeboat engines.

Table 3.2.4-2

Lifeboat Engine Emission Factors

Pollutant

Emission Factor

(g/kW-hr) Emission Factor Basis

Total VOC 1.53 AP-42

NOx 7.5 Certification

SO2 0.007 Mass Balance

CO 5.5 Certification

PM 0.60 Certification

PM10 0.49 Certification & AP-42

PM2.5 0.48 Certification & AP-42

CO2e 696.6 EPA

Lead 1.23E-04 EPA

Benzene 3.97E-03 AP-42

Toluene 1.74E-03 AP-42

Xylenes 1.21E-03 AP-42

Formaldehyde 5.02E-03 AP-42

Acetaldehyde 3.27E-03 AP-42

Acrolein 3.94E-04 AP-42

Naphthalene 3.61E-04 AP-42

1,3-Butadiene 1.66E-04 AP-42

3.2.5 Fast Rescue Boat Engines

The Developer is equipped with one fast rescue boat. The fast rescue boat is commonly

referred to as a “man overboard boat” or “MOB.” The fast rescue boat is equipped with a 163

hp (122 kW) engine that is operated during maintenance checks, safety exercises, or in the 

event of an emergency. The planned operating time for maintenance of the engine is one hour 

per month, which we have doubled to account for safety exercises. Since the potential 

emissions of regulated air pollutants are less than 2 tpy, and HAP emissions are less than 1,000 

lb/yr, the emission levels from the fast rescue boat engines are considered insignificant per 40 
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Emission Source Description 3-10 ENVIRON

CFR 71.5(c)(11)(ii) and will be included as such in the permit application forms. The table 

below summarizes the key operating parameters that are the basis of the potential emissions 

calculations for the fast rescue boat engine.

Table 3.2.5-1

Fast Rescue Boat Engine Operating Summary

Emissions Unit 

ID Source Description

Maximum 

Power Rating

(kW)

Run Time

hr/month hr/yr

MOB Fast Rescue Boat Engine 122 2 12

Below is a summary of the emission factors used to calculate annual and maximum hourly 

emissions for the fast rescue boat engine on the Developer.

Table 3.2.5-2

Fast Rescue Boat Engine Emission Factors

Pollutant

Emission Factor

(g/kW-hr) Emission Factor Basis

Total VOC 1.53 AP-42

NOx 7.50 Certification

SO2 0.007 Mass Balance

CO 5.00 Certification

PM 0.40 Certification

PM10 0.33 Certification & AP-42

PM2.5 0.32 Certification & AP-42

CO2e 696.6 EPA

Lead 1.23E-04 EPA

Benzene 3.97E-03 AP-42

Toluene 1.74E-03 AP-42

Xylenes 1.21E-03 AP-42

Formaldehyde 5.02E-03 AP-42

Acetaldehyde 3.27E-03 AP-42

Acrolein 3.94E-04 AP-42

Naphthalene 3.61E-04 AP-42

1,3-Butadiene 1.66E-04 AP-42

3.2.6 Storage Vessels

Emissions are generated from the storage of fuel and waste oil in tanks aboard the Developer. 

Diesel6 is used in the engines installed on the drilling vessel as well as the vessel’s lifeboat and 

fast rescue boat engines. Additionally, there are three storage tanks for aviation fuel, which is 

 6 Marine gas oil, diesel fuel, and distillate fuel oil No. 2 all have very similar properties and are collectively referred to 

as “diesel” in this permit application.
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Emission Source Description 3-11 ENVIRON

used to refuel helicopters. Finally, there are two storage tanks on the drilling vessel that are 

used to store waste oil that is collected from fuel system strainers, filters, and separators.

The EPA TANKS 4.09d computer software program was used to calculate the potential working 

and breathing emissions from the storage vessels located on the Developer. The default EPA 

TANKS 4.09d properties for Distillate Fuel Oil No. 2 were used to calculate emissions for the 

diesel and waste oil storage tanks. Additionally, the default EPA TANKS 4.09d properties for 

Jet Naphtha were used to calculate emissions for the aviation fuel storage tanks. For a 

particular storage tank, the maximum hourly emissions were estimated by dividing the annual 

emissions calculated for the tank using EPA TANKS 4.09d by the tank’s annual hours of 

operation.

Since the potential emissions of regulated air pollutants are less than 2 tpy, and HAP emissions 

are less than 1,000 lb/yr, the emission levels from the storage tanks are considered insignificant 

per 40 CFR 71.5(c)(11)(ii) and will be included as such in the permit application forms. The 

table below summarizes key design and operating parameters that are the basis of the potential 

emissions calculations for the storage vessels.

Table 3.2.6-1

Storage Vessel Inventory and Operating Summary

Emissions 

Unit ID Source Description

Capacity Working 

Capacity

(gal)

Throughput

m (gal/yr) 3 gal

FO ST Pontoon Fuel Oil Tank No. 1 (P) 1,305 344,715 310,244 700,000

Pontoon Fuel Oil Tank No. 2 (S) 1,305 344,715 310,244 700,000

Pontoon Fuel Oil Tank No. 3 (P) 875 231,087 207,978 700,000

Pontoon Fuel Oil Tank No. 4 (S) 875 231,087 207,978 700,000

FO SER ST Upper Hull Fuel Oil Tank No. 1 (P) 49 12,815 11,533 1,400,000

Upper Hull Fuel Oil Tank No. 2 (S) 57 14,952 13,457 1,400,000

FO SET ST Upper Hull Fuel Oil Tank No. 3 (P) 34 8,948 8,053 1,400,000

Upper Hull Fuel Oil Tank No. 4 (S) 35 9,230 8,307 1,400,000

FO E GEN ST Emergency Generator Fuel Oil 

Tank

8 2,113 1,902 5,000

FO CMV ST Cement Unit Fuel Oil Tank 2 549 495 4,000

FO LB ST Lifeboat No. 1 Fuel Tank 0.2 45 40 20

Lifeboat No. 2 Fuel Tank 0.2 45 40 20

Lifeboat No. 3 Fuel Tank 0.2 45 40 20

Lifeboat No. 4 Fuel Tank 0.2 45 40 20

FO MOB ST Fast Rescue Boat Fuel Tank 0.2 45 40 100

AV ST Aviation Fuel Tank No. 1 3 748 673 121,112

Aviation Fuel Tank No. 2 3 748 673 121,112

Aviation Fuel Tank No. 3 3 748 673 121,112

WO ST Waste Oil Tank No. 1 (P) 35 9,125 8,212 8,212

Waste Oil Tank No. 2 (S) 35 9,125 8,212 8,212
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Emission Source Description 3-12 ENVIRON

3.2.7 Fugitive Components

The Developer is equipped with piping and associated piping fugitive components that are used 

to convey fuel and waste oil on the vessel. Fugitive component counts were estimated based 

on a review of the Developer fuel system piping and instrumentation diagrams (P&IDs). 

Fugitive emissions have been calculated based on the number of components and the material 

contained or contacted by the components. The table below summarizes the component counts 

by service on the Developer.

Table 3.2.7-1

Fugitive Component Emissions

Component Type

Number of Fuel Service

Components

Number of Waste Oil

Service Components

Valve 263 4

Flange 525 8

Pump Seal 6 0

Other 36 0

The potential emissions for the fugitive components have been calculated using the oil and gas 

production operations average emission factors included in Table 2-4 of the Protocol for 

Equipment Leak Emission Estimates (EPA-453/R-95-017), November 1995 and the composition 

of the material to be contained or contacted by the components. Because a “heavy oil” pump 

emission factor was not identified, we used the “light oil” pump emission factor for all of the

pumps on the drilling vessel. For “other” component types, we used the “heavy oil” emission 

factor because the large majority of components on the vessel are in diesel service. Finally, 

Table 2-4 identifies separate emission factors for flanges and connectors. We conservatively 

used the higher of the flange and connector emission factors identified in the table to estimate 

emissions from the flanges/connectors located on the vessel. The emission factors used in the 

potential emissions calculations for fugitive emissions are summarized in the table below.

Table 3.2.7-2

Fugitive Component Emission Factors

Service

Valves

(kg/hr/source)

Connectors

(kg/hr/source)

Pumps

(kg/hr/source)

Other

(kg/hr/source)

Diesel 8.4E-06 7.5E-06 1.3E-02 3.2E-05

Waste Oil 9.8E-05 1.1E-04 2.4E-05 3.2E-05

3.2.8 Support Vessels

Specific support vessels are not solely dedicated to a particular drilling campaign. Instead,

Statoil relies on a support vessel fleet made up of many different vessels that fall into one of two

support vessel categories. Note that the proposed potential emissions included in this 

application for the Developer support vessels will apply to any support vessel that Statoil may 

use with the drilling vessel, which is expected to provide Statoil with the flexibility to utilize any 

vessel from the support vessel fleet to meet project needs. Additionally, a direct physical 

connection between the drilling vessel and a support vessel is an unusual event. Normally, the 
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Emission Source Description 3-13 ENVIRON

support vessels will be under their own power when adjacent to the drilling vessel for loading or 

unloading purposes. The only expected physical connection between the drilling vessel and a 

support vessel would be product transfer hoses such as those necessary for the transfer of fuel 

or drilling mud between the vessels.

To estimate annual emissions from the engines of each type of support vessel, Statoil estimated 

the total hours of operation of the particular vessel-type during the proposed drilling campaign 

(180 days) based on actual hours of operation for similar vessels during historical drilling 

campaigns. Statoil used the actual hours of operation (with a safety buffer) in conjunction with 

emission factors (certification, AP-42, etc.) to estimate annual emissions associated with the 

support vessel operations. To estimate maximum hourly emissions for each support vessel 

type, Statoil gathered specific engine data and emissions information for several vessels in each 

category. From that information, Statoil derived the emissions that could reasonably be 

expected from each type of support vessel during the drilling campaign. While actual emissions 

will vary between different vessels, the potential support vessel emissions proposed in this

application are a reasonable estimate of the emissions expected from a typical support vessel in 

each category.

3.2.8.1 Offshore Support Vessel Engines

OSVs transport personnel and supplies to and from the drilling vessel. OSVs are equipped with 

large engines that power generators, thrusters, and main propulsion devices. Additionally, the 

OSVs are equipped with small engines that are used to power emergency generators. Statoil 

used the engine inventory on the OSV Peyton Candies to represent typical engine emissions 

from an OSV.

The potential annual engine emissions from an OSV have been calculated based on the

estimated annual hours of operation of each engine on the vessel. Maximum hourly engine 

emissions from an OSV have been estimated by assuming each engine on the vessel operates 

at its highest load capacity for the hour. As previously noted, actual engine emissions may vary 

with different OSVs, but the potential OSV engine emissions proposed with this application are 

representative of a typical OSV. The table below summarizes the key operating parameters 

that are the basis of the potential emissions calculations for the OSV engines.

Table 3.2.8.1-1

Offshore Support Vessel Engine Operating Summary

Emissions 

Unit ID Source Description

Maximum 

Power Rating

(kW)

Normal 

Operation 

Power Rating

(kW)

Normal 

Operation 

Annual Hours

(hr/yr)

Maximum 

Hourly Power 

Rating

(kW)

OSV OSV Main Engine No. 1 1,765 1,765 3,059 1,765

OSV Main Engine No. 2 1,765 1,765 3,059 1,765

OSV Main Engine No. 3 1,765 0 3,059 1,765

OSV Main Engine No. 4 1,765 0 3,059 1,765

OSV Emergency 

Generator Engine

269 269 3,059 269
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-14 ENVIRON

Below is a summary of the emission factors used to calculate annual and maximum hourly 

emissions for the engines on the OSVs that will be associated with the Developer.

Table 3.2.8.1-2

Offshore Support Vessel Engine Emission Factors

Pollutant

Main Engine

Emission Factor

(g/kW-hr)

Emergency

Generator

Emission Factor

(g/kW-hr) Emission Factor Basis

Total VOC 0.43 1.53 AP-42

NOx 7.20 7.20 Certification

SO2 0.007 0.007 Mass Balance

CO 3.35 4.06 AP-42

PM 0.20 0.20 Certification

PM10 0.16 0.16 Certification

PM2.5 0.16 0.16 Certification

CO2e 696.60 696.60 EPA

Lead 1.23E-04 1.23E-04 EPA

Benzene 3.30E-03 3.97E-03 AP-42

Toluene 1.20E-03 1.74E-03 AP-42

Xylenes 8.22E-04 1.21E-03 AP-42

Formaldehyde 3.36E-04 5.02E-03 AP-42

Acetaldehyde 1.07E-04 3.27E-03 AP-42

Acrolein 3.36E-05 3.94E-04 AP-42

Naphthalene 5.54E-04 3.61E-04 AP-42

1,3-Butadiene -- 1.66E-04 AP-42

3.2.8.2 Crew Boat Engines

The crew boats transport personnel and supplies to and from the drilling vessel. Statoil does 

not currently know which specific vessel or vessels will serve as a crew boat during the 

proposed drilling campaign. Therefore, potential crew boat engine emissions have been 

estimated using an example of the type and size of crew boat that will be used by Statoil.

Statoil used the engine inventory on the crew boat Sybil Graham to represent typical engine 

emissions from a crew boat. While actual crew boat engine emissions may vary with different 

crew boats, the potential crew boat engine emissions proposed with this application are 

representative of a typical crew boat. The table below summarizes the key operating 

parameters that are the basis of the potential emissions calculations for the crew boat engines.
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-15 ENVIRON

Table 3.2.8.2-1

Crew Boat Engine Operating Summary

Emissions 

Unit ID Source Description

Maximum 

Power Rating

(kW)

Normal 

Operation 

Power Rating

(kW)

Normal 

Operation 

Annual Hours

(hr/yr)

Maximum 

Hourly Power 

Rating

(kW)

CREW Main Engine No. 1 1,342 1,342 618 1,342

Main Engine No. 2 1,342 1,342 618 1,342

Main Engine No. 3 1,342 1,342 618 1,342

Main Engine No. 4 1,342 1,342 618 1,342

Emergency Generator 

Engine No. 1

93 93 618 93

Emergency Generator 

Engine No. 2

93 93 618 93

Thruster #1 Engine 201 201 618 201

Thruster #2 Engine 201 201 618 201

Below is a summary of the emission factors used to calculate annual and maximum hourly 

emissions for the engines on the crew boats that will be associated with the Developer.

Table 3.2.8.2-2

Crew Boat Engine Emission Factors

Pollutant

Large Engine 

Emission Factor

(g/kW-hr)

Small Engine 

Emission Factor

(g/kW-hr) Emission Factor Basis

Total VOC 0.43 1.53 AP-42

NOx 7.20 7.20 Certification

SO2 0.007 0.007 Mass Balance

CO 3.35 4.06 AP-42

PM 0.20 0.30/0.20 Certification

PM10 0.16 0.25/0.16 Certification

PM2.5 0.16 0.24/0.16 Certification

CO2e 696.60 696.60 EPA

Lead 1.23E-04 1.23E-04 EPA

Benzene 3.30E-03 3.97E-03 AP-42

Toluene 1.20E-03 1.74E-03 AP-42

Xylenes 8.22E-04 1.21E-03 AP-42

Formaldehyde 3.36E-04 5.02E-03 AP-42

Acetaldehyde 1.07E-04 3.27E-03 AP-42

Acrolein 3.36E-05 3.94E-04 AP-42

Naphthalene 5.54E-04 3.61E-04 AP-42

1,3-Butadiene -- 1.66E-04 AP-42
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-16 ENVIRON

3.2.8.3 Drilling Mud

Drilling fluid (mud) is circulated between the drilling vessel and well during the drilling process to 

lubricate and cool the drill bit and transport drill cuttings. Additionally, the mud is needed to 

exert hydrostatic pressure in the well to prevent an influx of the formation’s fluids into the well 

bore. When the mud is circulated from the well to the drilling vessel, it is exposed to the 

atmosphere and the gas entrained in the mud, which can include hydrocarbons, flashes out of 

the mud to the atmosphere. Emissions may come from any of the drilling mud equipment,

including the shaker room and mud pit/tanks. The only appreciable hydrocarbon gases 

entrained in the mud are from rock cuttings generated when the drill bit passes through rock that 

is within a hydrocarbon zone. Statoil estimates that it will only encounter one day of appreciable 

hydrocarbon-containing rock per well drilled, and it is anticipated that Statoil will drill four wells 

during the drilling campaign. The following EPA document serves as the basis for the drilling 

mud operations potential emissions calculations: Atmospheric Emissions from Offshore Oil and 

Gas Development and Production (450/3-77/026), June 1977.

Below is a summary of the operating and emission factors used to calculate annual and 

maximum hourly emissions for the drilling mud operations on the Developer. Since potential 

emissions of regulated air pollutants are less than 2 tpy, and HAP emissions are less than 1,000 

lb/yr, the emission levels from drilling mud are considered insignificant per 40 CFR 

71.5(c)(11)(ii) and will be included as such in the application forms.

Table 3.2.8.3-1

Drilling Mud Operating Summary and Emission Factors

Pollutant

Annual Number of 

Wells Drilled

(wells/yr)

Emission Factor

(lb/well)

Emission Factor 

Basis

Total VOC 4 238.18 EPA

CO2e 12,057.49 EPA

3.3 Discoverer Americas Emission Calculation Basis

As previously discussed, the use of the Discoverer Americas is Operating Scenario 2. Similar to 

the Developer, the Discoverer Americas will be supported by various support vessels operating 

within 25 miles of its location. The support vessels will transport personnel and supplies to and 

from the drilling vessel. The Discoverer Americas drilling vessel does not require towing or 

anchoring vessels because the vessel is self-powered for transport and dynamically positioned 

when operating at the drilling location.

The following table summarizes the emissions units that are proposed for the Discoverer 

Americas.

Table 3.3-1

Discoverer Americas Emissions Units

Emissions Unit ID Source Description Quantity

GEN-1 thru GEN-6 Main Generator Engines 6
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-17 ENVIRON

Emissions Unit ID Source Description Quantity

EGEN Emergency Generator Engine 1

ACOMP-1 and ACOMP-2 Emergency Air Compressor Engines 2

LB Lifeboat Engines 6

MOB Fast Rescue Boat Engine 1

FO ST Fuel Oil Storage Tanks 3

FO SER ST Fuel Oil Service Tanks 2

FO SET ST Fuel Oil Settling Tanks 2

FO E GEN ST Emergency Generator Fuel Oil Tank 1

FO LB ST Lifeboat Fuel Tanks 1 per lifeboat

FO MOB ST Fast Rescue Boat Fuel Tank 1

AV ST Aviation Fuel Tank 1

WS ST Waste Oil Tanks 2

FUG Fugitive Component Emissions -

HTR Hot Oil Heater 1

OSV Offshore Support Vessels Multiple

CREW Crew Boats Multiple

Note that the wireline units located on the Discoverer Americas will be electric powered. 

Therefore, the units will not be directly powered by an internal combustion engine.

In the sections below, we discuss in detail the proposed potential emissions basis for each of 

the emissions units identified in the above table.

3.3.1 Main Generator Engines

The main generator engines located on the Discoverer Americas represent the “main” electric 

power generating engines on the drilling vessel. There are six identical 9,387 hp (7,000 kW) 

main generator engines on the Discoverer Americas, and these engines were manufactured by 

STX Engine Company. The following summarizes the proposed operating basis for the main 

generator engines on the vessel.

• “Normal Operations” Basis – The “Normal Operations” basis consists of operating 

three engines at 35% load while the remaining three engines are on standby at 0% 

load. Note that the proposed allowable annual emissions will apply to all of the 

engines as a group, which provides flexibility to operate any combination of the 

engines.

• Maximum Hourly Emissions Basis – The maximum hourly emissions basis consists 

of operating four engines at 80% load while the two remaining engines are on 

standby at 0% load. This scenario accounts for the most engines running during any 

given hour of operation at their highest power rating. Note that the proposed 
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-18 ENVIRON

allowable maximum hourly emission rate limits will apply to all of the engines as a 

group, which provides flexibility to operate any combination of the engines.

The table below summarizes key operating parameters that are the basis of the emission 

calculations for the main generator engines.

Table 3.3.1-1

Main Generator Engine Operating Parameters

Emissions 

Unit ID

Maximum Power 

Rating

(kW)

Normal Operation 

Power Rating

(kW)

Normal Operation 

Annual Hours

(hr/yr)

Maximum Hourly

Power Rating

(kW)

GEN-1 7,000 2,450 4,320 5,600

GEN-2 7,000 2,450 4,320 5,600

GEN-3 7,000 2,450 4,320 5,600

GEN-4 7,000 0 4,320 5,600

GEN-5 7,000 0 4,320 0

GEN-6 7,000 0 4,320 0

Below is a summary of the emission factors used to calculate annual and maximum hourly 

emissions for the main generator engines installed on the Discoverer Americas.

Table 3.3.1-2

Main Generator Engine Emission Factors

Pollutant

Emission Factor

(g/kW-hr) Emission Factor Basis

Total VOC 0.43 AP-42

NOx 12.1 (Avg.)/10.29 (Max.) Certification/Vendor Supplied

SO2 0.007 Mass Balance

CO 0.37 (Avg.)/ 0.18 (Max.) Vendor Supplied/Vendor Supplied

PM 0.15 Certification

PM10 0.15 Certification

PM2.5 0.15 Certification

CO2e 696.60 EPA

Lead 1.23E-04 EPA

Benzene 3.30E-03 AP-42

Toluene 1.20E-03 AP-42

Xylenes 8.22E-04 AP-42

Formaldehyde 3.36E-04 AP-42

Acetaldehyde 1.07E-04 AP-42

Acrolein 3.36E-05 AP-42

Naphthalene 5.54E-04 AP-42
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-19 ENVIRON

3.3.2 Emergency Generator Engines

The Discoverer Americas is equipped with an emergency generator driven by a 3,097 hp (2,309 

kW) diesel engine. The emergency generator engine is operated during maintenance checks or 

in the event of an emergency. The engine is planned to be operated for 7.0 hours per month, 

with one-half of this time for normal engine testing and maintenance hours and the other half for 

expected emergency use of the engine based on past operations. The table below summarizes 

the key operating parameters that are the basis of the potential emissions calculations for the 

emergency generator engine. The maximum hourly emissions for the engine are based on 

running the engine at 100% capacity for an entire hour.

Table 3.3.2-1

Emergency Generator Engine Operating Summary

Emissions 

Unit ID Source Description

Maximum 

Power Rating

(kW)

Run Time

hr/month hr/yr

EGEN Emergency Generator Engine 2,309 7.0 41

Below is a summary of the emission factors used to calculate annual and maximum hourly 

emissions for the emergency generator engine installed on the Discoverer Americas.

Table 3.3.2-2

Emergency Generator Engine Emission Factors

Pollutant

Emission Factor

(g/kW-hr) Emission Factor Basis

Total VOC 0.43 AP-42

NOx 9.80 Certification

SO2 0.007 Mass Balance

CO 0.26 Vendor Supplied

PM 0.30 AP-42

PM10 0.244 AP-42

PM2.5 0.237 AP-42

CO2e 696.60 EPA

Lead 1.23E-04 EPA

Benzene 3.30E-03 AP-42

Toluene 1.20E-03 AP-42

Xylenes 8.22E-04 AP-42

Formaldehyde 3.36E-04 AP-42

Acetaldehyde 1.07E-04 AP-42

Acrolein 3.36E-05 AP-42

Naphthalene 5.54E-04 AP-42
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-20 ENVIRON

3.3.3 Emergency Air Compressor Engines

The Discoverer Americas is equipped with two backup air compressors, each driven by a diesel 

engine. The backup air compressors are used when the primary air compressors are not 

operational. The emergency air compressor engines are operated during maintenance checks, 

safety exercises, or in the event of an emergency. Each engine is planned to be operated for 

1.0 hour per month for normal engine maintenance, testing, and expected emergency use. 

Since the potential emissions of regulated air pollutants are less than 2 tpy, and HAP emissions 

are less than 1,000 lb/yr, the emission levels from the storage tanks are considered insignificant 

per 40 CFR 71.5(c)(11)(ii) and will be included as such in the permit application forms. The 

table below summarizes the key operating parameters that are the basis of the potential 

emission calculations for the emergency air compressor engines. The maximum hourly 

emissions for each engine are based on running the engine at 100% capacity for an entire hour.

Table 3.3.3-1

Emergency Air Compressor Engine Operating Summary

Emissions 

Unit ID Source Description

Maximum 

Power Rating

(kW)

Run Time

hr/month hr/yr

ACOMP-1 Emergency Air Compressor

Engine No. 1

37 1 6

ACOMP-2 Emergency Air Compressor 

Engine No. 2

51 1 6

Below is a summary of the emission factors used to calculate annual and maximum hourly 

emissions for the emergency air compressor engines installed on the Discoverer Americas.

Table 3.3.3-2

Emergency Air Compressor Engine Emission Factors

Pollutant

Emission Factor

(g/kW-hr) Emission Factor Basis

Total VOC 1.53 AP-42

NOx 7.50 Certification

SO2 0.007 Mass Balance

CO 5.00 Certification

PM 0.40 Certification

PM10 0.33 Certification & AP-42

PM2.5 0.32 Certification & AP-42

CO2e 696.60 EPA

Lead 1.23E-04 EPA

Benzene 3.97E-03 AP-42

Toluene 1.74E-03 AP-42

Xylenes 1.21E-03 AP-42
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-21 ENVIRON

Pollutant

Emission Factor

(g/kW-hr) Emission Factor Basis

Formaldehyde 5.02E-03 AP-42

Acetaldehyde 3.27E-03 AP-42

Acrolein 3.94E-04 AP-42

Naphthalene 3.61E-04 AP-42

1,3-Butadiene 1.66E-04 AP-42

3.3.4 Lifeboat Engines

The Discoverer Americas is equipped with six lifeboats. Each lifeboat is equipped with a 36 hp 

(27 kW) engine that is operated during maintenance checks, safety exercises, or in the event of 

an emergency. The planned operating time for maintenance of the engines is one hour per 

month, which we have doubled to account for safety exercises. Since the potential emissions of 

regulated air pollutants are less than 2 tpy, and HAP emissions are less than 1,000 lb/yr, the 

emission levels from the lifeboat engines are considered insignificant per 40 CFR 71.5(c)(11)(ii) 

and will be included as such in the permit application forms. The table below summarizes the 

key operating parameters that are the basis of the potential emissions calculations for the 

lifeboat engines.

Table 3.3.4-1

Lifeboat Engine Operating Summary

Emissions Unit 

ID Source Description

Maximum 

Power Rating

(kW)

Run Time

hr/month hr/yr

LB-1 Lifeboat No. 1 Engine 27 2 12

LB-2 Lifeboat No. 2 Engine 27 2 12

LB-3 Lifeboat No. 3 Engine 27 2 12

LB-4 Lifeboat No. 4 Engine 27 2 12

LB-5 Lifeboat No. 5 Engine 27 2 12

LB-6 Lifeboat No. 6 Engine 27 2 12

Furthermore, below is a summary of the emission factors used to calculate annual and 

maximum hourly emissions for the Discoverer Americas lifeboat engines.

Table 3.3.4-2

Lifeboat Engine Emission Factors

Pollutant

Emission Factor

(g/kW-hr) Emission Factor Basis

Total VOC 1.53 AP-42

NOx 7.50 Certification

SO2 0.007 Mass Balance

CO 5.5 Certification

PM 0.60 Certification
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-22 ENVIRON

Pollutant

Emission Factor

(g/kW-hr) Emission Factor Basis

PM10 0.49 Certification & AP-42

PM2.5 0.48 Certification & AP-42

CO2e 696.60 EPA

Lead 1.23E-04 EPA

Benzene 3.97E-03 AP-42

Toluene 1.74E-03 AP-42

Xylenes 1.21E-03 AP-42

Formaldehyde 5.02E-03 AP-42

Acetaldehyde 3.27E-03 AP-42

Acrolein 3.94E-04 AP-42

Naphthalene 3.61E-04 AP-42

1,3-Butadiene 1.66E-04 AP-42

3.3.5 Fast Rescue Boat Engines

The Discoverer Americas is equipped with one fast rescue boat. The fast rescue boat is 

equipped with a 212 hp (158 kW) engine that is operated during maintenance checks, safety 

exercises, or in the event of an emergency. The planned operating time for maintenance of the 

engine is one hour per month, which we have doubled to account for safety exercises. Since 

the potential emissions of regulated air pollutants are less than 2 tpy, and HAP emissions are 

less than 1,000 lb/yr, the emission levels from the fast rescue boat engines are considered 

insignificant per 40 CFR 71.5(c)(11)(ii) and will be included as such in the permit application 

forms. The table below summarizes the key operating parameters that are the basis of the 

potential emissions calculations for the fast rescue boat engine.

Table 3.3.5-1

Fast Rescue Boat Engine Operating Summary

Emissions Unit 

ID Source Description

Maximum 

Power Rating

(kW)

Run Time

hr/month hr/yr

MOB Fast Rescue Boat Engine 158 2 12

Below is a summary of the emission factors used to calculate annual and maximum hourly 

emissions for the fast rescue boat engine on the Discoverer Americas.

Table 3.3.5-2

Fast Rescue Boat Engine Emission Factors

Pollutant

Emission Factor

(g/kW-hr) Emission Factor Basis

Total VOC 1.53 AP-42

NOx 7.50 Certification

SO2 0.007 Mass Balance
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-23 ENVIRON

Pollutant

Emission Factor

(g/kW-hr) Emission Factor Basis

CO 5.00 Certification

PM 0.40 Certification

PM10 0.329 Certification & AP-42

PM2.5 0.319 Certification & AP-42

CO2e 696.60 EPA

Lead 1.23E-04 EPA

Benzene 3.97E-03 AP-42

Toluene 1.74E-03 AP-42

Xylenes 1.21E-03 AP-42

Formaldehyde 5.02E-03 AP-42

Acetaldehyde 3.27E-03 AP-42

Acrolein 3.94E-04 AP-42

Naphthalene 3.61E-04 AP-42

1,3-Butadiene 1.66E-04 AP-42

3.3.6 Heaters

The Discoverer Americas is equipped with a diesel-fired cargo tank heater (Hot Oil Heater 

(Emissions Unit ID HTR)) that has a maximum heat input rate of 17.4 million British thermal 

units per hour (MMBtu/hr). This heater heats a thermal fluid that is used to transfer heat to 

cargo tanks on the vessel. Statoil does not propose to use the heater for normal drilling 

operations in the Gulf of Mexico. However, the heater will require periodic maintenance testing. 

The planned operating time for maintenance of the heater is two hours per year. Since the 

potential emissions of regulated air pollutants are less than 2 tpy, and HAP emissions are less 

than 1,000 lb/yr, the emission levels from the fast rescue boat engines are considered 

insignificant per 40 CFR 71.5(c)(11)(ii) and will be included as such in the permit application 

forms.

Table 3.3.6-1

Hot Oil Heater Operating Summary

Emissions 

Unit ID Source Description

Maximum Heat 

Input

(MMBtu/hr)

Run Time

hr/yr

HTR Hot Oil Heater 17.4 2

Below is a summary of the emission factors used to calculate annual and maximum hourly 

emissions for the hot oil heater located on the Discoverer Americas.
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-24 ENVIRON

Table 3.3.6-2

Hot Oil Heater Emission Factors

Pollutant

Emission Factor

(lb/Mgal) Emission Factor Basis

Total VOC 0.25 AP-42

NOx 20 AP-42

SO2 0.2 AP-42

CO 5 AP-42

PM 3.3 AP-42

PM10 1.0 AP-42

PM2.5 0.3 AP-42

CO2e 22,577 EPA

Lead 1.2E-03 AP-42

Benzene 2.14E-04 AP-42

Ethyl benzene 6.36E-05 AP-42

Formaldehyde 3.30E-02 AP-42

Naphthalene 1.11E-03 AP-42

1,1,1-Trichloroethane 2.36E-04 AP-42

Toluene 6.20E-03 AP-42

Xylene 1.09E-04 AP-42

Total PAH 1.19E-03 AP-42

Arsenic 5.5E-04 AP-42

Beryllium 4.1E-04 AP-42

Cadmium 4.1E-04 AP-42

Chromium 4.1E-04 AP-42

Mercury 4.1E-04 AP-42

Manganese 8.2E-04 AP-42

Nickel 4.1E-04 AP-42

Selenium 2.1E-03 AP-42

3.3.7 Storage Vessels

Emissions are generated from the storage of fuel and waste oil in tanks aboard the Discoverer 

Americas. Diesel is used in the engines installed on the drilling vessel as well as the vessel’s 

life boat and fast rescue boat engines. Additionally, there is a storage tank for aviation fuel, 

which is used to refuel helicopters. Finally, there are two storage tanks on the drilling vessel 

that are used to store waste oil that is collected from fuel system strainers, filters, and 

separators.

The EPA TANKS 4.09d computer software program was used to calculate the potential working 

and breathing emissions from the storage vessels located on the Developer. The default EPA 

TANKS 4.09d properties for Distillate Fuel Oil No. 2 were used to calculate emissions for the 
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-25 ENVIRON

diesel and waste oil storage tanks. Additionally, the default EPA TANKS 4.09d properties for 

Jet Naphtha were used to calculate emissions for the aviation fuel storage tanks. For a 

particular storage tank, the maximum hourly emissions were estimated by dividing the annual 

emissions calculated for the tank using EPA TANKS 4.09d by the tank’s annual hours of 

operation.

Since the potential emissions of regulated air pollutants are less than 2 tpy, and HAP emissions 

are less than 1,000 lb/yr, the emission levels from the storage tanks are considered insignificant 

per 40 CFR 71.5(c)(11)(ii) and will be included as such in the permit application forms. The 

table below summarizes key design and operating parameters that are the basis of the potential 

emissions calculations for the storage vessels.

Table 3.3.7-1

Storage Vessel Inventory and Operating Summary

Emissions 

Unit ID Source

Capacity Working 

Capacity (gal)

Throughput

m (gal/yr) 3 gal

FO ST Deck 2 Fuel Oil Tank No. 1 (P) 2,591 684,470 616,023 1,150,000

Deck 2 Fuel Oil Tank No. 2 (S) 2,591 684,470 616,023 1,150,000

Overflow Fuel Oil Tank No. 1 (P) 130 34,448 31,003 575,000

FO SET ST Deck 1 Fuel Oil Tank No. 3 (P) 216 56,955 51,260 1,150,000

Deck 1 Fuel Oil Tank No. 4 (S) 216 56,955 51,260 1,150,000

FO SER ST Deck 1 Fuel Oil Tank No. 5 (P) 108 28,478 25,630 1,150,000

Deck 1 Fuel Oil Tank No. 6 (S) 108 28,478 25,630 1,150,000

FO E GEN ST Emergency Generator Fuel Oil 

Tank

16 4,095 3,685 7,000

WO ST Waste Oil Tank No. 1 (P) 35 9,299 8,369 8,369

Waste Oil Tank No. 2 (S) 62 16,299 14,669 14,669

AV ST Aviation Fuel Tank 8 2,113 1,902 9,165

FO LB ST Lifeboat No. 1 Fuel Tank 0.2 45 40 22

Lifeboat No. 2 Fuel Tank 0.2 45 40 22

Lifeboat No. 3 Fuel Tank 0.2 45 40 22

Lifeboat No. 4 Fuel Tank 0.2 45 40 22

Lifeboat No. 5 Fuel Tank 0.2 45 40 22

Lifeboat No. 6 Fuel Tank 0.2 45 40 22

FO MOB ST Fast Rescue Boat Fuel Tank 0.2 45 40 130

3.3.8 Fugitive Components

The Discoverer Americas drill ship has fugitive emissions associated with components and 

associated piping to convey fuel from storage vessels to combustion units and waste oil, which 

is a waste material that is collected from the fuel system strainers, filters, and separators to 

storage vessels for proper disposal. Fugitive component counts were estimated based on a 

review of the Discoverer Americas Fuel System P&IDs. Fugitive component emissions are 

calculated based on the component count and component service. Since potential emissions of 

regulated air pollutants are less than 2 tpy, and HAP emissions are less than 1,000 lb/yr, the 
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-26 ENVIRON

emission levels from fugitive components are considered insignificant per 40 CFR 71.5(c)(11)(ii) 

and will be included as such in the application forms. The table below summarizes the 

component counts by service on the Discoverer Americas.

Table 3.3.8-1

Fugitive Component Summary

Component Type

Number of Fuel Service

Components

Number of Waste Oil

Service Components

Valve 293 4

Flange 586 8

Pump Seal 11 0

Other 18 0

The potential emissions for the fugitive components have been calculated using the oil and gas 

production operations average emission factors included in Table 2-4 of the Protocol for 

Equipment Leak Emission Estimates (EPA-453/R-95-017), November 1995 and the composition 

of the material to be contained or contacted by the components. Because a “heavy oil” pump 

emission factor was not identified, we used the “light oil” pump emission factor for all of the

pumps on the drilling vessel. For “other” component types, we used the “heavy oil” emission 

factor because the large majority of components on the vessel are in diesel service. Finally, 

Table 2-4 identifies separate emission factors for flanges and connectors. We conservatively 

used the higher of the flange and connector emission factors identified in the table to estimate 

emissions from the flanges/connectors located on the vessel. The emission factors used in the 

potential emissions calculations for fugitive emissions are summarized in the table below.

Table 3.3.8-2

Fugitive Component Emission Factors

Service

Valves

(kg/hr/source)

Connectors

(kg/hr/source)

Pumps

(kg/hr/source)

Other

(kg/hr/source)

Diesel 8.4E-06 7.5E-06 1.3E-02 3.2E-05

Waste Oil 9.8E-05 1.1E-04 2.4E-05 3.2E-05

3.3.9 Support Vessels

Specific support vessels are not solely dedicated to a particular drilling campaign. Instead, 

Statoil relies on a support vessel fleet made up of many different vessels that fall into one of two

support vessel categories. Note that the proposed potential emissions included in this 

application for the Discoverer Americas support vessels will apply to any support vessel that 

Statoil may use with the drilling vessel, which is expected to provide Statoil with the flexibility to 

utilize any vessel from the support vessel fleet to meet project needs. Additionally, a direct 

physical connection between the drilling vessel and a support vessel is an unusual event. 

Normally, the support vessels will be under their own power when adjacent to the drilling vessel 

for loading or unloading purposes. The only expected physical connection between the drilling 

vessel and a support vessel would be product transfer hoses such as those necessary for the 

transfer of fuel or drilling mud between the vessels.
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-27 ENVIRON

To estimate annual emissions from the engines of each type of support vessel, Statoil estimated 

the total hours of operation of the particular vessel-type during the proposed drilling campaign 

(180 days) based on actual hours of operation for similar vessels during historical drilling 

campaigns. Statoil used the actual hours of operation (with a safety buffer) in conjunction with 

emission factors (certification, AP-42, etc.) to estimate annual emissions associated with the 

support vessel operations. To estimate maximum hourly emissions for each support vessel 

type, Statoil gathered specific engine data and emissions information for several vessels in each 

category. From that information, Statoil derived the emissions that could reasonably be 

expected from each type of support vessel during the drilling campaign. While actual emissions 

will vary between different vessels, the potential support vessel emissions proposed in this

application are a reasonable estimate of the emissions expected from a typical support vessel in 

each category.

3.3.9.1 Offshore Support Vessel Engines

OSVs transport personnel and supplies to and from the drilling vessel. OSVs are equipped with 

large engines that power generators, thrusters, and main propulsion devices. Additionally, the 

OSVs are equipped with small engines that are used to power emergency generators. Statoil 

used the engine inventory on the OSV Peyton Candies to represent typical engine emissions 

from an OSV.

The potential annual engine emissions from an OSV have been calculated based on the 

estimated annual hours of operation of each engine on the vessel. Maximum hourly engine 

emissions from an OSV have been estimated by assuming each engine on the vessel operates 

at its highest load capacity for the hour. As previously noted, actual engine emissions may vary 

with different OSVs, but the potential OSV engine emissions proposed with this application are 

representative of a typical OSV. The table below summarizes the key operating parameters 

that are the basis of the potential emissions calculations for the OSV engines.

Table 3.3.9.1-1

Offshore Support Vessel Engine Operating Summary

Emissions 

Unit ID Source Description

Maximum 

Power Rating

(kW)

Normal 

Operation 

Power Rating

(kW)

Normal 

Operation 

Annual Hours

(hr/yr)

Maximum 

Hourly Power 

Rating

(kW)

OSV OSV Main Engine No. 1 1,765 1,765 3,059 1,765

OSV Main Engine No. 2 1,765 1,765 3,059 1,765

OSV Main Engine No. 3 1,765 0 3,059 1,765

OSV Main Engine No. 4 1,765 0 3,059 1,765

OSV Emergency 

Generator Engine

269 269 3,059 269

Below is a summary of the emission factors used to calculate annual and maximum hourly 

emissions for the engines on the OSVs that will be associated with the Discoverer Americas.
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-28 ENVIRON

Table 3.3.9.1-2

Offshore Support Vessel Engine Emission Factors

Pollutant

Main Engine

Emission Factor

(g/kW-hr)

Emergency

Generator

Emission Factor

(g/kW-hr) Emission Factor Basis

Total VOC 0.43 1.53 AP-42

NOx 7.20 7.20 Certification

SO2 0.007 0.007 Mass Balance

CO 3.35 4.06 AP-42

PM 0.20 0.20 Certification

PM10 0.16 0.16 Certification

PM2.5 0.16 0.16 Certification

CO2e 696.60 696.60 EPA

Lead 1.23E-04 1.23E-04 EPA

Benzene 3.30E-03 3.97E-03 AP-42

Toluene 1.20E-03 1.74E-03 AP-42

Xylenes 8.22E-04 1.21E-03 AP-42

Formaldehyde 3.36E-04 5.02E-03 AP-42

Acetaldehyde 1.07E-04 3.27E-03 AP-42

Acrolein 3.36E-05 3.94E-04 AP-42

Naphthalene 5.54E-04 3.61E-04 AP-42

1,3-Butadiene -- 1.66E-04 AP-42

3.3.9.2 Crew Boat Engines

The crew boats transport personnel and supplies to and from the drilling vessel. Statoil does 

not currently know which specific vessel or vessels will serve as a crew boat during the 

proposed drilling campaign. Therefore, potential crew boat engine emissions have been 

estimated using an example of the type and size of crew boat that will be used by Statoil.

Statoil used the engine inventory on the crew boat Sybil Graham to represent typical engine 

emissions from a crew boat. While actual crew boat engine emissions may vary with different 

crew boats, the potential crew boat engine emissions proposed with this application are 

representative of a typical crew boat. The table below summarizes the key operating 

parameters that are the basis of the potential emissions calculations for the crew boat engines.
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-29 ENVIRON

Table 3.3.9.2-1

Crew Boat Engine Operating Summary

Emissions 

Unit ID Source Description

Maximum 

Power Rating

(kW)

Normal 

Operation 

Power Rating

(kW)

Normal 

Operation 

Annual Hours

(hr/yr)

Maximum 

Hourly Power 

Rating

(kW)

CREW Main Engine No. 1 1,342 1,342 618 1,342

Main Engine No. 2 1,342 1,342 618 1,342

Main Engine No. 3 1,342 1,342 618 1,342

Main Engine No. 4 1,342 1,342 618 1,342

Emergency Generator 

Engine No. 1

93 93 618 93

Emergency Generator 

Engine No. 2

93 93 618 93

Thruster #1 Engine 201 201 618 201

Thruster #2 Engine 201 201 618 201

Below is a summary of the emission factors used to calculate annual and maximum hourly 

emissions for the engines on the crew boats that will be associated with the Discoverer 

Americas.

Table 3.3.9.2-2

Crew Boat Engine Emission Factors

Pollutant

Large Engine 

Emission Factor

(g/kW-hr)

Small Engine 

Emission Factor

(g/kW-hr) Emission Factor Basis

Total VOC 0.43 1.53 AP-42

NOx 7.20 7.20 Certification

SO2 0.007 0.007 Mass Balance

CO 3.35 4.06 AP-42

PM 0.20 0.30/0.20 Certification

PM10 0.16 0.25/0.16 Certification

PM2.5 0.16 0.24/0.16 Certification

CO2e 696.60 696.60 EPA

Lead 1.23E-04 1.23E-04 EPA

Benzene 3.30E-03 3.97E-03 AP-42

Toluene 1.20E-03 1.74E-03 AP-42

Xylenes 8.22E-04 1.21E-03 AP-42

Formaldehyde 3.36E-04 5.02E-03 AP-42

Acetaldehyde 1.07E-04 3.27E-03 AP-42

Acrolein 3.36E-05 3.94E-04 AP-42

Naphthalene 5.54E-04 3.61E-04 AP-42

1,3-Butadiene -- 1.66E-04 AP-42
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-30 ENVIRON

3.3.9.3 Drilling Mud

Drilling fluid (mud) is circulated between the drilling vessel and well during the drilling process to 

lubricate and cool the drill bit and transport drill cuttings. Additionally, the mud is needed to 

exert hydrostatic pressure in the well to prevent an influx of the formation’s fluids into the well 

bore. When the mud is circulated from the well to the drilling vessel, it is exposed to the 

atmosphere and the gas entrained in the mud, which can include hydrocarbons, flashes out of 

the mud to the atmosphere. Emissions may come from any of the drilling mud equipment,

including the shaker room and mud pit/tanks. The only appreciable hydrocarbon gases 

entrained in the mud are from rock cuttings generated when the drill bit passes through rock that 

is within a hydrocarbon zone. Statoil estimates that it will only encounter one day of appreciable 

hydrocarbon-containing rock per well drilled, and it is anticipated that Statoil will drill four wells 

during the drilling campaign. The following EPA document serves as the basis for the drilling 

mud operations potential emissions calculations: Atmospheric Emissions from Offshore Oil and 

Gas Development and Production (450/3-77/026), June 1977.

Below is a summary of the operating and emission factors used to calculate annual and 

maximum hourly emissions for the drilling mud operations on the Discoverer Americas. Since 

potential emissions of regulated air pollutants are less than 2 tpy, and HAP emissions are less 

than 1,000 lb/yr, the emission levels from drilling mud are considered insignificant per 40 CFR 

71.5(c)(11)(ii) and will be included as such in the application forms.

Table 3.3.9.3-1

Drilling Mud Operating Summary and Emission Factors

Pollutant

Annual Number of 

Wells Drilled

(wells/yr)

Emission Factor

(lb/well)

Emission Factor 

Basis

Total VOC 4 238.18 EPA

CO2e 12,057.49 EPA

3.4 Emergency Operations

Below we discuss certain emergency operations that could occur for the two drilling vessels and 

the emissions to the atmosphere that would likely be related with the emergency operations. 

However, because these emergency operations are outside of standard operating conditions for 

the drilling vessels, we are not proposing to include potential emissions in the permit for the 

operations. 

3.4.1 Relief Wells

The need to drill a relief well to control a blowout is highly unlikely, but it is possible that a relief 

well could be drilled. The drilling of a relief well would employ the same equipment that is used 

to drill an exploratory well. Therefore, all of the maximum hourly emissions shown in the tables 

of this section provide hourly emissions estimates for relief well drilling activities. No emissions 

would be associated with the emergency deployment of the BOP.

We note that EPA guidelines indicate that allowable emissions should not include emissions 

that would occur only as a result of events outside of standard operating conditions. The 
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-31 ENVIRON

following from 40 CFR part 51, Appendix W instructs that emissions resulting from malfunctions 

should not be factored into allowable emissions.

Malfunctions which may result in excess emissions are not considered to be a normal 

operating condition. They generally should not be considered in determining allowable 

emissions.

Emissions from emergency drilling operations, even more so than ordinary malfunctions, are 

highly unlikely events and should not be considered a “normal operating condition” of the drilling 

operation. Therefore, emergency drilling operations are not to be factored into the allowable 

emissions specified by a permit.

Statoil drilling plans, protocols, and procedures contain details for drilling operation precautions 

to avoid blowouts during drilling operations. In association with the exploratory drilling activities 

proposed with this permit application, the likelihood that a well control event would require a 

relief well is approximately 1 in 6,000. The inclusion of emissions from such an unlikely event 

would be unrepresentative of “annual” emissions and inaccurate for anticipated operations.

Because emissions from drilling a relief well are so unlikely and are not reasonably foreseeable, 

Statoil maintains that it is also not appropriate or practical to include such emissions in the 

emissions inventory or air quality modeling for the Developer or Discoverer Americas. In the 

highly unlikely event that, at some future time, the Developer or Discoverer Americas drilling 

operations were to cause a violation of an NAAQS or the PSD increment due to emissions 

produced during emergency relief well drilling at the end of a drilling season, it is acknowledged 

that the EPA would have discretion to take enforcement action against Statoil for such a 

violation under the Agency’s policy on “excess emissions” that result from, inter alia, 

malfunctions. See “State Implementation Plans: Policy Regarding Excess Emissions During 

Malfunctions, Startup, and Shutdown,” Steven A. Herman, Assistant Administrator for 

Enforcement and Compliance (September 20, 1999) (“Herman Memorandum”).7

3.4.2 Diverters

A diverter is a mechanical device located beneath the drill floor that protects drilling vessel

personnel in the event an influx is not caught at the BOP and enters the riser. This is very rare 

for the type of wells being proposed since the prospective hydrocarbons are at the very deepest 

section of the well. The influx for which the diverter could be used could consist of fresh or salt 

water, or gas. The diverter is viewed by Statoil in the same way as the BOP and both will be in 

place at every drilling event. It is a federal requirement for all drilling vessels operating in OCS 

waters to have a functioning diverter. As a rule, most drilling vessels have diverters whether or 

not they operate in OCS waters.

 7 This policy was reconfirmed in a memorandum issued by Eric Schaeffer, Director of the Office of Regulatory 

Enforcement, dated December 5, 2001, which clarified that the policy was intended to be applied prospectively to 

future SIP approvals. Although these guidance documents are designed to set out the standards under which the 

EPA will approve a SIP, they also provide the most applicable guidance to the EPA’s policy regarding excess 

emissions for all permits, those issued pursuant to a SIP and those issued under federal regulations.
Outer Continental Shelf Title V and PSD Permit Application

Emission Source Description 3-32 ENVIRON

The diverter directs any formation fluids away from the drilling vessel in the event an influx 

enters the borehole and is not caught in time at the BOP. The diverter does not shut the well in; 

it merely diverts the flow for discharge away from the rig until the influx in the riser is displaced. 

The diverter is used because the influx may have entrained gas that would put personnel 

working on the rig floor at risk. The entrained gas would expand rapidly as the influx in the riser 

migrates to surface and could result in a rapid unloading of the well bore at surface at the rig 

floor.

The likelihood of an influx entering the riser is quite small for the following reasons:

• Statoil conducts shallow hazards seismic surveys to delineate possible shallow gas 

intervals and has selected locations to avoid any likely potential shallow gas sites. Thus,

all potential hydrocarbons will be deep and will be caught at the BOP.

• Statoil drills with a drilling fluid density that exceeds the anticipated formation fluid 

pressure. There is substantial regional data to allow prediction of the anticipated 

pressures from offset wells, seismic velocity and geological study. Therefore, the 

probability of taking in influx is small in the first place.

• Statoil operates the rig with instrumentation that will allow spotting influx as small as a 

few barrels (bbls) and in the worst case 50 bbls (in inclement weather, marine vessels 

motion can preclude accurate measurement of fluid volumes). The smallest volume of 

mud between the first formation drilled and the BOP after it is installed is 1,300 bbls. 

This volume would only increase as the well is deepened. The mud system that is used 

dissolves any gas and the influx does not migrate upwards by itself. Therefore, the only 

way an influx could get above the BOP would be that the influx is missed altogether and 

it is inadvertently circulated above the BOP. This is highly unlikely as the 

instrumentation is automated, alarms are set, and it is monitored by the driller, mud 

logger and onshore real time operations center.

• Statoil has real-time drill string instrumentation that permits monitoring the bottom hole 

pressure so that the swabbing effect can immediately be recognized and appropriate 

countermeasures taken. For these reasons, the probability of gas to surface is quite 

small. From an industry standpoint, in the Gulf of Mexico, in the period 1992 to 2006, 

15,077 wells were drilled during which diverter use was documented 20 times, resulting 

in a probability of usage of 0.01%. Given the aforementioned precautions that will be 

taken in the exploration proposed with this permit application, the probability is likely 

substantially lower.8

In summary, the diverter is a safety device that would be used only in the unexpected event of 

an influx into the riser if it is not caught at the BOP. There would be emissions if the influx 

consisted of hydrocarbon gases, but they are unplanned and not quantifiable.

 8 Izon, David, et. al, Drilling Contractor, Absence of fatalities in blowouts encouraging in MMS study of OCS incidents 

1992-2006, July/August 2007.