09/23/2010

IMPERIAL COUNTY AIR POLLUTION CONTROL DISTRICT

Synthetic Minor Permit Review

Permit: 1641B-3

Source Name: ORMAT Nevada Inc. 

Heber Geothermal Company

Heber 1

Source Type: 62.5 MW Gross, 52 MW Net Geothermal 

Power Plant

Application for: Geothermal Power Plant Synthetic Minor

Source

Location: Heber Geothermal Company

895 Pitzer Road,

Heber, CA 92249

Mailing Address: ORMAT Nevada Inc.

947 Dogwood Road, 

Heber, CA 92249

Responsible Agent: Lee Jensen, Plant Manager

(760) 353-8200, Ext. 40227

Facility Contact: Sergio Cabañas, Environmental Engineer

(760) 353-8200, Ext. 40309

Permit Reviewer: Jaime Hernandez

Introduction 

Ormat Nevada Inc. currently operates the Heber Geothermal Company (HGC) facilities 

on 895 Pitzer Road, known as Heber 1. Ormat Nevada holds both a federal Title V 

permit V-1641 and an Imperial County Air Pollution Control District (ICAPCD) permit 

1641B-2 for the Heber 1 facilities. Ormat Heber 1 was classified a major source under 

ICAPCD Rule 900 because the facility had a potential to emit benzene, a hazardous air 

pollutant, in excess of 10 tons per year. 

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In 2007, Ormat Nevada voluntarily installed a regenerative thermal oxidizer (RTO) and 

caustic scrubber to control emissions of methane and benzene to lower emissions 

levels. As a consequence, the Ormat Heber 1 Geothermal Company has reduced 

emissions to below Title V levels. Having efficiently operated the RTO technology since 

2008, Ormat is now seeking Synthetic Minor status and relief from current Title V 

requirements. 

Ormat Heber 1 is further seeking clarification to the RTO optimum operating 

parameters. The RTO bed and chamber temperatures are currently 250° to 300° F 

higher than originally described. This is due to a decreased air inlet rate. The RTO 

NOx emission limits have remained below permitted standards while operating at this 

higher range. 

Source Description 

The HGC facility utilizes both flash and binary processes technologies in the generation 

of electricity. The facility has a combined nameplate generation capacity of 62.5MW. 

The original Heber 1 project was built as a duel-flash facility. Eventually, Ormat Nevada 

added the binary bottoming cycle in 2006. 

The flash process utilizes geothermal resources produced from 11 production wells in 

the well field. The two-phase resource is flashed into steam in high and low pressure 

flash tanks, and the steam passes through a turbine connected to a 52MW generator. 

The steam condenses in a surface contact condenser and is piped to cooling tower, 

where approximately 75% of the liquid evaporates and the balance injected into the 

reservoir. The brine from the high and low pressure flash tanks passes through 13 

injection wells. One of the OEC units generates 7MW(net) of electricity; the second unit 

generates 3.5MW(net) and the third drives a geothermal fluid injection pump. The OEC 

units employ closed, binary processes with no point of geothermal emissions other than

fugitives. The flash process, however, exposes the geothermal fluids to the 

atmosphere. Most of the noncondensable gases (NCG) are extracted from the 

condenser and emitted; a fraction of the NCG dissolves in the condensate and, if not 

oxidized, is released to the atmosphere in the cooling tower. 

The NCG in the geothermal resource at the HGC is primarily carbon dioxide (CO2), with 

small concentrations of hydrogen sulfide (H2S), methane (CH4), and benzene (C6H6). 

Below is a typical analysis of the NCG at HGC. The concentrations of nitrogen and 

oxygen reflect entrained air from the turbine gland seals. 

Typical Non-condensable Gas Concentrations*

Gas Dry Gas % by Volume

Carbon Dioxide 83.8

Hydrogen Sulfide 0.235

Ammonia 0.00391

Argon 0.184

Oxygen 0.223

2
Nitrogen 11.9

Methane 3.59

Benzene 0.0446

Hydrogen 0.0811

*Source: Thermochem, November 19, 2008 testing

The gases in the geothermal resource pass through the turbine with the high and low 

pressure steam and collect in the surface condenser. Approximately 90-95% of the 

NCG partitions into the high pressure steam with less gas produced in the low pressure 

flash tank, which operate at close to atmospheric pressure. A dual stage off gas ejector 

and vacuum pump system extracts the NCG from the condenser and vents it into the 

RTO and scrubber system, which controls hydrocarbon (CH4, C6H6, etc) and H2S 

emissions. 

The Adwest Technologies RETOX dual chamber RTO oxidizes the hydrocarbons in the 

NCG, including hydrogen, methane and benzene by more than 98% to form CO2 and 

water. The RTO also oxidizes H2S, forming sulfur dioxide (SO2). The installed control 

process includes a Bionomic Industries Proclean Type CT caustic scrubber which 

removes the SO2 from the RTO exhaust gases. The flameless combustion process 

was originally described as operating between 1,500 and 1,600 degrees Fahrenheit and 

producing small amounts of NOx. Ormat controls the addition of inlet air to the RTO to 

achieve approximately 2 to 5% excess exhaust oxygen. Typical NCG flows are 

approximately 250 acfm at 94°F at the RTO inlet, and 350 acfm at 132°F at the 

scrubber outlet.

During initial operations, a few modifications were performed in order to optimize control 

efficiency. Equipment was installed to remove NCG moisture before entering the RTO. 

Inlet air mixture was reduced, producing a lean combustion. This lead to higher 

operating temperatures and longer residence time. The moisture reduction also lead to 

a reduction in corrosion within the RTO. This RTO has been operating in a range of 

1500-1900°F since 2007 and has tested to be within permitted parameters in 2008, 

2009, and 2010.

Three binary OEC units receive brine at 212°F and use it to heat a working fluid, in this 

case isopentane, which passes through the turbines in each unit and condenses before 

being reheated. Irrigation water circulates through a cooling tower to cool the 

isopentane loops in the OECs. The geothermal brine passes through the two-level 

OEC units before being injected by the 13 injection wells at the project. The isopentane 

system is closed loop, but some gases (cooling water vapor, geothermal NCG, and 

degraded hydrocarbons, including methane) accumulate in the isopentane loop over 

time. Each of the six OEC condensers (two per OEC) contains a small (0.018cu ft) 

vapor recovery unit (VRU) that separates the gases, reclaims the isopentane, and vents 

the OEC NCG to the atmosphere. Each OEC VRU operates less than twice an hour. 

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Emissions Calculations

The operation of the installed RTO/scrubber unit under the ICAPCD Permit 1641B-2 

controls the benzene emissions and other regulated air pollutants at Heber 1. This 

permit restricts HGC operations without the RTO/scrubber abatement system to 360 

hours per year. The permit establishes daily benzene and hydrogen sulfide emission 

limits for the RTO exhaust and condensate lines when the abatement system is 

operating and daily limits for the other regulated pollutants and requires monthly and 

quarterly source testing to verify compliance with these limits. Emissions are also 

expected from the Ormat Energy Converters and the emergency fire water pump.

NCG Emissions

Since concentration of pollutants in the NCG varies, the permitted emission limits

represent the maximum potential to emit. This potential is based on the federally 

enforceable conditions under permit 1641B-2. These conditions limit benzene 

emissions to less than 1.24 tons/year, which is well below the 10 ton/year threshold of a 

major source. The conditions also limit the other regulated pollutants to less than 100 

tons/year. 

The RTO operates 8,400 hours/year (controlled emissions). Ormat Heber 1 is currently 

limited to a maintenance period of up to 360 hours/year, which is operation without the 

RTO system. The following are potential emissions:

The following are the controlled potential emissions (assuming 350 days of controlled 

emissions):

Maximum Daily NCG Potential To Emit -With Control

Pollutant RTO Stack 

(Lb/Day)

Condensate 

(Lb/Day)

Daily 

(Lb/Day)

Yearly 

(Tons/Yr)

Benzene 2.33 0.75 3.08 0.56

VOC(non-benzene) 0.24 0.24 0.04

Hydrogen Sulfide 2.74 18.73 21.5 3.92

PM10* 1.44 0.65 2.61 0.48

Ammonia - 869 869 158.59

Methane 12.52 - 12.52 2.28

Sulfur Dioxide 5.03 - 5.03 0.92

Nitrogen Oxides 11.66 - 11.66 2.13

Isopentane 99.6 18.18

*INCLUDES 0.52LB/DAY PM10 FROM OEC UNITS

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The ammonia emitted at Heber 1 is well below the 20% concentration that is regulated 

under Section 112(r). For Heber 1, the high pressure steam is typically 45.6 ppmw 

(0.0046%) and the low pressure steam is 33.9 ppmw (0.0034%). The condensate 

sampling has shown very consistent readings of approximately 32 ppmw over the years, 

and the emission from the cooling tower are diluted by the 7,192,505 cu ft/min of wet 

exhaust gas flow through the tower. Thus, the ammonia emissions at Heber 1 are not 

regulated pollutants under the Title V program and included for inventory purposes only. 

Although The RTO may operate all year long, a maintenance time of 360 hours/year is 

used to calculate uncontrolled emissions. 

NCG Maintenance Emissions

Pollutant Potential Lbs/Day Tons/Yr

Benzene 93.12 0.70

VOC(non-benzene) 22.7 17

Hydrogen Sulfide 250 1.88

PM10* 1.17 0.01

Ammonia* 873 6.55

Methane* 501 3.76

*PM10, ammonia, and methane calculated based on maximum values.

The abatement efficiency of the installed RTO was calculated at 97.5% destruction of 

benzene and other VOC’s. Quarterly testing shows that the RTO controls benzene by 

an average of 98.15%. 

Actual Benzene Emissions And Control Efficiency

Quarter Inlet lb/day Outlet lb/day Control Efficiency %

1st 44.96 1.12 97.52

2nd 59.60 1.14 98.08

3rd 50.08 0.70 98.60

4th 52.04 0.81 98.41

Average 51.43 0.94 98.15

Based on 2008 source test data.

Actual controlled benzene emissions (2008) are about 1.69 lbs/day (assuming 

condensate potential of 0.75). Approximately 78 lbs of benzene were emitted that same 

year in an uncontrolled basis, for a yearly total of 0.33 tons. 

Isopentane Emissions 

Isopentane emissions are also expected from the ORMAT Energy Converters normal 

operations and maintenance events. These emissions are fugitive in form. The 

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isopentane potential to emit has been calculated to be 99.6 pounds per day. These 

emissions will add to the facility wide ROC inventory. 

Emergency Fire Water Pump

The facility is equipped with an emergency fire water pump. This unit is operated on a 

regular basis for maintenance and testing purposes only. This unit is on standby 

emergency mode. The fire pump falls under the Airborne Toxic Control Measure for 

Stationary Compression Ignition (ATCM) and NFPA-25 requirements. This unit will be 

allowed to operate for testing and maintenance purposes a total of 40 hours per year.

Air emissions are calculated using AP-42 emission factors, Table 3.3-1. The fire pump 

is powered by a Cummins diesel-fueled engine, Model 833, rated at 290 HP@ 2100 

rpm. Emissions from the 40 hours of maintenance are considered.

Emissions From Fire Pump (40hrs)

Unit PM-10 CO TOC NOX SOX Benzene

lb/hr 0.64 1.94 0.72 8.99 0.60 1.89E-3

tons/year 0.01 0.04 0.01 0.18 0.01 0.00

The maximum annual emissions of major pollutants from Heber 1 is the sum of the 

maximum daily potential at dual-flash project with control, without control 

(maintenance), isopentane potential to emit, and emissions from the emergency fire 

pump engine. 

Title V Thresholds

Thresholds for Title V facilities are as follows; single HAPs emissions of 10 tons per or 

greater, combined HAPs emissions of 25 tons per year or greater, and 100 tons per 

year or greater for any single regulated air pollutant and 70 tons per year of PM10. The 

following are total facility wide potential emissions:

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HAP and Regulated Air Pollutant Yearly Emissions

Pollutant Yearly 

(Tons/Yr)

Benzene 1.24

VOC(non-benzene) 19.64

Hydrogen Sulfide 5.63

PM10 0.50

Sulfur Dioxide 0.93

Nitrogen Oxides 2.31

Benzene and hydrogen sulfide based on 8400 hours/year of RTO operation and 360 

hours of maintenance; PM10, sulfur dioxide, nitrogen oxides based on 8760 hours of 

RTO operation.

Applicable Rules Compliance Status

108 Inspections In Compliance

109 Source Sampling In Compliance

111 Equipment Breakdown In Compliance

201a Authority to Construct In Compliance

201b Permit to Operate In Compliance

204 Applications In Compliance

206 Processing of Applications In Compliance

207 New and Modified Stationary In Compliance

Sources

401 Opacity of Emissions In Compliance

403 General Limitations on the In Compliance

Discharge of Air Contaminants

405 Sulfur Compounds Emission Standards In Compliance

Standards, Limitations and Prohibitions

407 Nuisance Rule In Compliance

900 Procedures for Issuing Permits In Compliance

for Sources Subject to Title V 

of the Federal Clean Air Act 

Amendments of 1990

1002 California Airborne Toxic Control In Compliance

Measures

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CONDITIONS FOR AUTHORITY TO CONSTRUCT

AND PERMIT TO OPERATE #1641B-3

SYNTHETIC MINOR SOURCE

Permit to Operate Conditions 

A. General Conditions

A.1 Operation of this equipment shall be in compliance with all data and 

specifications submitted with the application under which this permit is issued 

unless otherwise noted below.

A.2 Operation of this equipment shall be in compliance with all applicable APCD

Rules and Regulations.

A.3 This Permit does not authorize the emissions of air contaminants in excess of 

those allowed by USEPA (Title 40 of the Code of Federal Regulations), the State 

of California Division 26, Part 4, Chapter 3 of the Health and Safety Code, or the 

APCD (Rules and Regulations).

A.4 This Permit cannot be considered permission to violate applicable existing laws, 

ordinances, regulations, rules or statutes of other governmental agencies.

A.5 No air contaminant shall be released into the atmosphere which causes a public 

nuisance.

A.6 The Permittee shall not release or discharge into the atmosphere from any single 

source of emission, any air contaminant as dark or darker as designated as No. 1 

on the Ringlemann Chart (20% opacity) for a period or periods aggregating more 

than three (3) minutes in any hour.

A.7 The Permittee shall comply with the general requirements for control of fine 

particulate matter (PM10); construction and earthmoving activities; bulk 

materials; carry-out and track-out; open areas; paved and unpaved roads; and 

conservation management practices.

A.8 The Permittee shall only burn CARB Diesel Fuel at any stationary equipment 

within the facility.

A.9 The emissions of any regulated pollutant, as defined pursuant to 40CFR70.2, 

shall be less than the major source threshold values of Rule 900B.20, of the 

Imperial County APCD, for all of the facility.

A.10 The emission of any single hazardous air pollutant, as defined pursuant to 

Section 112(b) of the 1990 Clean Air Act and Rule 900B.20, shall be less than 10 

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tons per year, for all the of the facility. Total combined emissions of all 

hazardous air pollutants, as defined pursuant to Section 112(b) of the 1990 

Clean Air Act and Rule 900B.20, shall be less than 25 tons per year, for all the 

facility.

A.11 Total facility wide benzene emissions shall not exceed 1.24 tons per year.

B. ORMAT Energy Converter Isopentane Emissions

B.1 Under all normal operating conditions (maintenance, Evacuation Skid SystemVapor Recovery Unit (VRU) purging, individual Ormat Energy Converter (OEC) 

vapor recovery units (purging units), and fugitive daily emissions) the total 

isopentane emissions shall not exceed 99.6 pounds per day from the entire 

facility, as determined by normal inventory and mass balance procedures.

(ICAPCD Rule 207)

B.2 OEC Purging Emissions

B.2.a All noncondensable gas (NCG) purging of any OEC Unit, shall be 

conducted through the facility’s Evacuation Skid System–Vapor Recovery 

Unit (VRU) or the individual OEC vapor recovery units (purging units). The 

purging of gases through the Evacuation Skid System-Vapor Recovery 

Unit (VRU) and/or individual OEC VRU (purging units) to the atmosphere 

shall be conducted only after the separation cycle of NCG and isopentane 

gases is completed. Purging of NCG to the atmosphere shall be 

conducted in a manner to minimize entrainment of isopentane gases with 

the NCG.

(ICAPCD Rule 207)

B.2.b Isopentane emissions occurring during normal purging events shall 

be considered part of the daily average isopentane emissions for the total 

isopentane loss for the reporting quarter.

(ICAPCD Rule 207)

B.2.c All combined purging and fugitive daily isopentane emissions shall 

not exceed 44 pounds per day.

1) Each individual Ormat Energy Converter (OEC) vapor 

recovery unit (purging unit) emission rate shall not exceed 0.005 lbs 

of isopentane per cycle.

2) Each individual Ormat Energy Converter (OEC) vapor 

recovery unit (purging unit) shall not be cycled more than 48 times 

in any given 24 hour period.

B.3 OEC Maintenance Emissions

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B.3.a The ICAPCD shall be notified by telephone or fax at least 48 hours 

prior to the time which an OEC Unit containing isopentane will be opened 

to the ambient air for scheduled maintenance.

(ICAPCD Rule 207)

B.3.b Unscheduled maintenance and repairs of an OEC Unit containing 

isopentane may be conducted without prior ICAPCD notification.

(ICAPCD Rule 207)

B.3.c Prior to conducting any scheduled or unscheduled maintenance or 

repairs to any OEC Unit where the isopentane may be exposed to the 

atmosphere, the isopentane in that portion of the unit shall be transferred 

to the isopentane storage tank or any type of vessel that serves as an 

isopentane storage tank, and any residual isopentane evacuated through 

the facility’s Evacuation Skid System-Vapor Recovery Unit (VRU) and/or 

individual OEC VRU (purging units). The OEC Unit shall be evacuated of 

isopentane in a manner that results in the minimum practical amount of 

isopentane being emitted to the atmosphere.

(ICAPCD Rule 207) 

B.3.d Venting isopentane from an OEC Unit to the atmosphere for the 

sole purpose of evacuation is prohibited. 

(ICAPCD Rule 207)

B.3.e Isopentane emissions occurring during normal repair and 

maintenance shall not be considered a breakdown and shall be 

considered part of the daily average isopentane emissions for the total 

isopentane loss for the reporting quarter.

(ICAPCD Rule 207)

B.3.f All combined maintenance isopentane emissions shall not exceed 

55.6 pounds per day calculated on a quarterly average.

(Permit Application)

B.4 OEC Breakdown Emissions

B.4.a Any breakdown, malfunction, or upset occurrence which constitutes 

a breakdown condition resulting in the emission of any air pollutant to the 

atmosphere, shall be reported to the ICAPCD as soon as reasonably 

possible but no later than two (2) hours after its detection, and should 

identify the time, specific location, equipment involved, and to the extent 

known the cause of the occurrence, and immediate remedial measures 

shall be undertaken to correct the problem and prevent further emissions 

into the atmosphere. The completion of corrective measures or the 

shutdown of emitting equipment is required within twenty four (24) hours 

of occurrence of a breakdown condition.

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(ICAPCD Rule 111)

B.4.b If the breakdown condition will require more than twenty four (24) 

hours to correct, the Permittee, in lieu of shutdown, shall submit a 

variance application to the Air Pollution Control Officer (APCO) requesting 

to commence the variance procedure set forth in the ICAPCD Hearing 

Board Procedures.

(ICAPCD Rule 111)

B.4.c Within ten (10) days after a breakdown occurrence has been 

corrected; the owner or operator shall submit a written report to the APCO 

which includes:

1) A statement that the occurrence has been corrected, 

together with the date of correction and proof of compliance.

2) A specific statement of the reason(s) or cause(s) from the 

occurrence sufficient to enable the APCO to determine whether the 

occurrence was a breakdown condition.

3) A description of the corrective measures undertaken and/or 

to be undertaken to avoid such an occurrence in the future.

4) An estimate of the emissions caused by the occurrence.

5) Pictures of the equipment or controls which failed, if 

available.

(ICAPCD Rule 111)

B.4.d Failure to comply, or comply in a timely manner, with the reporting 

requirements established in paragraph B.4.a shall constitute cause for 

enforcement action.

(ICAPCD Rule 111)

B.4.e Isopentane breakdown emissions and losses, shall be deducted 

from the total isopentane loss for the reporting quarter before calculating 

the daily average emissions. 

(ICAPCD Rule 111; ICAPCD Rule 207)

C. Evacuation Skid System-Vapor Recovery Unit (VRU) and OEC Vapor 

Recovery Units (Purging Units)

C.1 The facility Evacuation Skid System-Vapor Recovery Unit (VRU) and the 

individual OEC Vapor Recovery Units (Purging Units) shall each be maintained in 

good working order at all times and shall each achieve a minimum 95% 

isopentane vapor recovery efficiency during the NCG purging process of an OEC 

Unit.

(ICAPCD Rule 207)

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C.2 The Evacuation Skid System-Vapor Recovery Unit (VRU) and each individual 

OEC Vapor Recovery Unit (Purging Units) shall be source tested at least once, 

on a yearly basis, to verify the isopentane vapor recovery efficiency. The source 

test method shall receive prior Imperial County Air Pollution Control District 

(ICAPCD) approval. The Evacuation Skid System-Vapor Recovery Unit (VRU) 

and OEC Vapor Recovery Units (Purging Units) test shall be witnessed by the 

ICAPCD.

(ICAPCD Rule 109)

C.3 The Permittee shall submit the test results for the source tests required pursuant 

to condition C.2 within thirty (30) days of completion of tests.

(ICAPCD Rule 109)

C.4 Any breakdown, malfunction, or maintenance of the Evacuation Skid SystemVapor Recovery Unit (VRU) and/or individual OEC Vapor Recovery Unit 

(Purging Units) resulting in the emission of isopentane to the atmosphere, shall 

be reported to the ICAPCD as soon as reasonably possible but no later than two 

(2) hours after its detection and immediate remedial measures shall be 

undertaken to correct the problem and prevent further emissions into the 

atmosphere. The completion of corrective measures or the shut down of emitting 

equipment is required within twenty four (24) hours of occurrence of a breakdown 

condition.

(ICAPCD Rule 111)

C.5 If the breakdown condition will require more than twenty four (24) hours to 

correct, the Permittee, in lieu of shutdown, shall submit a variance application to 

the Air Pollution Control Officer (APCO) requesting to commence the emergency 

variance procedure set forth in the ICAPCD Hearing Board Procedures.

(ICAPCD Rule 111)

C.6 The Permittee shall install and maintain, in good working order, an in-line flow 

meter (cfm) at the inlet of the Evacuation Skid System-Vapor Recovery Unit 

(VRU). The flow meter shall be equipped with a totalizer.

(ICAPCD Rule 207)

C.7 The Permittee shall install and maintain, in good working order, a 

counter/totalizer to record the purging events conducted by each OEC Vapor 

Recovery Unit (Purging Unit).

(ICAPCD Rule 207)

C.8 A daily log shall be maintained on the premises showing Evacuation Skid 

System-Vapor Recovery Unit (VRU) hours of operation and/or purging events;

total purging events of each of the OEC Vapor Recovery Units (Purging Units); 

and routine repairs. This log shall be made available for inspection by the 

ICAPCD.

(ICAPCD Rule 207) 

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D. Regenerative Thermal Oxidizer/Scrubber Unit

D.1 The Permittee shall install, operate, and maintain the RTO/Scrubber system at all 

times the production wells are in use. 

a) Maintenance activities (operation without the RTO/Scrubber system) shall 

be restricted to a maximum of 360 hours per year. 

b) The ICAPCD shall be notified at least 24 hours in advanced via fax or 

telephone before any scheduled maintenance is performed on the 

RTO/Scrubber. 

D.2 For normal RTO/Scrubber operations, the following emissions limits from 

controlled NCG stack line shall not be exceeded:

a) Benzene emissions 2.33 pounds per day, compliance shall be 

determined based on quarterly emission rates and actual operating 

hours.

b) Hydrogen sulfide emissions 2.74 pounds per day, compliance shall 

be determined based on quarterly emission rates and actual 

operating hours.

c) Sulfur dioxide emissions 5.03 pounds per day, compliance shall be 

determined based on yearly emission rates and actual operating 

hours.

d) Nitrogen oxide emissions 11.66 pounds per day, compliance shall 

be determined based on yearly emission rates and actual operating 

hours. 

D. 4 The following emission limits from condensate line shall not be exceeded:

a) Benzene emissions 0.75 pounds per day

b) Hydrogen sulfide emissions 18.73 pounds per day 

D.5 During periods of operation without abatement system (RTO/Scrubber system) 

for maintenance activities, the following emissions from uncontrolled NCG stack 

and condensate line shall not be exceed:

a) Benzene emissions 93.12 pounds per day; if the uncontrolled 

benzene rate exceeds 93.12 pounds per day, total facility wide 

benzene emissions shall not exceed 635 pounds per quarter

b) Hydrogen sulfide emissions 250 pounds per day 

D.6 Except during maintenance activities, the RTO bed and chamber temperatures

shall be in the range of 1,500 and 1,900 degrees Fahrenheit.

D.7 The Permittee shall continuously monitor noncondensable gas flow into the RTO, 

RTO combustion bed and chamber temperature, and RTO exhaust temperature. 

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D.8 A log shall be maintained on the premises showing weekly hours of operation 

and routine repairs of the RTO/Scrubber system. This log shall be made 

available for inspection by the ICAPCD.

E. Emergency Firewater Pump

E.1 The diesel fueled emergency fire water pump shall be restricted to operate a 

total of forty (40) hours per year for maintenance and testing purposes. 

(ICAPCD Rule 1002; NFPA-25)

E.2 The diesel fueled emergency fire water pump shall not discharge into the 

atmosphere any visible air contaminant other than uncombined water vapor, for a 

period or periods aggregating more than three minutes in any one hour, which is 

20% opacity or greater.

(ICAPCD Rule 401)

E.3 Permittee shall install an operating hour meter on the diesel fueled engine.

(ICAPCD Rule 1002)

E.4 A log shall be maintained on the premises showing weekly hours of operation 

and routine repairs of the diesel fueled emergency fire water pump. This log shall 

be made available for inspection by the ICAPCD.

(ICAPCD Rule 207)

F. Monitoring, Testing and Analysis

F.1 The ICAPCD may, at any time, monitor emissions from any source within the 

facility.

(ICAPCD Rule 108; ICAPCD Rule 109)

F.2 The ICAPCD may, at any time, but no more often than once per year, authorize 

third-party air emissions testing and/or air emissions inventory of the facility. The 

cost of the air emissions testing shall be borne by the Permittee. The ICAPCD 

shall give advance notification to the Permittee prior to any air emissions testing 

or air emissions inventory required. 

(ICAPCD Rule 108; ICAPCD Rule 109)

F.3 The Permittee shall conduct the following analysis: First source test shall be 

conducted during 1998 and every four years thereafter as required under the 

Toxic Hot Spots Information and Assessment Act Emissions Inventory Criteria 

and Guidelines Report, Title 17, Section 93300.5. All analysis’ results shall be 

available at the facility for inspection.

a) Of turbine condenser condensate and cooling tower blowdown for; 

ammonia, arsenic, beryllium, cadmium, chromium, copper, hydrogen 

sulfide, lead, manganese, mercury, nickel, radon, selenium, and zinc.

14
b) Of the non-condensable gases vented for: hydrogen sulfide, 

ammonia, benzene, arsenic, mercury, radon, toluene, and xylene.

(ICAPCD Rule 207)

F.4 The Permittee shall conduct analysis of hydrogen sulfide and benzene content of 

NCG line before RTO /Scrubber system (uncontrolled) and after RTO/Scrubber 

system (controlled) on a monthly basis for hydrogen sulfide and on a quarterly 

basis for benzene. During the source test, the mass flow rate at both lines 

(condensate and NCG) shall be recorded and submitted with the report.

(ICAPCD Rule 207)

F.5 Hydrogen sulfide, benzene and ammonia concentrations of condensate shall be 

sampled at the port along the condensate line from the hot well as part of the 

quarterly source test.

F.6 Laboratory analysis shall use EPA approved methods. Test for emissions of 

hydrogen sulfide shall be conducted using U.S. EPA Method 11 or any other 

EPA Method approved by the District.

(ICAPCD Rule 900)

F.7 The Permittee shall calculate all isopentane and reactive organic compounds 

daily emissions of pounds per day based on a quarterly average. 

F.8 RTO/Scrubber system source test:

a) The Permittee shall source test the RTO/Scrubber system, within 30 days 

after commencing operations and every year thereafter. Source test shall 

be conducted for the following: benzene, hydrogen sulfide, NOx, total 

VOC and sulfur dioxide.

b) All source test analysis shall use US EPA approved methods or any other 

equivalent method approved by the District.

c) The Permittee shall calculate all the benzene, hydrogen sulfide, NOx and 

sulfur dioxide in pounds per hour.

d) The exhaust stack shall be equipped for source testing accessibility.

e) The Permittee shall submit the source test report within 30 days after 

source test completion. 

f) All official source tests shall be witnessed by an APCD official. This 

condition may be waived upon APCD written authorization. 

F.9 A performance test protocol shall be submitted to the APCO for approval 30 days 

prior to testing and should include at least the following:

a) Emission unit identification and description

b) Sampling and analysis procedures

c) Test schedule

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F.10 Performance tests for criteria pollutants, H2S and benzene shall be conducted in 

accordance with approved CARB or US EPA stationary source test methods (or 

alternate methods with prior written approval by the ICAPCD):

a) US EPA Methods 1-4 Sampling, Volumetric flow, Mw and %moisture

b) CARB Method 100 NOx, VOC, CO, CO2 and O2

c) SCAQMD Method 307 H2S

d) US EPA Method 6 SO2

e) CARB Method 410A Benzene

G. Reports

 At the end of each calendar quarter, and not more than thirty (30) days 

thereafter, the facility shall submit a report to the ICAPCD which contains the 

following information:

G.1 Quarterly emission report of hydrogen sulfide, benzene, ammonia and total 

Hazardous Air Pollutants(HAPs) based on analysis results conducted pursuant to 

the requirements of Sections F.3, F.4, F.5 and F.6. Emissions shall be reported 

in pounds per hour and HAPs pounds per quarter.

G.2 The total amount of isopentane renewals brought to the facility during the 

reporting quarter and the previous quarters of that calendar year. The report shall 

include the isopentane supplier’s name and address. These renewals shall be 

reported in pounds of isopentane at Standard Temperature and Pressure.

G.3 The total amount of isopentane present at the facility before renewals.

G.4 The number of NCG purges from the OEC Units that occurred through the facility 

Evacuation Skid System-Vapor Recovery Unit (VRU) and the number of NCG 

purges from the individual OEC Vapor Recovery Units (Purging Units) during the 

reporting quarter.

G.5 The number of isopentane withdrawals through the facility Evacuation Skid 

System-Vapor Recovery Unit (VRU) from the OEC Units and individual OEC 

Vapor Recovery Units (Purging Units) for hardware maintenance that occurred 

during the reporting quarter.

G.6 The number of OEC Units rotating seals replaced or installed or any other OEC 

Units seal or gasket failure that occurred during the reporting quarter.

G.7 The number of OEC Units pressure relief rupture discs removed and replaced 

during the reporting quarter.

G.8 The total flow, in cubic feet, through the facility Evacuation Skid System-Vapor 

Recovery Unit (VRU) in-line flow meter during the reporting quarter.

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G.9 The total number, in purging events, conducted by each OEC Vapor Recovery 

Units (Purging Units).

G.10 The combined daily total quantity of isopentane fugitive, purging and 

maintenance emissions from the OEC Units.

G.11 A report of days and hours of operation without RTO/Scrubber (uncontrolled) 

system.

G.12 At the end of February of each calendar year and not more than thirty (30) days 

thereafter, the Permittee shall submit to the ICAPCD an annual report of the 

previous calendar year, consisting of the following: The monthly diesel fuel 

consumption and hours operated per month of the diesel fueled emergency fire 

water pump.

(ICAPCD Rule 207)

G.13 The Permittee shall report to the ICAPCD by telephone all non-normal (upset) 

releases of isopentane or geothermal gases to the atmosphere as established on 

operating condition B.4.

G.14 The Permittee shall submit to the ICAPCD benzene and total HAP emissions 

based on analysis results conducted pursuant to the requirements of Sections 

F.3, F.4, F.5 and F.6 and hours of operation. These calculations shall be 

submitted at the end of February of each year and not more than thirty (30) days 

thereafter. 

H. Permit Compliance 

H.1. Emissions in excess of those pursuant under 40CFR70.2 defined under Rule 

900B.20, of the Imperial County APCD Rules and Regulations for all the facility 

shall require the Permittee to obtain a Title V permit.

I. Equipment List

I.1 Turbine Generator

Manufacturer: Mitsubishi Heavy Industries

Equipment Description: 52 MW (gross) dual-entry

double flow 5-stage turbine.

Maximum Design Process Rate: 8.2 x 106 lbs/hr geothermal 

fluid.

Additional Equipment: Surface Condenser, High & Low

Pressure Tanks.

I.2 Cooling Tower

Manufacturer: The Marley Cooling Tower Company

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Equipment Description: Model W499-6.0-5, five-cell,

Industrial Wood Counter flow Mechanical Draft. Each cell 

equipped with a fan, 250 HP motor; Drift Rate of 0.0005%.

Maximum Design Process Rate: 85,000 gallons/min

I.3 Cooling Tower

Manufacturer: The Marley Cooling Tower Company

Equipment Description: Model F467A-7.0-2, two-cell,

Industrial Fiberglass Counterflow Mechanical Draft. Each cell 

equipped with a fan,135 HP motor each; Drift Rate of 

0.001%.

Maximum Design Process Rate: 14,170 gallons/min

I.4 Cooling Tower 

Manufacturer: The Marley Cooling Tower Company

Equipment Description: Model F499A-5.91-A, four cell, 

Industrial Fiberglass Counterflow Mechanical Draft. Each cell 

equipped with a fan, 180 HP motor each, Drift Rate of 

0.001%.

Maximum Design Process Rate: 45,500 gallons/min

I.5 Ormat Energy Converter (OEC)

Manufacturer: Ormat

Equipment Description: OEC-11 thermodynamic organic 

Rankine cycle unit, composed of turbine, generator, 

isopentane motive fluid, oil system, electro–pneumatic 

control system, heat exchanger, vaporizer, preheater, 

condenser, geothermal brine piping, feed pump, and 2@ 

integrated vapor recovery units (purging units).

Design Capacity: 7 MW

I.6 Ormat Energy Converter (OEC)

Manufacturer: Ormat

Equipment Description: OEC-12 thermodynamic organic 

Rankine cycle unit, composed of turbine, generator, 

isopentane motive fluid, oil system, electro–pneumatic 

control system, heat exchanger, vaporizer, preheater, 

condenser, geothermal brine piping, feed pump, and 1@ 

integrated vapor recovery unit (purging unit).

Design Capacity: 3.5 MW

I.7 Ormat Energy Converter (OEC)

Manufacturer: Ormat

Equipment Description: OEC-13 thermodynamic organic 

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Rankine cycle unit, composed of turbine, generator, 

isopentane motive fluid, oil system, electro–pneumatic 

control system, heat exchanger, vaporizer, preheater, 

condenser, geothermal brine piping, feed pump, and 1@ 

integrated vapor recovery unit (purging unit).

Design Capacity: 3.5 MW Mechanical energy for injection 

pump

I.8 Evacuation Skid System-Vapor Recovery Unit (VRU)

Equipment Description: Vapor Recovery Unit composed of 

liquid motive fluid removal pump, motive fluid vapor knockout 

drum, vacuum pump, motive fluid vapor condenser, motive 

fluid liquid accumulator tank, pressure controlled vent valve, 

and activated carbon adsorption unit. 

I.9 Emergency Fire Water Pump

Equipment Description: Emergency fire water 

pump is powered by a Cummins diesel-fueled engine, Model 

833, rated at 290 HP@ 2100 rpm.

I.10 Regenerative Thermal Oxidizer

Adwest Technologies RETOX dual-chamber RTO unit 

I.11 Wet Scrubber

Bionomic Industries ProClean Type CT caustic scrubber 

I.12 Additional Equipment:

Auxiliary flash tank, high pressure flash tank, low pressure 

flash tank, surface condenser and ONE 10,000 gallon 

Isopentane storage tank.

Recommendations

It is recommended that a Synthetic Minor Permit be issued to Ormat Nevada Heber 1 

Facility for the above described operation. 

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