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Natural Gas Interchangeability Integrating supply diversity and end-use predictability
Jennifer Baber Deegan Federal Regulatory Affairs Washington Gas Light CompanyApril 28, 2004
Washington Gas Light Company (WGL)
Natural gas local distribution
company serving Washington
D.C. and the surrounding
metropolitan region in Maryland
and Virginia
970,000 customers; 90%
residential
1.7 Bcf peak day requirement;
100 MDth per day base load
20+ gate stations connect WGL
with four upstream interstate
natural gas pipelines
Gate Stations on CPLNG pipeline1 Centreville 2 White Plains 3 Gardiner Road4 Chalk Point 5 Prince Frederick 6 Patuxent
Cove Point
1
6
3 4 5
2
WGL has 6 Direct-Connect Gate Stations on the Cove Point LNG pipeline - the Transco, DTI & TCO Gate Stations are downstream of Cove Point
Washington Gas System Profile
Dominion Cove Point LNG
§January 2001 Reactivation Application
7.8 Bcf LNG Storage Capacity1 Bcf/day Sendout CapacityReactivation Summer 2003
§Washington Gas protestNatural gas interchangeability concernsLack of competitive alternatives to LNG imports
§FERC reactivation authorization, but without quality ranges desired by Dominion Cove Point and LNG importers
Dominion Cove Point Initial Gas Quality Criteria
§ Maximum high heating value (HHV) of LNG received: 1138 Btu/scf(dry basis)
At Cove Point’s option, higher HHV permitted to be received
But only if can be modified to meet sendout criteria (below)
§ Maximum HHV of vaporized LNG sent out: 1100 Btu/scf
Prior to sendout, inject with nitrogen as necessary to lower HHV to 1100 Btu/scf
Maximum nitrogen in sendout gas: 4.0%
§ Specific composition limits typical of domestic pipeline tariffs (e.g. maximum 1.0% CO2 ; 0.02% O2)
80%
85%
90%
95%
100%
Nigeria Abu-Dhabi
Algeria Qatar
Methane Ethane Propane Butane Pentane Nitrogen CO2
1143 1142
10981132
10651036
1066
Nigeria Abu-Dhabi
Algeria Qatar Trinidad WGL
Expected high Btu of LNG relative to WGL history of traditional supply
WGL
More heavy hydrocarbons can produce undesirable combustion characteristics
•Carbon monoxide production•Reduced appliance life•Environmental compliance implications
Source: TIAX Interchangeability Assessment for WGL’s Service Territory July 7, 2003 Final Report (Cove Point LNG Docket No. CP01-76)
Btu Interchangeability
Potential Changes in Combustionwith the introduction of LNG
§ Thermal effects
Greater or lesser heat input compared to rating
Potential for thermal stress
§Lifting
Gases with higher inerts have lower average flame velocity
May become less than velocity of gas through burner ports -- flame will lift
§Flashback
Gases with higher flame velocity (e.g. hydrogen)
May burn back through ports into burner
Normal
Lifting
Potential Changes in Combustion with the introduction of LNG
§Yellow-tippingHigher heating value gases need more primary airLower ratio of primary air to fuel leads to flame yellowing and elongation, impingement on surfaces, sooting
§Incomplete combustionCan occur alone or in combination with the above Excessive production of carbon monoxideParticularly critical with unvented appliances (cooking, fireplaces, heaters)
Yellow-tipping
Maintaining end-use predictability and supply diversity
§ WGL seven step approach focused on field and lab testing
§ Provided a method to manage diversity in LNG sources with a minimum investment in blending and dilution facilities
WGL Interchangeability Approach
1. Identify Historical Range
Variation can serve as a benchmark for tolerancesEvaluate length of time of sustained extreme conditionsEvaluate impact of other resources on-system and downstream
Gardiner Road
1025
1030
1035
1040
1045
1050
1055
1060
1065
1070
1075
1080
11/1/98 2/9/99 5/20/99 8/28/99 12/6/99 3/15/00 6/23/00 10/1/00 1/9/01 4/19/01 7/28/01
Date
He
ati
ng
Va
lue
(B
tu/s
cf)
Daily average heating value
Average heating value
2. Determine the appliance characteristics of the affected area
3. Select representative appliances for testing
4. Establish baseline appliance performance criteria
5. Lab test actual consumer appliances from impacted area and new appliances
Rates of CO production
Yellow-tipping characteristics
Sooting potential
Lifting tendencies
6. Identify supply and dilution combinations that produce results comparable to the baseline
WGL Interchangeability Approach
7. Translate supply source’s molecular components and dilution combinations into quality criteria
Dominion Cove Point LNG Interchangeability Settlement
§5-Party Agreement between
WGL, Dominion Cove Point
LNG and LNG importers
§Interchangeability study
conducted based on an
agreed-upon methodology
Provided information to all parties that a wider range of interchangeability results can be incorporated
§Competitive alternative
provided (Cove Point East
CP03-74)
§Interchangeability limits for
delivery to WGL incorporated
into the Dominion Cove Point
LNG tariffYellow-tippingLiftingIncomplete CombustionHeating Value (Btu)
§Natural gas quality
monitoring capability
establishedMonitor hourly
Remedy within 3 hrs
Natural Gas Quality & Interchangeability
Quality - Merchantable; operator flexibility Btu range Objectionable Properties
Particles, liquid or solid matter Hydrogen Sulfide Sulfur Nitrogen Carbon Dioxide Oxygen Harmful Contaminants Bacteria or bacterial agent
Molecular Structure Hydrocarbon Dew Point (HDP)
Interchangeability - Extent to which a substitute gas can replace the gas normally used and produce similar combustion characteristics
Lessons Learned
Local, historical natural gas characteristics are the starting point for developing interchangeability indices because every market developed differently
Heating value is not the sole factor for determining interchangeability; the ratio of heavier hydrocarbons to methane must be considered
Current pipeline tariff gas quality ranges/limits do not necessarily reflect the actual historic gas quality at the appropriate level of detail
Burner-tip solution is not viable and would limit future access to alternative supplies
No broad assumptions can be made about the ability of design certified appliances to operate with a wide variety of gases absent field testing
Interchangeability indices can provide flexibility for alternative supplies while facilitating greater predictability in appliance response to variations in gas supply
Thank you
©2003 WGL Holdings, Inc. For questions or copies, please contact Jennifer Baber Deegan at [email protected], or 703.750.5146