The Impact of Using LNG-Derived Natural Gas in the South Coast Air Basin

1
The Impact of Using LNG-Derived Natural Gas in
the South Coast Air Basin

• January 2006

2
Background

• Future natural gas demand in the United States
  will rise
• Traditional natural gas sources are increasing in
  cost and new supplies will not meet demand
• Regassification of LNG imports is commercially
  feasible and economically beneficial
• Imported LNG typically has higher heat content
  (HHC) than current NG in the South Coast
• More ethane, propane, butane
• Less N2, CO2, and O2

3
Air Quality Background

• South Coast is a severe-17 ozone non-attainment
  and serious PM10 non-attainment area
• NOx is an ozone and PM10 precursor
• 2003 AQMP reduce NOx 48 from 2003 to 2010
• Combustion of HHC (e.g. LNG-derived) NG may
  increase NOx and CO emissions from some types of
  equipment
• 2003 AQMP control measure MSC-07 proposes upper
  limit on heating value
• Condensing (e.g. extracting) out higher
  hydrocarbons
• Adding inerts (e.g. N2, CO2)
• Question what would be the impact of HHC NG on
  South Coast emissions and air quality?

4
Impact Analysis Approach

• Review relevant emission inventories for SCAB
  natural gas combustion emission categories
• Compare to overall SCAB inventory
• Review equipment test data comparing the
  emissions from HHC gas combustion to base gas
  combustion
• Apply emission ratio to SCAB stationary source
  natural gas combustion inventory categories and
  assess the inventory impact
• Apply applicable SCAQMD regulatory limits, where
  possible assess inventory impact

5
SCAB Emission Inventory
tons/day
Source CARB, 2003 Inventory for SCAB,
anthropogenic only
6
Contributions to 2003 NOx Inventory

Stationary Source Combustion Sources
1049 tons/day NOx
Other fuels include diesel, propane, distillate
oil, LPG, gasoline, etc.
7
South Coast Energy from Different Fuels
Total energy consumed 1,723,000 Bbtu/year Based
on reported fuel consumption from 2000 Fuel Tax
Report, SoCalGas
8
HHC Emission Studies

• Initial SoCalGas sponsored tests of gas-fired
  equipment (2005 Final Report, SoCalGas)
• Tests used NG with higher heating values and
  Wobbe numbers, compared to base gas
• Wobbe heating value / square root of specific
  gravity
• Equipment was NOT modified / adjusted for HHC gas
• Gas 6 (HHV1100, Wobbe1400) results were used
  in the analysis
• Gas 3 (HHV1150, Wobbe1430) used for
  residential forced air heating units since
  equipment was not tested on Gas 6
• 2003 LNG Research Study Phase I for IC engines

9
NOx Test Results for Base and HHC Gas (Gas 6)
Emissions (ppm _at_ 3 O2)
ICE
Note For HCFAU, Gas 3 results used. For ICE,
2003 LNG Study Report results (after controls)
10
Emission Impact Analysis

• Total Basin natural gas usage 2.04 Bcf/day
• Assessed the emission impact from two scenarios
• Replacement of 1 Bcf/day with HHC gas
• Replacement of 0.5 Bcf/day with HHC gas
• Adjusted the emissions from each source category
  with related test results
• Assessed impact for the effect of certain SCAQMD
  rules

11
Applicable Test Results
5.8 tpd from residential (cooking and
other)and 3.3 tpd from gas turbine engines
generallyin RECLAIM

• LNG study April 2005, except as noted
• LNG Research Study Phase 1, 2003
• Gas 3 results used

12
Rule Adjustments

• Almost all in basin sources that emit over 4
  tons/day of NOx are in RECLAIM
• Net Basin change in emissions from those sources
  would be zero
• RECLAIM applied to
• All electric utilities, co-generation, oil / gas
  production, petroleum refining, and industrial /
  manufacturing categories
• No rule or permit limits applied to any other
  categories

13
NOx Impact of HHC Gas
NOx tons/day
14
Seasonality

• Ozone season is summer/early fall
• Emissions are seasonal
• Greater electrical generation in summer
• Sources under RECLAIM, BACT
• Residential emissions reduced in summer
• No space heating July through October
• Reduced water heating needs
• Pool heaters not used during hottest periods
• Commercial/Industrial less seasonality

15
VOC Emission Impacts
Emissions (ppm _at_ 3 O2)
Analysis shows a 0.8 ton/day reduction for
Scenario 1
16
Latest SCAQMD Modeling Analysis

• Black lines are ozone episode isopleths
• Colored lines are annual average PM2.5 isopleths
• Ozone decreases as NOx increases
• PM2.5/PM10 insensitive to NOx changes
• Ozone and PM2.5/PM10 decrease as VOC decreases

Source SCAQMD, 2007 AQMP Technical Advisory
Group, 12/7/05
17
Other Air Quality Impact Issues

• NOx emissions from residential and service /
  commercial sources are spread throughout the SCAB
• For example, emissions changes in San Fernando
  Valley do not affect peak Inland Empire areas
• Weekday/Weekend Effect
• Natural gas usage 13 higher on weekdays, but 65
  of ozone exceedences occur on weekends
• Uncertainty in mobile source emissions greater
  than potential NOx increase due to HHC combustion
• Air quality modeling possible, but may be
  insensitive to such small emission changes
• Ozone and PM2.5/PM10 air quality impacts expected
  to be negligible, with impact potentially
  beneficial

18
Preliminary Conclusions

• 0.11 annual increase in NOx emissions if 1.0
  Bcf/day of LNG-derived natural gas is used
• 0.06 increase for 0.5 Bcf/day
• Does not account for reductions from proper
  tuning
• Does not account for non-RECLAIM emission limits
• Ozone and PM10 air quality impact expected to be
  negligible, with impact potentially beneficial
• Given the small potential impact, other more
  cost-effective, local approaches should be
  considered
• Expanded use of natural gas instead of higher
  emitting diesel and gasoline