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Comparison of Water Supply Projects Based on Carbon Footprint Analysis
EWRIPalm Springs, CaliforniaKeeley KirkseyMay 25, 2011
Topics
Project Background Carbon Footprints Application of Carbon Footprint Results
Project Background
Analysis performed to evaluate multiple water supply alternatives
Client has existing facilities in the area
An inventory of greenhouse gas (GHG) emissions caused by an organization, event, or product over a given period of time
Typically expressed in terms of carbon dioxide equivalents.
What is a Carbon Footprint Analysis?
Type of Greenhouse Gas CO2eq
Carbon Dioxide (CO2) 1Methane (CH4) 25Nitrous Oxide (N2O) 298
Some clients are setting criteria on sustainability Required in proposals
Beneficial for clients at the planning level Insight into the most “environmental friendly” option Possibly the most cost effect option
Public Perception Tool for Clients Carbon footprint analysis provides a means of showing
the use of low emission water supply options
Why Perform a Carbon Footprint Analysis?
Comparative Analysis
3 project types: Reservoir Raw water transmission pipeline
Transmission and desalination
3 distinct phases Construction Lake inundation Operation
Carbon Sources
GHG emissions caused by an activity Emitted carbons (directly
associated with activity) Construction equipment Energy – operation Clearing/burning
Embodied carbons (materials)
Removal of carbon sinks
Comparative Projects Similar size and water quantity Delivery to the same WTP 100‐year life
Simplification – Comparative Purposes GHG for WTP not included in total emissions (same for each project)
Major contributors
Assumptions
Summary of Projects
StrategyAmount of Supply (ac‐ft/yr)
Length of Transmission
System (miles)
Number of Pump Stations
Other Facilities
Reservoir 123,000 31 1 Dam, ReservoirTransmission Pipeline 123,000 218 7
Desalination 123,000 52 3* RO WTP, Brine disposal wells
* Two new pumps at existing facility, 1 pump station for brine disposal system
New Reservoir
Lake Inundation
Carbon Uptake – lake area 16,643 acres
GHG Flux – Lake surface Initial decay of vegetation On‐going flux
Clearing and burning ~ 19% cleared ~ 3% burned
35%
29%
24%
10%
2%
Wetland
Grassland
Forest
Cropland
Water
Reservoir Land Cover Types
GHG – Lake Inundation
‐
100
200
300
400
500
600
1 4 10 16 22 28 34 40 46 52 58 64 70 76 82 88 94 100
CO2e
q Em
ission
s (m
illions of lbs
/yr)
Years after Reservoir Creation
Total CO2eq Emissions
Emissions during Construction Dam Construction 31 mile, 90‐inch pipeline Intake pump station
Embodied Carbon Dam (concrete, soil cement, steel, sand, HDPE liner) 31 mile, 90‐inch pipeline (steel, liner and coatings)
Operation Emissions 12,000 HP intake pump station
Emissions of Reservoir Project
Raw Water Transmission Pipeline
Emissions during Construction 218‐mile, 96‐inch pipeline 7 pump stations
Embodied Carbon 218‐mile, 96‐inch pipeline (steel, liner and coatings) 7 pump stations
Operation Emissions 7 pump stations
Emissions of Raw Water Transmission Pipeline
Desalination
Emissions during Construction 42 miles of 90‐inch pipeline 80 MGD RO treatment plant Brine disposal pipeline and wells (30) Pump station
Embodied Carbon 42 miles of 90‐inch pipeline (steel, liner and coatings) 80 MGD RO Treatment Plant Brine disposal pipeline and wells (30) Pump station 2 new pumps at existing facility
Emissions from Desalination Project
Operation Emissions 80 MGD RO Treatment Plant Brine disposal wells and pump station for disposal
conveyance system 2 pumps at existing facility
Emissions from Desalination Project, Continued
Calculations
Construction Component Type of construction
equipment used Amount of time each piece of
equipment was used The horsepower for each type
of equipment EPA1 emission factor (EF)
1 Environmental Protection Agency (EPA), Exhaust and Crankcase Emission Factors for NonroadEngine Modeling – Compression – Ignition, 2004
Construction Calculations
Type of Construction Equipment
Emissions during construction in pounds
CO2eq (lbs during
construction) CO Nox
Excavator 3,165 10,377 3,095,522Excavator 2,447 8,028 2,394,648Excavator 2,284 7,538 2,248,619Track loader 1,012 3,753 1,119,317Track dozer 881 2,774 827,454Compactor 757 2,376 708,693Wheel loader 1,142 4,177 1,245,864Wheel loader 627 2,330 694,948Articulated truck 2,663 8,693 2,593,241Backhoe loader 1,501 1,762 526,618Crane 1,227 4,516 1,347,083Subtotal 17,706 56,323 16,802,00720% for Miscellaneous 3,541 11,265 3,360,401Total 21,247 67,588 20,162,408
Embodied Calculations
Embodied Component Quantity of material Density or weight of material
Embodied energy factor (Inventory of Carbon and Energy, ICE)
Embodied Energy Factors and Density of Materials
Material Embodied Energy (MJ/kg)Density of
Material (lb/ft3)CMU 0.81 105
Concrete1.11 (RO Plant and Pump Stations) or
1.39 (Dam)150
Copper (for pump calculation) 55 N/A*High Density Polyethylene (HDPE) Liner 76.7 58.7
High Density Polyethylene (HDPE) Pipeline 84.4 41.71**Metal (Galvanized Steel) 39 546
Mortar Coating 1.55 137Mortar Lining 1.55 137
Polyurethane Coating 72.1 66Reinforcing Steel 24.6 490
Sand 0.1 100Soil Cement 0.85 94
Steel34.4 (Pipeline) or 35.3 (Pumps and
mechanical components of the WTPs)490
Steel Well Casing 56.7 546
* The weight of the copper was used (as obtained from pump submittals).**This is the weight of the HDPE pipeline in lbs/ft.
Energy Component eGRID emission rates (lbs/MWh) Amount of energy used (MWh/yr)
2005 Electricity Emission Rates (in Pounds per Megawatt Hour)
Power Consumption Calculations
E.H. Pechan & Associates, Inc. (2009, April). The Emissions & Generation Resource Integrated Database. Retrieved June 17, 2010, from Environmental Protection Agency: http://www.epa.gov/cleanenergy/energy‐resources/egrid/index.html
Carbon Dioxide Methane Nitrous Oxide1,324.35 0.01865 0.01511
Unit MWh/yr
Amount of GHG Emissions (mil lbs/yr) CO2eq
(Mil lbs/yr)Carbon
Dioxide Methane Nitrous Oxide
Segment APump Station 1 96,266 127.5 0.00180 0.00145 128Pump Station 2 68,761 91.1 0.00128 0.00104 91Pump Station 3 48,133 63.7 0.00090 0.00073 64
Segment EPump Station 1 30,943 41 0.00058 0.00047 41
Segment FPump Station 1 41,257 54.6 0.00077 0.00062 55
Segment to WTPPump Station 1 34,381 45.5 0.00064 0.00052 46Pump Station 2 41,257 54.6 0.00077 0.00062 55
Total 478 0.00673 0.00545 480
Calculations – Power Generation
Total CO2 Equivalents – 100 years
Total Carbon Dioxide Equivalents (100 yrs)
StrategyAmount of Supply(ac‐ft/yr)
Lake Inundation CO2eq* (Mil lbs)
Construction CO2eq (Mil lbs)
Embodied CO2eq (Mil lbs)
Power CO2eq (Mil lbs)
Total CO2eq (Mil lbs)
Unit CO2eq of Water Supply (lbs CO2eq/ac‐
ft)Reservoir 123,000 2,098 10 376 6,611 9,096 740Raw Water Transmission Pipeline 123,000 N/A 21 1,948 40,657 42,627 3,466
Desalination 123,000 N/A 14 417 11,774 12,205 992* Does not include long‐term reservoir flux. General consensus is that the long‐term flux should not be included as part of the project carbon emissions.
GHG Emissions – 100 Years
1
10
100
1,000
10,000
100,000
Construction Embodied Power Total
Million Po
unds of C
O2e
Reservoir Transmission and Desalination Raw Water Transmission Pipeline
Unit Carbon Equivalent Emissions
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
Unit C
O2e
q of W
ater Sup
ply (lb
s CO
2eq/ac‐ft
)
Reservoir Desalination Transmission Pipeline
Cumulative GHG Emissions
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
45,000
0 10 20 30 40 50 60 70 80 90
CO2e Emission
s (M
il lbs/yr)
Years Since Creation
Reservoir Transmission Pipeline Desalination
Items to determine upfront Comparison vs. actual number Direct vs. indirect emissions
Important Things to Consider
Closing Thoughts
Largest influencing factor is the energy used to operate each project
Ways to Reduce a Carbon Footprint
Improving the operational efficiency
Using renewable energy
The design of equipment
