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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

Keeley Kirkseykek@freese.com

817‐735‐7476

Contact Information