Optimizing Water Delivery System Storage & Its
Influence on Air Pollutant Emission Reduction
Steven Jin, P.E.
The 4th IGCC June 27, 2013
Water Transmission and Distribution Operations
• Many water delivery systems do not own enough storage capacity.
• They adjust pumping to roughly match the water system demand variations.
• More water is pumped during peak hour periods and less water is pumped during off-peak hours.
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Optimizing Water Delivery Systems
1. Pumping & Water Storage
Optimization
2. Energy Use Changes
Case Studies - Pumping Energy Optimization
• DWSD (1993, 2007)• City of Pontiac (2009)• Monroe (GLPF, 2011)• Oakland County
(2012)• Other Studies
Optimizing Water Delivery Storage
• Adding more water storage would reduce on-peak pumping requirements.
• Pumps can be run at constant or near constant rates for both on-peak and off-peak periods.
• That reduces energy costs by minimizing the electrical demand charge.
Optimizing Water Delivery Systems
1. Pumping & Water Storage
Optimization
2. Energy Use
Changes
3. Pollutant Emission Reduction
Emission of CO2 by Potable Water
Delivery*
• 40% of total U.S. CO2 emission produced by electricity generation
• Water delivery energy: 3% of the nation’s electricity consumption
* University of Michigan Center for Sustainable System factsheets (online).
Example - DWSD Water System• Service Area –
1,000 square miles (population near 4 Million).
• 2012 average water demand -556 MGD.
• 2012 maximum day demand - 960 MGD.
DWSD Water System
• 5 Water Treatment Plants
• 20 Pumping Stations• Over 3,840 mi Water
Main• Serve City of Detroit• Serve 127 Communities
(Distribution Systems)
• Select 12 Largest Distribution Systems with No Storage (1/4 total DWSD demand).
• DWSD Directly Pumping to Supply Peak Hour Demands
Selection of Distribution Systems without Storage
Modeling Water Storage in the System
• Cyber water storages were added model (5 groups).
• Peak hour pumping reduction was investigated by modeling.
How Does Water Storage Help
• On-peak water demand hours overlap all or part of the on-peak electrical demand hours.
• With optimal water storage, on-peak pumping requirements can be shifted to off-peak hours.
• Using hydraulic model to simulate how water storage can help.
Facts about Generation• Nuclear and renewable power
plants can only be operated as a base plant (not as a peaking plant).
• Nuclear/renewable plants emit no CO2.
• Peaking plants are required to be started or shut off quickly.
• Peaking plants are powered by natural gas & fuel oil.
Facts about Generation
• Relative to other fuels, nuclear or renewable fuels are cheaper.
• During low electrical demand hours, marginal power plants might be nuclear or renewable fuel type.
• Shifting on-peak electrical demand reduce energy cost and CO2 emission.
Identifying Hourly Marginal Generation Types *
*LMP method, by T. H. Carter, 2011 based on the studies using MISO’s data
Regional Hourly Marginal Generation Types on June 27, 2012
Calculate CO2 Emission Reduction
• Using the LMP method to find hourly marginal generation types.
• Using data in EPA’s eGRID to calculate pollution emission factors (in lbs/kWh).
• CO2 Emission Rate for Coal fuel Generation is 2.07 (lbs/kWh)
CO2 Emission Reductionby Adding Water Storage(in 12 Distribution Systems)
Energy Reduction x Emission Rate = CO2 Emission Reduction= 27,757 (kWh) x 2.07 (lbs/kWh) = 57,457 (lbs, or 26.1 tonnes)
Water Storage Optimization Results (Optimizing 12 distribution systems for the maximum demand day, June 27, 2012)
City of Pontiac: Typical Mid-Size Distribution System
Verify the approach
City of Pontiac Water System• Serving a
population of 50,000
• 2012 average water demand 6.8 MGD
• 2012 maximum day demand 11.4 MGD
Two Supplies to Pontiac
Storage of Pontiac
DWSD Supply Flow to Pontiac (Maximum Day, June 27, 2012)
Modeled Supply without Using Storage
Modeled Hourly Pumpage without Using Storage
Water Storage Fill and DrainNight/Morning Filling (MG) 1.05Day-time Draining (MG) 1.13
Evening Filling (MG) 0.08
Pontiac CO2 Emission Reduction on Maximum Demand Day (June 27, 2012)
Energy Reduction x Emission Rate = CO2 Reduction= 1,754 (kWh) x 2.07 (lbs/kWh) = 3,631 (lbs, or 1.65 tonnes)
Conclusion:Reducing CO2 Emission by Optimizing Water Delivery Pumping & Storage
1. Pumping & Water Storage
Optimization
2. Energy Use
Changes
3. Pollutant Emission Reduction
Questions?
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