Community Water SupplyEfficiency Improvements

Potential Savings for the 6th Power Plan

September 30th, 2008Regional Technical Forum

Water Supply Overview• Processes

– Collection– Treatment– Distribution

• Energy Consumption: – Pumping 80%– Treatment 20%– New regulations for treatment may

change the mix slightly» Ozonation» Membrane Filtration» UV Disinfection

• Source Type– Surface Water

» More treatment energy» Less pumping energy

– Ground Water» Less treatment energy» More pumping energy

Community Fresh Water in the PNW• USGS: 80% of PNW Population served by Community Water Systems

• 56% is Surface Water*

• 43% is Ground Water*

• EPA: 4,570 community water systems in the 4 PNW states.• 240 plants serve 80% of population served by CWS’s

* By volume

An In-Depth Look at the Largest Supplier: Seattle Public Utilities

• Serves a retail population of nearly 650,000 (6% of PNW population)• Also wholesales water to water utilities serving a population of over

700,000 (6%)

• The next four slides are from Seattle Public Utilities…

Energy Savings Measures• VFD’s and low head loss valves• Distribution system pressure optimization (strategic use of booster

pumps)• Fix leaks in distribution system• Optimize filtration (pre-treat before filtering)• Pump efficiency optimization• Premium efficiency motors• Low pressure UV lamps versus med. pressure• High efficiency single stage blowers• Compressed air efficiency measures• Use of low friction linings or coatings in piping• Lighting

5th Plan

• Total Energy Use:– 117 aMW

• Technical Potential:– 29 aMW

• Economic Potential:– 25 aMW– 1.3 cents/kWh

• Assumptions:• 20% savings• Costs same as wastewater• O&M/NEB’s same as

wastewater

6th Plan (proposed): Energy Consumption

Data• Assuming:

• Groundwater = 1800 kWh/MG

• Surface Water = 1400 kWh/MG

• PNW Energy Use (2008)Groundwater: 72 aMWSurface Water: 73 aMW Total = 145 aMW

Water Source kWh/MGGroundwater 1,810Surface water (large plant) 1,404Surface water (small plant) 1,470

Water Source kWh/MGGroundwater 1,800Surface water 1,400

435 kWh/MG

EPRI (1996)

Seattle Public Utilities (2008)

Energy Center of Wisconsin (2003)

Data: Energy Use and Flow for each plant in WI

Data: Plant-Specific Energy Use and Flow

Data: Engineering Estimates?

6th Plan Assumptions (proposed)

• Achievements Since 5th Plan– ETO

• 20 Projects• Savings = 0.8 aMW (at $6.7million)• Savings cost $0.92/kWh

• Energy use tracks with population increase• Energy savings = 15%– Very limited data: BacGen (2003) 7% to 23%

• Technical Potential: 27aMW• Cost: $0.92/kWh?• Measure Life: 10 years?

Data Needs

• Plant Energy Use• Measure Savings– Energy Savings– Non-Energy Benefits

• Measure Cost• O&M Costs