And Greenhouse Gases

CO2

CH4

N2OOrganic Waste Management

Compost Pile1 ton Carbon => 3.6 Tons CO2

Carbon-rich organics

Soil-enriching compost

Incineration

CO2

H2O

CO

C

N2O

Anaerobic Decomposition

Carbon/Water to CO2Carbon/Water to CH4

Sequestered Carbon

Palo Alto Composting & CO2

• 21,000 tons/yr (60% water)• 8,400 tons dry, 50% Carbon

• Methane production is negligible • 15,120 tons of CO2

• Biogenic CO2, not counted in “footprint”

• Transportation Concerns: – 1,100 tons additional if trucked to Sunnyvale

then Gilroy– Anthropogenic, counted in “footprint”– Traffic impact; Roadway maintenance

• Carbon Credit prices vary, but center around $20 / metric ton

• Added to costs of trucks, fuel, drivers, & acceptance fees.

What’s 1,100 Tons Worth?

$22,000 / year

1,100 tons = + 0.15%

Landfilled Compostables

tons

tons

tons

Compostables are 29% of Palo Alto’s “black bin” waste.

22,737 Tons of

Modern Landfill Design

Palo Alto Food and Green Waste in Landfill

– 15,934 tons wet (60% water) – 2,692 tons of Carbon (40% of dry is carbon) – 1,346 tons Carbon released in 1st year

• 50% into CO2: 2,424 tons CO2

• 50% into CH4: 50,880 tons CO2 Equivalent

– 1,346 tons Carbon remaining

Palo Alto Landfilled Compostables, after Cap

• 1,346 tons Carbon from food/green waste carryforward• 2,457 tons Carbon from other compostables (based on 45%

carbon in dry weight)

• Total: 3,803 tons carbon• 70% decomposes (2662 tons carbon)

– 85% captured and combusted to CO2

• 8,146 tons of CO2

– 15% escapes capture• 719 tons CO2

• 15,099 tons CO2 Equivalent (methane)

Total GHG Emissions from Landfilled Compostables

• For one year’s waste: – 79,262 tons CO2 Equivalent !

• If diverted and composted:– 18,534 tons CO2

• Full diversion would reduce PA Carbon Footprint by 60,728 tons of CO2e! – 2.7 tons CO2e per ton food/yard waste

• (carbon credit value $54)

Single Family vs MF/C

• Greenwaste Palo Alto Target:– 9000 tons– (comm/mf)– $70/ton +/-

• 13,700 tons still going to landfill– 37,000 tons CO2e

Organics GHG Reduction

• Part of the Zero Waste Plan

• Execution of plan is what matters

• What we do matters more than where

• Attention, Measurement, Reporting, Evaluation, & Improvement

Organics GHG Reduction

#1

Move Aggressively on MF/Commercial Food Waste Collection! (& 3500 tons of leaves & grass)

(‘000s tons CO2e reduction)

Organics GHG Reduction

#2

Implement Residential Food Waste Collection!

(‘000s tons CO2e reduction)

C

Organics GHG Reduction

#3Transform to BioChar/Bioenergy!

• All green bin contents = minus 7,000 tons CO2e

• 50% blackbin compostables = - 4500 tons CO2e

• Wastewater sludge = - 6,000 tons CO2e

CO2

CO2

Organics Management

PassiveCriteria:• lowest cost disposal

• diversion mandates

ActiveCriteria:• Resource recovery• GHG minimization• Long-term cost

?

Organics Management Passive Active

Palo AltoOperation

Multi-cityPartnership

Contracted

Location &Technology

Organics Management

Control

Economiesof Scale

City-Owned

Multi-City

Contracted

Multi-tech Organics Approach

Composting

Digestion

Soils Restoration

Sequestration

Green Energy

Green Bins

Wastewater

Black BinsPyrolysis

Location Possibilities

• Expansion of WWTF• Industrial sites in

Palo Alto• Industrial sites

elsewhere• Energy/GHG

Efficiency tradeoff: – Large scale

operations vs – Local operations

GHGs in Perspective

• Compost just a small piece of the opportunity

• What more important than where.

• Audit, execute, and improve.

• Regional partnership (we are not alone)