Numbers, Numbers, Numbers

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1 Numbers, Numbers, Numbers Standard Conversion Formulae 1 mt (metric ton)= 1,000 kg = 2,200 lbs 1 ft 3 = m 3 1 Therm = 100 ft 3 = m 3 1 W (watt) = 1 J/s (joule per second) 1 kw = 1000 W = 1000 J/s 1 MW = 1000 kw = 1,000,000 J/s 1 kwh (kilowatt hour) = 1 kw x 3600 s = 3.6 MJ = 3414 BTU 1 MWh = 1000 kwh 1 GWh = 1000 MWh = 1,000,000 kwh Consumption The average California home consumes about 580 kwhr per month (EIA, 2007), or about 6960 kwhr per year. Approximately 27,700 households in Palo Alto (source: ABAG Projections 2005 with US Census 2000 Baseline) Palo Alto City, residents and businesses consume about 1 GWh electricity per year (source: Utilities Department) Palo Alto City, residents and businesses consume about million cubic meters of natural gas per year (source: utilities department) Palo Alto weighted average cost of natural gas = $7.74 (2011 forward price 1 ) Methane CH 4 Specific volume (1.013 bar and 21 C (70 F)): 1.48 m 3 /kg (0.676 kg/m 3) Methane Energy Content o 1 ft 3 CH 4 = 1000 BTU = MJ (mega joule) = kwhr at 100% efficiency o 1 m 3 CH 4 = 35,315 BTU = MJ = 9.8 kwhr at 100% efficiency o 1 MMBTU = 1 million BTU = 1000 ft 3 CH 4 = m 3 CH 4 Biogas Methane Content: 55 65%. 2 Fun fact: 3.74 m 3 CH 4 = energy content of 1 US gal. gasoline Combustion of 1 m 3 CH 4 releases 1 m 3 CO 2 = 1.85 kg CO 2 = mt CO 2 Methane Production from Anaerobic Digestion EBMUD 2008: o Food Waste: m 3 CH 4 per metric ton o Wastewater sludge: m 3 CH 4 per metric ton (80 avg) Kelleher 2007: o Municipal Organic Wastes: m 3 CH 4 per metric ton ( m 3 biogas) Ostrem 2004: 1 Source: Palo Alto Utilities Advisory Commission 2 Kelleher, BioCycle V. 48, No. 8, p.51; also EBMUD March 2008; also Ostrem, 2004 Greening Waste: Anaerobic Digestion for Treating the Organic Fraction of Municipal Solid Wastes.

2 o Municipal Organic Wastes: m 3 CH 4 per metric ton ( m 3 biogas) KompoGas o Municipal Organic Wastes: 83 m 3 CH 4 per metric ton Conservative estimate: 80 m 3 CH 4 per metric ton food & green waste Electric Generation from Methane Production: 75 m 3 CH 4 per metric ton municipal organic waste Energy Content: 1 m 3 CH 4 = 35,315 BTU = MJ Generator Efficiency (electricity only) o KompoGas: 30% o Opra (generator manufacturer): 26% o Ostrem: 38% o Working estimate: 30% Electricity Production o Ostrem: 3.73 kwh/m 3 CH 4 o KompoGas: 2.94 kwh/m 3 CH 4 o Opra: 2.55 kwh/m 3 CH 4 o Working estimate: 3.0 kwh/m 3 CH 4 Percent Electricity used by system: o Ostrem: 26% o KompoGas: 27% o Working estimate: 30% Cogeneration Heat: Ostrem: o 3.36 kwh(th)/m 3 CH 4 = 11,471 BTU/m 3 CH 4 o Export heat: 2.18 kwh/m 3 CH 4 = 7,442 BTU/m 3 CH 4 KompoGas: o 3.48 kwh(th)/m 3 CH 4 = 11,870 BTU/m 3 CH 4 o Export heat: 2.26 kwh/m 3 CH 4 = 7,722 BTU/m 3 CH 4 Working Estimate o 3.4 kwh(th)m 3 CH 4 = 11,600 BTU/m 3 CH 4 o Or, 1.13 kwh(thermal) for every 1 kwh(electricity) o Export heat: 2.21 kwh/m 3 CH 4 = 7,540 BTU/m 3 CH 4 o Export heat: 0.73 kwh heat for every 1 kwh electricity generated Compost: KompoGas: o 0.36 mt mature compost per 1.0 mt MSW compostables Working Estimate o 0.35 mt mature compost per 1.0 mt MSW compostables Palo Alto Waste to Energy Sewage: Sludge: 24,000 mt annually

3 Methane: (80 m 3 CH 4 / mt) x (24,000 mt) = 1,920,000 m 3 CH 4 annually Electricity: (3.0 kwh/m 3 CH 4 ) x (1,920,000 m 3 CH 4 ) = 5,760,000 kwh Electricity used by system (30%)= 1,728,000 kwh Saleable electricity = 4,032,000 kwh = enough for 521 CA homes after 10% transmission loss Heat: 6,528,000 kwh (thermal) Heat used by system (35%): 2,284,800 kwh(t) Heat exported: 4,243,200 kwh (t) Incineration avoidance: o 2,830,000 m 3 CH 4 = 99,929 MMBTUs o At $7.74 MMBTU market rate, worth $773,450 Compost quantity: unknown. Compost value: low but positive Yard clippings, food, and other compostable organics (current collections) Yard clippings (green bins + self haul): 21,000 mt Food and other compostables: 9000 mt Methane: (30,000 mt) x (80 m 3 CH 4 /mt) = 2,400,000 m 3 CH 4 annually Electricity: (3.0 kwh/m 3 CH 4 ) x (2,400,000 m 3 CH 4 ) = 7,200,000 kwh Electricity used by system = 2,160,000 kwh Saleable electricity = 5,040,000 kwh = enough for 651 CA homes after 10% transmission loss Heat: 8,136,000 kwh (thermal) Heat used by system: 2,847,600 kwh(t) Heat exported: 5,288,400 kwh(t) Compost: 0.35 x 30,000 mt = 10,500 mt annually Single Family Residential Food, and other compostable organics Food and other compostables, 50% collection rate: 2910 mt Methane: (2910 mt) x (80 m 3 CH 4 /mt) = 232,800 m 3 CH 4 annually Electricity: (3.0 kwh/m 3 CH 4 ) x (232,800 m 3 CH 4 ) = 698,450 kwh Saleable surplus electricity = 489,000 kwh Compost: 0.35 x 2910 mt = 1,018 mt annually Sewage and Compostables Combined, excluding single family residences: Natural Gas consumption avoided by eliminating incineration: o 2,830,000 m 3 CH 4 = 99,929 MMBTUs o At $7.74 MMBTU market rate, worth $773,450 o 3% of Palo Alto natural gas consumption Natural Gas production: o 4,320,000 m 3 CH 4 annually o Approximately 35% required to run system o Remainder is 2,808,000 m 3 CH 4 annually o Energy content equivalent to 750,800 gallons of gasoline o 2,808,000 m 3 = 99,153 MMBTU o At $7.74 per MMBTU, worth $767,444 o 3% of total Palo Alto natural gas consumption Or, convert surplus natural gas to green electricity = 9,072,000 kwh o 1% of total Palo Alto electricity consumption o enough for 1,173 CA homes after 10% transmission loss

4 o at $0.11 per kwh, worth $997,920 Heat exported: 9,531,400 kwh(t) useful for o Other RWQCP processes o Nearby commercial buildings o Demonstration greenhouses?? Compost: o 10,500 mt high $27/mT = $283,500 per year 3 o 4,800 (est) for non food crop use. Value unknown. Ash disposal cost avoided: $234,000 (source???) Single Family Residence Collections Additional Revenues Surplus sold as green natural gas: approx. $63,000 Surplus sold as green electricity: approx. $82,000 Greenhouse Gas Numbers Total Community + City Emissions, per CPP: 793,621 mt CO 2 E Landfilled Annual Waste Related Emissions, per CPP: 24,823 mt CO 2 E California Electrical Generation: mt CO 2 per MWh Coal Electrical Generation: 0.8 mt CO 2 per MWh Wastewater Sludge Incineration Avoidance CO2 equivalents reported for the Incinerator for 2007: o From burning Natural Gas 2,712 mt/year CO 2 E = 1.47 Mm 3 CH 4 (calculated) o From burning Landfill Gas 2,522 mt/year CO 2 E = 1.36 Mm 3 CH 4 (calculated) Could be used elsewhere to offset consumption o Total avoidable: 5234 mt/year CO 2 E Anaerobic Digestion CO2 Offsets (current collections) Green natural gas production from anaerobic digestion o Surplus 2,808,000 m 3 CH 4 annually 5195 mt CO 2 E credit if sold as green natural gas o Or, 9,072,000 kwh of green electricity 2,495 mt CO 2 E credit (offsetting average mix) 7258 mt CO 2 E credit (offsetting coal) Anaerobic Digestion CO2 Offsets (Residential foodwaste program) Green natural gas production from anaerobic digestion o Surplus 232,800 m 3 CH 4 annually 428 mt CO 2 E credit if sold as green natural gas o Or, 489,000 kwh of green electricity 134 mt CO 2 E credit (offsetting average mix) 391 mt CO 2 E credit (offsetting coal) Avoided methane release from landfill o 2914 CO 2 E credit 3 Based on $27.30 per mt finished compost price from Palo Alto composting operations in 2007 (Compost Feasibility Report).

5 GHG Emission Reductions Summary: Avoiding Incineration: 5234 CO 2 E credit AAD current collections: CO 2 E credit AAD Residential Foodwaste CO 2 E credit TOTAL 10,777 13,771 CO 2 E credit 1.5% reduction of City Emissions from CPP baseline. For Reference: Existing Commercial Food Waste Program: 9,013 mt CO 2 E reduction, based on avoided methane release Approximately 1000 mt CO 2 E reduction for each additional ton collected. From a GHG perspective, one of the most important things we can do is to get wet organic materials out of the landfill. Moisture-rich organic materials, particularly food scraps, leaves and grass clippings, quickly begin to decompose in the landfill and generate methane. Within 120 days, food waste and grass clippings may be nearly fully decomposed, with substantial methane generation. 4 Thus the majority of methane release from wet organics occurs long before any methane recovery systems are put in place at the landfill (usually 2-5 years after disposal). The EPA s WARM model can be run on just the food waste, grass and leaves portion of our landfill waste stream under the assumption of no methane recovery to get a conservative 5 estimate of 9,013 mt of CO2e that would be avoided if we could divert the target 9000 tons of commercial and multifamily compostable organics. If we could achieve a 50% diversion of all the residential and commercial compostables, we would avoid 11,427 mt of CO2e. 4 Eleazer, W.E., W.S. Odle, Y. Wang, and M.A. Barlaz Biodegradability of municipal solid waste components in laboratory scale landfills. Environ. Sci. Technol. 31: Brown, et al, J. Environ. Qual. 37: Landfill operations, design, climate, and waste composition will affect the timing and degree of wet organics decomposition, but specific data for the Kirby Canyon landfill was not available for this analysis. In the absence of actual site specific data, it is best not to make any optimistic assumptions. 5 For this estimate, the WARM model was run only on the food scraps and green plant material in our landfill waste stream. Other materials such as paper and cardboard also generate methane over a long period of time, but this was excluded under the assumption that much of the decay would occur after methane recovery was put in place.