Power Generation from Dairy Manure and Other Wastes:

Role of the Municipal UtilityRuth MacDougall - SMUD

916-732-6625 rmacdou@smud.org

Sacramento Municipal Utility District (SMUD)

Renewable Energy from Biomass

SMUD’s Renewable Portfolio Standard (RPS) to acquire 10% our electricity from renewable sources by 2006 and 20% by 2011 In 2006, about 20% of SMUD’s renewable energy is expected to come from Biomass

Biomass20%

Wind40%

Solar1%

Small Hydro15%

Geothermal24%

Leader in Renewable Energy

Renowned Solar Energy Program– 10 MW of Photovoltaic (PV)– 50% utility scale and 50% distributed energy– Over 900 PV systems connected at customer sites

Distributed Energy at 3 Cogeneration Sites• Campell Soup • Proctor & Gamble • Carson Energy – uses biogas from Wastewater Treatment

RFO to Acquire Conventional & Emerging Renewables– 15 ‘Conventional’ Biomass proposals– 4 ‘Emerging’ Biomass proposals

Developing Local Biomass

Benefits of Local Biomass Projects– Relatively low cost energy 5 to 9 cents/kwh– Reduce air emissions– Reduce groundwater contamination – Mature technologies– Sustainable fuel supply– Serve other waste disposal purposes

Biomass Fuels Inventory

Identify unexploited waste residues or resources– Search state or federal government databases and survey waste

generators themselves– Waste type and quantities– Existing waste disposal methods– Cost of collection, transport, tip fees– Interest in alternative disposal or energy generation

Technology Assessments & Economic Assessments– Consultants such as UC Davis and RIS International, Inc.– Determine viable technologies and sustainable economic

conditions

Inventory Results Thus Far*

Preliminary Results - Sacramento County Existing plus Technical Potential

FeedstockWet Tons per year

Conversion Technology

Average Power Production

(MW)

Potential Electric

Generation (MWh), η=30%

Conversion rate technical source

Green Waste 260,000 AD 5.7 50,293 OWS-DrancoFood Waste 416,000 AD 12.9 113,261 OWS-DrancoDairy Manure (VS) 37,321 AD 0.85 7,453 Sacramento projectsWastewater Treatment 312,500 AD 5.8 50,352 Regional WWTPsMSW OF-diverted 562,600 AD 12.8 112,520 OWS-DrancoLandfill Gas zero new Waste-in-Place 11.7 92,243 Existing & PlannedTOTAL 50 426,122

*Potential from urban and agricultural wood waste not yet determined; *Potential from additional conversion technologies not yet determined

Research, Development & Demonstration

Research and Development Activities – Needed to resolve technology challenges, such as

engine emissions, techniques for managing waste

– SMUD manages several biomass R&D projects under a CEC Public Interest Energy Research (PIER) contract

– Developing proposals under R&D solicitations from USDA, DOE, EPA, CEC, CARB, CIWMB

CEC Funded R&D Projects

Yolo County Accelerated Anaerobic Bioreactor Landfill

Full-scale landfill bioreactor demonstrates accelerated anaerobic digestion from injection of water into the landfillExtensive monitoring

of the landfill mass and biogas generation

Accelerated Biogas Generation

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Anaerobic Bioreactor Landfill

Conventional Landfill

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Demonstration Programs and Policies

Goals of Demonstrations:– Increases familiarity with technology– Stimulates investment by private sector

SMUD Demonstrations and Policy:– Incentives help overcome economic challenges – Biomass Rate for facilities <1 MW– Pilot Dairy Digester Incentive Program

Pilot Dairy Digester Program

– USDA Rural Development provides 25% funding for Renewable Energy projects

– Sacramento has 43 dairies - SMUD offered 13% funding to match USDA 25%

– Five dairies submitted proposals and 3 were awarded • Elk Grove • Galt #1• Galt #2

– Completion of digesters is expected in late 2005

Sacramento County Dairies

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Total Cows in Top 15out of 43 Dairies

– 1435A – 1075

– 1020B – 953

– 837C – 745D – 728E – 693F – 589G – 563H – 520I – 468J – 468K – 451L – 399

Manure Management Methods

Each cow produces 120 pounds of manure a day!Manure is managed by a scrape method or flush methodDigester type depends on manure management method and percent solids

Scrape Manure Management

Plug Flow Digester: 11-14% solids

Flush Manure Management

Flush Manure Management

Covered Lagoon Digester: 1.5% solids

Covered Lagoon Digester by RCM Digesters Castelanelli Dairy in Lodi

Complete Mix Digester: 3-11% solids

Electricity Generation Equipment

Genset at Castelanelli Dairy in Lodi

Dairy Manure Energy Potential

Location of Dairy Type of Digester

Biogas Production

(ft3/Day)kW *MWhr /

Year

Elk Grove (w/o food waste) Ambient Covered Lagoon 55,898 113 891

Elk Grove (w/ food waste)

Heated, Complete Mix, Covered Lagoon 115,343 186 1,466

Galt #1 Ambient Covered Lagoon 37,076 77 607Galt #2 Ambient Covered Lagoon 44,070 92 725

*Total MW-hr potential from 3 dairies is 2,800 MW-Hrs (w/food waste) from a total of 355 KW capacity

Cost and Payback Analysis

Type of Digester Capital Cost ($)

Cost per Animal Unit ($)

Cost per kW

($)

Estimated Levelized Cost per kWh ($)

Estimated Payback w/o

Incentives (Yrs)

Total Cost to Dairy After Incentives

($)

Estimated Payback with

Incentives (Yrs)

Ambient Covered Lagoon 793,129 421 7,019 0.087 8.8 396,565 4.4

Heated, Complete Mix, Covered Lagoon 820,724 436 4,412 0.055 4.1 410,362 2.5

Ambient Covered Lagoon 607,392 425 7,888 0.098 13.8 380,272 8.6Ambient Covered Lagoon 450,866 334 4,901 0.061 7.9 290,422 4.9

* All livestock, including milk cows, dry cows, heifers, and calves, are normalized to 1000 pound animal units

Environmental Benefits – Reduction of VOCs and Greenhouse Gases

Location of Dairy

Number of Animals

*Total VOC Reduction (Lbs/Year)

**Methane Reduction

(Tons/Year)

CO2 Equivalent (Ton/Year)

Elk Grove 1,435 8,565 534 11,738

Galt #1 1,100 6,426 172 3,776

Galt #2 1,020 6,075 204 4,489

TOTAL 3,555 21,066 910 20,003

**Assuming the biogas produced contains 60% methane

*Based on SMAQMD Title V Emissions estimate; VOC reduction from the dairy planning addition of food waste, is based on manure only.

Future Dairy Digester Program

– SMUD plans to continue dairy digester program– Estimated potential of all 15 largest dairies:

• 850 KW • 7,500 MW-hrs

– Research and development planned / proposed: • Side by side test of low NOx Deutz engine• Community digester feasibility study • Modeling co-digestion of commercial food waste

Research and Development

Side by side test of low NOx Deutz engine– Test Deutz low NOx

engine side by side with Caterpillar engine

– Perform emission testing on start up and after six months of operation

Research and Development

Feasibility of community digester concepts – Compare costs of central

digester and central gensetcollecting manure vs. biogas

– Develop business model for sharing cost of O&M and compensating each dairy for their contribution

– Compare emissions of one large clean genset vs. a number of small gensets

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Research and Development

Modeling co-digestion of food waste proposed– UC Davis and RCM

Digesters will develop a predictive model for co-digestion of manure and food waste

– Project will develop infrastructure with partners, dairy, waste hauler, and City of Sacramento

Green Waste to Energy Potential

– City has 1 million trees which result in 35% of residential waste stream as garden refuse

– Second highest number of trees per capita in the world, second only to Paris, France

City of Sacramento is called the City of Trees

Availability of Green Waste Feedstock

– Sacramento Waste Authority (SWA) collects 200,000 tons/year of Green Waste

• Sacramento County• City of Sacramento • City of Citrus Heights

– SWA is searching for Composting Site for 100,000 tons/year for development in 2008

• Reduce transportation costs and emissions from 80 mile trip • Gain local control and jobs

Anaerobic Digestion of Green Waste

AD is a Viable Alternative– Will be easier to site:

• Little or no odor • Smaller space requirement

– Produces renewable energy supplanting fossil fuels• Electricity generated on site, or• Biogas can be piped to a SMUD cogeneration plant

– Reduces ammonia and volatile organic compounds (VOCs) normally released from aerobic composting

Environmental Benefits of AD

Reduction of Ammonia and VOC emissionsSacramento Emissions Forecast Comparison

(260,000 [tons GW/year]

NH3 Rate [lbs/ton GW]

VOC Rate [lbs/ton GW]

NH3 [tons/year]

VOC [tons/year]

Aerobic Composting* 0.85 3.84 111 500

Anaerobic Digestion 0 0 0 0

* rates taken from SCAQMD Assessment for PR1133

AD Economic Feasibility Study

Performed by RIS International, Inc., andMacViro Consulting– Collected and evaluated data about viability

of mature AD technologies– Identified capital and operating costs– Identified potential amount of green power

AD Technology Examples

APS - Onsite PowerValorga

OWS - Dranco

How Mature is Anaerobic Digestion?

Experience with AD technology– Well established in wastewater treatment plants and

food processing operations – Applications in municipal solid waste have doubled

in last 10 years, some experienced with green wasteCurrent status– 74 full scale AD facilities elsewhere, none in U.S.– 17 have capacities of over 50,000 ton/year – 57 have less than 50,000 ton/year capacity– 33 more plants are planned or under construction

Different AD Technology Types

Green Waste Feasibility Study Results

Can produce 6 MW or 50,000 MW-hrs/year, but with higher tip fees than aerobic composting Opportunities to reduce costs should be explored:– Co-location with other facility, e.g. MRF or landfill,

allows dual use of personnel and equipment– Co-digestion of food waste helps economics and biogas

production– Increase tip fee for green waste by reducing other solid

waste collection costs – Obtaining capital grants from government agencies can

reduce tip fees to existing levels

SMUD’s Biomass Strategy - Summary

Build on success of SMUD’s Renewable Energy Program when developing Biomass ProgramFirst projects in Anaerobic Digestion are designed for early success by using non-controversial, mature technology, already eligible for diversion creditsPlan to incorporate other conversion technologies in the future to acquire sustainable and renewable energy from biomass while providing our customers with local benefits