UC Davis Biogas Energy Project

Ruihong Zhang, Professor Biological and Agricultural Engineering

University of California, Davis Email: rhzhang@ucdavis.edu

AWWEE Workshop: Major Drivers to Transformation in California Energy and Water Markets

May 22, 2012, Sacramento

Presentation Outline

• Status of anaerobic digestion technologies and opportunities for further development

• UC Davis Biogas Energy Project for new technology development, demonstration and commercialization

Value Positioning of Biogas Energy Systems

Biogas

Sugars, Amino acids, Fatty acids

CH4, CO2

Anaerobic Digester

H2 , CO2

Organic acids

Biogas Energy Electricity and heat Natural gas Compressed natural gas Liquefied natural gas GasolineChemicals

DigesterEffluent NutrientsFibers Water

Organic Waste Food Collected Green Agricultural

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$$$ Carbon Credit

Wastewater Digestion Technologies

• Current status– Well established for treatment of sewage, animal manure

(swine and dairy), and some food processing wastewater– Common technologies: covered lagoon, completed mixed

digester, plug flow digester, upflow sludge blanket reactor (UASB)

• Opportunities for new technology development – Creative digester design and integration of unit operations to

provide higher energy efficiencies and more capabilities to handle variable influent

– Co-digestion of different wastes (e.g. food waste with sewage or manure)

Solid Waste Digestion Technologies• Current status – Europe has several technologies in commercial use

for more established markets.– US has the first commercial technologies for

emerging markets

• Opportunities – Digester technology implementation and

integration of digestion with waste preprocessing and composting operations

– US project and business models

Organic Resource Recovery with Advanced Anaerobic Digestion

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Solid Organic Residuals: Food Processing and Agricultural Residues, Animal Manures,

Municipal Solid Waste,

A Real Problem with Solid Waste

• Millions of tons of organic waste dumped in landfills every year result in harmful greenhouse gas (GHG) emissions

• Mandates require businesses producing high volumes of organic waste to seek more sustainable waste disposal solutions

• Businesses have committed to sustainability and are now scrambling to follow through– Wal-Mart: Zero waste by 2014; all suppliers must report

waste and greenhouse gases http://walmartstores.com/sustainability/9292.aspx

– Campbell: new sustainability policy http://www.campbellsoupcompany.com/csr/planet.asp

• Anaerobic digestion (AD) of organic solid waste has not been successfully implemented in the US to date in commercial scale

Food Scraps in the US (EPA)

• Amount of food scraps– 44 million tons per year– 25% food prepared

• Cost of disposal– $1 billion per year– $20 per ton

• Current method of management – 97% disposed in landfill– 3% recovered for composting

or combustion

Needs For Efficient Solid Waste Digester Technologies

• Capable of handling multiple and variable biomass feedstock from different supply sources

• Can be easily scaled up and down • Easy to operate and maintain (automation)• High conversion efficiencies and smaller foot

prints • Affordable cost

Biogas Energy Project at UC Davis

• Research and demonstration of new anaerobic digestion and biogas energy technologies for converting various organic residuals into biogas energy and biobased products

• Public education on waste to energy conversion and environmental management

UC Davis Biogas Project Sponsors

UC Davis Technology Anaerobic Phased Solids (APS) Digester

• Two-stage digestion system that has first stage sequential batch loaded digester and continuous second stage digesters

• Allows for high system stability regardless of fluctuations in loading and waste composition

• Provides even gas production and rapid waste digestion • Mesophilic and thermophilic temperature options• Can be configured for sustained hydrogen and methane

production• Well suited for treating high-solids (10 - 50% total solids)

lignocellulosic waste streams, such as:– Municipal solid wastes– Green and food wastes– Agricultural residues

Hydrolysis Reactors Converting Solids into Organic Acids and Producing

Hydrogen Gas

Day 10-12

Biogasification Reactor Digesting Organic Acids and

Producing Methane Gas Separated Water Returned to Tank; Excess Discharged for Treatment & Recycling

Separated SolidsPost treatment for Soil Amendment

Residual Material & WaterDrained & Separated

APS Digester Technology

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Biogas

• Three stage anaerobic digestion • Well suited for treating highly degradable

solids waste streams and mixed solid/liquid waste streams, such as:– Municipal food waste– Food processing waste– Biosolids– Meat product waste

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UC Davis Technology High Rate Digester (HRD)

HRD: High Rate Digester

Liquid Feed

Solids Feed

Grinder

Hydrolysis Reactor (HR)

Wet Grind

BiogasificationReactor (BGR)

Solids

Separator

Water Recycle

BiostabilizationReactor (BSR)

BiogasOut

Liquid Effluent

CONTROLS ANDDATA ACQUISITION

PROPRIETARY MIXING, CONTROL & MEDIA

PRESSURE, TEMPERATURE, MASS FLOW, pH, LEVEL, OTHER INPUTS

INPUTS OUTPUTSVALVES, PUMP BOILERMIX, PUMP OVER, TRANSFER PERF., PERFORMANCE & DATA TREND

APS Digester Demonstration System

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UC Davis Biogas Project

Digester capacity – 3-5 tons per day,

Digestion temperature – 125-135 F , Digester volume – 50,000 gal

Expected biogas yield –350-583 m3/day,

Electricity output – 600- 1200 kWh/day

Food Processing Residuals from Campbell Soup Plant in Sacramento

Food Waste (Average): Moisture – 80%Total Solids – 20%Volatile Solids – 19%

APS-Digester Performance

• Digester testing with 200 tons of food processing residuals from June 2008 to April, 2009

• Digester Performance Summary:– Solids reduction in food waste:

89.5% for total solids, 90% for volatile solids – Biogas production: average 4,600 ft3/ton (wet) – Methane production: average 2760 ft3/ton (wet) (7 ft3/lb VS) – Energy content in biogas: 27 therm/ton (wet)– Biogas composition: 55-60% methane, 2-5% hydrogen– Digester pH: 5-7 for hydrolysis reactor and 7-8 for biogasification

reactor.

Clean World Partners Commercial Projects

• American River Packaging – 8-10 ton per day mixed organics (papers and food waste)

• City of Sacramento – 25 ton per day organic waste with a potential to expand to 300 ton per day capacity

• UC Davis Renewal Energy Anaerobic Digestion Project - 22-35 ton per day mixed campus waste (animal manure, food scraps, papers, yard waste, etc.)

Clean World Partners Built the First Commercial Digesters for Food and Paper Waste at American River

Packaging, Sacramento

www.cleanworldpartners.com

Clean World Partners Projects American River Packaging (ARP): Packaging manufacturer with corrugated waste• 8 tons per day (0.5 cardboard and 7.5 tons food

waste)• System size 10 tpd (accounting for paper

absorption)• Producing 1300 kWh per day of electricity with

micro-turbines for use on site• Food waste coming from local food processors• System continuously operating since March 16,

2012slide

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ARP Organic Waste Recycling Center

Clean World Partners Current Projects

UC Davis: Moving towards zero waste and showcasing conversion of closed landfill into valuable resource• Phase I - 25 tons per day manures from campus and

food waste from campus dining facilities• Phase II – 35 to 50 tpd separated organics from MSW• Allow other surrounding communities to use digester

system• Combining landfill collection and digester gas streams• Producing electricity to feed its net zero community• Sophisticated preprocessing system• Opening December 2012

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UC Davis CWP Project

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Successful Technology Development and Commercialization

• Research innovation and technology development

• Public and private investment and partnership• Competent and effective technical,

management, and business development • Favorable market environment