Evaluation of a Continuously-Mixed Farm-Based Anaerobic Co-Digestion System

CCurt urt GGooch, P.E.ooch, P.E.andand

Rodrigo Labatut, Ph.D.Rodrigo Labatut, Ph.D.Cornell UniversityCornell University

www.manuremanagement.cornell.eduwww.manuremanagement.cornell.edu

2015 Waste to Worth Conference

Two-year Continuously-Mixed Farm-Based Anaerobic Co-digestion System

Monitoring – Final Project Results

Presentation Overview

1. Background/overview

2. Main results

3. Some detailed results

4. Conclude

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AK- 1.3U.S. Dairy Farm Demographics

Thousands of Cows per State

On-Farm Anaerobic Digestion in New York State

Operating (22)

Under Construction (0)

Planning/Design (5)

Decommissioned (4)

Dairy Cows Supplying Anaerobic Digesters and AssociatedIn-place Generation Capacity (kW) in New York State by Year

Synergy Digester – Located in Wyoming County, New York

Project Funding

Wyoming County Industrial Development Corporation

and

Cornell PRO-DAIRY Program

EPA / ASERTTI ProtocolKey Prerequisites

1. Evaluation for at least 12 months

2. Conducted after start-up is completed (continuous operation for at least 5 HRTs)

3. Monthly influent/effluent & biogas sampling

EPA / ASERTTI Protocol General Requirements

1. Process Performance Characterization

2. Biogas Production and Utilization

3. Economic Analysis

AA DairyRidgeline

Dairy

New Hope View Dairy

Noblehurst Farm

Patterson Farm

Emerling Farm

Sunny Knoll Farm

Other NYS Anaerobic Digesters Monitored to Date

Farber Farm

Synergy Farm MonitoringExecutive Summary

• Synergy Co-digestion system constructed 2011

• System monitored from June 2012 to May 2014

• Avg. daily AD loading rate = 80,408+/-19,266 gal manure from avg 1,891+/-62 lactating Holstein cows imported organics was 25+/-6% on a volume basis


• Avg hydraulic retention time (HRT) was 29+/-7 days

• Avg organic matter reduction = 42%

• Avg and VFA reduction = 75%

• Avg biogas production = 495+/-78 ft3/day per 1,000 wet lbs. of influent added (173+/-34 ft3/cow-day)


• 1.4 MW IC engine-generator set produced on average 23+/-7 MWh of electricity per day

• AD system’s average daily parasitic electric load was 3+/-1 MWh (14% of energy generated)

• Capacity factor was 0.66 over monitoring period

• On-line efficiency was 80% over monitoring period


• Thermal to electrical conversion efficiency was 42%

• 13% of the total biogas energy was recovered as hot water from the engine-generator set

• Average monthly income from energy and renewable energy credit sales was $56,710

Project Report Available on: www.manuremanagment.cornell.edu

Tests and Test Methods Used:Solids, VA, and COD

• Total Solids EPA 160.3

• Total Volatile Solids EPA 160.4

• Volatile Acids SM18 5560C

• COD SM18 5220B

Tests and Test Methods Used:Nutrients (food waste only)

• TKN EPA 351.4

• Ammonia-N SM18 4500F

• Organic-N Subtraction• Total Phosphorus EPA 365.3

• Ortho Phosphorus EPA 365.3

• Potassium EPA SW 6010

EPA / ASERTTI ProtocolProcess Performance Characterization

1. Degree of waste stabilization: ∆TS, ∆TVS, ∆COD, and ∆TVA by anaerobic digestion (not by settling).

Influent Effluent Percent Change in Constituent Concentration

% Change = [influent] – [effluent] x 100[influent]

Constituent % Change Due to Anaerobic Digestion

80% VFA influent reduction54% COD influent reduction

57% VS reduction of the influent organic matter



2. Ideally, ∆TKN, ∆ON, ∆NH3-N, ∆TP, and ∆S = 0




3. Recommend bench-scale trials to establish the readily biodegradable fraction of TVS




3. Recommend bench-scale trials to establish the readily biodegradable fraction of TVS

4. Recommend Pathogen Analysis

Influent/Effluent Percent Change:Solids and Pathogens

Source: Gooch and Inglis, 2006

EPA / ASERTTI ProtocolBiogas Production

1. Temperature and pressure compensated meters (0°C and 1 Atm)

2. Biogas meter calibration

3. Biogas water vapor adjustment


Source: Richards et al., 1991


Overall Project Average Biogas Moisture Content = 8.5% (v/v)

Biogas (ft3) Production per Lactating Cow

Overall, 173+/-34 ft3 of biogas per lactating cow-day was produced.

Moisture Corrected Biogas Methane and Carbon Dioxide Content

(Pre Scrubber)

Overall Methane and Carbon Dioxide Content was 60% and 37%


1. Temperature and pressure compensated meters (0°C and 1 Atm)

2. Biogas meter calibration

3. Composition: CO2, CH4 & H2S bi-weekly

4. CO2 , H2S, CH4, and NH3 quarterly

Biogas Scrubber Performance(Hydrogen Sulfide)

Overall, hydrogen sulfide was reduced from 1,209 to 488 ppm,resulting in an efficiency of 62+/-29%.

Total Biogas Thermal Energy (MMBtu) produced by Monitoring Period

Overall, avg. energy produced was 4,766+/-1,340 MMBtu per period.

EPA / ASERTTI ProtocolBiogas Utilization

1. Thermal (LHV) to electrical conversion

2. Eng.-gen. set operating hours

3. Capacity factor


(Thermal to electrical conversion by CHP)

Overall, avg. daily electrical energy produced was 23 MWh/day.

↓ Biogas ProductionCHP Unit Challenges

↓ Biogas Production Multiple Mech. Problems

Thermal to Electrical Conversion Efficiency and Volume of Biogas to Produce a Unit of Electrical Energy

From PD 10 to 24, avg. thermal conversion efficiency averaged 44%.

CHP Unit:Capacity Factor and Online Efficiency

Overall, the avg. capacity factor and online efficiencywere 0.66+/-0.22 and 80+/-23%, respectively.

CHP UnitCapacity Factor and Online Efficiency

CHP Unit: Thermal Heat Recovered and Percent of Recovered Energy to the Total

Produced by the Digester

Overall, an average of 801±260 MMBtu of combustion heat per periodwas harvested or 13±5% of the total thermal energy produced digester.

CHP Unit: Monthly Electrical Energy Generated and Parasitic Energy for System

Overall, the avg. monthly energy generated was 671±258 MWh and theavg. monthly parasitic energy was 92±30 MWh or 14% of that generated.


Greenhouse gas reduction do to AD:

Estimate reduced ghg emissions by comparing predicted differences in long-term storage emissions with and without pretreatment by AD

EPA / ASERTTI ProtocolEconomic Analysis

1. Cash flow approach

2. Annual capital cost (turn key approach)

3. Annual operating and maintenance costs

4. Revenue

Capital CostsComponent Cost ($)

Interconnection and switchgear 1,250,000

Site work 1,200,000

Mechanical systems 350,000

Heat exchange and pasteurization 400,000

Digester vessel 1,250,000

Biomass and gas storage vessel 350,000

Hydrogen sulfide scrubber 150,000

CHP unit 1,250,000

Motor control systems 300,000

Engineering installation 1,250,000

Total 7,750,000

Project Grants

$1,000,000 from the New York State Energy Research Development Authority

$800,000 in performance payments (3-yrs.)

$200,000 in capacity payment

Project Revenue

Electrical energy sales ~$45/MWh

Renewable Energy Credits (RECs) ~$50/MWh

Tipping fees

Overall, the avg. monthly sum of the electrical and REC revenues was $56,700.

Three Observations

1. Mass flow quantification is key

2. Implementation of the ASERTTI protocol is beyond almost all farms to do or pay for

3. Multiple factors have to be addressed for wide-span adoption of AD. Data shows one such factor is low capacity factors.

Why are you here:

Networking opportunitiesShare knowledgeLooking for new opportunitiesRepresenting products/services for saleLearn about anaerobic digestionMoney

Information on Manure Treatment, Information on Manure Treatment, Including Anaerobic Digestion,…Including Anaerobic Digestion,…

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Evaluation of a Continuously-Mixed Farm-Based Anaerobic Co-Digestion System

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