Project Updates: Small-scale Solar-Biopower Generation For Rural Central

America

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WHA Costa Rica Project TeamNovember, 2012

Biosystems & Agricultural Engineering, Michigan State UniversityAgricultural Engineering, University of Costa Rica

A Solar-Biopower Concept

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Integrating wastes utilization with solar and biological technologies will create a novel self-sustainable clean energy generations system for small-medium scale operations

Fertilizers

Reduced GHG

Animal Manure

Other Wastes

BioenergySolar

Energy

AnaerobicDigestion

Biological Post-treatment

Clean Water

A Solar-Biopower Concept

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Benefits of system integration

Overcome the disadvantages of individual technologies Unsteady energy flow for solar power generation

Low efficiency of mesophilic anaerobic digestion on degradation of organic matter

Higher energy requirement of thermophilic aerobic digestion

Provide sufficient and stable energy for small-medium sized rural community

Solar energy utilization

Improved efficiency of anaerobic digestion on degradation of organic matter

Biogas energy as chemical storage – steady energy flow

A Solar-Biopower Concept

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System flowchart

Mass balance

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Predicted mass balance for the integrated solar-bio system on 1,000 kg of mixed sludge and food wastes

a. The calculation of mass balance was based on the expected results that will be achieved by this project. b. A kg COD destroyed produces 350 L methane gas.

Mixture of feedstocks:Total amount: 1,000 kg/dayTotal solid: 10% COD: 90 g/kg

Thermophilic CSTRReaction temp.: 50°CRetention time: 15 daysCOD reduction: 50%Total solid reduction:40%

Biogas production from anaerobic treatmentMethane: 18,000 L/day

Liquid effluentAmount: 595 kg/dayTotal solid: 10 g/kg effluentCOD: 45 g/kg effluent

Generator

Solid residue accumulated from the CSTRAmount: 360 kg/day wet solidDry matter: 15%

Boiler

To wetland

BioenergyAmount: 684 MJ/day

A Solar-Biopower Concept

Energy balance

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Potential energy generation based on 1,000 kg of mixed influent per day

Approximately 200% more net energy output (maximum) generated from solar-biopower system with the system under the optimal conditions.

Time courses of maximum energy generation

Time courses of potential net energy generation of solar-biopower system

Maximum daily net energy generation

A Solar-Biopower Concept

Objectives

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1. Optimize local thermophilic anaerobic microbial consortia on mixed waste streams 90% completion A publication is under preparation

2. Design and implement a solar-biopower generation system on mixed waste streams 80% completion The full demonstration system is up and being tested

3. Evaluate the technical and economic performance of the demonstration system for rural communities in Central America 20% completion A prototype portable unit has been designed and tested at MSU The 500 L portable unit is under fabrication

4. Establish an outreach program in Central America 30% completion

Objective 1

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Optimize local thermophilic anaerobic microbial consortiaMicrobial community in anaerobic digestion

Pyrosequencing (454) analysis of six reactors. Mixed manure and fiber (50 g/L of COD, three mixture ratios of 90:10, 80:20, 70:30) and two temp. of 25 and 45°C

Unclassified bacteroidetes

Distribution of phylum Bacteroidetes in bioreactors

Culture at 45°C, waste ratio of 80:20

Neighbor joining tree of the unique Bacteroidetes genera (cluster 78 and 89) from 45°C culture and their closely related species in Silva database.

1 µm

SEM picture of unclassified bacteroidetes

Objective 1

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Optimize local thermophilic anaerobic microbial consortia

Biogas accumulation from manure/food wastes mixture at 50°C digestion (90:10 vs. 80:20)

Biogas Production on Mixed Waste Streams

Biogas accumulation from manure/food wastes mixture at 35°C digestion (90:10 vs. 80:20)

Objective 2

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Design and implement a solar-biopower generation system on mixed waste streams

Major system components (16) 2x1 m flat-plate solar collector with support (1) 22 m3 anaerobic digester with a 50 m3 gas bag (1) 16 kW combined heating and power unit (4) 100 m2 wetland/sandfilter cells

Located at Fabio Buadrit Experimental Station, UCR

Solar-bio-reactor Wetland/sandfilters

Objective 2

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Design and implement a solar-biopower generation system on mixed waste streams

Solar-bio-reactor

Wetland/sandfilters

Objective 3

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Evaluate the technical and economic performance of the demonstration system for rural communities in Central America

: Heat flow

: System monitor and control

Evacuated tube solar collector

Flat-plate solar collector

Solar thermal transfer system Heat

exchanger CSTR anaerobic digester

Control unit

Portable-Scale Solar-Biopower System Design

Objective 4

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Establish an outreach program in Central America 30% completion

1 workshop (team members from Costa Rica, Panama, Nicaragua attended) has been held at MSU at the end of 2011

1 seminar conference has been held at UCR in March, 2012

A meeting with industrial sector and university was held during the May visit to Nicaragua (2012)

2 undergraduate students did intern at MSU in 2012

A small-scale demonstration digester unit has been fabricated at UNAN-Leon (Nicaragua).

A group of 13 students from both MSU and UCR will visit the pilot facility at Fabio

From: http://www.usda.gov