Program Name or Ancillary Text eere.energy.gov

Ryan Gist, Venkatesh Iyer (BioLite), Kirk Smith (UCB), Omar Masera (UNAM), Victor Berrueta (GIRA)

DOE BETO Cookstoves Program Review

EE0006088 February, 2015

Heart of the Hearth: Making the Popular Clean, not the Clean Popular

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• Apply BioLite’s fan-assisted combustion technology to a clean burning and reliable “combustion core” that can be generally incorporated into the most popular stove types

• Supports the DOE Bioenergy goals towards reducing pollutant emissions from biomass cooking by 90% and fuel usage by 50%

Heart of the Hearth: Making the Popular Clean, not the Clean Popular

Goal Statement

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Quad Chart Overview

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Highest performing cleanest biomass cookstove configurations are often not consistent with traditional cooking and fuel preparation practices • Can we apply a simple and robust

approach to air-assisted combustion that maintains traditional cooking for widespread adoption?

Timeline

Budget

Barrier

• University of California Berkeley • Groupo Interdisciplenario de

Tecnolagica Rural Apropiado (GIRA)

• National Autonomous University of Mexico (UNAM)

Partners FY 13 Costs FY 14 Costs Total Planned

Funding (FY 15-Project End Date

DOE Funded

$ 37k $ 405k

$ 441k

Project Cost Share (Comp.)

$ 3k

$ 46k

$ 51k

• Project Start: June 2013 • Project End: December 2015 • 60% Complete

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Project Overview

• Historically, the cleanest biomass stove configurations have been top-lit gasifier stoves that require a high level of fuel preparation and are not compatible with traditional tending and cooking practices

• The project objectives are to: – Identify critical fluid-dynamic and heat transfer mechanisms that lead

to high combustion and thermal efficiencies – Design non-invasive hardware to replicate these conditions inside

any general stove architecture – Minimize impact to traditional user behaviors and fuel preparation – Demonstrate user acceptance and improved stove performance

under real-world usage conditions

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Technical Approach

Modular stove testing platform

Application to specific stove phenotypes

User demonstrations and feedback for refinement

Investigation of fundamental performance and efficiency factors

1 2 3

Metric Current Benchmark

Fuel Usage (Thermal efficiency) 30 to 42% > 30%

Particulate Emissions (PM_2.5 per mega joule)

50% reduction from Patsari

70% reduction

Unit Cost Approx $20 $15 USD

Main Technical Challenge: Producing concentrated high temperature for clean combustion while providing uniformly distributed heat for cooking (Temp Uniformity Metric)

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Technical Approach - Tools

Combination of analysis and empirical lab testing to establish feasibility and performance limits – then validate hypotheses

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pm)

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CO2 and CO Emissions During Test CO2

bkgx

bkgco2

hotco2

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simmer

1-D analytical

model

CFD

Emissions testing

Water Boil Tests (WBT)

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Management Approach

Approach Structure

• Performance-based approach with increasingly more strict phase gates between project phases (Consistent use of DOE PMP tool)

• Performance-based approach with increasingly more strict phase gates between project phases

• Clearly defined sub-contractor roles and scope • Building commercial viability on top of existing successful stove projects Success Factors

• Fuel usage and particulate emissions benchmarks • Temperature uniformity (User acceptability) benchmark • Cost target benchmark Potential Challenges

• Emissions reductions targets may not be possible without more intrusive changes to stove design and user behavior

• Benefits of clean cooking and lower emissions may not provide enough customer value to motivate purchase

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Progress Summary

Fundamental Parameter Investigation

• CFD analysis to bound limits and inform empirical design space • Parametric testing with modular stove platform 1st Gen Prototype • Interim efficiency and emissions targets achieved • Milestone #1: Proof of concept 2nd Gen Prototype

• Lower cost design and improved temperature uniformity 3rd Gen Prototype

• Further simplification and cost reduction • Milestone #2: User acceptability achieved • Milestone #3: Cost of goods target achieved In-Home Trials

• Maximize emissions performance within cost / acceptability bounds • Milestone #4: Independent 3rd party evaluation of pollutant & IAP reduction • Milestone #5: Evaluate Project for Results and Commercial Suitability

Feb 2013

March 2014

Nov 2013

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Detailed Technical Progress

Fundamental Parameter Investigations

• Thermal efficiency parameter sensitivity • Air injection interaction with natural draft • Char oxidation parameter sensitivity

Application to Patsari plancha stove and user feedback • Temperature uniformity optimization • Automated activation and fan control • Reduced noise level 2nd and 3rd Gen Prototypes

• Achievement of temperature uniformity and cost benchmarks • Application of fundamental performance parameters to maximize emissions

reductions • Opportunity for further improvement with double-height chimneys

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Chamber size, air injection, and reverse flow

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Fan

Air

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Air injection location Single-stage Multi-stage

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Staged injection

Staged air injection and larger chamber size allow higher fan flow rates before the onset of reverse flow

Smaller Chamber

Larger Chamber

Smaller Chamber

Larger Chamber

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Increasing pot gap → lower scrubbing velocities → lower heat transfer rates

Thermal efficiency and pot gap

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Ther

mal

Effi

cien

cy (%

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Pot gap (mm)

Exit diameter

Reverse flow limit

Smallest

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Large

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Char Reduction Approach

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sid

ual

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arco

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g) Cold Start Hot Start Simmer

Baseline Char Tray Air Access Door Hybrid

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Cold Start Hot Start

Baseline Char Tray Air Access Door Hybrid

65% reduction

10% increase

Candidate charcoal tray

Charcoal tray installed in combustion

chamber

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Application to Patsari Stove

• Application considerations: – Plancha stove architecture is

very different from rocket elbows like HomeStove

– Different cooking style

– Tasked with improving already improved stove

– High electrification rates in Mexico make thermoelectric unattractive

– In-built fixed stove

1st Gen: Direct application of modular stove

2nd Gen: Tailored design to balance

performance, usability & cost

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Low cost simplified design

• Challenges: – Trade-off between comal

temperature uniformity and clean combustion

– Patsari already reduces indoor emissions. This injection technology cuts outdoor emissions by a significant amount in addition to further reducing indoor concentrations

– Cost and affordability – Audible impact of fan on cooks

3rd Gen: Improved, low profile, low cost

prototype

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Lab and Kitchen Performance Testing

Controlled Cooking Tests (CCTs)

Water Boil Tests (WBTs)

Temperature Profile Tests (TPTs)

Comal Olla Comal Plancha

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0.000.200.400.600.801.001.20

Patsari 2nd Gen 3rd Gen

CO (g/min)

Lab and Kitchen Performance Testing - Results

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PM (mg/min)

TPT

At current PM_2.5 emission rates, tier 3 can be achieved w/ 20% flow leakage

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Relevance

• Project approach is user focused

• Provides community insight into how high performance conditions established in the lab can be applied to traditional stove archetypes without having to change fuels or cooking behaviors

• Design for manufacture (DFM) has been employed to minimize cost of production and reduce cost barrier to adoption

• Project will employ an independent emissions monitoring assessment to determine the level of “real-world” improvement achieved in the user-focused framework

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Future Work

• March – May – Optimize and redesign prototypes for in-home testing – BioLite, GIRA

and UNAM – Achieve minimum 50-70% PM_2.5 reduction vs. Patsari – Go/No-Go

• May - June – Release BioLite turbo attachment design for fabrication (8-10 units) –

BioLite – User training for Emissions equipment and CCTs – UC-Berkeley – Select 8-10 homes for testing; build/modify Patsaris and install

BioLite turbo attachment – GIRA • June - July

– Conduct in-home trials – UC-B & GIRA • Aug – Dec

– Analyze data and prepare final report – UC-B, GIRA, UNAM, BioLite – Evaluate commercialization opportunity – Go/No-Go

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• Overview: – Project is beyond 50% completion with key milestones met and remaining

milestone objectives within reach • Approach:

– Milestone management plan is guided by PMP – Unique technical approach is to establish key performance parameters, meet

user acceptability and affordability targets, then apply performance parameters to maximize emissions performance within those bounds

• Technical Accomplishments: – Excellent temperature uniformity (user acceptability) and low cost achieved

while reducing PM_2.5 emissions to tier 2-3 levels • Relevance:

– Providing a uniquely user-focused project to demonstrate how large emissions reductions are possible within adoptability and cost limitations

• Future Work: – 10 Home trial with production-like prototype with independently evaluate

emissions reduction of accepted stove configuration

Summary