Invention saving lives

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Clean Biomass CookstovesJanuary 27, 2018

Dan Lieberman, Intellectual Ventures LabDean Still, Aprovecho Research Center

Global Good Fund - Partnering for Invention

Government, Multilateral NGO and Commercial Sectors

Late stage

Execution

Invention TechnologyDevelopment

ProductDevelopment

Piloting Clinical

and Field trials

Manufacturing Capacity

SalesMarketing

Distribution

Early stage

High risk

Focus on humanitarian impact in developing countries, philanthropic in approach

Target health solutions for countries defined by the World Bank as having low-income economies or LMICs

Team

University of WashingtonClean Cookstoves

• Dean Still• Sam Bentson• Andy McClean

• Jonathan Posner, PhD• John Kramlich, PhD• Garrett Allawatt• Anamol Pundle

• Dan Lieberman, PhD• Michael Barbour• Van Dinh, PhD• David Bell, MD

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Methodology

Use case

Computation

Concepts

Experiment.

Entrainment

MixingDraft

Unvented VentedPM2.5 (mg/min) 1.75 7.15CO (g/min) 0.35 1.45ηthermal (%) 45 45

WHO Intermediate Targets (Tier 4)

Some stove variations and conjectures(with help from Kirk Harris and Mr. Shen)

Rocket Stove Typical Real Time Data

PM spikes each time the stick fuel is advanced into the stove

Inside the combustion chamber:

When smoke is being produced try reducing the amount of wood burning while maintaining a temperature above 609C

Control the Rate of ReactionReduce the Primary Air

Super Insulate

Mixing:Better mixing of wood gas and air within the flame reduces

emissions (forced air)

Natural Draft Mixing

2.25” ID orifice Stationary fan

“Umbrella spokes” cut up flame

Dwell time

Providing the well mixed flame with sufficient time for more complete combustion to occur reduces emissions

Pressure Difference

When the pressure difference between the flame and the secondary air is greatest mixing may be more effective

Vertical and horizontal “TLUD” type combustion chambers seem to operate with some similar characteristics

Horizontal “TLUD” combustion chamber

Batch loaded sticks burn back by themselves

Rocket stove with horizontal “TLUD” combustion chamber

Mixing by fan and orifice. Secondary air is introduced downstream of the orifice.

Preliminary Horizontal “TLUD”/Rocket ResultsStove type/model

Ceramic Hybrid Test 1

Ceramic Hybrid Test 2

Ceramic Hybrid Test 3

Test Conditions Insulated feed tube, tight fuel pack

Wood species Douglas Fir Dimensionally Cut Sticks

IWA Performance Metrics units Value Value Value

High Power Thermal Efficiency % 36.8% 36.4% 37.3%

High Power PM mg/MJd 68.4 47.5 52.4

Indoor Emissions PM mg/min 6.6 5.1 5.8

Tier Tier Tier

High Power Thermal Efficiency 3.1 3.1 3.2

High Power PM 3.7 3.9 3.9

Indoor Emissions PM 3.2 3.4 3.3

Temp-Corrected Time to Boil min 21.0 20.0 19.0

Firepower watts 4,367 4,918 4,936

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Path forward: develop cleaner, scalable, and more affordable rocket stoves

• Evaluating partnerships with stove manufacturers and distributors in specific locations, traditions and cooking behaviors (e.g. India, East Africa)

• Open-innovation approach to our technology development

• Exploring cost offsets with credit or subsidy programs