biofuel cells and bioenergy

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O2

H2OOrganic

Carbon/ Reduced

substrate

CO2 + H2O

Bio

cat

alyt

ican

od

e

Cat

ho

de

Biofuel cell

e- e-

H+

H+

H+

H+

CxHyOz CO2 + H+ + e- H+ + e- H2O

Eo = 1.1 V

Nutrients

Cell mass O2

H2OOrganic

Carbon/ Reduced

substrate

CO2 + H2O

Bio

cat

alyt

ican

od

e

Cat

ho

de

Biofuel cell

e- e-

H+

H+

H+

H+

CxHyOz CO2 + H+ + e- H+ + e- H2O

Eo = 1.1 V

Nutrients

Cell mass

Waste

EnergyBiofuel cells and BioEnergy Production

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Waste To Energy

A P Borole, Ph.D.Oak Ridge National Laboratory

Biofuels

Human Energy

Biofuel Cells and BioEnergy

Acknowledgements:Jennifer Tyrell, Jeffersen County High School

Julia Abbott, Bo Cumberland, ORAU.

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Why are we here today?

• Make friendship with biology!• Learning Objectives– Learning about waste to energy conversion– Understand how living beings generate energy– Why is energy important?– How my body makes energy?– Can tiny microbes make energy for us?– Can waste be converted into energy?– Why does it matter and how can you help?

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Do you think ‘Biology’ is dry?

BI

OL O

GY

+

How about adding some catalyst (water) to make it more fun?

Can we make THIS happen?

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Outline

1. Learn about ‘Bio-Electricity’Observe and explore models of bioelectricity

producing devices

2. Learn about Bio-energy production processes in living organisms

ATPNanowires

3. How can we impact this world by converting waste to energy.

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Section I

Bio-Electricity

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Fuel Cell

• What is anode• What is cathode• Fuel cell catalysts

– Platinum

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Introducing my friend…

Electro-Dude

:-)

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Welcome to Electro-Dude’s Home

CO2

Oxygen

Sugar (food)

A microbial fuel cell (MFC)

e-

Anode

H+

H+

e-

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Electricity production by Electro-Dude

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Microbial fuel cells• Anode– Organic carbon vs. H2 as

energy source.– Bacteria vs. Pt as

catalyst

• Cathode – Same as PEM fuel cell– Can also use bacteria as

catalyst

O2

H2OOrganic

Carbon/ Reduced

substrate

CO2 + H2O

Bio

cat

alyt

ican

od

e

Cat

ho

de

Biofuel cell

e- e-

H+

H+

H+

H+

CxHyOz CO2 + H+ + e- H+ + e- H2O

Eo = 1.1 V

Nutrients

Cell mass O2

H2OOrganic

Carbon/ Reduced

substrate

CO2 + H2O

Bio

cat

alyt

ican

od

e

Cat

ho

de

Biofuel cell

e- e-

H+

H+

H+

H+

CxHyOz CO2 + H+ + e- H+ + e- H2O

Eo = 1.1 V

Nutrients

Cell mass

MICROBIAL FUEL CELL (MFC)

Display 1

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Type of MFCs

• Sediment MFCs (low power)• Engineered MFCs (High power)

Neither MFC can work for cars

Display 2-3(Hands-on activity)

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Sediment MFCs• Uses sediment organic

carbon as energy source• Potential use as a bio-

battery for under-water energy harvesting

• Potential to last for ever (almost!)

• Let us test one!

Lenny Tender, NRL

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Engineered MFCs• MFCs designed to deliver

maximum power density– Optimized electrogenic

microbes– Engineered electrodes– Controlled process conditions

• For treatment of wastewater from domestic households, industry (biorefineries, food industry, etc)

ORNL MFC 1

ORNL MFC 2

ORNL MFC 3Display 3

Display 2

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Display 2 – Dismantle and assemble.

Carbon felt bioanode

/Carbon

100mm

100mm

25mm

150mm150mm

25mm

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Section II

Science of ‘Bio-Energy’ production

Biofuels

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What is energy?• Potential• Kinetic• Mechanical, Chemical, Electrical, Biological…• Energy Carriers (Direct and Indirect producers)

– Chemistry• Fuels: gasoline, diesel, hydrogen• Batteries

– Physics • Electrons (e.g., in a Cu wire, semiconductors)• Photons (sunlight)• Energized particles (Radiation)

– Biology• ATP (Primary energy molecule)• Macromolecules: glucose, food…

Direct

Indirect

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Journey through living systems Understanding various types of BioEnergy

MFC anode

Yellowstone Park

Microbial world

Mammalian world

Ener

gy P

rodu

ction

Elec

tron

Tra

nsfe

r

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Human Energy (Biological energy)

• How does our body generate energy?

– ‘Burning’ of carbs…• What is ATP?

Food (C6H12O6, glucose) + O2 CO2 + H2O + ATP (Adenosine TriPhosphate)

Video: 4:25 to 8:25 min (http://www.youtube.com/watch?v=i8c5JcnFaJ0)

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ATP-based ‘pump’

• Proton gradient• Electron gradient• (vides from 25 sec to 2:15 sec):

http://www.youtube.com/watch?v=kN5MtqAB_Yc

• http://www.youtube.com/watch?v=PjdPTY1wHdQ (Video from 0 to 1:20 min)

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Chemistry of energy production

• Two half reactions– Oxidation (glucose

conversion to CO2)

– Reduction (oxygen conversion to water)

Sugar (food)

H+e-

O=O H=O=H

Redo

x gr

adie

nt

Energy(ATP orElectricityEtc.)

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BioEnergy and Human Health

Food Oxygen

Energy

Human Energy

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Microbes with different ‘Energy’ character

Aerobes (using oxygen)

Anaerobes (Electro-Dude - microbes using other oxidizer molecules)

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Redox scale

} d = - 320 mV NAD+ / NADH c = -200 mV, FMN / FMNH2

b = +120 mV, Cytochrome box / Cyt bred

a = +220 mV, Cytochrome cox / Cyt credab

c

d

OxygenNitrate

Mn+2

Fe+2

SO4-2

CO2

High energy level(Aerobes)

Low energy level

Anaerobes

Energy produced redox gradient

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Science of electron transfer by Electro-Dude

• Scientific name:‘Electrogen’

electrode

BiologicalNanowires

Potential applications: Interfacing biology and electronicsNanocapacitors, nanotransducers, nanoconductors…

Bio-nano-electronics

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Section III

Estimating energy production from waste and its impact

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Waste

• Food waste (restaurants, home)• Plants and natural carbon cycle

• Human population: 7 billion, will reach 9 billion by 2035.

• Two billion people go hungry every day• Need to develop creative ways to generate

energy (waste to energy) using natural processes

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Wastewater treatment

• Goal: Remove organic matter

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Impact of ‘waste to energy’• Example calculation of

how much electricity can be generated from Knoxville municipal wastewater treatment plant

• Treatment of 44 MGD wastewater

• Capacity for 120 MGD

44 x 106 gallons/day x 3.785 Liters/day= 166 x 106 Liters/day x 0.2 g(organic matter)/Liter= 33 x 106 g/day / 30 g/mole (organic matter)[Organic matter CH2O = 12+2+16 = 30 g/mole]When organic matter is converted to electrons in MFC anode, it produces 4 electrons /mole as follows:

CH2O + H2O CO2 + 4 H+ + 4e-

= 1.11 x 106 moles/day x 4 moles of electrons/mole organic matter

= 4.44 x 106 moles e-/dayx 1 day/24 hours x 1 h/3600 s

= 51 moles e-/s

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How much energy can be made using wastewater?

• Energy can be measured in megawatt hours/ day.

• Wastewater is measured in million gallons/day.

• How can we convert facts we know in MGD to find out how much energy can be produced in MWh/day?

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Dimensional Analysis• It is easy to convert units using dimensional analysis. • Example: How many seconds are in a day?• Start with a known value and your desired end value units. • Fill in the chart with “equalities” that cause your units to

cancel. A unit on the bottom can cancel out the same unit on top.

• Multiply numbers on top and bottom to get your end value in the correct units.

60 min 60 sec 24hr

1 hr 1 min 1 day

86400 sec1 day=

End valueStarting “known” value

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Electron flow is measured as current in amperes (A)1 A = 1 Coulombs/s1 mole e- = 96485 Coulombs (Faraday constant)

Therefore, 51 moles e-/s= 51 x 96485 Coulombs/s= 4.9 x 106 Coulombs/s = 4.9 x 106 A or 4.9 MegaA

An MFC produces about 0.2 volts (V)Therefore, the MFC using wastewater would produce4.9 x 106 A x 0.2 V= 1 x 106 Watts (W) = 1 MegaW or 1 MWTo convert to MWh/day,1 MW x 24 h/day= 24 MWh/day

1 home uses 31 kWh/day,Thus, 24 MWh/day will serve 775 homes.

Conversion factor calculationmoles e-/s to MWh/day.

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Exercise

• Calculating electricity production from – The state of TN (replace all WWTPs with MFC)– All of US

• Impact on US energy production• See instruction sheet…

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Purpose: You will use dimensional analysis to determine the amount of energy in MWh/day (Megawatt hours/day) produced by a particular amount of waste water in MGD (million gallons per day).

• Instructions• Start with a known value and your desired end value units. • Fill in the chart with “equalities” from the list to the right that cause your units to cancel. A unit on the

bottom can cancel out the same unit on top. • Continue to cancel units using equalities until you are only left with your desired end value units on the top

and bottom.• Multiply numbers across the top and bottom to get your end value in the correct units.

Equalities

1 day = 24 hours 0.2g organic matter = 1 L3.785L = 1 gal 1 mole organic matter =

30g organic matter1 hour = 3600 sec 4 moles e- = 1 mole

organic matter

Beginning value

End Value

gal = moles e-

day sec

___________moles e-

xFill in conversion to do

=___________MWh

sec math on slide 28 day

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Greenhouse gases and global warming

• Relationship of MFC technology to global warming

• 1 MW 250 tons of carbon dioxide• Exercise for home: – Prove the above correspondence using completed

exercise

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What can you do?

• Contribute through educating yourself and others

• Participate in science research • Contribute through scientific discovery

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