recovery of ammonia energy from municipal and · pdf filefrom municipal and agricultural...

Recovery of Ammonia Energyfrom Municipal and AgriculturalWastewater: AmmoniaElectrolysis

Gerardine G. BotteAssociate Professor, ChE

Director Electrochemical Engineering ResearchLaboratory

John HolbrookDirector

AmmPower LLC

Ammonia the key to US energy independenceGolden, ColoradoOctober 2006

Electrochemical Engineering Research Lab, Ohio University 2

• Background

• How to get energy out?

• Ammonia Electrolysis

– Electrolysis of ammonia effluents

– Hydrogen Production

• Economic Analysis

• Conclusions

• Future Work

Outline


• All mammals (human and animal) produce liquid andsolid waste which contains considerable “undigested”energy

• Extensive activity ongoing worldwide in extractingresidual energy from solids. Most visible example isanaerobic digesters, but biomass gasification andanaerobic pyrolysis (destructive distillation) also viable.

• Little R&D effort in capturing the residual energy in liquidwaste, which is largely in the form of ammonia andammonia compounds (e.g. urea)

• Mammal urine contains ~5% urea; average humanexcretes 3-5 liters of urine daily; average cow excretes5-7 gallons

Background

• Background

• How to get energyout?

• AmmoniaElectrolysis

– Effluents

– H2 Production


• Conclusions

• Future Work


• Aqueous urea is chemically 2 parts NH3 and 1 part CO2

(overall about 8% hydrogen)

• Urea decomposes naturally at ambient temperatures toyield NH3 via urease bacteria action, but this is asluggish process

• Above 500F urea decomposes thermally very rapidly;this process used extensively in de-NOx (NH3 + NOx !N2 + H20)

• Urea also broken down in pressurized water reactors at~200C, but much of the energy in the urea is consumed

• Electrolysis of ammonia/urea solutions could provide alow-T, energy efficient way to get the energy out of urea

How to get energy out?

• Background



– Effluents

– H2 Production


• Conclusions

• Future Work


Ammonia Electrolysis: In Situ H2

Production

• Anode: Ammonia Oxidation

H2O

NH3

KOH

H2N2

0

3 2 22 6 6 6 E =-0.77 vs SHE

! !+ " + +NH OH N H O e

0

2 22 2 2 E 0.82 V vs SHE

! !+ " + =H O e H OH

0

3 2 22 3 E 0.059 V! + =NH N H

• Background



– Effluents

– H2 Production


• Conclusions

• Future Work

• Cathode: Water Reduction

• Overall Reaction


Comparison with Water Electrolysis

• Using Solar Energy at $0.214/kW-h

• Ammonia cost at $300 per ton metric

2.007.1Hydrogen Cost($/kg H2)

1.5533Energy (W-h/gH2)

NH3

ElectrolysisWater

Electrolysis

SAVING95% LOWER ENERGY

71 % CHEAPER H2

• Background



– Effluents

– H2 Production


• Conclusions

• Future Work

Theoretical (Thermodynamics) Calculations


Advantages of Technology

• Minimization of hydrogen storage problem

• Electrolytic on-board reforming

• Zero green house emissions

• Fuel Flexibility

• Low temperature operation

• Compatibility with renewable energy sources (e.g. solar, wind)

• Fertilizer plants, municipal waste water treatment stations, andmodern engineered dairy/hog/poultry farms could potentiallyproduce their own energy from waste

• Background



– Effluents

– H2 Production


• Conclusions

• Future Work


Technology Objectives

• Ammonia removal from wastewater

– Protect rivers, lakes and groundwater

– Protect atmosphere

– Reduce wastewater processing costs

• Efficient hydrogen generation

– In-situ energy production

– Renewable source

– Low-cost hydrogen

• Background



– Effluents

– H2 Production


• Conclusions

• Future Work


Project Vision

EnergyEnergy

NHNH33+H+H22OO

(Waste water)(Waste water)

Clean energy supplyClean energy supply

HydrogenHydrogen

Clean waterClean water

NN22

Ammonia

Electrolysis for the

Production of

Hydrogen

NH3 fromlivestock (lagoon)


Key Point: Electrolysis of Ammonia Effluents (why?)


Ammonia Air Emissions

• Over 5 Million Ton per year (2002)1

1. G. E. Mansell, "An Improved Ammonia Inventory for the WRAP Domain (FinalReport)", ENVIRON International Corporation, Report No. 415.899.0700, March 7

(2005)

Native Soils

32%

Fertilizer

28%

Wild Animals

3%

Domestic

3% Livestock

34%

US Ammonia Production(Million Ton per year)

•2000: 11.8

•2001: 9.1

•2002: 10.1

•2003: 8.8

•2004: 8.9


Ammonia Air Emissions

1. G. E. Mansell, "An Improved Ammonia Inventory for the WRAP Domain (FinalReport)", ENVIRON International Corporation, Report No. 415.899.0700, March 7

(2005)

US Ammonia Production(Million Ton per year)

•2000: 11.8

•2001: 9.1

•2002: 10.1

•2003: 8.8

•2004: 8.9

Fertilizer, livestock, anddomestic 3.25 Million

Ton per year1

36.5% of 2004annual production


Impact of Recovery of Effluents for H2

Production

• Assumptions

– Recovery of fertilizer, livestock, and residentialsources

– Use to power residential houses with a consumptionof 12,000 Kw-h per house

– Combination of solar panel with ammonia electrolyticcell (AEC)

• Impact

– Produce enough energy to power over 900,000residential houses per year if all ammoniaemissions captured from fertilizer, livestock, andresidential sources

– Minimization of 1% CO2 emissions coming from theresidential sector by replacing fossil fuels

• Background



– Effluents

– H2 Production


• Conclusions

• Future Work


• Design Electrodes capable of electrolyzingammonia at low concentrations

• Unknown kinetics at low concentrations ofammonia

• Unknown effect of contaminants present inwaste waters (urea, proteins, salts, suspendedsolids, etc)

• Durability/reliability/lifetime of cells andelectrodes

Challenges. Technologyimplementation

• Background



– Effluents

– H2 Production


• Conclusions

• Future Work


• Design and evaluate electrode materials toimprove kinetic performance at lowconcentrations of Ammonia

Objectives

• Background



– Effluents

– H2 Production


• Conclusions

• Future Work


Methodology


• Two different substrates tested

– Raney Nickel

– Carbon fibers

• Substrates plated with combinations of noblemetals for the electro-oxidation of ammonia

Methodology

Substrates

• Background



– Effluents

– H2 Production


• Conclusions

• Future Work


Testing Cell

H2

N2


Removal of Ammonia

Performance of Pt-Ir-Rh Electrode, Initial conditions 21.5 mM NH3 and 0.2M KOH

IMs

Fnmt

!!

!!=

Final NH3 concentration1.83 mM

13.82 h

13.78 h


Faradaic Efficiency and Conversion at 25 mA/cm2

100o f

o

C Cx

C

!= "

100f

t

m

m! = "

91.5%

91.8%

Where:

x: conversion of ammonia

Co: initial concentration of ammonia, mM

Cf: final concentration of ammonia, mM

!: ammonia faradaic efficiency

mf: final mass of ammonia, g

mt: theoretical mass of ammonia, g

Successfullydemonstrated


Key Point: Hydrogen Production, Ammonia as a Hydrogen Carrier


• Evaluate the Feasibility of the technology forDistributed Size Onsite Hydrogen Production(480 kg H2/day)

– Energy balance

– Economics analysis

Objectives

• Background



– Effluents

– H2 Production


• Conclusions

• Future Work


Energy Balance


Operating Options (Day): Theoretically

Air

Electrical Energy

NH3/KOH/H2O

OU

AMMONIA IN

SITU H2

GENERATOR

FUEL

CELL

H2

H2O

Heat

Electrical

Energy

33 W-h/g H2

1.55 W-h/g H2

N2


Operating Options (Night): theoretically

Electrical

Energy31 W-h/g H2

Electrical

Energy

NH3/KOH/H2OOU

AMMONIA IN

SITU H2

GENERATOR

FUEL

CELLH2

H2O

Heat

1.55 W-h/g H2

N2

AirNo H2 Storage

Is this feasible?


Energy Balance at 25 oC

-10

0

10

20

30

40

50

0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035 0.040

Hydrogen Mass Flow, g/h

En

erg

y,

Wh

/gH

2

Net Energy

Energy used by Ammonia

Electrolytic Cell

Energy produced by PEM

Fuel Cell

Energy used by a Water

Electrolyzer

Theoretical Energy used by

Ammonia Electrolytic Cell

1M NH3

5M KOH


Economics Analysis and Comparison with Other Technologies forDistributed Size Onsite Hydrogen Production (480 kg H2 per

day)

1. Same assumptions as the Hydrogen Economy by the National Academy ofScience

2. Cost of Ammonia $300 per Metric Ton

3. Cell Operating at 50 oC with 0.058 cell Voltage

4. Energy consumption of by electrolysis 1.55 Kw-h/kg of H2. 100% ElectricEfficiency

5. Electricity at $0.07 per kwh

CAPACITY: 480 kg H2 per dayANNUAL AVERAGE OPERATING LOAD: 90%

TOTAL CAPITAL COST $ 0.743 millionTOTAL VARIABLE COST $ 285,000 /year AMMONIA at $ 300 per ton ELECTRICITY at $ 0.07 per kwh

CAPITAL CHARGES: $ 20,000 /year

NH3 113.4 Kg/h

N2 per 93.2 Kg/h

Same assumptions as

reported by the National

Academy of Engineering

ELECTROLYZER

H2

TO 400 ATM

H2 STORAGETO 400 ATM7 HOURS AT

PEAK SURGE

H2

dispenser

to

vehicles

20 kg

H2/hr

Proposed System for

Distributed Power

Generation

Up to 1000 kg H2/

day


Economic Analysis at Current Operating Conditions


Testing Loop

NH3 Electrolytic

Cell

NH3/KOH/water

feed tank

KOH/water

feed tank


The Ammonia Electrolytic Cell


Optimization of AEC Performance

ResultsRundomized

Order

KOH

Concentration (M)

NH3

Concentration (M)

Current

(mA)

Temperature

(°C)

Power

Consumption

(W-h/gH2)

1 0.5 0.5 300 25 15.5

2 0.5 0.5 100 25 12.2

3 0.5 5 100 25 9.0

4 0.5 5 300 50 11.5

5 7 0.5 300 50 11.3

6 7 5 300 25 13.6

7 0.5 0.5 300 50 12.2

8 7 5 100 50 8.6

9 0.5 5 100 50 8.7

10 7 0.5 100 50 9.4

11 7 0.5 300 25 14.0

12 0.5 5 300 25 14.4

13 0.5 0.5 100 50 9.9

14 7 5 300 50 10.2

15 7 0.5 100 25 11.6

16 7 5 100 25 10.0

V=0.34 V

Energy

V=0.33 V


Comparison with Other Technologies for Distributed Size Onsite HydrogenProduction (480 kg H2 per day)

1. Same assumptions as the Hydrogen Economy by the National Academy ofScience

2. Cost of Ammonia $300 per Metric Ton

3. Energy consumption based on real laboratory data

4. Electricity at $0.07 per kwh

3.37

1.02

NH3

Electrolysis

(8.7 Kwh/kgH2. 18.5%

ElectricEfficiency

2.00

0.743

NH3

Electrolysis

(1.55 Kwh/kgH2. 100%Electric

Efficiency

3.51

1.85

Natural GasSteam

Reforming*

6.58Hydrogen Cost($/kg H2)

2.54CapitalInvestment(Million $)

WaterElectrolysis

(52.49 Kwh/kgH2. 75% Electric

Efficiency)

CurrentTechnologies

SAVINGS 8.2 % CHEAPER H2 than NG reforming

At $ 0.07 KWh

48.7% CHEAPER H2 than Water Electrolysis


Sensitivity Analysis

1. Cost of Power can change depending on the source

2. The cost of ammonia can change. If ammonia from waste is used, it isestimated that no charges will be involved

3. Current density: 25 mA/cm2

4. Cell Operating at 50 oC with 0.34 cell Voltage


0

1

2

3

4

5

6

7

0 50 100 150 200 250 300

Cost of Ammonia, $/ton metric

Cost

of

H2 f

rom

Am

mo

nia

Ele

ctro

lysi

s, $

/Kg

NH3 Electrolysis with Solar Energy, Current

Technology ($0.319 per KWh)

DOE Goal

NH3 Electrolysis with Solar

Energy, future optimism ($0.098 per KWh)

NH3 grid power, current

technology ($0.07 per KWh)

NH3 wind/turbine power,

current technology ($0.06 per KWh)

NH3 wind/turbine power, future

optimism ($0.04 per KWh)

Water Electrolysis= $28/kg

Water Electrolysis= $6.58/kg

Water Electrolysis= $6.18/kg


Conclusions

• Efficient removal of ammonia achieved

• Ammonia Electrolysis is much cheaper than waterelectrolysis

• The ammonia electrolytic cell can operated with any sourceof renewable energy

• H2 can be produced at less than $2.00 per Kg for distributedpower

• The economic feasibility of the technology for distributedpower has been demonstrated

• The key for the process is to use ammonia from waste. Inwhich case, up to $100 per ton metric of ammonia can bespent to purify the waste stream if needed.

• Ammonia electrolysis may be even cheaper as NO hydrogenstorage tanks NEEDED.


Farm of the Future

Lagoon

Pretreatment and

Electrolyte Recovery

Units

Sun

Solar

panels

Bench scale AEC PEM fuel cell Fan power by PEM

fuel cell

Lagoon

Pretreatment and


Units

Sun

Solar

panels


fuel cell


Future Work

• Improve efficiency of theprocess

• Determine reaction rate toscale up and design AECto pilot scale to determinemore accurate costs

• Determine energyefficiency of Power Source(integrated AEC/PEM fuelcell)

• Define pre-treatment unitsto use ammonia fromwaste

Lagoon

Pretreatment and


Units

Sun

Solar

panels


fuel cell

Lagoon

Pretreatment and


Units

Sun

Solar

panels


fuel cell


Acknowledgements

• Army Research Office (DURIP award)

• NSF Path Award

• 1804 Fund Award by the Trustees of the Ohio UniversityFoundation Office of the Vice-President for Research, OhioUniversity

• Student Enhancement Award (Office of the Vice-President forResearch, Ohio University)

• Dr. Ingram Department of Physics, Ohio University


The EERL Group

For more information visit:http://webche.ent.ohiou.edu/eerl/

www.ohio.edu/engineering

Contact:Gerri Botte at [email protected]

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