sustainable energy storage in chemical fuels for co2 ... · dissociation with plasma? can it be...

Sustainable energy storage in chemical fuels for CO2 neutral energy generation:

a plasma perspective

Richard van de Sanden

Dutch Institute for Fundamental Energy Research, P.O.Box 1207, 3430 BE Nieuwegein, The Netherlands

Conférence de l’Institut Coriolis pour l’Environnement de l’École Polytechnique 2013

The TeraWatt Challenge (15 TW)

see also :

M.I. Hoffert et al. Nature 385, 881 (1998)

R.E. Smalley, MRS Bulletin 30 412 (2005)

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CO2!

The Terawatt challenge

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The Terawatt challenge

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DOE/EIA-0383(2011)

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The TeraWatt Challenge

see also :

M.I. Hoffert et al. Nature 385, 881 (1998)

R.E. Smalley, MRS Bulletin 30 412 (2005)

Sustainable, CO2 neutral, energy infrastructure essential

Contents

The TeraWatt Challenge: CO2 neutral energy supply Sustainable Energy Generation Storage and Transport of Energy: Solar Fuels

Solar Fuels from CO2 and H2O: conversion processes

Water splitting CO2 activation Plasma activation of CO2

Conclusions and Outlook

Sustainable energy - is there enough?

More sustainable energy than global energy demand

The big sources: solar wind biomass

geothermal ocean/wave hydro

Sustainable energy – future

• ITER: 2020 first plasma

• Commercial: 2040 ?

• Transport: need for fuels (air transport)

Solar power generation: DoE Sunshot

Price-experience curve of silicon PV modules (combined effects of innovation, experience and scale)

Solar power generation: Economy of scale

Grid parity ~1 €/Wp

Clear economy of scale

Grid parity in Europe

From 2020 a significant fraction is sustainable !

2025

However…….

Sustainable power generation is booming but it is

with time-scales ranging from minutes to months

Mismatch between supply and demand

German solar and wind energy

Solution: Energy storage

inhomogeneous and intermittent

Sustainable energy - storage needed

water reservoirs

chemical batteries

stored heat

Artificial chemical fuel

Storing energy: mechanical electrical electro-chemical chemical

Storing and Transport of Energy

Presently: 85% of the global energy is transported by fuels

Carbon containing fuels (hydrocarbons, alcohols, etc.) generated from CO2 and H2O to store sustainable energy:

Solar Fuels

Solar Fuels

• Large potential to contribute to a CO2 neutral energy infrastructure

• Storage and transport of sustainable energy in chemical bonds: close to present infrastructure

• Large efforts world wide on Solar Fuels:

Solar Fuels

• Large potential to contribute to a CO2 neutral energy infrastructure

• Storage and transport of sustainable energy in chemical bonds: close to present infrastructure

• Large efforts world wide on Solar Fuels:

Basically splitting H2O or activating CO2 using direct solar (heat & light) or sustainably

generated electrical energy

End product carbon containing fuels:

Solar Fuels

Fuel processing from H2O

Basically production of H2 : By splitting H2O: 1) H2O H2 + ½ O2

H2 production main activity globally

Hyundai i35 first commercial car on H2 + fuel cell

Fuel processing from H2O or CO2

Basically production of H2 or CO : By splitting H2O: 1) H2O H2 + ½ O2

or activating CO2: 1) CO2 CO + ½ O2

Cars fueled by wood or coal gas during WWII

Fuel processing from CO2 and H2O: syngas

Production of syngas H2 and CO : By splitting H2O: 1) H2O H2 + ½ O2

2) followed by a reverse watershift reaction

H2 + CO2 H2O + CO (endothermic) or activating CO2: 1) CO2 CO + ½ O2

2) followed by a watershift reaction

CO + H2O CO2 + H2 (exothermic)

Syngas: by means of Fisher-Tropsch process carbon containing fuels

FT=Fischer-Tropsch reaction (R)WGS=(reverse) watergas shift

H2

Captured CO2

CO2

WGS

RWGS Air Solar energy conversion: H2 O H2 + ½O2 CO2 CO + ½O2

CO2 Hydrogenation

Methane Methanol

CO FT Fuel

H2

CO

water

Solar Fuels

Courtesy Wim Haije (ECN)

Gas-to-liquid from syngas: Fisher-Tropsch

Shell Qatari plant (2009) Methane reformation: CH4 + H2O CO + 3H2 C-fuels Investment of 19 B$; Revenue 4 B$/yr Large scale proven

Ref. Bloomberg

However still based on fossil fuels

Gas (or fossil)

Plant

Sun or Wind Energy Plant

Sun

Electricity grid

Gas grid

Fossil

Wind

Water Liquid fuels or raw materials for industry

Gas buffer Fossil

current infrastructure of energy system

Current Energy generation infrastructure

Gas (or fossil)

Plant


CO2 Solar Fuel Plant

Sun

Electricity grid

Gas grid

Fossil

Wind


Gas buffer Fossil

Direct

Indirect

Solar Fuels Production from CO2 and H2O using sustainable energy fitted in our current infrastructure

Towards the Renewable Energy infrastructure

Gas Plant


CO2 Solar Fuel Plant

Sun

Electricity grid

Gas grid

Wind


Gas buffer

Direct

Indirect

Solar Fuels Production from CO2 and H2O as storage using intermittent sustainable energy

Full Sustainable Energy Infrastructure

Contents






H2

Captured CO2

CO2

WGS

RWGS Air Solar energy conversion: H2 O H2 + ½O2 CO2 CO + ½O2

CO2 Hydrogenation

Methane Methanol

CO FT Fuel

H2

CO

water

Solar Fuels


Biomass (< 1%)

Photosynthetic Micro organism (> 5%)

Man-made, articifical

(modified) natural, living

Solar

European Science Foundation, Science Policy Briefing 34 (Sept. 2008)

Primary and secondary

biofuels

Courtesy Wim Sinke (ECN)

Solar energy conversion (direct & indirect)

Biomass (< 1%)




Thermochemical Conversion (> 5%)

Solar



biofuels



Concentrated solar power (CSP)

CeO2 + sunlight CeO2-x + 1/2x O2 CO2 + CeO2-x CO + CeO2 Or based on ZnO, Fe3O4

Steinfeld group (ETH Zurich), Science 330 1798 (2010)

Thermochemical using CSP (direct)

Cyclic, solar to CO efficiency: 3-4% Nanostructured materials + catalysis essential


Biomass (< 1%)


Photocatalytic Nanodevices (> 5%)




Solar



biofuels


Direct photocatalytic conversion of H2O

Which approach is most promising ?

The challenge

Nanostructured materials and catalysis essential

But also photon management: plasmonics, etc.

Courtesy Roel van de Krol (HZ Berlin)

Different anorganic materials

Direct sunlight into hydrogen 1-3%

2H2O 2H2 + O2

Science 331 746 (2011)

Photocatalytical splitting of water


Graetzel, Nature, 414, 15 Nov. (2001) 338.

Water splitting

Courtesy Kevin Sivula

Photo-electrochemical cells: generation of solar H2

For large scale deployment:

Elements of hope

2H2O 2H2 + O2

Watersplitting using electrochemical cell

Nocera group (MIT): basically tandem a-Si solar cell with Co based catalyst

Direct photocatalytic conversion of CO2

Roy, Varghese, Paulose, Grimes, ACSNano 4, 1260 (2010)

η = 0.0148%

To tailor the catalyst to optimally use the solar spectrum for activating the

catalyst

The challenge

CO2 + 2H2O CH4 + 2O2


Difficult to activate CO2

by photocatalysis


Biomass (< 1%)






Solar

PV conversion + Electrolysis (> 20%)



biofuels


2H2O 2H2 + O2

Efficiency >> 20 %

Watersplitting using PV & electrolyser

Efficiency 70-80 %

Advantage: separate optimization possible Current bottleneck: use of scarce materials (a.o. Pt)

sustainable energy

*H2 generation from steam reformation

2H2O 2H2 + O2

Efficiency >> 20 %

Watersplitting using PV & electrolyser

Efficiency 70-80 %

Advantage: separate optimization possible Current bottleneck: use of scarce materials (a.o. Pt)

sustainable energy

> 8 €/kg* >16 €/kmol

*H2 generation from steam reformation

Electric energy conversion: electrolysis

Electrochemical Conversion

K.P. Kuhl et al., Energy Environ. Sci. 5 7050 (2012)

Electrical energy to CO > 10%

Electric energy conversion: electrolysis

Electrochemical Conversion

K.P. Kuhl et al., Energy Environ. Sci. 5 7050 (2012)

Electrical energy to CO > 10%

Difficult to activate CO2

due to solubility

Contents






Biomass (< 1%)






Solar

PV conversion + Electrolysis (> 20%)

Solar to electricity + Plasma conversion



biofuels

Solar Fuels



H2

Captured CO2

CO2

WGS

RWGS Air

CO2 Hydrogenation

Methane Methanol

CO FT Fuel

H2

CO

water

Solar Fuels


Conversion: • Electrocatalysis • Photocatalysis • Thermocatalysis • Plasma activation

Direct plasma activation of CO2

Plasmachemical activation of CO2

Plasma-chemical Conversion

Energy efficiency: ~ 41%

Why plasma?

• Higher energy density medium

• Exploit the nonequilibrium??

Concentrating the energy input on degrees of freedom which are essential for CO2

dissociation!!

Thermodynamics

Alex Fridman (Drexel Univ., US)

What is plasma?

Gaseous medium composed of :

Atoms

Molecules

Radicals

Ions (negative, positive)

Electrons

All possibly in the excited state (internal energy!)

Nonequilibrium medium nonequilibrium distributions

(non-Maxwellian, non-Boltzmann)

p

T

Telectron

Tgas

1 eV

1 atm

*1 eV = 11600 K

Used abundantly in e.g. materials processing

Electric energy conversion: plasmachemical

Plasmachemical Conversion

Energy efficiency: ~ 41%

Thermodynamics Why plasma?

• Higher energy density medium

• Exploit the nonequilibrium??

• No use of scarce materials: free electrons and electric field do the job

• Large scale possible (15 TW !!)

Plasmas and large scale

Acetylene production from coke and natural gas in Hüls arc reactor

H2 and carbon black production from coke and natural gas thermal arc reactors

But also note that many large scale industries heavily depend on plasma technology: IC, display, coatings, solar, etc.

Hüls reactor

Energy efficient dissociation using plasma?

Can it be done energy efficiently?

Cost of plasmas expensive energy-wise: • Creating electron-ion pair typically > 30 eV !*

*1 eV = 100 kJ/mol

ionization

electrons

electric field

collisions

Energy efficient CO2 dissociation with plasma?


Cost of plasmas expensive energy-wise: • Creating electron-ion pair typically > 30 eV !*

• Dissociation energy CO2 5.5 eV, but more is needed to get dissociation by direct electron impact (dissociative branch)

If electrons must do the job directly: no energy efficient dissociation possible !!

CO2 potential

1000

2000

3000

Vib.

Ene

rgy

[cm

-1]

ν2

ν1 ν3

Optimal vibrational state CO2 dissociation

(4.26 µm: IR)

Rusanov et al. Usp. Fiz. Nauk. 134 185 (1981)

ν2

electrons

electric field

collisions

vibrational excitation

Can we controle this?

Electron energy loss in CO2 plasma


electrons

electric field

collisions


Electron energy loss depends on reduced electric

field depends on average electron energy

V-V exchange and VT relaxation


electrons

electric field

collisions


V-V relaxation much faster than V-T relaxation for low v number: leads to Tvib > Tgas

Nonequilibrium effects: Treanor distribution


electrons

electric field

collisions


Telectron > Tvib > Tgas

Treanor–like distribution: overpopulation of higher vibrational

states leads to lower activation energies, faster kinetics

Energy efficient dissociation using plasma?


electrons

electric field

collisions

radical

chemistry

Cost of plasmas expensive energy-wise: • Creating electron-ion pair typically > 30 eV !

• Additionally use radical O (!) CO2 CO + O (ΔH=5.5 eV) followed by CO2 + O CO+ O2 (ΔH=0.3 eV) so overall CO2 CO + ½O2 (ΔH=2.9 eV)

A.V. Eletskii, B.M. Smirnov, Pure. Appl. Chem. 57 1235 (1985)

Energy efficient dissociation of CO2


Yes if the following plasma aspects are considered:

• Create nonequilibrium plasma with Telectron > Tvib> Tgas

• Low mean electron energy (1-2 eV) to excite dominantly lower

vibrational states and sufficient ionization degree (>10-5): Vibrational pumping (nonequilibrium effect!) and low V-T relaxation takes

care of high population of vibrational states required for efficient dissociation and fast kinetics

• Re-use atomic oxygen to dissociate aditionally CO from CO2 (high p, low conversion!)

Energy efficient dissociation of CO2


Yes if the following plasma aspects are considered:

• Create nonequilibrium plasma with Telectron > Tvib> Tgas

• Low mean electron energy (1-2 eV) to excite dominantly lower

vibrational states and sufficient ionization degree (>10-5): Vibrational pumping (nonequilibrium effect!) and low V-T relaxation takes

care of high population of vibrational states required for efficient dissociation and fast kinetics

• Re-use atomic oxygen to dissociate aditionally CO from CO2 (high p, low conversion!)

Engineering specs to choose plasma:

• Use kinetics, time scales of relaxation

• Design electric field configuration

• High pressure to minimize wall losses

DBD/Packed bed Catalytic reaction enhanced by Plasma catalysis. http://www.jeh-

center.org/electro/plasma/theory.html

Corona discharge

http://www.pages.drexel.edu/~rpg32/Research.htm

Dielectric barrier discharge

Gliding arc

Surface discharge

• Non-thermal process (room temp) • Throughput necessary (scale !) • Scalable (stacked microreactors?) • Essentially nonequilibrium • Controle of EEDF

Courtesy Tomohiro Nozaki (Tokyo Institute of Technology)

1-5mm

Choice of plasma

Microwave discharge

Sub-atmospheric CO2 plasmas: CO2 CO + ½O2

(Sub-)atmospheric μwave discharge

Various nozzle positions/types explored

Nozzle Positions I z = -3 cm II z = 0 cm III z = 12.4 + 0 cm IV z = 12.4 + 5 cm V z = 12.4 + 3 cm

4 3

2 1

Cavity (12.4 cm)

IV I II III V z

Nozzle configurations/types: 1. Straight (∅ 26 mm) 2. Symmetric (∅ 26 mm: ∅5 mm & ∅10 mm throat) 3. Laval (∅ 26 mm: ∅5 mm throat) 4. Double nozzle (Laval/Cu exit nozzle of ∅5 mm)

1 2

3 4

915 MHz E010 or TM010 mode @ 3kW: Emax = 27 kV/m

Engineering knobs to controle plasma generation to obtian high power efficiency

of CO2 activation

0

10

20

30

40

50

60

70

80

0 2000 4000 6000 8000

Out

put f

low

[slm

]

Power [W]

Experimental Results: supersonic region

CO produced at expense of CO2 CO2 CO + ½O2 ∆H = 2.9 eV

Constant CO2 flow of 75 SLM

η = ∆H/ECO

Energy efficiency:

10 mm symmetric nozzle at exit of RF cavity RF input power 3020-8010 W Gas pressure reaction chamber 190-250 mbar Expansion chamber 0.3..0.4 mbar Energy spent per CO2 molecule 0.56..1.49 eV

CO2

CO O2

0

10

20

30

40

50

60

70

0 2000 4000 6000 8000

Effic

ency

[%]

Power [W]

Energy efficiency [%]

Conversion efficiency [%]

0

10

20

30

40

50

60

70

80

0 2000 4000 6000 8000

Out

put f

low

[slm

]

Power [W]


CO produced at expense of CO2 CO2 CO + ½O2


η = ∆H/ECO

CO2

CO

O2

ηpower

βdiss

0

10

20

30

40

50

60

70

0 2000 4000 6000 8000

Effic

ency

[%]

Power [W]

Energy efficiency [%]

Conversion efficiency [%]

0

10

20

30

40

50

60

70

80

0 2000 4000 6000 8000

Out

put f

low

[slm

]

Power [W]


CO produced at expense of CO2 CO2 CO + ½O2


η = ∆H/ECO

CO2

CO

O2

ηpower

βdiss

Power efficiency ≈ 60% Dissociation (@3.6kW) ≈ 11%

η = ΔH/ECO CO2 CO + ½O2 ΔH = 2.9 eV

From A. Fridman, “Plasma Chemistry” (Taylor&Francis 2009)

Literature reports > 50% energy efficiency of CO2

dissociation !

Key is reduced electric field and energy per molecule!

Energy efficiency

Reported results on energy efficiency

CO2 CO + ½O2

Efficiency > 20 %

CO2 activation using plasma

Efficiency 70-80 %

Advantage: separate optimization possible

sustainable energy

*compare with electrolysis H2O > 16 €/kmol

CO2 CO + ½O2

Efficiency > 20 %

CO2 activation using plasma

Efficiency 70-80 %

Advantage: separate optimization possible

sustainable energy

97 kWh/kmol* @ ηpower =80%

*compare with electrolysis H2O > 16 €/kmol


Sustainable energy generation within reach : Clear economy of scale, hugh capacity deployed

Next challenge: storing sustainable energy in solar fuels Cost effective CO2 neutral energy infrastructure In line with the present energy infrastructure Several approaches are adopted: H2O splitting prominent, CO2

activation still in infancy phase, direct and indirect

Plasma activation of CO2 approach highlighted: Nonequilibrium essential to obtain high energy efficiency Power efficiency obtained so far ~ 60% ; 80% within reach Next challenge: - diagnose the plasma (E/ngas, CO2(r,v), ne, etc.) - gas stream separation without energy penalty

Directing Matter and Energy “Five challenges for science and the imagination”, Report Basic Energy Science Advisory Committee

How do we characterize and control matter away, especially very far away, from equilibrium?

Nonequilibrium: controlling complexity

One of the five challenges directly linked with plasma science:

Ackowledgements

FOM-DIFFER (Solar Fuels) Waldo Bongers Adelbert Goede Martijn Pieter-Willem Groen Institute fur Plasmaforschung Jochen Kopecki

Martina Leins

Andreas Schulz

Matthias Walker

FOM-DIFFER (Fusion) Tony Donne et al. Greg De Temmerman et al.

TU/e Richard Engeln

Stefan Welzel

Srinath Ponduri

Florian Brehmer

Ma Ming

Sustainable energy storage in chemical fuels for CO2 neutral energy generation: �a plasma perspective��Richard van de Sanden�The TeraWatt Challenge (15 TW)Slide Number 3The Terawatt challengeThe Terawatt challengeThe TeraWatt ChallengeContentsSustainable energy - is there enough?Slide Number 9Slide Number 10Slide Number 11Slide Number 12However…….Sustainable energy - storage neededSlide Number 15Solar FuelsSolar FuelsSlide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25ContentsSlide Number 27Solar energy conversion (direct & indirect)Slide Number 29Slide Number 30Solar energy conversion (direct & indirect)Direct photocatalytic conversion of H2OSlide Number 33Slide Number 34Slide Number 35Direct photocatalytic conversion of CO2Solar energy conversion (direct & indirect)Slide Number 38Slide Number 39Electric energy conversion: electrolysisElectric energy conversion: electrolysisContentsSolar energy conversion (direct & indirect)Slide Number 44Plasmachemical activation of CO2What is plasma?Electric energy conversion: plasmachemicalPlasmas and large scale Energy efficient dissociation using plasma?Energy efficient CO2 dissociation with plasma?Slide Number 51Slide Number 55Slide Number 56Slide Number 59Energy efficient dissociation using plasma?Energy efficient dissociation of CO2Energy efficient dissociation of CO2Choice of plasma(Sub-)atmospheric μwave discharge Various nozzle positions/types exploredSlide Number 66Slide Number 67Slide Number 68Slide Number 69Slide Number 70Slide Number 71Conclusions and OutlookSlide Number 73Ackowledgements

sustainable energy storage in chemical fuels for co2 ... · dissociation with plasma? can it be...

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