Chemical energy conversion
More than just “storage”
Robert Schlögl
Fritz-Haber-Institut der MPG
Max-Planck- Institut für Chemische
Energiekonversion Mülheim
(MPI CEC)
www.fhi-berlin.mpg.de
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ESYS in dialogue with Politics and „Society“
Status:
We work since
autumn 2013.
First ad hoc groups
deliver results.
First round of
dialogue-oriented
advice to politics in
planning for Q2
2014.
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MPI CEC:
basic concepts of energy integration
Catalysis as chemoelectro- and photocatalysis
is the enabling basic
science of energy
storage.
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A systemic solution
Storage (transport) of large amounts of energy
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The energy challenge is systemic
storage is important but not the only option
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(Chemical) Energy storage
CEC costs substantial activation
Larger for multiple steps (life)
Kinetics requires additional contribution
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Sustainable energy (technical)
and water splitting
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• Primary electricity is volatile: energy
carrier molecules will always be
needed:
• Storage of electrical energy into
molecules indispensable for largescale renewable energy systems.
• Water splitting is the key reaction to
connect the electrical with the
chemical world.
• Electro-catalysis is the underlying
science.
• The most critical part is the
performance and stability of the
oxygen evolution reaction.
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The potential of Biomass: energy carrier
• Biomass is ubiquitous.
• It can be used without
interference to food.
• It is low in specific energy
content.
• It requires complex
refining:
– Direct conversion
(fermentation)
– pyrolysis
– gasification
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Energy carrier
Energy
Biodiesel (raps)
1.7
Bioethanol (maize)
3.5
Bioethanol (sugar cane)
4.5
Bioethanol (switch grass)
2.0
Biogas (silage)
10.0
PV (D)
90
PV (BR)
170
Free energy production
from solar conversion in kWh/m2/a:
Source: recalculated from data Leopoldina Biomass
study 2012
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Biological water splitting: the PS 2 system
cytoplasm
CP43
D1
D2
CP47
cyt b-559
In the biological
photosynthesis chain
the water splitting
system is a Mn
oxocluster in a most
complex environment
enabling water splitting
for about 30 min
PsbV
PsbO
PsbU
lumen
C2-Axis
W. Lubitz, F. Neese and teams
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Ir-oxyhydroxy species as OER catalysts
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The over potential of OER
can be almost eliminated by
replacing IrO2 catalysts by
[Irx(O)y(OH)z] oligomeric
molecules contacted with a
glassy carbon or gold
electrode
2 nm
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Biological vs technical water splitting:
the oxygen evolution side
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Abundant metals with dynamical
oxo-linkers allowing hinge function
Complex ligand systems prevents
structural collapse of dynamical
sites
No high-energy intermediates: one
electron per metal atom.
Specific binding of water
molecules such that O-O bond
formation is prepared.
Optimized mesostructure for all
elementary steps.
Proton-coupled charge transfer:
charge neutrality preserved.
Self-repair mechanisms.
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Noble metals with oxy-hydroxo
ligands allowing hinge function
Conducting oxide occurs during
degradation: stabilizing ligands
are missing
Metallic core screens large
charges.
Statistical distribution, lattice
hydroxide concept.
Glassy gel-like active layer on
rigid support.
Charge separation of proton
from the electrode.
Structural dynamics and lattice
hydroxide regeneration.
What to do with the renewable hydrogen?
CO2 hydrogenation (http://www.hypos-eastgermany.de)
The most simple
reaction seems to be
methanation. Potent
catalysts show grave
stability problems when
operated at high load.
The hydrogenation of
COx to alcohols is a
more robust reaction to
obtain solar fuels and
platform chemicals.
Nanostructuring of metal
particles is the critical
tool for controlling
selectivity.
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H2, (CO, CO2)
50-100 bar, 210-260°C
CH3OH + H2O
Lurgi
AG
G.A. Olah, A. Goeppert ,G.K.S. Prakash
J. Org. Chem. 74 (2009) 487.
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Why CEC is catalysis science
also downstream of hydrogen generation
CO2 hydrogenation
CO hydrogenation
Reverse water gas shift
Cu
Stepped Surface
H2 / [CO+CO2] = 75 / 25, 50 bar
T (K)
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Methanol Chemistry, in Chemical
Energy Storage (R. Schlögl, Ed.) de
Gruyter 2012.
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Can we become better after all those years?
Catalysts can become
substantially better when
we learn to control the
interaction between the
two co-systems.
Yes, we can !!
Both theory and in-situ
experimentation have
shown that the system is
dynamical and can be
controlled through its
medium-scale electronic
structure that has until
now not been studied.
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The energy challenge is systemic:
useful large scale storage by chemistry is possible
• Renewable energy at large cannot be sustainable without either coutilization of fossil energy (near future) or with large-scale energy
storage (medium future).
• The missing large scale energy storage options do not impede more
primary renewable electricity, rather some regulatory misconceptions
and the difficulty of systemic solutions.
• CEC is not ready yet: however first test realizations on grid scale
possible within the next decade (funding as „experiments“ necessary,
pre-technology despite large scale).
• Fundamental approaches and a grassroots approach deliver still missing
understanding and unexpected options.
• Chemistry and catalysis will have to play a dominant role in sustainable
energy supply and efficient energy utilization.
• Change management begins with systemic understanding of energy
utilization; the energy system is dynamical and multi-scale!
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Dem Anwenden muss das Erkennen vorausgehen
Max Planck
Thank You
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