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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
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Catalysis as chemo-
electro- and photo-
catalysis
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
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CEC costs substantial activation
Larger for multiple steps (life)
Kinetics requires additional contribution
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Sustainable energy (technical)
and water splitting
• Primary electricity is volatile: energy
carrier molecules will always be
needed:
• Storage of electrical energy into
molecules indispensable for large-
scale 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
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
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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
CP43
CP47 D1
D2
lumen PsbO PsbU
PsbV
cytoplasm
C2-Axis
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
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
• 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.
• 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.
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What to do with the renewable hydrogen?
CO2 hydrogenation (http://www.hypos-eastgermany.de)
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• 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
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Lurg
i
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
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Cu
Stepped Surface
T (K)
H2 / [CO+CO2] = 75 / 25, 50 bar
Methanol Chemistry, in Chemical
Energy Storage (R. Schlögl, Ed.) de
Gruyter 2012.
CO2 hydrogenation
CO hydrogenation
Reverse water gas shift
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Can we become better after all those years?
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Catalysts can become
substantially better when
we learn to control the
interaction between the
two co-systems.
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.
Yes, we can !!
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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 co-
utilization 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
