resource recovery
The Microbial
Rechargeable Battery:
energy storage
through acetate
Sam Molenaar
[email protected]
Motivation
Charge
e-
em
e
m
b
r
a
n
e
energy density (kWh/m3)
350
300
250
H/
200
150
n
olte
100
50
0
d
aci
dlea
0
m
t
sal
M
Ni-
>
m>
iu
Lith
0,5
1
1,5
max. attainable acetate concentration (M)
Fe2+
Cathode
m
e
m
e
b
r
a
n
e
e-
eDischarge
Research goals
• Deliver the proof-of-concept
• Increase energy density by optimization of acetate concentration
during charging
• Improve cell voltage and footprint by selection and testing of
suitable counter electrode reactions
• Obtain high power density and energy efficiency by smart system
design
2
Figure 4 Maximal achievable energy density of the MRB (blue line) as a function of
maximal attainable acetate concentrations when fully charged, with indication of conventional battery technologies for reference. Based on published data [3] on maximal
biologically attainable acetate concentration, energy density could reach up to roughly
120 kWh/m3 (red arrow)
www.wetsus.eu
www.wur.nl
Fe3+
Acetate
Bioanode
Technological challenge
While both microbial electrosynthesis (MES) and microbial fuel cells
(MFCs) have been subject of intensive study over the last decades [1,2],
they have not yet been integrated into one system, with the objective
to store and recover electricity. For this new concept, we introduce
the name Microbial Rechargeable Battery (MRB). In a MRB, during
the MES phase, electrical energy is consumed to form acetate,
while during the MFC phase, electrical energy is generated by
consumption of acetate. The proposed system therefore requires
stable intermittent operation of both biocathode, bioanode, and
their counter electrodes. It is our challenge to proof this concept,
and then improve it.
Anode
Biocathode
CO2
With ever increasing worldwide energy demands and raised
concerns about the environmental impacts of burning fossil fuels,
renewable energy sources are slowly but steadily gaining ground.
One of the major challenges for implementing renewable electricity
is the variability in generation of sun and wind energy and matching
this with a fluctuating demand. Energy storage devices will likely
become a necessity with further increasing renewable electricity
shares. Current storage systems often cope with safety issues
or toxicities and require scarce and non-renewable materials.
Therefore, a safe, renewable and low-cost system for householdscale energy storage would bear high potential.
Bioelectrochemical systems (BESs) could play an important role
in future energy storage, as the catalysts in these systems (i.e.
microorganisms) (re)generate and use renewable and widely
available substrates, namely water, CO2 and nutrients.
[1] Sleutels, T. H. J. A., Ter Heijne, A., Buisman, C. J. N. & Hamelers, H. V. M. Bioelectrochemical systems:
an outlook for practical applications. ChemSusChem , (2012) 5, 1009-1012.
[2] Rabaey, K. & Rozendal, R. A. Microbial electrosynthesis - revisiting the electrical route for microbial
production. Nat. Rev. Microbiol. (2010) 8 706–716
[3] Demler, M.; Weuster-Botz, D. Reaction Engineering Analysis of Hydrogenotrophic Production of Acetic
Acid by Acetobacterium Woodii. Biotechnol. Bioeng. (2011) 108 (2), 470–474
S. Molenaar, dr.ir. A. ter Heijne,
dr.ir. T.H.J. Sleutels, prof.dr.ir. C.J.N. Buisman