Transcript Document

Energie uit water
KIVI/NIRIA
16 oktober 2006
prof.dr.ir. Cees J.N. Buisman
www.wetsus.nl
Sub-department of
Environmental Technology
06-0068
www.ete.wur.nl
De wereldcapaciteit wordt overschreden
Sub-department of
Environmental Technology
06-0068
Bio-energie op dit moment
belangrijkste renewable
Source IAE 2003
Sub-department of
Environmental Technology
06-0068
Biomassa is geen schone brandstof
Source: Exploring the future Shell International
Sub-department of
Environmental Technology
06-0068
Bio-energie acetaat ipv suiker
Primaire
productie
Suiker
energie
Primaire
productie
Acetaat
energie
Sub-department of
Environmental Technology
06-0068
Via acetaat is er veel meer
energiepotentieel in biomassa
POTENTIAL [PJ/yr]
160
140
120
100
80
60
40
20
0
Sugar
Acetate
Source SenterNovem 2003
Sub-department of
Environmental Technology
06-0068
Schone conversie essentieel
Hydrogen
: 3 $ct/MJ
Ethanol
: 3 $ct/MJ
Electricty
: 2 $ct/MJ
WET BIOMASS
via acetate
Methane
Sub-department of
Environmental Technology
06-0068
: 1 $ct/MJ
Elektriciteitsproductie
uit Rioolwater
Biobrandstofcel
+ 2 kWh/kg COD
Aërobe zuivering
- 0,5 kWh/kg COD
Anaërobe zuivering
+ 0,9 kWh/kg COD
Sub-department of
Environmental Technology
06-0068
COD
• COD = Chemical Oxygen Demand
• Used to generalize all dissolved (bio)-oxidizable material
in wastewaters.
• Value expresses the amount of oxygen needed to
completely oxidize the (bio)-oxidizable material.
• Represents the amount of potential energy contained in
the wastewater.
Sub-department of
Environmental Technology
06-0068
Electrochemically Active
Micro-organisms
Biological Anode
COD in
Wastewater
(e.g. fatty acids)
e-
ee-
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ee-
Electrons
Sub-department of
Environmental Technology
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A
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Bio-electrochemistry
Electrochemically Active Micro-organisms
Sub-department of
Environmental Technology
06-0068
Source: http://www.geobacter.org
Nano Wires
Source Nature Reviews 2006
Sub-department of
Environmental Technology
06-0068
Biological anodes
Electron production
• Glucose:
 C6H12O6 + 6 H2O  6 CO2 + 24 H+ + 24 e-
• Acetic Acid:
 CH3COOH + 2 H2O  2 CO2 + 8 H+ + 8 e-
• Sulfur:
 S0 + 4 H2O SO42- + + 8 H+ + 6 e-
• Etc.
• These electrons are released at a high energy level!
Sub-department of
Environmental Technology
06-0068
Microbial Fuel Cell
Example Acetic Acid
• Biological Anode:
 CH3COOH + 2 H2O  2 CO2 + 8 H+ + 8 e-
• Cathode:
 2 O2 + 8 H+ + 8 e-  4 H2O
• Overall:
 CH3COOH + 2 O2  2 CO2 + 2 H2O +
electricity
 In theory:
~1 Volt
Sub-department of
Environmental Technology
06-0068
Microbial Fuel Cell
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EnergyConsumption
Consumption
Bacteria
Energy
Energie
Opbrengst
Bacteriën
Bacteria
(= Potential loss)
-0.5
-0.4
Glucose/CO2 (-0.41 Volt)
-0.3
Acetic Acid/CO2 (-0.27 Volt)
Biological Anode Potential
(~ -0.2 Volt)
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
Bio-electricity
(+1.02 Volt)
0.6
0.7
0.8
O2/H2O
0.9
(0.82 Volt)
Bio-Anode Cathode
1.0
Sub-department of
Environmental Technology
06-0068
Microbial Fuel Cell
CO2
Exhaust
e-
H2O
H2O
O2 + H+
H+
Cathode
Sub-department of
Environmental Technology
Anode
Wastewater
(COD-rich)
CO2 + H+ COD
Effluent
(COD-poor)
e-
Air
= Electrochemically Active MO
06-0068
Configurations
Sub-department of
Environmental Technology
06-0068
Performance
• Perspectives
• Status
 Power Density:
1000 W/m3
 Voltage:
0.5-0.7 Volt
 Efficiency:
~60%
 Power Density:
~100 W/m3
 Voltage:
0.2-0.6 Volt
 Efficiency:
15-30%
For comparison: conventional anaerobic treatment coupled to a
gasmotor also produces approximately 1000 W/m3.
Sub-department of
Environmental Technology
06-0068
Bio electrochemie maakt grote stappen
voorwaarts
5000
COMMERCIEEL INTERESSANT
4500
Vermogensdichtheid
(mW/m2 anode oppervlak)
4000
3500
3000
2500
2000
1500
1000
500
0
8-jul-02
8-jul-03
7-jul-04
7-jul-05
7-jul-06
Datum
Sub-department of
Environmental Technology
06-0068
7-jul-07
6-jul-08
6-jul-09
The next step
SOLAR ENERGY
CO2 O2
ASSIMILATES
ELECTRICITY
MICROBIAL FUEL CELL
Sub-department of
Environmental Technology
06-0068
Biocatalysed Electrolysis
Example Acetic Acid
• Biological Anode:
 CH3COOH + 2 H2O  2 CO2 + 8 H+ + 8 e-
• Cathode:
 8 H+ + 8 e-  4 H2
• Overall:
 CH3COOH + 2 H2O  2 CO2 + 4 H2
 In theory:
0.14-0.22 Volt required
 In practice:
<0.5 Volt required
Sub-department of
Environmental Technology
06-0068
Biocatalysed Electrolysis
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-0.5
-0.4
Energy Consumption Bacteria
Energie Opbrengst Bacteriën
(= Potential loss)
H+/H2
Glucose/CO2 (-0.41 Volt)
(-0.42 Volt)
-0.3 Acetic Acid/CO2 (-0.27 Volt)
-0.2
-0.1
Biological Anode Potential
(~ -0.2 Volt)
0.0
0.1
Hydrogen production requires an
input of electricity (-0.22 Volt)
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Bio-Anode Cathode
1.0
Sub-department of
Environmental Technology
06-0068
Biocatalysed Electrolysis
CO2
e-
H2
H+
e-
H+
Cathode
Sub-department of
Environmental Technology
Anode
Wastewater
(COD-rich)
CO2 + H+ COD
Effluent
(COD-poor)
H2
Power
Supply
= Electrochemically Active MO
06-0068
Configuration
Power Supply
Electrochemical
Cell
Sub-department of
Environmental Technology
06-0068
Bio-electrochemical System
2 kWh
1 kg COD
1.6 m3 H2
Sub-department of
Environmental Technology
06-0068
Bio-electrochemical
Processes
Electricity and hydrogen from sustainable sources
160 MW
(1.3 % NL consumption)
Sewage
NL
1.1 billion m3 H2
(19 % car km NL)
675 MW
(5.4% NL consumption)
Manure
NL
Sub-department of
Environmental Technology
06-0068
4.6 billion m3 H2
(79 % car km NL)
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Sub-department of
Environmental Technology
06-0068