M. Specht1, U. Zuberbühler1, M. Sterner2, G. Waldstein3
1)
Centre for Solar Energy and Hydrogen Research (ZSW), Stuttgart2)
Fraunhofer
Institute for Wind Energy and Energy System Technology (IWES), Kassel 3)
SolarFuel
GmbH, Stuttgart
Storage of Renewable Energy in the Natural Gas Grid“Power-to-Gas –
Technology”
Speicherung Erneuerbarer Energie im Erdgasnetz
Deutsche Umwelthilfe, Congress “Energy Storage and Nature Conservation”,21.02.2011, Berlin
Agenda: Storage of Renewable Energy (RE) in the Natural Gas Grid
GoalSNG Production Routes from RE
Biogas SNG (Fermentative Route)Biomass Gasification SNG (Thermo-chemical Route)CO2 + Power SNG“Biogenic C”
+ Power SNG
Conversion EfficiencyEnvironmental Benefits of SNG from REConclusion / Next Steps
SNG: Substitute
Natural
Gas
Long Term Storage of Renewable Energy - FAQ -
How is long-term storage of energy realised today?
How much capacity do we need for RE storage?
What is the best way to collect and to store RE?
Can the existing infrastructure be used to store and to distribute RE?
What are the environmental impacts of storage technologies?
Land consumption of storage sites
Land consumption for power transmission
Other impacts like interference with landscape, electro smog, etc.
Energy Consumption and Storage Capacity in Germany (2008)
Electricity Natural gas Liquid fuels1)
Consumption [TWh/a] 615 930 707
Average power [GW] 70 1062) 81
Storage capacity [TWh] 0,043) 2174) 2505)
Calculated operating range of installed storage capacity6) [h] 0,6 2000 3100
1) Petrol, diesel, kerosene2) Seasonally fluctuating3) Pumped hydro storage4) 47 Underground gas storage facilities [Landesamt
für
Bergbau, Energie
und Geologie
(LBEG), Hannover]5) Provisioning of petrol, diesel, kerosene and heating oil6) Related to average power
Required storage capacity for electricity grid in DE: 20 -
40 TWh
!
Options for Long Term (Seasonal) Energy Storage: Chemical Energy Carriers
Hydrogen
Substitute Natural Gas (SNG)
Liquid Hydrocarbons
Renewable Energy Storage Systems: Capacity and Discharge Time
0,001
0,01
0,1
1
10
100
1000
10000
1 kWh 10 kWh 100 kWh 1 MWh 10 MWh 100 MWh 1 GWh 10 GWh 100 GWh
1 m
1 h
1 d
CAES
1 TWh 10 TWh 100 TWh
CAES
Fly
Wheels
Storage capacity of different storage types
Dis
char
ge ti
me
[h]
CAES Compressed
air
energy
storage
PHS Pumped
hydro
storage
SNG Substitute
natural
gas
Batteries
PHS
1 a
SNG
H2
Agenda: Storage of Renewable Energy (RE) in the Natural Gas Grid
Goal SNG Production Routes from RE
Biogas SNG (Fermentative Route)Biomass Gasification SNG (Thermo-chemical Route)CO2 + Power SNG“Biogenic C”
+ Power SNG
Conversion EfficiencyEnvironmental Benefits of SNG from REConclusion / Next Steps
SNG: Substitute
Natural
Gas
(Digestive) Biomass SNG: State-of-the-Art - Technology
AnaerobicDigester
Plant
Gas Cleaning /Conditioning
Bio-Gas
50 - 70 vol.-%CH4
DigestiveBiomass
Compost
SNG
Separation of• CO2
• H2O• Impurities
(to Grid orFilling
Station)
(Digestive) Biomass SNG:Pressure Swing Adsorption (PSA) Gas Upgrading
Biogas
Vacuum pump
Off-gas(CO2)
Flushing gas
SNG
Water separator
Compressor
Des
ulph
uris
atio
n
Ads
orbe
r uni
t
Agenda: Storage of Renewable Energy (RE) in the Natural Gas Grid
Goal SNG Production Routes from RE
Biogas SNG (Fermentative Route)Biomass Gasification SNG (Thermo-chemical Route)CO2 + Power SNG“Biogenic C”
+ Power SNG
Conversion EfficiencyEnvironmental Benefits of SNG from REConclusion / Next Steps
SNG: Substitute
Natural
Gas
(Woody) Biomass SNG:“BtG” Biomass-to-Gas
CO, H2
, CO2
, CH4
Gasification
Biomass
Producer Gas
SNG(CH1.52
O0.65
)
(Synthesis Gas)
(Gas conditioning,stoichiometry
adjustment)
1st
Step 2nd
Step
Synthesis
1st
Step: (Woody) Biomass Producer Gas:Gas Composition of Different Biomass Gasifiers
0%
20%
40%
60%
80%
100%
RENUGAS (1)
Carbo-V
(2)
HTW (3
)DMT (4
)MTCI (5
)DM2 (
6)Batt
elle (
7)Wrig
ht/Malt
a (8)
Hynol
(9)FIC
FB (10)
AER (11)
Vol
. %
H2 CO CO2 CH4 Ethane+Ethylene
autothermal allothermal
2nd
Step: Producer Gas SNG:Methanation of COx
CO + 3 H2 CH4 + H2
O(g)
ΔH298K
= -
206.2 kJ/molCH4
CO2 + 4 H2
CH4
+ 2 H2
O(g)
ΔH298K
= -
165.5 kJ/molCH4
2 CO + 2 H2
CH4
+ CO2
ΔH298K
= -
246.8 kJ/molCH4
SNG Generation in Fixed Bed Molten Salt Cooled Reactor
SNG
Product Gas from AER-Process
Salt Loop C
atal
yst
Zone
IZo
ne II
Zone
III
Dec
reas
ing
Tem
pera
ture
Goal:SNG without downstream CO-shift
and without CO2
separation
due to in situ AER adjustment of Syngas
stoichiometry
Demo-plant: 100 kWSNG
Concept presented at ACHEMA Fair in May 2009 (cooperation ZSW with MAN-
DWE, Germany)
AER Producer
Gas SNGExperimental Results
Vol.%
H2
67,5
CO2
12,0
Methanation
H2
3,5
CO2
6,0
CH4
90,5
Vol.%
AER producer
gas CH4
-rich product
gas
Parameter of methanation:
T = 250 -
500 °C
pe
= 6,5 bar
SVwet
= 3000 1/h
CO
8,5
CH4
12,0
Agenda: Storage of Renewable Energy (RE) in the Natural Gas Grid
Goal SNG Production Routes from RE
Biogas SNG (Fermentative Route)Biomass Gasification SNG (Thermo-chemical Route)CO2 + Power SNG“Biogenic C”
+ Power SNG
Conversion EfficiencyEnvironmental Benefits of SNG from REConclusion / Next Steps
SNG: Substitute
Natural
Gas
Power-to-Gas (PtG) -
Concept: Basic Layout
CCPP / B-CHP
CO2
buffer
Grid Gas distribution system
Electrolysis /
H2
bufferMethanation
H2
CO2
CH4
POWER GENERATION
ELECTRICITY STORAGE
CO2
Gas
storage
Solar
Wind
H2
CO2
CCPP: Combined Cycle Power Plant; B-CHP: Block-type Combined Heat and Power Station
Power-to-Gas -
Concept: Interconnection with Mobility
EV:
Electric Vehicle
BEV: Battery Electric Vehicle
FCEV: Fuel Cell Electric Vehicle
CNG-V: Compressed Natural Gas Vehicle
Plug-In HEV: Plug-In Hybrid Electric Vehicle
(especial: Plug-In Electric Drive Motor Vehicles / Range-Extended Electric Vehicle)
CCPP Combined
Cycle
power plant
B-CHP Block-type combined heat and power station
Solar
WindCCPP / B-CHP
CO2
buffer
Electricitygrid
Gas distribution
system
Electrolysis
/
H2
bufferMethanation
H2
CO2
CH4
POWER GENERATION
ELECTRICITY STORAGE
CO2
Gas
underground
storage
Electricity H2 SNG
BEV FCEV CNG-V
Mobility
H2
CO2
Plug-In HEV Plug-In HEV
Power-to-Gas -
Technology: Technical Realisation for SolarFuel
Company
CH4
-Filling stationca. 15 kg, 200 bar
Electrolyser
CO2
-Recovery
CO2
+ Power SNGExperimental Results
Vol.%
H2
79,5
CO2
20,5
Methanation
H2
4,6
CO2
5,3
CH4
90,2
Vol.%
Synthetic educt
gas CH4
-rich product gas
Parameter of methanation:
T = 250 -
500°C
pe
= 6 bar
SVwet
= 4000 1/h
Agenda: Storage of Renewable Energy (RE) in the Natural Gas Grid
Goal SNG Production Routes from RE
Biogas SNG (Fermentative Route)Biomass Gasification SNG (Thermo-chemical Route)CO2 + Power SNG“Biogenic C” + Power SNG
Conversion EfficiencyEnvironmental Benefits of SNG from REConclusion / Next Steps
SNG: Substitute
Natural
Gas
Utilisation of Biogenic CO2
Resources for PtG-Process
C6
H12
O6
3 CH4
+ 3
CO2
Simplified overall reaction
C6
H12
O6
2 C2
H5OH + 2
CO2
Biogas production:
Ethanol production:
Biogas plant, Foto: Krautkremer
EtOH
plant in Nebraska, USA
Power-to-Gas -
Concept: Option 1 –
Interconnection with Biogas Plant
CCPP / B-CHP
CO2
buffer
Grid Gas distribution system
Electrolysis /
H2
bufferH2
CO2
CH4
POWER GENERATION
ELECTRICITY STORAGE
CO2
Gas
storageBiomass
Solar
Wind
H2
Biogas plant with
SNG production
CH4
Methanation
Heat
CCPP: Combined Cycle Power Plant; B-CHP: Block-type Combined Heat and Power Station
Power-to-Gas -
Concept: Option 2 –
Interconnection with Biogas Plant
CCPP / B-CHP
CH4
/CO2
buffer
Grid Gas distribution system
Electrolysis /
H2
bufferH2
Biogas
CH4
POWER GENERATION
ELECTRICITY STORAGE
Biogas
Gas
storageBiomass
Solar
Wind
H2
Biogas
plant
Methanation
HeatCH4
/CO2CH4
/CO2
CCPP: Combined Cycle Power Plant; B-CHP: Block-type Combined Heat and Power Station
Power-to-Gas -
Container: Operation at a Biogas Plant with Biogas and PSA Off-Gas
Power-to-Gas -
Container: Operation with PSA Off-Gas at a Biogas Plant
0
10
20
30
40
50
60
70
80
90
100
00:00 01:00 02:00 03:00 04:00 05:00 06:00 07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00
Dauer [hh:mm]
y_C
H4 [
Vol-%
]
0
10
20
30
40
50
60
70
80
90
100
y_C
O2,
y_H
2, y_
O2 [
Vol-%
]
CH4 H2 CO2 O2
Power-to-Gas -
Concept: Option 3 –
Interconnection with Biomass Gasification
CCPP / B-CHP
H2
/CO/CO2
buffer
Grid Gas distribution system
Electrolysis /
H2
bufferH2
Syngas
CH4
POWER GENERATION
ELECTRICITY STORAGE
Syngas
Gas
storageBiomass
Solar
Wind
H2
Gasifi-
cation
Methanation
H2
/CO/CO2 H2
/CO/CO2
O2
CCPP: Combined Cycle Power Plant; B-CHP: Block-type Combined Heat and Power Station
Agenda: Storage of Renewable Energy (RE) in the Natural Gas Grid
Goal SNG Production Routes from RE
Biogas SNG (Fermentative Route)Biomass Gasification SNG (Thermo-chemical Route)CO2 + Power SNG“Biogenic C”
+ Power SNG
Conversion EfficiencyEnvironmental Benefits of SNG from REConclusion / Next Steps
SNG: Substitute
Natural
Gas
Schematic
Diagram of a Wind-to-SNG
-
Plant for
IPSEpro Process
Simulation (Feed: CO2
/H2
and Biogas/H2
)
SettingsEnergy demand electrolysis:
4 kWhel
/mN3H2
System pressure:
7 barabsGrid pressure:
16 barabs
Energy Flow of a Wind-to-SNG -
Plant
Case
1: “CO2
/H2
-to-SNG"Case
2: "Biogas/H2
-to-SNG“
(50 / 50 [Vol.%CH4
/ Vol.%CO2
] in biogas)Case
3: "Biogas/H2
-to-SNG“
(70 / 30 [Vol.%CH4
/ Vol.%CO2
] in biogas)
Influence of Electrolysis Efficiency on Wind-to-SNG System Efficiency (CO2
/H2
-to-SNG)
40
45
50
55
60
65
70
3,5 3,7 3,9 4,1 4,3 4,5 4,7 4,9 5,1
Electrolysis power requirement [kWhel
/mN3H2
]
Sys
tem
effi
cien
cy [%
]
Comparison Storage Efficiency incl. Re-Conversion: H2
vs. SNG
SNG
100 60 ca. 35
ElectrolysisMethanisation
Gas/steampower plantη
= 58 %
H2
100 75 ca. 34
Electrolysis Gas engineη
= 45 %
Agenda: Storage of Renewable Energy (RE) in the Natural Gas Grid
Goal SNG Production Routes from RE
Biogas SNG (Fermentative Route)Biomass Gasification SNG (Thermo-chemical Route)CO2 + Power SNG“Biogenic C”
+ Power SNG
Conversion EfficiencyEnvironmental Benefits of SNG from REConclusion / Next Steps
SNG: Substitute
Natural
Gas
Land Consumption: Pumped Hydro Storage vs. Power-to-Gas Storage
Goldisthal Source: e.on
Hanse
Pumped hydro power
Water surface, Dam, Bank reinforcement
Land use: 2 -
44 kWhpot
/m2
ηturbine
=
88 %ηpump
= 85 %
Underground storage facilities / PtG
Well site: 40 m x 60 m; Over ground facility, gas compression station: 200 m x 200 m; Security area
Land use: ca. 100 000 kWhSNG
/m2
ηSNG electricity < 60 %ηelectricity SNG = 60 - 65 %
Landscape Impact of Electricity Transmission
Transmission power line
Land Consumption: SNG Transmission vs. Electricity Transmission
Sources: Wuppertal Institut
für
Klima, Umwelt
und Energie; P. Konstantin; G. Wossog; H. Brakelmann; OMV
Gas Electricity
Pressure Diameter Transmission power
Protection strip Voltage
Trans-
mission
power
Overhead line, Route width
Underground
cable,
Protect. strip
[bar] [DN] [GW] [m] [kV] [GW] [m] [m]
< 0,1 50-600 < 0,1 2 -
10 0,4 (low) 10 1
> 0,1-1 100-400 0,01 -
0,2 2 -
8 1-24 (medium) 20 4
> 1-16 300-600 0,8 -
3 6 -
10 50-170 (high) 0,3 44 7
> 16
900 9 -
12 8 -
10 220 (high) 0,5 55 9
1000 12 -
16 8 -
10 380 (high) 0,9 70
1400 21 -
28 8 -
10
Transmission power:
Gas pipeline < 70 GW Power line < 7 GW
Environmental Benefits: Emissions Reduction through CNG-Vehicles
-80% -80%
-20%
-40%
-10%
-60%
-90%
-10%
-80%
CO NMHC GHG OZONE CO NMHC NOx GHG OZONE
in relation to gasoline in relation to Diesel
Source: nach
Fachverband
der
Gas-
und Wärmeversorgungsunternehmen, Wien
1) 1)
1) Green house gas reduction by using natural gas;nearly 100 % reduction by using renewable SNG!
Environmental Benefits -
SNG Utilisation in CNG Cars: “Wind Energy for Mobility”
Opel Zafira
1.6 CNG ecoFLEX
Turbo, CNG cruising range: 370 km
85 000 CNG vehicles on the road875 filling stations
(Germany, 2009)
VW Passat
1.4 TSI EcoFuel,CNG cruising range: 480 km
Daimler B 180 NGT, CNG cruising range: 370 km
Environmental Benefits -
SNG Utilisation in CNG Trucks: Clean Fuel for Densely Populated Areas
Environmental Benefits -
SNG Utilisation in μ-CHP: Virtual Power Plant
SNG
100 65 ca. 60
ElectrolysisMethanisation
μ-CHPpower plantη
< 60 % (electric)
Today:Lichtblick-Conceptwith VW μ-CHP,ηel
= 33 % Tomorrow:BlueGEN
SOFC fromCeramic FuelCells Limited,
ηel
= 60 %
∆+
Agenda: Storage of Renewable Energy (RE) in the Natural Gas Grid
Goal SNG Production Routes from RE
Biogas SNG (Fermentative Route)Biomass Gasification SNG (Thermo-chemical Route)CO2 + Power SNG“Biogenic C”
+ Power SNG
Conversion EfficiencyEnvironmental Benefits of SNG from REConclusion / Next Steps
SNG: Substitute
Natural
Gas
Integration of Renewable Energy in Electricity and Gas Grid
Natural Gas (NG)
Load = Feed (at any time)
Load ≠
Feed (at the same time)
FEED LOAD
Electricity Grid
GRID
Conventional Power
Gas Grid
Gas Storage > 200 TWh
„Electricity“
Storage 0,04 TWh
Fluctuation Electricity from Renewables
Gas from Renewables
Backup Power
Production and Utilisation Flexibility of Renewable SNG
Upgraded biogas via anaerobic digestion
Bio-SNG via biomass
gasification
E-Gas via Power-to-
Gas-Process
Electricity generation (EEG)
Mobility
Heating market, Industry
Combined cycle power plant
Peak power (gas turbine)
GtL
plant (Aviation Fuel)
Production Utilisation
Pool renewable
SNG
H2
μ-CHP (virtual power plant)
Conclusion: Advantages of Renewable SNG / PtG
-
Technology
Inspired by nature: “PtG as artificial photosynthesis”
Increasing importance of (S)NG backup power for load balancing
SNG is an ideal chemical storage medium for RE
Storage of RE with “unlimited” storage capacity in the gas grid
Utilisation of existing underground gas storage facilities
Stabilization of electricity grid (positive and negative control power)
Merging of the energy sectors “electricity grid”, “gas grid”, and “mobility”
Conclusion: Combination Renewable Electricity and Bio-energy
Biomass contains renewable carbon and is therefore predestined for the generation of carbon-based fuels
The combination biomass/electricity from RE offers a 3 times higher output of carbon-based fuels compared to biomass alone
Biomass and renewable electricity are ideal partners !
Conclusion: Environmental Benefits
No environmental disadvantages of renewable SNG compared to other existing storage technologies for RELong term storage in the form of SNG enables a 100 % RE system (without coal and nuclear power plants)PtG-Technology without limitation of agricultural areaReduced land consumption for SNG transmission via pipelines compared to high voltage electricity transmissionReduced land consumption for the SNG storage facility compared to pumped hydro powerCO2-neutral Carbon-based fuel for mobility
Reduced traffic pollutant emissions (no particles, 90 % NOxreduction vs. Diesel engines, etc.)
Vision: Wind Energy for Mobility –
NOW!
SNG as CO2
- neutral fuel for
sustainable mobility
Timeline Commercialisation
Alpha-plant (25 KWel): Nov. 2009
Alpha-plus-plant (250 kWel): spring 2012
Beta-plant (6 MWel): 2013
Gamma-plant(> 6 MWel
, commercial product):
2015
Co-operation partners of ZSW:
An interesting discussion !
Thanks for your kind attention.