Power-2-Gas
Future Use of the Gas Grid
for Renewable Energy Storage
Fritz Crotogino + Sabine Donadei
KBB Underground Technologies GmbH, Hannover, Germany
EnergyWise12th ANNUAL GLOBAL GAS VILLAGE SUMMIT
Creating Value in a Shifting UGS Marketplace
KBB Underground Technologies GmbHHannover, Germanywww.kbbnet.de
2
KBB UT plans and builds underground storages for
air
natural gasoil
hydrogen
natural gas
crude oil, gasoline, LPG
electric power viacompressed air (CAES) or hydrogen
caverns in salt formation 3natural gas
Content
1. Future gas market
2. Transition to renewable energies
3. Large scale energy storage - overview
4. Power-2-Gas
4.1 Direct use of green hydrogen
4.2 Adding H2 to natural gas grid
4.3 Methanation
4.4 Comparison of Power-2-Gas options
5. Summary
4
1. Future gas marketGoals of German government
Reductions until 2050
5
Reductions – how to achieve?
less
more
gas
Fluctuating
energy sources
wind and solar
6
Impact on traditional gas market:
demand forresidential heating
natural gas sales
7
2. Transition to renewable energiesEnergy supply chain – Today: Based on fossil sources
Power vs. Time
Storage Grid
Primary Energy Source Electric Power
Storage of energy source/fuel beforeconversion to required energy form.
Conversion to
Power
Primary EnergySource
Power vs. Time
Storage
8
Energy Supply Chain – TomorrowBased on Renewable Sources
Primary EnergySource
Power vs. Time
StoragePower
vs. TimeStorage Grid
Primary Energy Source Electric Power
Storage of electric energy after conversion.
Conversion to
Power
9
- for natural gas- theoretical valuefor hydrogen
Capacity of existing undergroundgas storages in Germany:
10Untertage-Gasspeicherung in Deutschland
ERDÖL ERDGAS KOHLE 127, Jg. 2011, Heft 11
200 TWh natural gas
40 GWh electric power
Energy supply chain – tomorrowbased on renewable sources
Primary EnergySource
Power vs. Time
StoragePower
vs. TimeStorage Grid
Primary Energy Source Electric Power
Storage of electric energy after conversion.
Conversion to
Power
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3. Large scale energy storage - overviewPumped hydro plant
1000m
upper pond12 mio m³
lower pond
12
Goldisthal, Germany, P = 1 060 MW / W = 8 h * 1 060 MW / eta > 80%
Adiabatic Compressed Air Energy Storage
compressor
power in
e-motor
heat storage
air turbine
generator
compr. air
power out
salt cavern
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Hydrogen – storage - system
electrolyser CC GT
fuel cell
underground
storage
user
transmission
H2
gas station
wind energy
wind power > hydrogen > storage > power
14
Existing hydrogen storage facility
Sabic Petrochemicals H2 caverns at Teesside, UK
3 caverns a 70,000 m³
p = 45 bar constant
depth ca. 370 m
Volumetric energy densities
H2 (100%) H2 (60%) AA CAES pumped hydrocombined cycle GT plant
170 kWh/m³
2,4 kWh/m³ 0,7 kWh/m³
assumptions:H2 / CH4 ∆p = 120 baradiab. CAES ∆p = 20 barpumped hydro ∆h = 300 m
Vo
lum
etri
c e
ner
gy d
en
sity
in k
Wh
/m³
methane1.100 kWh/m³
280 kWh/m³
energy density after conversion to power
heating value
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4. Power-2-Gas4.1 Direct use of green hydrogen
H2O O2
renewable CO2
H2
caverns
electricity
mobility
industry
methani-
zation
natural
gas net-
work
electrolyzer
CH4
17
Large scale underground storagein depleted oil / gas field or aquifer formation
PorenspeicherPorenspeicherwater
gas
18
Large scale underground storage in man-made salt caverns
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Transmission power for electrical power vs. natural gas
transmission
line
gas pipeline
po
we
r / M
W4.2 Adding H2 to natural gas grid
20Gert Müller-Syring: Wasserstoff als Speichermedium im Erdgasnetz, Workshop Regelenergie, Lösungsansätze mit Wasserstoff- und Brennstoffzellentechnologie, Darmstadt, 16.08.2011
- for natural gas- theoretical valuefor hydrogen
Capacity of existing undergroundgas storages in Germany:
21Untertage-Gasspeicherung in Deutschland
ERDÖL ERDGAS KOHLE 127, Jg. 2011, Heft 11
50 TWh hydrogen
200 TWh natural gas
40 GWh
DVGW: Add hydrogen to natural gas system
gas grid
gas storage
consumer
H2
O2
electrolyser
H2O
How wind + PV power convert to gas
renewable energies
H2
excess
wind power
excess
PV power
DVGW: German Technical and Scientific Association for Gas and Water
22
Limiting values for hydrogen within natural gas
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(rough estimates only!)
???
4.3 Methanation
Methanation
H2O water
H2 hydrogen CH4 methane
4 H2 + CO2 > CH4 + 2 H2Ohydrogen + carbon dioxyde > methane
H2 hydrogen
CO2 carbon dioxyde
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wind power
natural gas grid
electrolysis
methanation
cng gas station
transmission grid
Audi balanced mobility project /CNG production from green energy
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Linking power + gas grid via methanation
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4.4 Comparison of Power-2-Gas options
pros cons
direct use of hydrogen
• use for chemical industry
• use future fuel cell cars
• use for H2 gas turbines
• highest efficiency when re-converted to power
• need for separate pipeline system and storages
addition of hydrogen to natural gas grid
• (limited) use of existing natural gas infrastructure
• limitations due to user restrictions
• risks to reservoir storages
• no fuel for fuel cell cars
methanation
• unlimited use of existing natural gas infrastructure
• 3-times more energy per m³ storage volume
• no need for adaptation of equipment in case of industrial users
• energy losses due to conversion
• need for CO2 source
• lowest efficiency when re-converted to power
• no fuel for fuel cell cars
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5. Summary
Future large amounts of excess wind + PV power will be converted to greenhydrogen (Power-2-Gas!)
Salt caverns are the prime large scale storage option; other options are naturalreservoirs (aquifer formations)
Options for green hydrogen use
• Direct use for chemical industry, fuel cell cars, power production+ high efficiency- need for separate infrastructure
• Addition to natural gas infrastructure+ use of existing gas infrastructure- lower efficiency- various limitations in case of larger H2 percentage
• Conversion to green methanehowever hight costs+ unlimited use of existing gas infrastructure+ no limitations for gas users- high costs, lower efficiency- need for CO2 source
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Prognosis for possible future gas composition
natural gas
CH4
biogas
H2CH4
SNG (wood)
29Dr. Hartmut Krause, Dr. Matthias WerschyDBI-Fachforum Energiespeicherkonzepte und Wasserstoff, Berlin, 13. – 14. September 2011
