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René Bañares-Alcántaraand Richard Nayak-Luke
‘Green’ ammonia: the missing piece to enable hydrogen penetration?
Department of Engineering Science
Hydrogen Energy Storage (Table 3, Panel B)Energy Storage in the Electric Network workshop14-16 November, 2017INEEL, Cuernavaca, Mexico
2
© R Banares-Alcantara
Renewable Energy and Energy StorageIncreased Renewable Energy (RE) penetration requires additional
flexibility.
Energy Storage (ES) can provide it.
• how much energy storage is needed? (capacity)
• for how long we need to store the energy? (duration)
We propose:
use of ammonia (NH3) as a long-duration energy storage vector
3
We have developed a methodology to determine the distribution of
short- vs. long-duration Energy Storage (ES) technologies.
The SDI (Storage Duration Index) is a metric that quantifies the
required storage duration and magnitude.
INPUT: Location (RE sources), RE mix, RE penetration
{{ ES losses, ES round-trip efficiency,
demand side management, curtailment }}
The SDI can be the basis to select, size and cost ES technologies.
© R Banares-Alcantara
Storage duration studies
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Lerwick (Shetland Islands): 0.48kW average demand; RE supply: 50% wind, 50% solar
100% RES penetration (i.e. no dispatchable supply)
© R Banares-Alcantara
Storage Duration Index (SDI)
ES technology 1ES technology 2ES technology 3Different energy density, CAPEX, round-trip efficiency, losses, etc.
Total energy stored over
the 16.25 year time period
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Energy Storage technologies
• which ES technologies?
© R Banares-Alcantara
• capacity / duration / cost
• consideration of complete life-cycle, i.e.
harvest / storage / transportation / energy recovery
• energy density
• discharge time / round-trip efficiency
• flexibility: e.g. for power generation and transport systems
6
© R Banares-Alcantara
Energy Storage technologies – selection criteria
Y-Values
7
Coal
29,900 GWh
14.3 GW
Natural gas
47,100 GWh
32.1+ GW
1 year
1 month
1 week
1 day
1 hour
1 min
1 sec
100 ms
1 kWh 1 MWh 1 GWh 1 TWh Storage
capacity
Release
time
Pumped
Hydro
27.6 GWh
2.90 GW
Batteries
2.34x10-2 GWh
0.0239 GW
Flywheel*
5.56x10-3 GWh
0.400 GW
Storage technologies
Mechanical
Electro-chemical
Chemical
Note:+ CCGT (30.9 GW) and
OCGT (1.2 GW)
* EFDA JET Fusion flywheel
Source: presentation by N Olson (NH3 Fuel Association), Rotterdam, May 2017.
Adapted from Hydrogenius Technologies. Nuclear and Oil neglected due to data availability
Estimates from Wilson (2010), MacKay (2008), BEIS DUKES (2016), REA (2010) © R Banares-Alcantara
Current energy storage technologies
Y-Values
8
Chemical
1 year
1 month
1 week
1 day
1 hour
1 min
1 sec
100 ms
1 kWh 1 MWh 1 GWh 1 TWh
Pumped Hydro
Batteries
Flywheel
Storage technologies
Mechanical
Electro-chemical
Chemical
Electrical
Superconducting coil
Capacitor
Redox-flow
Lead-acid
Lithium-ion
Compressed air
Hydrogen
Ammonia
Storage
capacity
Release
time
Source: presentation by N Olson (NH3 Fuel Association), Rotterdam, May 2017.
Adapted from Hydrogenius Technologies. © R Banares-Alcantara
Available energy storage technologies
• Storage (high pressure or low temperature)
ammonia requires 5 times less energy for a given amount of
hydrogen
• Transportation (storage vessels or pipeline)
ammonia is a more efficient energy carrier – higher energy
capacity and lower costs
9
© R Banares-Alcantara
H2 vs NH3
10Source: J.R. Bartels, “A Feasibility Study of Implementing an Ammonia Economy”, MSc Thesis, Iowa State
University (2008) © R Banares-Alcantara
H2 vs NH3 costs of production, transportation
and storage
NH3
Cos
t [U
SD
/kg
H2]
Product &
Transport + 182
day storage
Product &
Transport
Product &
Transport + 15
day storage
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Ammonia (NH3) as an Energy Storage option
© R Banares-Alcantara
12
Technological characteristics
Current NH3 worldwide production is ~180 MT/y (increasing 50% by 2050)
and represents a market of > 100 bn£/y
Chemical characteristics
Lower Heating Value = 14,100 MJ/m3 (vs. H2: 8,400 or gasoline: 29,800)
Boiling points:
(similar to C3H8)
Stable chemical w/ high H content (x1.3 more H than liquid H2 per unit vol)
(Relatively) safe: non-explosive, narrow flammability range, easy to detect
Ammonia Hydrogen
1 bar 33.3oC 1 bar 253oC
10 bar 20oC < 240oC (Tcrit)
existing infrastructure
easy to transport & store
unlimited storage time
safe
© R Banares-Alcantara
Some information about ammonia (NH3)
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• renewable energy storage medium
as a fuel, NH3 can be used in
• Fuel cells
catalysed decomposition to H2 at > 500oC; also electro- or photochemical;
NH3 poisons PEM fuel cells
• Combustion
- Gas Turbines
can be cracked before combustion for NH3/H2 mix
- ICE engines
can be mixed in NH3-gasoline dual fuel, e.g. see http://nh3car.com
as a commodity,
• fertilisers (biodegradable; consumes 88% of NH3 worldwide production)
• refrigerant
© R Banares-Alcantara
End-use flexibility of NH3
14
Haber-Bosch process:
• from H2 and N2
• P = 150 – 250 bar
• T = 300 – 500 oC
• conversion = 15 – 25%
• capacity: 1 – 500 kT/yr
• catalysts: Fe–based and Ru–based
– Fe: not the most active but robust to impurities
– Ru: an order of magnitude more active, but sensitive to impurities
– potential for other modified transition metals, e.g. Co-Mo-N
• Future technologies: obtain NH3 directly from H2O and N2
© R Banares-Alcantara
Current NH3 production process
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• 95% of the H2 produced globally comes from fossil fuels, e.g. through
the Steam Reforming of methane (natural gas)
• currently, to produce NH3
o 1.8% of global fossil fuels consumption
o 420 MT/yr of CO2 are emitted ( 1.3% of global CO2 emissions)
• it is possible to avoid ~90% of the CO2 from SMR at a cost of 74
USD/T using carbon capture and storage (Source: IEA GHG Technical Report 2017-2)
© R Banares-Alcantara
…but H2 for NH3 is produced from natural gas
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‘Green’ ammonia with existing technology
© R Banares-Alcantara
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‘Green’ ammonia can be produced with existing technology from water
(electrolysis) and air (cryogenic separation):
• cheap and readily available raw materials (water + air); natural gas
represents about 75% of production costs
• “green” end products when recovering stored energy (N2 and water;
or N2 and H2)
Source: Morgan, 2013© R Banares-Alcantara
Energy storage and ‘green’ NH3
Electrolysers,
93.5%
Other,
6.5%
ASU,
0.7%
MVC,
0.3%HB loop,
5.5%
Power CAPEX
Electrolysers,
65%
Other,
14%ASU,
6%
MVC,
5%
HB loop,
21%
Storage,
3%
Capital expenditure (CAPEX)
HB: Haber-Bosch; ASU: Air separation unit; MVC: Mechanical vapour compression
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“Thanks to the recent cost reductions of solar and wind
technologies, ammonia production in large-scale plants based
on electrolysis of water can compete with ammonia production
based on natural gas, in areas with world-best combined solar
and wind resources.”
“Only detailed, specific studies with hourly output of solar and
wind can help optimise the respective capacities of solar, wind
and electrolysers, the design of the NH3 plant, and the means
to prevent undesirable disruptions in the synthesis loop.”
Cédric Philibert, Senior Analyst
Renewable Energy Division, IEA
16 May 2017
https://www.iea.org/media/news/2017/FertilizermanufacturingRenewables_1605.pdf
© R Banares-Alcantara
Wind Power
profile
Power from
NH3
H2 production
N2 production
NH3 production
air
H2
N2
NH3water
Demand
profile
NH3
storage
Energy Storage System (ESS)
surplus
electricity
electricity
electricity NH3
MVC
H2
storage
1. Techno-economic assessment (EngSci)
2. Thermo-catalytic review (Chemistry)
3. Market analysis (Smith School)
19
© R Banares-Alcantara
Islanded NH3-based energy storage system
(2015)
MVC: Mechanical vapour compression (for desalination)
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Given a geographical location, i.e. set of RE intermittent profiles, estimate:
• optimal solar/wind/grid supply mix
• size of ESS components
• LCOA (Levelised Cost of Ammonia)
Production cost variables:
• LCOE (Levelised Cost of Electricity)
• electroliser CAPEX per kW of rated power
Production process variables:
• RE sources ratio
• minimum power consumption of ASU/HB process (plant size)
• maximum ramping rate of ASU/HB process [MWh/hr]Note: the ramping bottleneck is the Haber-Bosch catalysts due to sintering.
© R Banares-Alcantara
Five key variables w/ significant impact on LCOA
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Note: In other locations the LCOE for renewable electricity is currently
significantly cheaper (in Saudi Arabia the spot price for solar
photovoltaic has dropped to as low as 13.4* GBP/MWh)
2025/30 estimate using
all five key variables
588 GBP/T
* Masdar and Electricite de France SA’s bid for 300 MW Sakaka project
Source: Bloomberg Markets 3rd October 2017 © R Banares-Alcantara
LCOA sensitivity to LCOE
22
Being built at Rutherford Appleton Laboratory, near Oxford
Source: Ian Wilkinson, Siemens.
Siemens 0.3 MW
proof-of-concept plant
23
‘Green’ ammonia with future technology
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Reactors with:
- reacting fluid, i.e.
- solid catalyst phase A, e.g. Fe- or Ru-based catalyst pellets
- solid absorption/adsorption phase B, e.g. MgCl2 particles
could drive equilibrium to the right, thus achieving higher conversions.
3H2 N2 2NH3
~100% conversion
Mark Gowers (2016)
© R Banares-Alcantara
Multifunctional reactors
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Produce NH3 directly from H2O and N2 (reduction of energy requirements, CO2
generation and CAPEX)
• electrochemical or photochemical route
– reported synthesis rates in the order of 10–9 mol s–1 cm–2,
at least two orders of magnitude lower than required by industry
– need electro- or photocatalysts with better activity, selectivity and stability
• chemical looping
a) metal to metal nitride
b) hydrolysis of metal nitride to NH3 + metal oxide
c) reduction of metal oxide to metal
this step requires 1800 K (2300 K in some sources)
© R Banares-Alcantara
Future technologies for NH3 production
University of Oxford: Prof. Edman Tsang’s group
26
Conclusions
© R Banares-Alcantara
27
• energy storage is key to Renewable Energy (wind/solar) penetration
• short-duration storage (batteries) is necessary but not enough, long-duration
storage is also needed
• ‘green’ ammonia is a clean option for long-duration ES
• we have developed a model that, for a given location, estimates
o ratio of wind/solar PV
o size of ‘green’ ammonia production plant
o operation of plant (ramping rates)
that minimise LCOA.
• it has becoming possible to produce ‘green’ ammonia with existing
technology that is commercially competitive, i.e.
o potential business game-changer
o up to a 420 MT/y CO2 reduction
© R Banares-Alcantara
Conclusions
28
Thank you