The role of green ammonia in decarbonising energy

Transcription

1 The role of green ammonia in decarbonising energy René Bañares-Alcántara and Richard Nayak-Luke Department of Engineering Science Decarbonising UK Energy workshop 4-6 October, 2017 The Royal Society

2 Renewable Energy and Energy Storage Increased 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 (NH 3 ) as a long-duration energy storage vector 2

3 Storage duration studies 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. 3

4 Storage Duration Index (SDI) Lerwick (Shetland Islands): RES supply: 100 MW average ; 50% wind, 50% solar ; 100% RES penetration ES technology 1 ES technology 2 ES technology 3 Different energy density, CAPEX, round-trip efficiency, losses, etc. 4

5 Energy Storage technologies which ES technologies? 5

6 Energy Storage technologies selection criteria 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

7 Current energy storage technologies Release time 1 year 1 month 1 week Natural gas 47,100 GWh GW Y-Values Coal 29,900 GWh 14.3 GW 1 day 1 hour 1 min Batteries 2.34x10-2 GWh GW Pumped Hydro 27.6 GWh 2.90 GW Note: + CCGT (30.9 GW) and OCGT (1.2 GW) * EFDA JET Fusion flywheel Storage technologies 1 sec 100 ms Flywheel* 5.56x10-3 GWh GW Mechanical Electro-chemical Chemical 1 kwh 1 MWh 1 GWh 1 TWh Storage Source: presentation by N Olson (NH3 Fuel Association), Rotterdam, May Adapted from Hydrogenius Technologies. Nuclear and Oil neglected due to data availability Estimates from Wilson (2010), MacKay (2008), BEIS DUKES (2016), REA (2010) capacity 7

8 Available energy storage technologies Release time Y-Values Chemical 1 year Hydrogen 1 month Pumped Hydro Ammonia 1 week 1 day Batteries 1 hour Redox-flow Lead-acid Compressed air Storage technologies 1 min 1 sec Capacitor Lithium-ion Flywheel Mechanical Electro-chemical Chemical Electrical 100 ms Superconducting coil 1 kwh 1 MWh 1 GWh 1 TWh Source: presentation by N Olson (NH3 Fuel Association), Rotterdam, May Adapted from Hydrogenius Technologies. Storage capacity 8

9 Cost [USD/kg H 2 ] H 2 vs NH 3 costs of production, transportation and storage NH3 Source: J.R. Bartels, A Feasibility Study of Implementing an Ammonia Economy, MSc Thesis, Iowa State 9 University (2008)

10 Ammonia (NH 3 ) as an Energy Storage option 10

11 Some information about ammonia (NH 3 ) Technological characteristics Current NH 3 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/m 3 (vs. H 2 : 8,400 or gasoline: 29,800) Ammonia Hydrogen Boiling points: 1 bar 33.3 o C 1 bar 253 o C (similar to C 3 H 8 ) existing infrastructure 10 bar 20 o C 350 bar 20 o C easy to transport & store Stable chemical w/ high H content (x1.3 more H than liquid H 2 per unit vol) unlimited storage time (Relatively) safe: non-explosive, narrow flammability range, easy to detect safe 11

12 End-use flexibility of NH 3 renewable energy storage medium as a fuel, NH 3 can be used in Fuel cells catalysed decomposition to H 2 at > 500 o C; also electro- or photochemical; NH 3 poisons PEM fuel cells Combustion - Gas Turbines can be cracked before combustion for NH 3 /H 2 mix - ICE engines can be mixed in NH 3 -gasoline dual fuel, e.g. see as a commodity, fertilisers (biodegradable; consumes 88% of NH 3 worldwide production) refrigerant 12

13 Current NH 3 production process Haber-Bosch process: from H 2 and N 2 P = bar T = o C conversion = 15 25% capacity: 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 NH 3 directly from H 2 O and N 2 13

14 but H 2 for NH 3 is produced from natural gas 95% of the H 2 produced globally comes from fossil fuels, e.g. through the Steam Reforming of methane (natural gas) currently, to produce NH 3 o 1.8% of global fossil fuels consumption o 420 MT/yr of CO 2 are emitted ( 1.3% of global CO 2 emissions) it is possible to avoid ~90% of the CO 2 from SMR at a cost of 74 USD/T (Source: IEA GHG Technical Report ) 14

15 Green ammonia with existing technology 15

16 Energy storage and green NH 3 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 (N 2 and water; or N 2 and H 2 ) Power CAPEX Electrolysers, 93.5% Other, 6.5% HB loop, 5.5% ASU, 0.7% MVC, 0.3% HB loop, 21% Electrolysers, 65% Other, 14% MVC, 5% Storage, ASU, 3% 6% Source: Morgan,

17 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 NH 3 plant, and the means to prevent undesirable disruptions in the synthesis loop. Cédric Philibert, Senior Analyst Renewable Energy Division, IEA 16 May

18 Islanded NH3-based energy storage system (2015) Wind Power profile Energy Storage System (ESS) surplus electricity water air MVC H2 production N2 production H2 storage H2 N2 NH3 production NH3 storage NH3 electricity Demand profile electricity Power from NH3 NH3 1. Techno-economic assessment (EngSci) 2. Thermo-catalytic review (Chemistry) 3. Market analysis (Smith School) 18

19 Five key variables w/ significant impact on LCOA 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. 19

20 LCOA sensitivity to LCOE 2025/30 estimate using with all five key variables 588 GBP/T Note: In other locations the LCOE for renewable electricity is currently significantly cheaper (in Saudi Arabia solar photovoltaic has dropped to as low as 13.4* GBP/MWh) * Masdar and Electricite de France SA s bid for 300 MW Sakaka project Source: Bloomberg Markets 3 rd October

21 Siemens 0.3 MW proof-of-concept plant Being built at Rutherford Appleton Laboratory, near Oxford Source: Ian Wilkinson, Siemens. 21

22 Green ammonia with future technology 22

23 Multifunctional reactors 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. MgCl 2 particles could drive equilibrium to the right, thus achieving higher conversions. 3H 2 N 2 2NH 3 Mark Gowers (2016) ~100% conversion 23

24 Future technologies for NH 3 production Produce NH 3 directly from H 2 O and N 2 (reduction of energy requirements, CO 2 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 NH 3 + metal oxide c) reduction of metal oxide to metal this step requires 1800 K (2300 K in some sources) 24

25 Conclusions 25

26 Conclusions 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 o o ratio of wind/solar PV size of green ammonia production plant 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 o potential business game-changer up to a 420 MT/y CO 2 reduction 26

27 Thank you 27