Automotive requirements for future H 2 -storage systems

Transcription

1 Automotive requirements for future H 2 -storage systems FuncHy Workshop, Geesthacht

2 DOE-Targets H 2 -Storage-Systems 2

3 Pressurized Storage vs. Customer Expectations Target 400mi. Honda FCX 156,6L Range cycl. 220mi. Toyota FCHV 136L Range cycl. 190mi. Range real 130 mi. Source: Toyota

4 Complete Storage System Approach Source: Sandia National Lab

5 Module Definitions Storage System - Tank-module = assembly of cylinders, hydride-pack, pressure regulator, main valves, heater and heat-management devices, safety devices (check valves, excess flow valves, pressure relief devices), mounting hardware, insulation or shielding - Fuelling-module = filling receptacle, filter, filling line / interface to check valve Tank-module - Defuelling-module = defueling receptacle, defueling line to manual shut-off valve fuel line interface - Venting-module =vent-cap and venting line from junction of all venting lines of tank-module safety devices - pressure relief valves and PRD s heat management Cylinder venting line vent-cap Heater Cylinder pressure regulator system isolation valve fuel line de-fueling receptacle de-fueling line check valve manual shut-off valve de-fueling line filling line filling receptacle 5

6 Vehicle Constraints For Solid State H 2 Storage Systems Hydrogen Storage System HEX-System Q therm 1. External thermal power not available before fuel cell system start-up up. 2. Limited power of vehicle radiator during standstill for cooling hydride pack while fuelling MH-cylinder 3. Direct interdependence between storage start-up time target and maximum vehicle battery energy content El. Heater H 2 P el Fuel Cell System BOP* Fuel Cell Battery System 12V Traction - - DC/DC - - DC/DC E-Motor _ ~ Freq. Converter Transm. 4. El. consumption has the most adverse effect on overall efficiency 5. Limited availability of el. energy during cold-start (battery) before first H2-feed (fuel( cell) * Balance of plant 6

7 Status Solid Storage Materials Temperatures >120 C not achievable by vehicle cooling circuit 100 bar is a reasonable value with respect to carbon fibre cost Start of desorption <-20 C to avoid excessive start-up time and energy Desorption pressures >6bar abs necessary for operation of anode module of the fuel cell system 7

8 Specifications for Solid State H 2 Storage Systems Usable H 2 -content: Storage pressure: >4 kg end of life) Desorption temperature: -40 X 100 C Feed pressure: H 2 flow rate: Operation and feed temperature: -40 to +85 C System lifetime: Shock / vibration resistance (system): Gravimetric storage density (system): Volumetric storage density (system): Cost target: Dynamik response 10-90% / 90-0%: Fuelling rate: 10 X < 350 bar (ideally100 bar) 6-10 bar const. independent from state of charge 0-2 g/s (=240 kw th,h2 for fuel cell appl.; ICE factor 3-5 higher) 15 years; cycles 20 g longitudinal; 8 g horizontal, perpendicular tdd 2,0 kwh/kg net / 6 weight.-% 1,5 kwh/l net 4 $/kwh net $/kwh netto (benchmark CGH 2 ) 0,75 s 1,5 kg H 2 /min Enthalpy of formation: <<20 kj/mol H2 (target max. 2,0 MJ/kg, corr. to 4 kj/mol H2 ) Start-up time to max. H 2 -flow: 4 20 C 8

9 Technical Issues Solid State H 2 Storage Systems Reversibility: Divergence between stored mass and released mass under automotive terms e.g. two-stage desorption process of NaAlH 4 (1.Stage below 180 C with 33% Residual) Cycle stability: Feed rate: Feed pressure: MH-coagulation, catalyst segregation, intolerance against humidity and impurities Low desorption rates (NaAlH 4 approx. 1 kw th,h2 /kg SM at 100 C) Desorption pressures above 10 bar only at elevated operation temperatures Start-up behaviour: Volume MH-Mixtures: Fueling: System energy density: Commercialization: Operation at desorption temperatures < -20 C Heat-up rate and energy to reach 10bar feed-pressure Energy balance including electrical heaters Low density e.g. Sodium-Alanate 1,25 kg/l High adsorption enthalpy during charging Realisation of fueling rates ~1,5 kgh 2 /min difficult Additional effort necessary for MH-substrate, cooling-system, electrical heater, etc. Availability and target costs for base materials (Benchmark: $/kwh for carbon fiber pressure storage) 9

10 Thank you