Fuel Cell Research and Development for Earth and Space Applications

https://ntrs.nasa.gov/search.jsp?R=20190001140 2019-08-30T10:13:59+00:00Z

National Aeronautics and Space Administration

Ian Jakupca, NASA Glenn Research Center 17 July 2018

1 National Aeronautics and Space Administration Presentation Outline

• NASA – Overview and Scope • Background • Power and Energy Systems • Applicable Types of Electrochemical Systems • Energy Storage: Batteries vs. Regenerative Fuel Cells (RFC) • Comparison of Fuel Cell Technologies: Aerospace vs. Terrestrial • Active NASA Fuel Cell research • Power Generation • Energy Storage • Commodity Generation • Review

2 NASA Centers and Facilities

3 LUNAR EXPLORATION CAMPAIGN

4 5 NASA's Lunar Reconnaissance Orbiter (LRO) Data

• The average temperature on the Moon (at the equator and mid latitudes) varies from 90 Kelvin (-298 degrees Fahrenheit or -183 degrees Celsius), at night, to 379 Kelvin (224 degrees Fahrenheit or 106 degrees Celsius) during the day. • Extremely cold temperatures within the permanently shadowed regions of large polar impact craters in the south polar region during the daytime is at 35 Kelvin (-397 degrees Fahrenheit or -238 degrees Celsius) • Lunar day/night cycle lasts between 27.32 and 29.53 Earth days (655.7 to 708.7 hours) • Regulating hardware in this environment requires both power and energy 6 Power and Energy Systems

Power Generation Energy Storage Discharge Power Only Charge + Store + Discharge Description Description • Energy conversion system that • Stores excess energy for later use supplies electricity to customer • Supplies power when baseline system power supply (e.g. PV) is no longer • Operation limited by initial available stored energy • Tied to external energy source

Examples Examples • Nuclear (e.g. RTG, KiloPower) • Rechargeable Batteries • Primary Batteries • Regenerative Fuel Cells • Primary Fuel Cells • Photovoltaics NASA Applications: NASA Applications: Missions without access to Ensuring Continuous Power continuous power (e.g. PV) • Satellites (PV + Battery) • All NASA applications require • ISS (PV + Battery) electrical power • Surface Systems • Each primary power solution fits (exploration platforms, ISRU, crewed) a particular suite of NASA • Platforms to survive Lunar Night missions 7 Summary of Applicable Electrochemical Chemistries

Low Temperature Moderate Temperature High Temperature Proton Exchange Phosphoric Acid Molten Carbonate Cell Type Alkaline (AEM) Alkaline (AFC) Solid Oxide (SOFC) Membrane (PEM) (PAFC) (MCFC) Ionic Polymer Anionic Polymer KOH in asbestos Phosphoric Acid in Liquid carbonate in Anionic Conducting Electrolyte Membrane Membrane matrix SiC structure LiAlO2 structure Ceramic Operating 10 – 80 °C 20 – 70 °C 70 – 225 °C 200 – 250 °C ~650 °C 600 – 1,000 °C Temperature

+ - - + 2- 2- Charge Carrier H OH OH H CO3 O Load Slew Rate Very High High High High Low to Medium Low Capability (> 1k’s mA/cm2/s) (~ 1k’s mA/cm2/s) (~ 1k’s mA/cm2/s) (~ 1k’s mA/cm2/s) (~100’s mA/cm2/s) (~10’s mA/cm2/s) Fuel Pure H Pure H H , CO, Short Hydrocarbons 2 Feasible for2 2 Product Water Cavity Oxygen Hydrogen Hydrogen Oxygen Hydrogen Product Water Liquid ProductAerospace Operation defines Applications product water state Vapor, externally separated CO Tolerance < 2 ppm < 2 ppm < 5 ppm < 50 ppm Fuel Reformer Very High High High Minimal Complexity No longer in Aerospace Viability Promising TBR (Low TRL) Not Viable Not Viable Promising production Terrestrial High Developmental Moderate Moderate High N/A Availability (Increasing) (Increasing) (Stable) (Increasing) (Increasing)

Terrestrial Markets Transportation, Transportation, Co-generation and Co-generation and C = Commercial Logistics, Stationary Logistics N/A Stationary Power (C) Stationary Power Stationary Power I = Industrial R = Residential Power (C, I, & R) (C) (C & l) (C, I, & R)

8 Summary of Applicable Electrochemical Chemistries

PEM AEM Alkaline Solid Oxide • Commonly used in mobile • Solid polymer electrolyte • Liquid electrolyte suspended in • Commonly used in stationary terrestrial applications • Developing technology not yet asbestos structure terrestrial applications • Terrestrial systems vent Oxygen to deployed • Hydrogen recirculates to remove • Terrestrial systems vent hydrogen remove product water from stack product water from stack to remove product water from stack • Mature for terrestrial applications, • Used in Space Shuttle • Mature for terrestrial applications,

Key Key Notes needs development for Aerospace needs development for Aerospace • Rapid reaction kinetics support • Reaction kinetics support transient • Reaction kinetics support transient • Wide range of fuels (Anode) transient load response capability load response capability load response capability • Can be configured to internally • Support wide range of current • Relatively high tolerance to • Relatively high tolerance to reform hydrocarbons densities contaminant gases contaminant gases • Relatively high tolerance to • Minimal start times • Solid polymer eliminates migration • Higher pH enables larger selection contaminant gases in Hydrogen (typ. < 1 min) of corrosive electrolyte for wetted materials • Resistant to freezing when stored • Demonstrated high pressure • Higher pH enables larger selection operation for wetted materials Advantages • Solid polymer electrolyte eliminates migration of acidic electrolyte • Very sensitive to CO or Sulfur • Limited operational life • No longer available as company • Ceramic electrolyte limits transient contaminants in Hydrogen stream • Limited pressure capability divested both IP and fabrication load response capability • Water-based system limits capability • Ceramic electrolyte limits start-up temperature regimes • EPA restricted use of asbestos times to 10’s of minutes to hours • Liquid electrolyte migrates • Seals need development for throughout fluid system requiring Aerospace applications frequent and expensive servicing • Limited to low-pressure

Disadvantages applications

9 Aerospace Electrochemical Systems

Fuel Cell Regenerative Fuel Cell Electrolysis Power Generation Energy Storage Commodity Generation Discharging Only

2 H2O 2 H2+ O2 Discharging

or Solar Array Load

Hydrogen

Charging Electrolyzer Fuel Cell

Oxygen 2 CO2 2 CO + O2 Description • Converts supplied reactant to Water Description DC electricity Description • Converts chemical feedstock • Operation limited by supplied • Stores supplied energy as gaseous reactants into useful commodities reactants • Discharges power as requested by external load • Tied to external energy source • Not tied to external energy • Tied to external energy source source NASA Applications: NASA Applications: Life-support, ISRU NASA Applications: Ensuring Continuous Power • Oxygen Generation Sustained High-Power • Surface Systems • Propellant Generation • Crewed transit vehicles (exploration platforms, ISRU, crewed) • Material Processing (Apollo, Gemini, STS, etc.) • Platforms to survive Lunar Night • Power-intense rovers/landing platforms 10 Example H2/O2 Aerospace Fuel Cell Systems Fuel Cell Regenerative Fuel Cell Electrolysis Power Generation Energy Storage Commodity Generation - - 2H2 + O2 → 2H2O + 4e + Heat 2H2O + 4e → 2H2 + O2 + Heat ɳCycle = ~50%

O2 H2 O2 H2 O2 H2

ΔP ΔP ΔP ΔP

QTH

QTH QTH

H2O H2O

QELE QELE QELE H2O QELE DischargingDischarging Charging Charging Interconnecting Regenerative Fuel Cell = Fuel Cell + + Electrolysis Fluidic System 11 Definitions: Power and Energy System Metrics

Fuel Cell Regenerative Fuel Cell Electrolysis Power Generation Energy Storage Commodity Generation Primary Metrics Primary Metrics Primary Metrics • Specific Power (W/kg) • Specific Energy (W•hrs/kg) • Production Rate (kg/day) • Output Power (Watts) • Reliability (Years) • Reliability (Months/Years) • Mass (kg) • Stored Energy (kW•hrs) • System Pressure (Atm) • Volume (L) • Mass (kg) • Mass (kg) • Reliability (Hours/Days) • Volume (L) • Volume (L)

Technical Challenges Technical Challenges Technical Challenges • Water Management • Component Reliability • System Pressure • Reactant Purity • Corrosion/Chemical Compatibility • Component Reliability • Thermal Control • Reactant Purity • Corrosion/Chemical • Con-Ops • Water Management Compatibility • Shelf-life • Con-Ops • Fluid Purity • Thermal • Con-Ops • EZ System Pressure • Maintenance • Maintenance • Shelf-life

12 Comparison of Fuel Cell Technologies

Aerospace Terrestrial

Space Shuttle Fuel Cell Stack 1 (1979 - 2014) Toyota Mirai Fuel Cell

Differentiating Characteristics Differentiating Characteristics  Pure Oxygen (stored, stoichiometric)  Atmospheric Air (conditioned, excess flow)  Water Separation in µg  High air flow drives water removal Fluid management issues and environmental conditions make aerospace and terrestrial fuel cells functionally dissimilar

Notes: 1 = http://www.toyota-global.com/innovation/environmental_technology/technology_file/fuel_cell_hybrid/fcstack.html

13 Cross-Cutting Technologies: Fuel Cells, Electrolyzers, and RFCs

Aerospace Portability of Terrestrial Technology Remaining Technical Component TRL Level to Aerospace Applications Challenge Electrochemistry 9 High Electrolyzer Materials 5+ High High Pressure, Mass Technology Seals 5+ High High Pressure, Mass Gas Management 5+ Moderate High Pressure, Mass Flow Fields 5+ High Bipolar Plates 5+ Moderate O vs air Fuel Cell 2 Materials 5+ Moderate O vs air Technology 2 Electrochemistry 5+ Low O2 vs air, Performance Water Management 5+ Low Flow Rate, µg Fluidic Components 8+ Moderate O vs air Reactant 2 Procedures 5 Moderate O vs air, Performance Storage 2 Thermal 8+ Moderate µg, Vacuum and Materials 8+ Low O2 vs air Management Water Management 5+ Low O2 vs air, µg Hardware/PCB 8+ High FC / EZ / RFC Power Management 8+ High System Structure 8+ High Avionics Thermal 8+ High Instrumentation 8+ Moderate

NOTE: Not all relevant technologies exist within the same application. Elements of

multiple terrestrial applications are required to meet various NASA mission requirements. 14 Cross-Cutting Technologies: Fuel Cells, Electrolyzers, and RFCs

RFC systems, along with their core fuel cell and water electrolyzer technologies, share common reactants (hydrogen, oxygen, water) with multiple subsystems while supporting an electrical power interface.

15 NASA Fuel Cell Applications Powering exploration activities • Power Generation: Fuel Cells  Electrification of Aircraft  High-power rovers  Entry/Descent/Landing (EDL) • Upper Stage Platforms/Long loiter systems

Commodity Generation: Electrolysis Legend  ECLSS – Oxygen Generation  Hardware Development  ISRU – Propellant Generation  Analytical Development • Recent work not funded  ISRU – Reduction fluids for Material Processing and this Fiscal Year Fabrication

Energy Storage: Regenerative Fuel Cell  Lunar Surface Systems  Lunar Landers / Rovers • HALE Un-crewed Aerial Systems (UAS) NASA Fuel Cell Applications Powering exploration activities • Power Generation: Fuel Cells  Electrification of Aircraft  High-power rovers  Entry/Descent/Landing (EDL) • Upper Stage Platforms/Long loiter systems

Energy Storage: Regenerative Fuel Cell  Lunar Surface Systems  Lunar Landers / Rovers • HALE Un-crewed Aerial Systems (UAS) Power Generation: Fuel Cell Analytical Activities

High Power Fuel Cells Entry Descent and Landing (EDL)  Concept: Crewed transit vehicles, crewed  Concept: Utilize excess propellant to provide rovers, or rovers with energy-intense electrical power from Mars orbit insertion through experiments descent, landing, and start-up of primary surface  Application Power: 1 kW to >10 kW power system  Future activities: Laboratory testing of next-  Application Power Level: ~34 kW generation air-independent stacks ranging  Future activities: Laboratory evaluation of pre- from 250 W to 1.2 kW on pure and propellant- prototype

grade reactants sub-scale fuel cell stack operating on O2/CH4  Special Notes: Recent advances demonstrated autonomous operation and tolerance to vibration loads at launch levels

18 Power Generation: Fuel Cells Electrification of Aircraft

• Convert experimental X-57 to an High-Performance Baseline electric aircraft • 160-190 knots cruise on 130-190kW • 1100+ pounds for motor & energy • Integration of key technologies to system yield compelling performance to early adopters – Useful payload, speed, range for Efficient Powertrain point-to-point transportation • Turbine-like power-to-weight ratio at 90+% efficiency – Energy system that uses infrastructure-compatible reactants, allowing for immediate integration Hybrid Solid Oxide Fuel Cell – High efficiency for compelling Energy System reduction in operating cost • >60% fuel-to-electricity efficiency • Early adopters serve as gateway to • Designed for cruise power; larger commercial market overdrive with moderate efficiency hit at takeoff and climb power

Primary Objective: Demonstrate a 50% reduction in fuel cost for an appropriate light aircraft cruise profile (payload, range, speed, and altitude).

POC: Nicholas Borer, [email protected] 19 Energy Storage: Battery vs Regenerative Fuel Cell

Use Battery Use Regenerative Fuel Cell

Estimated cost to Lunar Surface: $1.5 M/kg to $1.8 M/kg Required Trade System Mass System Typically 10 to 18 hours (Energy dependent)

Hours Days Weeks Discharge Time

Energy Storage Options for 300 Wele Lunar Surface System By Location Shaded Energy Li-ion LRFC $ Savings @ Lunar Site Period Storage Mass Mass $1.5 M/kg hours kW•hrs kg kg $M South Pole 73 22 137 40 $145.5 Equator 356 107 668 194 $711 Lacus Mortis (45°N) 362 109 679 197 $723

20 Energy Storage: Regenerative Fuel Cell System

Each RFC sub-system traded across multiple parameters

Fuel Cells Electrolyzers Storage Max = 56.4 Max = 63.6 Max = 57.2

21 Energy Storage: Regenerative Fuel Cell Trade Studies

Regenerative Fuel Cell (RFC) Model 10 kW PEM RFC Energy Storage • Developed detailed RFC integrated system System for Equatorial Lunar Outpost model to conduct sensitivity studies and Everything else mission trades • Conducted parameter sensitivity study Location primary parameter Round-trip efficiency dominant metric • Compared Solid Oxide and PEM chemistries Reactants SOE not feasible for high pressure gas storage SOFC limits electrical slew if sole power source • Rotating components fail at a higher rate than Volume (m3) electrochemical hardware Everything Crewed Surface Outpost Trade Study Results else • System development at low TRL • Location determines required energy storage which sizes RFC Reactants • PEM-based RFC near-term solution for Lunar base • Burdened2 RFC could achieve up a specific energy to Mass (kg) 510 W•hr/kg

22 Energy Storage: Regenerative Fuel Cell System

Relative Category Element Notes Maturity PEM: Electrolysis Advanced ISS has flown but with major servicing requirements (every 201 days) and low pressure PEM: Fuel Cell Medium Terrestrial hardware available but no Flight qualified hardware exists

Low MOXIE promising but existing leak rates challenging for H2/H2O/O2 RFC application Electrochemical Solid Oxide: Electrolysis Seal and pressure impose severe limitations for RFC application. Very Low Increasing scale a major concern. Limited CO/CO2 life data available Low Terrestrial hardware available but has unacceptable seal and pressure issues for an Aerospace application Solid Oxide: Fuel Cell Very Low Increasing scale a major concern. Limited CO/O2 life data available Storage Mature Many examples of fluid storage flight hardware Reactant Fluid Management Medium Life, durability, and reliability issues for components and system Management Reactants Medium Material Compatibility and contamination issues over projected mission duration Purity and freezing issues over projected mission duration. Water Management Low Most ECLSS solutions not applicable to RFC application Control Medium New bus voltage and new operating environment require new designs and test programs PMAD System Medium Thermal and electrical insulation/grounding at new power levels Deployment Medium Surface deployment options not yet demonstrated at scale required by RFC Thermal Surfaces Medium Maintaining radiative surface not demonstrated in relevant environment at scale without servicing Demonstrated RFCs require prohibitive maintenance schedules subject to a range of operational ConOps Low methodologies Reliability / Life Very Low Limited life data available in relevant environment except for computer (CPU) System Instrumentation Low Calibration drift and durability are mission-limiting issues Maintenance and servicing a mission-limiting issue. Robotic servicing reduces maintenance complexity and Maintenance Very Low required spares. Robotic capabilities not demonstrated.

23 Commodity Generation: Oxygen

• Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) – Flight demonstration experiment as a part of the Mars 2020 rover mission

– Generates gO2 from CO2 in Mars atmosphere (~1% scale) using Solid Oxide Electrolysis (SOE) – Proof-of-concept for generating propellant oxygen for Mars Ascent Vehicle (MAV) or breathing oxygen for astronauts

• Oxygen Generator Assembly (OGA) – ECLSS recovers ~ 90% of all water – Existing technology on-board the ISS since 2008 – Advancing towards a smaller and lighter-weight version for scheduled upgrade in FY21 – Hazard evaluation testing at WSTF

• Flight-qualified High Pressure electrolysis

– ECLSS systems to generate 3,000 psi gO2 by FY24 – Evaluating existing system modifications to maintain mass while increasing generation pressure

– Investigations into conserving gH2 by-product 24 Commodity Generation: Hydrocarbon Fuel Synthesis

A Green Energy Application for SOE Co-Electrolysis:

Manufacture of synthetic fuels from captured CO2 and renewable energy

• Combined CO2 and H2O electrolysis produces CO and H2, a basic feedstock in the chemical industry (referred to as synthesis gas, or “syngas”) • Syngas can be utilized to produce a wide variety of liquid hydrocarbons via the Fischer-Tropsch (F-T) process.

– F-T process is a mature technology presently used to manufacture synthetic lubricants, etc.

– Sasol (South Africa) produces gasoline and diesel fuel on a large scale via F-T.

• Recent review paper trade study concluded that synthetic Two possible CO2-recycling scenarios: gasoline could be produced for costs as low as $2/gal.* (a)CO2 recycled from industrial plant emissions (potential to reduce CO2 net emissions by 50%). (b) Closed loop carbon recycling via CO capture • Allows the “recycling” of atmospheric CO while maintaining our 2 2 from Earth’s atmosphere (near-zero net present hydrocarbon fuel infrastructure. emissions).

* Study and above graphic from Graves et al., Renewable and Sustainable Energy Reviews, 15, (2011) 1-23. 25 IN-SPACE MANUFACTURING ON-DEMAND MANUFACTURING TECHNOLOGIES FOR DEEP SPACE MISSIONS

3-D printer installed on International Space Station in 2014. Crews aboard station have successfully used the printer to manufacture parts and tools on-demand.

In-Space Manufacturing logo created through Freelancer crowd- sourced challenge.

Issued new appendix to NextSTEP Broad Agency Announcement soliciting proposals for development of First student-designed 3-D tool printed first-generation, in-space, multi-material fabrication aboard station in 2016 laboratory, or FabLab, for space missions. 26 NASA Fuel Cell Applications Powering exploration activities

Electrified Aircraft Primary Power

Martian Outposts and Rovers Primary Power Landers Lunar Outposts Energy Storage Primary Power Energy Storage Commodity Generation National Aeronautics and Space Administration 28 Back-up Slides

Summary of Applicable Electrochemical Reactions

Recombination Electrolysis Fuel Cell Reaction SOFC AFC PEMFCPEMEZ AEZ SOE Cathode Anode H2O Oxygen H2O e- e- O= OH- H+ Ion H+ OH- O= e- Conductor e-

H2O H2O Hydrogen H2O H2O + + Inter- Load e- 600 to 20 to 20 to 20 to 20 to 600 to e- Supply 1,000 oC 225 oC 80 oC connect 80 oC 225 oC 1,000 oC - - H O H O 2 Oxygen 2

Ion e- O= OH- + + OH- O= e- H Conductor H

e- e- H2O H2O Hydrogen H2O H2O Anode Cathode

32 Habitation Systems

Habitation Systems Elements TODAY FUTURE Space Station Deep Space

Excursions from Earth are possible with artificially produced breathing air, drinking water and other conditions for survival. ~50% O Recovery from CO LIFE 2 2 75%+ O2 Recovery from CO SUPPORT 2 90% H O Recovery 2 98%+ H2O Recovery Atmosphere Waste Management Management < 6 mo mean time >30 mo mean time Water before failure (for some before failure Management components)

NASA living spaces are designed with controls and integrity that ENVIRONMENTAL ensure the comfort and safety of inhabitants. Limited, crew-intensive On-board analysis MONITORING on-board capability capability with no sample return

Reliance on sample Identify and quantify Pressure Particles Chemicals return to Earth for species and organisms O & N in air & water 2 2 Moisture Microbes Sound analysis

Astronauts are provided tools to perform successfully while CREW preserving their well-being and long-term health. Bulky fitness equipment Smaller, efficient HEALTH equipment Limited medical capability Onboard medical capability Monitoring Diagnostics Food Storage & Management Frequent food system Long-duration food Exercise Treatment resupply system

Long-term exploration depends on the ability to physically investigate EVA: EXTRA- the unknown for resources and knowledge. Upper body high mobility Full body mobility for expanded VEHICULAR for limited sizing range sizing range ACTIVITY Low interval between Increased time between maintenance, contamination maintenance cycles, sensitive, and consumables contamination resistant system, limit EVA time 25% increase in EVA time Mobility Science and Exploration Construction and repair Geological sampling and Life focused tools; excessive surveying equipment; Support inventory of unique tools common generic tool kit 33 Habitation Systems

Habitation Systems Elements TODAY FUTURE Space Station Deep Space Node 2 crew quarters (CQ) During each journey, radiation from the sun and other sources poses with polyethylene reduce Solar particle event storm a significant threat to humans and spacecraft. impacts of proton irradiation. Large multi-layer detectors & shelter, optimized position of RADIATION small pixel detectors – real-time on-board materials and CQ dosimetry, environment PROTECTION monitoring, tracking, model Small distributed pixel validation & verification detector systems – real- time dosimetry, environment Modeling Bulky gas-based detectors Monitoring – real-time dosimetry monitoring, and tracking Tracking Mitigation Small solid-state crystal detectors Small actively read-out – passive dosimetry (analyzed detectors for crew – real-time post-mission) dosimetry Throughout every mission, NASA is committed to minimizing critical risks to human safety. FIRE SAFETY Large CO2 Suppressant Water Mist portable fire Tanks extinguisher 2-cartridge mask Single Cartridge Mask Detection Suppression Obsolete combustion Cleanup Exploration combustion Protection prod. sensor product monitor Only depress/repress Smoke eater Sustainable living outside of Earth requires explorers to reduce, clean-up recycle, reuse, and repurpose materials.

LOGISTICS Manual scans, displaced Automatic, autonomous items RFID Disposable cotton clothing Long-wear clothing/laundry Bags/foam repurposed Tracking Packaging Packaging disposed w/3D printer Clothing Trash Bag and discard Resource recovery, then disposal Powerful, efficient, and safe launch systems will protect and deliver crews and materials across new horizons. CROSS- Minimal on-board autonomy Ops independent of Earth & crew CUTTING Up to 40-minute comm delay Near-continuous ground- crew communications Widespread common Communication Avionics, Materials interfaces, modules/systems Robotics Autonomy Some common interfaces, integrated & Software modules controlled separately Manufacture replacement Power Docking Thermal parts in space 34 NASA Fuel Cell Applications

Lunar Architecture Studies identified regenerative fuel cells and rechargeable batteries as enabling technologies, where enabling technologies are defined as having: “overwhelming agreement that the program cannot proceed without them.”

Surface Systems

Surface Maintenance-free operation of regenerative fuel cells for >10,000 hours using Power: ~2000 psi electrolyzers. Power level TBD (2-3 kW modules for current architecture). Reliable, long-duration maintenance-free operation; human-safe operation; architecture compatibility; high specific-energy, high system efficiency.

Mobility Reliable, safe, primary power from batteries and fuel cells, and energy storage Systems: from secondary batteries and regenerative fuel cells in small mass and volume. Human-safe operation; reliable, maintenance-free operation; architecture compatibility; high specific-power and high specific- energy.

Lander

Descent Functional primary fuel cell with 3-kW nominal power, 6-kW peak power. Stage: Human-safe reliable operation; high energy-density; architecture compatibility (operate on residual propellants).