Hydrogen Basics Douglas Conde
Hydrogen Basics • Hydrogen Gas (H2). • Very reactive. • Most Common element in the universe. • Never run out.
Hydrogen Basics Cont. • Does not pool • Dissipates quickly • Burns with out dangerous vapors • Invisible flame
Energy Content Comparison • Pound for Pound Hydrogen packs the most punch.
Current Storage Inadaquete • Cost • Weight and Volume • Efficiency • Durability • Refueling Time • Codes and Standards • Life-cycle and Efficiency Analyses
Department of Energy Objectives • BY 2005, develop and verify on-board hydrogen storage systems achieving 1.5 kWh/kg (4.5 wt%), 1.2 kWh/L, and $6/kWh by 2005 • By 2010, develop and verify on-board hydrogen storage systems achieving 2 kWh/kg (6 wt%), 1.5 kWh/L, and $4/kWh. • By 2015, develop and verify on-board hydrogen storage systems achieving 3 kWh/kg (9 wt%), 2.7 kWh/L, and $2/kWh. • By 2015, develop and verify low cost, off-board hydrogen storage systems, as required for hydrogen infrastructure needs to support transportation, stationary and portable power markets.
Current Storage Technologies • Low and High-Pressure Gas • Liquid • Metal Hydrides • Chemical Hydrides • Physisorption • Current Methods
Gaseous Hydrogen Storage • H2 gas tanks are the most proven of hydrogen storage technologies. • Carbon-fiber-reinforced. • Up to 10,000 psi. • High pressure tanks present safety hazard. • Concerns over Hydrogen/tank molecular interactions lead to embitterment.
Hydrogen Gas Storage • Commercially available • Cannot match gasoline for energy compactness
Hydrogen Gas: Bulky Storage • Higher Pressure, more energy per unit volume. • Gasoline = 34.656 MJ/L • Uncompressed Hydrogen 10.7 kJ/L
Liquid Hydrogen • BMW working with on board liquid hydrogen for vehicles. • Likely storage for larger applications such as transportation or production storage. • Highly energy intensive to liquefy. • Concerns over safety due to extremely cold temperatures.
Liquid Hydrogen: • High Pressure low tempature. • (22K at 1 ATM)
Liquefaction of Hydrogen gas The Joule-Thompson Cycle Energy required is currently 1/3 of the energy stored
Liquid Storage Options Non Portable Liquid Hydrogen Storage • No way to prevent Boil off. • Spherical Tanks. • More suited for transportation and non vehicular storage. • 8.4 MJ/L twice the density of compressed H2
Metal Hydride Families • Conventional Metal Hydrides (Naturally reversible) • AB5 most common (NiMH batteries) (1-1.25 rev wt%) • AB2 very common (1.3 rev wt%) • AB (TiFe - 1.5 rev wt%) • A2B (Mg2NiH4 - 3.3 rev wt%) • AB3, A2B7 • Complex Hydrides (Naturally irreversible) • Catalysts and dopants used to destabilize hydride phase • Two types • Transition Metal • Mg2FeH6 (5.5% max wt%) • Non-transition metal • Be(BH4)2 (20.8% max wt%) • NaAlH4 (4.2% rev wt%, 5.6 th rev wt%) (110C)
Remaining Issues • Reversible capacity • Reaction pressure and temperature • Absorption/Desorption rates • Cyclic stability • Reactive with air and water
Chemical Hydrides • NaH, LiH, NaAlH4, NaBH4, LiBH4, CaH2 • Advantages/ Disadvantages
Hydrogen Storage by Physisorption Graphite Nanofibers Nanotubes Zeolites Henry S Grasshorn Gebhardt
The solution for storing hydrogen, some say, is to “put rocks into your tank.”
Graphite Nanofibers • Inconsistent results: 0.08 wt.% to 60 wt.% • Most likely up to 10-13 wt.% • Lots of research needed (a) Herringbone, (b) Tubular, (c) Platelet
Multi-Wall Carbon Nanotubes • Giant Molecules • Length: a few microns • Inner Diameter: 2-10 nm • Outer Diameter: 15-30 nm • Much larger MWNTs have been observed. • Not much H2 adsorption?
Single-Wall Carbon Nanotubes • Lots of small micropores • Minimal macroporosity • High thermal conductivity → Bundled SWNTs
Where the H2 would be... Maximum of ~8 wt.%, or, ~1 H-atom for every C-atom.
Doped Nanotubes • Transition metals and alloys • Boron and Nitrogen • Other elements • Possibility of tuning the adsorption and desorption to the desired temperature. • Preliminary: ~1 wt.% without optimization.
Zeolites • An ion (Na+) serves as a “door” to micropores: • Lower temp.: closed • Higher temp.: open • Temperature difference is small for some zeolites Si and Al.
Hydrogen uptake in Zeolites • Most of the innumerable zeolites haven’t been studied yet in this respect. • At least 2 wt.%
Automobiles Testing with Hydrogen Fuel Toyota, Ford, BMW, Honda, Nissan, United Nuclear
Toyota => FCHV-4 Vehicle Maximum speed ~ 95 mph Cruising distance = Over 155 miles Seating capacity = 5 persons Fuel cell stack Type = Polymer electrolyte fuel cell Output = 120 HP (90 kW) Motor Type = Permanent magnet Maximum output = 107 HP (80 kW) Maximum torque = 191 lb-ft (260 Nm) Fuel Type = Pure hydrogen Storage method = High-pressure hydrogen storage tank Maximum storage pressure = 3,600 PSI Secondary battery Nickel-metal hydride battery
Ford => Model U Performance Engine horsepower: 118 hp (88 kW) at 4,500 rpmMHTS assist: 33 hp (25 kW) continuous / 46 hp (35 kW) peakTotal combined horsepower: 151 hp (113 kW) at 4,500 rpmTorque: 154 foot-pounds: (210 Nm) at 4,000 rpmEstimated fuel economy: 45 miles per kg hydrogen (= to 45 mpg gas)Emissions: PZEV or better Powertrain Hydrogen 2.3-liter ICE with supercharging and dual-stage intercooling Modular Hybrid Transmission System
BMW => 745h • testing with the simple principles of nature • liquid hydrogen is generated from energy and water • in engines - the hydrogen combusts with oxygen -> returns to water • cycles through this process to fuel the car
Honda => FCX ENGINE Motor Type = AC Synchronous Electric Motor (permanent magnet) Maximum Output (horsepower) = 80 Fuel Cell Stack Type = PEFC (polymer electrolyte fuel cell) Fuel Cell Maximum Output (kW)* = 78 Maximum Speed (mph) = 93 Vehicle Range (miles, EPA mode) = 160 • . FUEL Type = Compressed hydrogen gas Storage = High-pressure hydrogen tank Tank Capacity (L) = 156.6 Gas Volume when Full (kg) = 3.8 Maximum Pressure when Full (PSI) = 5000.0
Nissan => X-TRAIL FCV Vehicle Seating capacity = 5 Top speed (km/h) = 145 Cruising range (km) = Over 350 Motor Type = Coaxial motor integrated with reduction gear Maximum power (kW) = 85 Fuel cell stack Fuel cell = Solid polymer electrolyte type Maximum power (kW) = 63 Supplier = UTC Fuel Cells (USA) Storage battery Type = Compact Lithium-ion Battery Fueling system Fuel type = Compressed hydrogen gas Max. charging pressure (MPa) = 35
United Nuclear • took a 1994 Corvette and created a hydrogen fuel system • Driving range is 700+ miles per fill with a near-zero fuel cost
United Nuclear • stores the hydrogen in hydride tanks, which absorb the hydrogen like a sponge soaking up water • this is actually a safer storage system than a gasoline tank is