Better Storage Through Chemistry

This article focuses on production of a hydrogen fuel system for a DaimlerChrysler fuel cell minivan by Millennium Cell Inc., a developmental-stage company based in Eatontown. Millennium Cell’s hydrogen-on-demand system stores hydrogen in the form of sodium borohydride, a chemical whose chief use today is for bleaching paper. Mixed with water, the chemical makes a fuel that can be stored as a liquid in plastic vessels under ambient temperature and pressure. The mixture is neither flammable nor explosive. Millennium Cell continues its research. It is attempting to drive down catalyst costs. Improving catalyst durability is another constant challenge. The company continues making key changes in the packaging of its hydrogen-on-demand technology to reduce the space it occupies. As for Millennium Cell’s researchers, their desks filled with abundant technical challenges, they undoubtedly have plenty to do besides worrying about the future.

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ZERO EMISSION SAILING SHIP – CONCEPTUAL DESIGN –

10.3940/rina.win.2019.10 ◽

2019 ◽

Author(s):

K Ouchi ◽

T Omiya

Keyword(s):

Fuel Cell ◽

Wind Speed ◽

Electric Motor ◽

Hydrogen Fuel ◽

Liquid Form ◽

Zero Emission ◽

Temperature And Pressure ◽

Weak Winds ◽

Sailing Ship ◽

Rigid Wing

When a sailing ship which has large rigid wing sails such as the Wind Challenger Sail runs in a sufficiently windy sea, the thrust by sails is utilized to not only drive the ship at the proper speed but also to rotate an underwater turbine at significant speed and torque. The turbine generates electricity which is used for the electrolysis of water to generate hydrogen. The hydrogen is stored using toluene in the form of methylcyclohexane (MCH), which is in liquid form under normal temperature and pressure. MCH is stored in the ship's tank as hydrogen fuel. In the case of weak winds when the sails cannot generate sufficient thrust, using the hydrogen generated by the dehydrogenation device, the fuel cell works and supplies electricity to the electric motor propeller for the ship's propulsion. Thus, the ship can run at a constant speed regardless of wind speed and direction.

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Reactant Feeding Strategy Analysis of Sodium Borohydride Hydrolysis Reaction Systems for Instantaneous Hydrogen Generation

Energies ◽

10.3390/en13184674 ◽

2020 ◽

Vol 13 (18) ◽

pp. 4674

Author(s):

Yih-Hang Chen ◽

Jhih-Cyuan Lin

Keyword(s):

Transfer Function ◽

Dynamic Response ◽

Sodium Borohydride ◽

Hydrogen Generation ◽

Feeding Strategy ◽

Step Function ◽

Hydrolysis Reaction ◽

Demand System ◽

Liquid Volume ◽

On Demand

In this study, the operational procedure of an experiment and simulation for a hydrogen-on-demand system using sodium borohydride hydrolysis is proposed. For an isothermal operating condition of a packed-bed reactor, the dynamic response between the input NaBH4 feed (FNaBH4,0(S)) and the output hydrogen flowrate (FH2(S)) of the reactor can be analytically derived and is a first-order transfer function. The time constant of this transfer function is a function of the reciprocal of the product of the reaction rate constant and the catalyst weight into the liquid volume of the reactor. The kinetic parameters of Co-B/IR-200 catalysts are regressed from the experimental NaBH4 hydrolysis reaction. The result shows a 30 °C operating temperature increase (from 40 °C till 70 °C) can shorten the dynamic response time of the hydrogen generation rate by around two-thirds. From theoretical derivation, a feeding strategy which supplies the combination of impulse function and step function of the NaBH4 feed flowrate can produce a hydrogen-on-demand system. However, for real applications, a combined pulse and step function of the NaBH4 feed flowrate is used due to limitations in pump capacity. Hence, a systematic feeding procedure can then be constructed to achieve the US Department of Energy’s fuel cell start-up time target of less than 5 s. to produce hydrogen. Finally, the experiment was set-up to validate the simulation result.

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Diurnal Temperature and Pressure Effects on Axial Turbomachinery Stability in Solid Oxide Fuel Cell-Gas Turbine Hybrid Systems

Journal of Fuel Cell Science and Technology ◽

10.1115/1.4003163 ◽

2011 ◽

Vol 8 (3) ◽

Cited By ~ 1

Author(s):

James D. Maclay ◽

Jacob Brouwer ◽

G. Scott Samuelsen

Keyword(s):

Fuel Cell ◽

Ambient Temperature ◽

Gas Turbine ◽

Solid Oxide ◽

Inlet Temperature ◽

Electrolyte Temperature ◽

Turbine Inlet Temperature ◽

Compressor Surge ◽

Turbine Shaft ◽

Temperature And Pressure

A dynamic model of a 100 MW solid oxide fuel cell-gas turbine hybrid system has been developed and subjected to perturbations in diurnal ambient temperature and pressure as well as load sheds. The dynamic system responses monitored were the fuel cell electrolyte temperature, gas turbine shaft speed, turbine inlet temperature, and compressor surge. Using a control strategy that primarily focuses on holding fuel cell electrolyte temperature constant and secondarily on maintaining gas turbine shaft speed, safe operation was found to occur for expected ambient pressure variation ranges and for ambient temperature variations up to 28 K when tested nonsimultaneously. When ambient temperature and pressure were varied simultaneously, stable operation was found to occur when the two are in phase but not when the two are out of phase. The latter case leads to shaft overspeed. Compressor surge was found to be more likely when the system is subjected to a load shed initiated at minimum ambient temperature rather than at maximum ambient temperature. Fuel cell electrolyte temperature was found to be well-controlled except in the case of shaft overspeeds. Turbine inlet temperature remained in safe bounds for all cases.

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Evaluation of an Alkaline Fuel Cell for Multi-Fuel System

2nd International Conference on Fuel Cell Science, Engineering and Technology ◽

10.1115/fuelcell2004-2538 ◽

2004 ◽

Cited By ~ 1

Author(s):

A. Verma ◽

A. K. Jha ◽

S. Basu

Keyword(s):

Fuel Cell ◽

Power Density ◽

Current Density ◽

Sodium Borohydride ◽

Potassium Hydroxide ◽

Maximum Power ◽

Carbon Paper ◽

Maximum Power Density ◽

Alkaline Fuel Cell ◽

Fuel System

The performance of an alkaline fuel cell is investigated using three different fuels, e g., methanol, ethanol and sodium borohydride. Pt/C/Ni was used as anode whereas Mn/C/Ni was used as standard (Electro-Chem-Technic, UK) cathode for all the fuels. Thus, the alkaline fuel cell is used for multi-fuel system. Fresh mixture of electrolyte, potassium hydroxide (5M), and fuel (2M) was fed to and withdrawn from the AFC at a rate of 1 ml/min. The anode was prepared by dispersing platinum and activated carbon in Nafion® (DuPont USA) dispersion and placing it onto a carbon paper (Lydall, USA). Finally prepared anode sheet was pressed onto Ni mesh and sintered to produce the required anode. The maximum power density of 16.5 mW/cm2 is obtained at 28 mA/cm2 of current density for sodium borohydride at 25 °C. Whereas, methanol produces 31.5 mW/cm2 of maximum power density at 44 mA/cm2 of current density at 60 °C.

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Diurnal Temperature and Pressure Effects on Axial Turbo-Machinery Stability in Solid Oxide Fuel Cell-Gas Turbine Hybrid Systems

ASME 2009 7th International Conference on Fuel Cell Science, Engineering and Technology ◽

10.1115/fuelcell2009-85057 ◽

2009 ◽

Author(s):

James D. Maclay ◽

Jacob Brouwer ◽

G. Scott Samuelsen

Keyword(s):

Fuel Cell ◽

Ambient Temperature ◽

Gas Turbine ◽

Solid Oxide ◽

Inlet Temperature ◽

Electrolyte Temperature ◽

Turbine Inlet Temperature ◽

Compressor Surge ◽

Turbine Shaft ◽

Temperature And Pressure

A dynamic model of a 100 MW solid oxide fuel cell-gas turbine (SOFC-GT) hybrid system has been developed and subjected to perturbations in diurnal ambient temperature and pressure as well as load sheds. The dynamic system responses monitored were the fuel cell electrolyte temperature, gas turbine shaft speed, turbine inlet temperature and compressor surge. Using a control strategy that primarily focuses on holding fuel cell electrolyte temperature constant and secondarily on maintaining gas turbine shaft speed, safe operation was found to occur for expected ambient pressure variation ranges and for ambient temperature variations up to 28 K, when tested non-simultaneously. When ambient temperature and pressure were varied simultaneously, stable operation was found to occur when the two are in phase but not when the two are out of phase. The latter case leads to shaft over-speed. Compressor surge was found to be more likely when the system is subjected to a load shed initiated at minimum ambient temperature rather than at maximum ambient temperature. Fuel cell electrolyte temperature was found to be well-controlled except in the case of shaft over-speeds. Turbine inlet temperature remained in safe bounds for all cases.

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