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Ontario researchers develop new water plasmolysis method for production of hydrogen

Researchers at the University of Ontario Institute of Technology are developing a new method to dissociate water vapor into hydrogen gas by microwave-generated plasma (plasmolysis). A paper on their work appears in the journal Fuel.

Chehade

(A) An experimental setup for full microwave hydrogen production and (b) Schematic of the plasma reactor placed inside the microwave. Chehade et al.


Hydrogen production has become the center of attention for carbon-free solution, and more attention has been given to clean methods of hydrogen production. The generation of pure hydrogen gas requires a great deal of energy. However, considering the diatomic molecules are emission free upon combustion, hydrogen gas is scientifically desired and thus greatly researched in lowering the effective cost of production for countless numbers of applications.

The microwave plasma source (MPS) based method is one of the promising technologies for hydrogen production. … Despite the previously published studies of plasma-chemical hydrogen-producing methods from hydrocarbon solutions, there have been very few experimental studies on direct decomposition of water vapor using direct plasma discharge and no studies for antenna based microwave hydrogen production. In this study, a unique novel system is designed to decompose water vapor in a commercial modified 2.45 GHz microwave using pure and 2% ceriated tungsten antenna.

—Chehade et al.

In the system, steam flows by direct discharge at a temperature of 107 ˚C into a custom-developed reactor inside a 900 W microwave. The high energetic electrons produced by electric field acceleration of 2.45 GHz microwave collide with water vapor molecules; these molecules are ionized and dissociated into hydrogen and oxygen radicals.

Ionization, recombination, decomposition of water vapor occur at the tip of the ceriated tungsten. Undecomposed water vapor condenses in the reflux condenser to avoid any recombination of H2 and O2 and to separate and dry the produced gases. The dry gases flow through the outlet of the condenser to the flowmeter and the catalytic hydrogen sensor.

The energy and exergy efficiencies are 53% and 44% respectively, while the maximum energy yield for hydrogen is found to be 13.3 g/kWh. The hydrogen production rates are found in the range of 25.7 to 78.3 mL/s.

Thus, the high efficiency and productivity of this unique system raise the hope to solve many important problems in energy and sustainability.

—Chehade et al.

Resources

  • Ghassan Chehade, Spencer Lytle, Haris Ishaq, Ibrahim Dincer (2020) “Hydrogen production by microwave based plasma dissociation of water,” Fuel, Volume 264 doi: 10.1016/j.fuel.2019.116831

Comments

Engineer-Poet

This doesn't even come close to the best electrolyzers; 43 kWh (154.8 MJ) in yields 145.8 MJ HHV out.  That's 94% (the big losses are where you try to convert back to electricity).

Davemart

A process does not have to be 'the best' on all metrics to be useful.

Of course this is less efficient than conventional electrolysis, but look at the very small scale of it, which means that hydrogem can be generated right on the spot.

There might also be the possibility of using the process heat for hot water etc, so overall thermal plus electrical efficiency might be a different matter.

deepthort

From a systems perspective:
Converting water to hydrogen (fuel ?) and then fuel (same hydrogen) to water requires an energy input in order to have an energy output.
Regardless of the process, starting with water and ending with water implies no additional energy release, so the energy cost is that put in to produce hydrogen from water. Hydrogen can therefore be considered equivalent to a battery, an energy storage system rather than a fuel - hence my question mark above.

The important questions remain 1. what is the conversion energy (loss) and 2. where is this energy going to come from?


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