Concept may make it profitable to obtain hydrogen fuel from water. Laboratory tests have demonstrated that method enables decomposition of water several orders of magnitude beyond equilibrium state where only small amounts of free hydrogen are present

Downs, W. R.

Mcbryar, H.

Sanders, A. P.

Williams, R. J.

English

NASA Technical Reports Server

- 
/ 
H20 02 and Some H20 
Figure 1. Separation Tunnel Conceptual Sketch (Not To Scale)
December 1975	 B75-10314 
fl	 NASA TECH BRIEF 
Lyndon B. Johnson Space Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Using Permeable Membranes to Produce Hydrogen and Oxygen From Water 
fl
A new concept may make it profitable to obtain a 
usable fuel, hydrogen, from one of the Earth's most 
abundant resources, water. In a process now under 
study, superheated steam is fed into a long tunnel 
made of a selectively permeable membrane. This 
input superheated steam consists of a natural 
balance, or equilibrium, between water vapor and a 
small percentage of free hydrogen and oxygen. 
As the steam moves along the tunnel, the initial free 
hydrogen escapes through the membrane, and the 
water vapor and the oxygen remain inside the tunnel. 
This upsets the natural water/oxygen/hydrogen 
equilibrium in the steam, and results in the 
decomposition of some of the water molecules into 
more hydrogen and oxygen. Some of this hydrogen is 
removed thereby causing further decomposition of 
water molecules to provide more hydrogen for 
subsequent removal. Thus, as the gaseous mixture 
passes through the long tunnel, hydrogen will be 
continuously formed and removed.
In the past, attempts had been made to remove free 
hydrogen from water vapor using selectively permea-
ble membranes. The productivity of these methods 
was limited to the recovery of the small amounts of 
free hydrogen naturally present in the water vapor. 
The features that make this new process superior are: 
a. The flowing vapor is contained within the mem-
brane, under conditions favoring decomposition, 
for a long period of time. 
b. This extended period of time allows the water/ 
oxygen/hydrogen system to produce hydrogen 
through the decomposition of water. 
c. The process continues, and new hydrogen is pro-
duced as long as the gaseous mixture is in the 
tunnel. 
Figure 1 shows one possible configuration for the 
separation tunnel. It consists of two thin sheets of a 
hydrogen-permeable material, such as palladium, 
bonded together to form a long continuous maze. 
(continued overleaf) 
This document wa orepared under the Sponsorship of the National
	
Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19750000314 2020-03-19T20:20:25+00:00Z
S Preheater l 
(Purge Gas) I	 Compressor 
H2	 Turbine 
PurgeGas+ 
I 
(Solar or	 H20	 1	
I	 Fuel Cell 
Heat	 1	 I
Electrical (Atomic)	 H2+1 /20]	
Cooling	 H20+ 
i H
2+1 /202 
Energy 
r	
-	
0	 fTurbine 
Reacto 
1H 2 0— H 2 +1 /2 02
	 I Compressor 
Figure 2. Proposed System for Generating Electricity
Power
is Steam would flow through the tunnel at a temperature 
of 600°C (1112° F) or higher, and at approximately 10 
atmospheres pressure. As hydrogen passes through 
the membrane, it would be flushed away by an inert 
gas. The removal of the hydrogen outside the tunnel 
keeps the system out of equilibrium and enhances the 
production of new hydrogen inside the tunnel. 
Laboratory tests have demonstrated that the method 
enables the decomposition of water several orders of 
magnitude beyond the equilibrium state (where only 
small amounts of free hydrogen are present). 
A system that might be used to produce electricity 
by recombination of the separated hydrogen and 
oxygen is shown in Figure 2. Preheated steam is 
decomposed into hydrogen and oxygen in the 
separator. Hydrogen is flushed from outside the 
membrane tunnel, and oxygen and water vapor are 
taken from inside the tunnel. The hot gases must be 
cooled; and since the gases are hot enough, turbines 
are used in the cooling process to add to the overall 
system output. The cooled gases are then recombined 
in a hydrogen/oxygen fuel cell to produce the major 
electrical output of the system.
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Johnson Space Center 
Code AT3 
Houston, Texas 77058 
Reference: TSP75-10314 
Patent status: 
Inquiries concerning rights for the commercial use 
of this invention should be addressed to: 
Patent Counsel 
Johnson Space Center 
Code AM 
Houston, Texas 77058 
Source: A. P. Sanders, R
	 illiams, 
W. R. Downs, and
-
 H. McBryar 
MSC-12600) 
Categories: 04 (Materiiils) 
B75-10314	 03 (Physical Sciences)


Using permeable membranes to produce hydrogen and oxygen from water

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server