Power Sources. Research and Development in Non-Mechanical Electrical Power Sources

631 Pages·1967·16.488 MB·English

by  D. H. Collins (Eds.)

Other titles in this series
BATTERIES. Research and Development in Non-Mechanical Electrical Power
Sources. Edited byO. H. COLLINS, 1963
BATTERIES, 2. Research and Development in Non-Mecfcanical Electrical Power
Sources. Edited by D. H. COLLINS, 1965
Power Sources
1966
Research and Development in
Non-Mechanical Electrical Power Sources
Proceedings of the 5th International Symposium
held at Brighton, September 1966
Sponsored by the Joint Services Electrical
Power Sources Committee
Edited by
D. H. COLLINS
SYMPOSIUM PUBLICATIONS DIVISION
PERGAMON PRESS
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Copyright © 1967
Pergamon Press Ltd.
First edition 1967
Library of Congress Catalog Card No. 62-22327
Printed in Great Britain by Bell and Bain Limited, Glasgow
(3106/67)
SYMPOSIUM COMMITTEE
REPRESENTING THE JOINT SERVICES ELECTRICAL POWER SOURCES COMMITTEE :
D. H. COLLINS, M.B.E. Admiralty Engineering Laboratory {Chairman)
L. H. CATT Post Office Engineering Department
Dr. R. K. PACKER Admiralty Underwater Weapons Establishment
A. L. TAYLOR Fighting Vehicles Research & Development
Establishment
Dr. R. G. H. WATSON Admiralty Materials Laboratory
REPRESENTING INDUSTRY :
Dr. M. BARAK The Chloride Electrical Storage Co. Ltd.
J. M. BRISCOE The Ever Ready Co. (G.B.) Ltd.
J. C. HART Energy Conversion Ltd.
M. J. H. LEMMON The McMurdo Instrument Co. Ltd.
L. R. PROUT Oldham & Son Ltd.
Dr. P. REASBECK Joseph Lucas (Electrical) Ltd.
V
FOREWORD
THE International Power Sources Symposia are sponsored by the British
Government Joint Services Electrical Power Sources Committee which has
taken over the activities of the Inter-Departmental Committee on Batteries.
The first four Symposia although nominally limited to batteries included
papers on other power sources and when the terms of reference and title of
the sponsoring committee were changed to include all power sources, other
than rotating machinery, similar changes in the title of the Symposia and
associated books were clearly due.
This book contains the papers presented at the 5th Symposium and the
discussion on them. It marks the end of the " Batteries " series associated
with previous Symposia and the beginning of the " Power Sources " series.
The Symposia are organized by a working committee on which British
commercial and government organizations are equally represented. The
commercial organizations provided the initial financial backing for the
Symposia and also provide many of the services which are essential for the
efficient organization and running of such events.
The Symposia are the only regular international meetings covering this
particular field, apart from those held in North America. They offer there-
fore a rare opportunity for the workers and users to discuss their subject. To
enable delegates to make good use of this opportunity, pre-prints of the papers
are issued in advance of the Symposia so that the time required for their
presentation can be kept to the minimum and the time for discussion on them
to a maximum. These discussions are recorded and, in an edited form,
included at the end of each paper in these Proceedings.
As a further step, to assist delegates to meet outside of the regular sessions
of the Symposia, and so to encourage discussion, attendance is limited to a
maximum of 400 delegates. Apart from this, there are no restrictions on
attendance at the Symposia and a large number of both delegates and the
papers presented come from overseas countries. The majority of the papers
come from industry, government and other establishments where work on
power sources is in progress, but papers from universities and users are
encouraged. This is of particular value as it brings to the attention of a wide
audience not only the little known background work associated with power
sources, but also the nature of the users' requirements and the problems with
which he is faced when selecting a power source for a particular application.
The Symposia will continue to be held at two-yearly intervals and the next
will be held at Brighton on 24, 25 and 26 September 1968.
vii
OPENING ADDRESS
S. F. FOLLETT
I WAS most gratified when Mr. Lewis, the Chairman of the J.S.E.P.S.
Committee, asked me some months ago if I would make the opening address
at this symposium and it gives my wife and I much pleasure to be here today
and to meet many of my old friends.
In view of the eminence of the four previous opening speakers at these
symposia, I was at a loss to understand why I had been approached—and no
doubt you are also similarly mystified—Mr. Lewis was kind enough to say
that I had " started it all " by organizing the first Inter-Service Committee
on Batteries in 1947 and acting as Chairman for its first few years. The
purpose of this Committee was primarily to provide a means for the few
battery enthusiasts who had collaborated during the war to continue to
discuss their work and its probable future, to consider reported new ideas,
to advise and encourage the industry to undertake new developments and to
stimulate the production of any novel batteries of special merit in their
formative stages.
The early meetings of the Committee were essentially friendly gatherings
of enthusiastic scientists and technologists interested in a rapidly expanding
technological field affecting directly most phases of public life as well as the
more sophisticated needs of the defence scientist; a field which in the past had
been much neglected by the research worker. I think that in those early days,
we did encourage industry to consider the more fundamental aspects and by
our mutual support we were able, by providing much needed financial
assistance, to prevent at least one promising new battery, now firmly
established in this country, from expiring in early childhood. We did, at
least, encourage each other—and enjoy the various meetings.
Early in the proceedings, members of the Committee were invited to take
part in conferences on batteries held in the United States at Fort Monmouth
and I remember that it was one of the Chairman's less enviable tasks to give
advice to their Departments on which members should go to these Confer-
ences.
This international collaboration was most fruitful and it is, therefore, with
great pleasure that today I see from the list of authors that there are papers
from six European countries, Canada and Japan, as well as the U.S.A.
Now this early Battery Committee is no more as it was replaced two years
ago by the Joint Services Electrical Power Sources Committee covering all
xiii
xiv S. F. FOLLETT
sources of electrical power, other than rotating machinery; a much wider
field of work. I note, however, that the new Committee has one of the original
founder members still on it, Mr. F. C. B. Smith. Mr. Lewis succeeded me as
Chairman in 1950 and is still the Chairman while Mr. Collins has been the
Secretary since 1951. He is also the Chairman of the Committee of this
Symposium which is comprised of representatives from Industry and from the
Committee. I think we are particularly indebted to these gentlemen for
their great efforts which have made this Symposium possible. I would also
like to mention the late Mr. Frank Booth who was largely instrumental in
starting these Symposia.
It is an interesting reflection that it is just 100 years ago that Georges
Leclanche took out his patent for the cell that bears his name while Plante
evolved his reversible lead-acid storage battery in 1859.
In these days of rapidly advancing technology, it is remarkable that by
far the majority of batteries now in use still use variations on these two basic
themes. A large amount of work has been done in recent years on selecting
and examining possible alternative couples and while for special purposes
some useful combinations have been developed, Leclanche and lead-acid
cells continue to dominate the general cell situation and one must ask why
these two forms of batteries are so successful. I believe that this success is
due to the unrelenting study of the technology of these cells and the application
to them of developments of scientific method and new materials. In this
manner, they have been built up from relatively unpromising materials into
power sources, which, while not perfect, give a satisfactory practical perform-
ance for most purposes. For example, what more unsuitable materials for a
vehicle battery could be devised than a soft lead sheet and a corrosive acid ?
But from this unpromising start, the present reliable, inexpensive car battery
has been developed. Many scientific and engineering disciplines and tech-
niques have contributed to this result. For example, the metallurgists were
needed to devise lead alloys of sufficient strength to withstand the stresses due
to the expansion and contraction of the active material but which had to be
readily castable and would not, in use, contribute to the self discharge of the
cell. The chemist had to investigate the numerous forms of lead oxide and its
preparation on a large scale and its formulation in the form of a paste able to
withstand the strains of charge and discharge when supported in a thin grid.
Good engineering was necessary to design that grid to give sufficient current
collection and to provide methods of assembling groups of plates together
and into batteries with low connector resistance. The plastic manufacturer,
as well as providing acid-resisting cases and seals capable of resisting vibration
and shock, succeeded in the difficult task of supplying a porous synthetic
separator able to withstand the onerous conditions at and between the plate
surfaces.
There are, of course, many other detailed improvements such as additives
Opening Address xv
to the active materials but I think that enough has been said to show how
study of the practical problems and the use of new materials and new tech-
niques, both of investigation and manufacture, have brought an electro-
chemist's laboratory experiment to a practical device.
An enormous amount of work on electro-chemical power sources was done
in the period from roughly 1880 to 1905 much of which was not of much
practical value because of limitations of materials and techniques but with
the materials and techniques now available this earlier work is becoming of
greater usefulness. I am, therefore, hopeful that as a result of this new
knowledge, novel batteries superior in " cost-effectiveness "—that fashion-
able term—to our old friends may yet appear.
I would stress that in underlining our dependence on Leclanche and lead-
acid cells, I have not forgotten certain other cells which, by reason of the
special properties needed for particularly onerous conditions, have been
developed by the use of modern techniques and materials to a high standard.
The example which first occurs to me is the nickel-cadmium battery used in
satellites. Here the batteries must be effectively sealed and must work in a
temperature cycle which the satellite designer would like to extend from
— 15°C to +60°C but which from his kindness of heart to the battery, he
restricts to 0°C to + 40 °G. Daily charging and discharging by automatic
means are provided but no further attention is possible. The battery enables
the satellite to function when it is in the earth's shadow and if the battery
fails, the effectiveness of the satellite is much reduced. Since the cost of
launching the satellite may have been of the order of a million pounds,
battery life, measured both in maintenance of cell performance and mech-
anical integrity of the case, is essential and special measures to select batteries
are justified. A spare battery can be carried at a severe weight penalty but as
satellite lives increase from the present target for the U.K.3 satellite of 1 year
to lives of 5 or more years which commercial communication satellites
should have, the battery problem will clearly become even more pressing.
Another battery in which reliability, rather than life, is absolutely essential
is the reserve battery. In this case, indefinite storage is required with instant
readiness of action. Any failure in performance or hesitation can have cata-
strophic results to, for example, a weapon, costing many thousands of pounds,
of which it forms part. Here, the most extreme precautions during manu-
facture to produce a reproducible, reliable battery are justified.
I would also like to mention the mercury battery which allied with
transistorized amplifiers has by its miniaturization done so much to popularize
the personal type of equipment such as the deaf-aid.
It is, however, when one considers the extension of your interests from
batteries to other power sources that one can see the exciting and almost
limitless possibilities arising from the developments of new materials and
techniques.
xvi S. F. FOLLETT
The first work on fuel cells was done in the year 1839 but, except for the
sterling work of Bacon in this country, this power source had received little
attention until recently. It is a measure of their development in the U.S.A.
that fuel cells were used as a power source in the Gemini satellite. In this
particular context, I suppose some moral may be drawn from the fact that
the water formed in the cells, the removal of which is normally a problem,
became a major virtue or advantage.
A simple, efficient and long-life fuel cell capable of running unattended
would have great possibilities for electricity in remoter regions. The
fallibility of very large inter-connected electricity systems was recently
demonstrated in the U.S.A. Is it too futuristic to suggest that we might have
fuel cells in each house fed from gas mains filled from the natural gas now
available so generously from under the North Sea ?
Another attractive possibility for the fuel cell is its use as a convertor of the
simpler end-products of biochemical action on primary reactants such as
starch, protein or carbohydrate. Methane and ammonia can be produced
by anaerobic digestion of sewage. These gases have a good heating value and
the former has been used as a source of power at sewage works. The greater
efficiency of the fuel cell would increase the power yield several times.
Ammonia has, of course, already been used as a source of hydrogen for fuel
cells.
Another desirable development would be a biochemical gas generator
which would consume as its primary fuel, commonly available forms of
vegetation such as grass, leaves or wood. Such a device connected to a fuel
cell would have obvious military as well as commercial use. Some prototype
gas generators have been built using potatoes, crushed fruit and coconut
juice but there is a long way to go before the fading of the television picture
will be the signal for father to put another log in the generator!
Under the stimulus of space exploration, solar cells have been the object of
much investigation and while great strides have been made, the efficiency of
the cells and the maintenance of their performance under the environment of
space require considerable improvement. At present, solar cells are used in
satellites for the operation of the satellite equipment such as communication
repeaters and similar duties. Recent work by Burt of the Royal Aircraft
Establishment has, however, shown that solar cell energized plasma motors
can provide an economical means of adjusting the orbit of the satellites; a
task for which large chemical motors are now used. Thus, once the satellite is
in, say, a low polar orbit, the application of a very low thrust for a relatively
long period could change the orbit to, say, a geo-stationary orbit. Existing
satellite launchers would by the application of this principle be enabled to
put very much heavier loads into the high orbits needed for communication
satellites.
Burt has estimated, for example, that for the Black Arrow satellite
Opening Address xvii
launcher, which in its present form has no geo-stationary orbit capability,
a load equal to 60 per cent of the low polar orbit load could be put into a syn-
chronous orbit. For this purpose, a supply of about 1 kW would be needed
from the solar cells for the plasma motors. To provide this supply in a
reasonable size and weight, an improvement in solar cell output per unit
weight of two to three times is required for the full exploitation of the idea.
A further advantage of this system would be that when the satellite was in
its chosen orbit, a large electrical power supply, very much larger than now
exists, would be available for communication purposes and, without time
limit, for Thrusters for satellite stabilization purposes.
I believe, that by the processes I have mentioned previously, such
improvements in solar cells could be attained in a year or two and I heartily
commend this problem to the solar cell experts.
Thermoelectric generators are emerging as quiet and portable power
sources and one form in which the couples are heated by propane is described
in Paper No. 13.
Radio-isotope-thermoelectric generators appear even more attractive
since by choosing an isotope with a half life much greater than the expected
life of the equipment to be supplied, a nearly constant output can be obtained
over a number of years. The cheap isotope, strontium-90, unfortunately
suffers from the grave disadvantage that very heavy shielding is needed to
enable the generator to be safely transported. Nevertheless, where unattended
power sources are essential such as for navigation lights or weather stations, a
heavy source could be tolerated. At this point in my original draft, I had
written that such radio-isotope-thermoelectric generators have been produced
experimentally. The progress of science is, however, such that in the August
1966 issue of the Scientific American, there is an advertisement for a power
source of this kind guaranteed to give a 25 watt supply for 5 years, weighing
3000 lb and costing the small sum of $63,320 f.o.b. Baltimore.
I have endeavoured to show the vast range of possibilities which face the
members of this symposium and I envy them the interesting problems which
lie ahead of them in so many associated fields. I have no doubt that the
application of scientific method and new materials will in the near future
provide small power sources which are very much greater advances on our
present equipment than were the achievements of the last century on the
original ideas of Plante and Leclanche.
I wish you a very interesting and productive symposium.