Advances in Solar Energy: An Annual Review of Research and Development, Volume 1 · 1982

313 Pages·1985·12.228 MB·English

by  Raymond J. Bahm (auth.), Karl W. Böer, John A. Duffie (eds.)

Advances in
Solar Energy
Volume 1 • 1982
EDITORIAL BOARD
Co-Editors-in-Chief
Karl W. Boer
University of Delaware and SES, Inc.
Newark, Delaware
John A. Duffie
University of Wisconsin at Madison
Madison, Wisconsin
Associate Editors
Ki nsell L. Coulson
Mauna Loa Observatory
Hilo, Hawaii
K.G.T. Hollands
Department of Mechanical Engineering
University of Waterloo, Waterloo, Canada
Michael Seibert
Solar Energy Research Institute
Golden, Colorado
Horst Selzer
Erno-Raumfahrttechnik
Bremen, West Germany
Dona Id Watson
Yale School of Architecture
New Haven, Connecticut
Advances in
Solar Energy
An Annual Review of Research and Development
Volume 1 • 1982
American Solar Energy Society, Inc.
New York Boulder
NOTICE
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ISSN 0731-8618
ISBN 978-1-4684-8994-1 ISBN 978-1-4684-8992-7 (eBook)
DOI 10.1007/978-1-4684-8992-7
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FOREWORD
The field of solar energy conversion has become an important discipline with a
recognized potential to significantly contribute to the world supply of energy. It is
diversified and encompasses a wide variety of disciplines - from mechanical engineering
to physics, from biology to architecture, from ocean science to agriculture, from chemistry
to atmospheric science, to name some of the major fields. It involves fields which have
matured to the engineering aspects, such as the conversion of solar energy into heat or of
wind into shaft work. It includes other fields in which more basic science research is
necessary to unravel the micro-structures of nature, as, for example, for photovoltaic
conversion or for certain bioengineering tasks.
Several of these fields have elements which have been common knowledge for
centuries but sometimes forgotten at times of cheap energy supplies, while others have
barely started with first studies. Most of the fields have seen during the last decade a
substantial advance in sophistication, in theoretical understanding, in demonstrated
feasibility, in developing hardware, in field testing, with some moving into a phase of initial
commercialization.
As a field matures, need develops for a periodic, extensive survey on a larger sphere
and level of completion than is usually covered in journals. These surveys are customarily
the domain of "Advances in ... " or other review volumes. Their aim is to assist the
newcomer through a critical overview and a guide to who's who in the field. At the same
time they assist the experienced researcher by providing a comprehensive and critical
survey.
The state of development of solar energy conversion now demands such
comprehensive reviews, and Advances in Solar Energy is designed to meet this need. The
reviews will serve to bring together in a single document the results of years of work by
many researchers in various locations, and also provide a comprehensive bibliography.
There is sufficient knowledge in many facets of the field to warrant a detailed and
comprehensive review, and to enlist the most qualified reviewer to present the material in
a critical, yet not one-sided approach. We will proceed, therefore, according to the state of
readiness of each of the topics, rather than along a sequential arrangement as is found in
textbooks. Each of the topics shall be self-contained and may, in turn, reference not only
original work but sub-topics reviewed in journals. As time progresses we will update
reviews of subjects which, in the meantime, have advanced substantially.
Early volumes of this series will tend to emphasize more mature subjects. Later
volumes may, in addition, start to treat areas that are not so mature, where the research is
more current, and where implications of some results of the research may be more
speculative.
The reader will find in the writings in this first volume of Advances in Solar Energy
some variations in style and scope of the reviews. This is to be expected. Some of it will
vanish as the field and this series mature; some of it will persist as we are serving a wide
variety of readers.
To close this foreword, we express gratitude to the American Solar Energy Society for
recognizing the timeliness and importance of this series and having offered to act as
publisher, to Albert Henderson, as Director of the Publications Office, for having stimulated
and encouraged the start-up, and to Barbara Bradley, as Publications Production Manager,
for having put this volume together with patience and attention to the whole as well as to
minute details.
Karl W. Boer
John A. Duffie
Co-Editors-in-Chief
TABLE OF CONTENTS
Radiometry-The Data 1
Raymond J. Bahm
Solar Radiation Measurements: Calibration and Standardization
Efforts 19
G. A. Zerlaut
Biomass Pyrolysis: A Review of the Literature
Part 1 - Carbohydrate Pyrolysis 61
Michael Jerry Antal, Jr.
Recombinant Genetic Approaches for Efficient Ethanol Production 113
H. W. Stokes
S. Picataggio
D. E. Eveleigh
Crystalline Silicon as a Material for Solar Cells 133
M. Rodot
A Review of Large Wind Turbine Systems
Large Wind Turbine Systems in the United States 175
James J. Lerner
Large Wind Turbine Systems Seen from the European Viewpoint 188
H. Selzer
Controls in Solar Energy Systems 209
C. Byron Winn
Passive and Hybrid Cooling Research 241
John I. Yel/ott
Passive Solar Heating Research 265
J. Douglas Balcomb
Subject Index 305
Author Index 311
Advances in Solar Energy. ~ 1983 American Solar Energy Society, Inc.
RADIOMETRY-THE DATA
RAYMOND J. BAHM
Raymond J. Bahm and Associates, Albuquerque, New Mexico 87120
Abstract
This chapter presents a summary of many of the important advances in the art and science of the use
of solar radiation measurements. Emphasis is placed on those advances which will have the most
impact in the utilization of solar energy. The work cited is mainly that done since 1977. The literature
includes more comprehensive texts on solar radiation measurement, 1-3 a bibliography,. and a previous
review of this field.5
USES OF SOLAR RADIATION DATA Any designer of modem, high-rise buildings will
Today most people are aware that solar energy is analyze the projected solar energy gain of the
potentially a major energy source for the world. building as part of the design process. Solar
Already there are significant applications where radiation data is a necessary input to this
solar energy is replacing other energy sources in analysis.
a cost-effective manner. The most common of Meteorologists and climatologists use solar
these are: radiation data in modeling the energy flows with
in the atmosphere. The energy input to this
• domestic water heating;
system is almost exclusively from the sun.
• space heating of buildings;
Understanding the climate and weather requires
• electric power for remote installations; and
a detailed knowledge of the solar radiation avail
• electric power for spacecraft
ability.
A variety of other applications are possible for Agriculture is a major user of solar radiation
the future. data. Plants convert the available solar radiation
One of the major benefits of the solar energy by photosynthesis into chemical energy or
resource is that it is generally available at the biological energy. Models of agricultural produc
location where the energy is needed. Thus, tivity often include solar radiation measures.
transmission lines or transportation of fuel is un The irrigation requirements for crops are highly
necessary. However, since the availability of dependent upon evapotranspiration, which in
solar radiation does vary from place to place and tum is a function of solar radiation.6 Brown et.
time to time, a knowledge of the expected future al., state that forecasts of solar radiation avail
availability is necessary for the design of solar abilities are used for scheduling irrigation.7 The
systems. Solar system designers are the largest
group of users of solar radiation data.
Another important use of solar radiation
resource data is economic planning. Global and
Raymond J. Bahm is a principal in the firm of Ray
national energy resource planning is beginning to
mond J. Bahm and Associates, which specializes in the
include solar radiation availability as a signifi collection, analysis and use of solar radiation data. He
cant factor. has worked on numerous projects for the U.S. Depart
ment of Energy and the State of New Mexico analyzing
Solar radiation provides both desirable and
and el'{lluating measurements of the solar resource,
undesirable energy contributions to buildings. and authored numerous papers in that area.
forecasting is important because the magnitude standing of the energy available for the growth of
of the irrigation system requires many days of crops and the energy inputs for weather phe
advance planning. nomena. The most recent interest in the
Solar radiation is a major factor causing the measurement of solar radiation has been for a
weathering of materials. The precise measure better understanding of the energy impacts of
ment of solar radiation and knowledge of its climate on buildings and the development of
distribution is important to testing ofthe durabil solar energy systems.
ity of materials.s Historically, solar radiation data have been
Recently, it has been recognized that high summarized and published in the form of daily or
levels of solar radiation, especially in the ultra monthly averages. However, the increased use
violet, may be an important factor in causing of electronic digital computers has caused the
human skin cancer. use of detailed simulation models to be devel
Statistics on use of solar radiation data show oped, and the demand for solar radiation data on
that in 1979 alone the Environmental Data Ser an hourly basis has increased. Many researchers
vice of the National Climatic Center responded have demanded actual measures of hourly data
to 1,714 separate requests for solar radiation in order to investigate the dynamic performance
data. These are in addition to the over 300 regu of systems in a realistic environment. Within the
lar recipients of published solar radiation data. 9 past year (1981), hourly solar radiation data have
Many of these are institutions which then pro even become available for microcomputers on a
cess the data and pass on the results in a different floppy diskette.1O
form to groups of users. The basic instruments for the measurement
of solar radiation are pyranometers, which mea
sure the radiation incident on a horizontal sur
TRENDS IN DATA COLLECTION AND USE
face, and pyrheliometers, which measure the
Today there is a strong trend toward improved
beam radiation in a plane normal to that beam.
data collection methods and instrumentation,
Historically, a variety of other names have been
resulting in more accurate, more meaningful,
applied to these instruments, but the type of
and more useful data. The major elements caus
measurement has been typically one of these
ing this trend are:
two. Recent improvements, such as temperature
• much greater use of the data by a wider popu compensation, have made these instruments
lation of users; more accurate and easier to use.
• increasing availability of higher quality sen- The best quality pyranometers are thermo
sors; pile instruments. The stability of the calibration
• increased use of high quality sensors; of instruments is very important, and has been a
• improved data recording devices; major problem for both manufacturers and
• more accurate calibration methods and more users. The Precision Spectral pyranometer
widespread knowledge about their use; (PSP) of the Eppley Laboratory is widely
• increased use of digital computers and avail accepted as the best quality, commercially avail
ability of solar radiation data in computerized able instrument because of its demonstrated
form; and stability and other inherent characteristics. A
• better data processing methods, including new instrument was announced in 1981 by Kipp
better methods for detecting and correcting & Zonen, which is similar to the PSP, except
errors. that the manufacturer uses thick-film, mass
production techniques for the thermopile. If this
Solar radiation has been measured regularly
instrument proves to be sufficiently stable, then
at many locations since the early 1900s. The
it is likely it will be adopted widely ifit maintains
earliest measures were attempts to determine the
a lower cost.
value of the "solar constant" * and its possible
Until the mid 1970s, few long-term, con
variation by careful measures of the direct solar
tinuous measurements were made of the direct
beam radiation at a variety of locations. Later
beam solar radiation. The major problem had
measures were directed more toward the under-
been the design of an instrument which would
reliably track the diurnal and annual motions of
"The solar constant is the flux of solar radiant energy
the sun. The Eppley Tracker, which tracks the
across a unit area oriented normal to the solar beam at
the mean earth-sun distance. diurnal motion, has made beam measurements
2
practical in some climates, but a number of prob itself, problems with the instruments or record
lems still remain. These are: ing system can often be detected before many
data are lost.
• the difficulty in aligning the tracker axis
Much of the need for measures of solar
paraUel with the earth's polar axis to the
radiation is for the availability on surfaces which
necessary precision;
are nonhorizontal. The most convenient and
• the need for once or twice weekly manual ad
generally adequate method for obtaining these
justment of the tracker to account for the
data is by the use of models. The reason for this
change of declination of the sun; and
is that a significant portion of the solar energy
• the inability to set or align the tracker when
available on nonhorizontal surfaces is reflected
the sun is obscured by clouds.
from the ground and other surroundings, and
New trackers have now been developed which the reflectivity of these surroundings changes
alleviate the last two of these problems. These drastically even over very short distances. Thus,
trackers are controlled by microprocessors and nonhorizontal measures of the energy incident
foUow both the diurnal and annual motions of the on surfaces at one point are not necessarily rep
sun. A problem with these trackers is that they resentative of those at another point, even a
are expensive. short distance away. Models are used to trans
Data coUection, in the past, has been treated form the measures of the solar radiation incident
one parameter at a time. Temperature was re on a horizontal surface to those on a nonhori
corded by one instrument, the data were pro zontal surface. The improved measurements
cessed in one way at one time, archived in one mentioned in the foregoing paragraphs, and
place, and published in one document. Wind was specialized measures of solar radiation on non
treated separately. Solar radiation data were still horizontal surfaces where the reflectivity is
different. The data user had to search in different known, are promoting the deVelopment of
places for different parameters covering the better models.
same time period at the same location. It was up Another use of specialized measures of
to the user to fill in missing data or to find com solar radiation is the use of "reference cells" for
plete data sets for matching time periods. Solar the testing of photovoltaic devices. A reference
data were integrated over one time period ceU is a photovoltaic cell, usuaUy from the same
related to solar time, and temperature data were production process as those to be tested, which
integrated over another, related to local standard has been calibrated by a testing laboratory. The
time. The result was that people relied heavily use of a reference cell is necessary because other
on statisticaUy developed, representative-of instruments for measuring solar radiation do not
average data sets for design purposes. have the same spectral response as the photo
Today, the data are beginning to be col voltaic devices to be tested. The choice of a cell
lected by one data recording system using from the same production process is intended to
standard times for aU parameters and recording minimize the effect of the natural spectral varia
aU the data on one computer-readable medium. tions in solar radiation on the test results.
Combined data sets prepared for specific pur There has. been an increased awareness of
poses are beginning to emerge. The SOLMET the importance of measurements of the spectral
data available for the U.S. is an example. These distribution of solar radiation. The need to esti
data provide a much improved dynamic picture mate the solar radiation resource availability for
of the environment for building and solar system photovoltaic devices has caused many persons
designers. to look for data which show the impact of the
Along with the coordinated data collection spectral characteristics of atmospheric absorp
systems, better data processing methods are tion on the solar radiation resource availability
developing. Models are being used to check the for photovoltaic devices. There are a number of
reasonableness of the measured data. Two basic factors which must be considered. These are:
types of checks are used: the first is a check to
see if the values are reasonable for the date of • most measures of solar radiation availability
recording, and the second is the comparison of are made with instruments having equal sensi
related measures by using a model which pre tivity to the aU parts of the solar spectrum;
dicts one from the other. When these checks are • photovoltaic devices are sensitive to only a
applied during, or soon after, the measurement restricted part of the solar spectrum;
3
• different photovoltaic devices have different number of recent publications and workshops
spectral sensitivities; have helped eliminate the gap in that knowledge.
• the spectral transmission of the atmosphere Representative of these are:
varies with the varying climatic conditions, (a) The California SoLar Data Manual. 11
the major effects being absorption by water This publication provides general solar radiation
vapor, and absorption and scattering by data for the state of California, along with
atmospheric dust and gaseous molecules; general formulas and other appropriate informa
tion for design of solar systems.
and
(b) Radiation Measurement. This booklet
12
• some of the energy scattered from the solar describes instruments, their installation, calibra
beam reappears as diffuse solar radiation. This tion, and use. It is intended for the scientist or
scattering is strongly dependent on the wave engineer who wants to set up a sophisticated
length, and has its most rapid change in the solar radiation measuring station.
region of the spectrum where the photovoltaic (c) An Introduction to MeteoroLogical Mea
sensitivity is the greatest. surements and Data HandLing for SoLar Energy
AppLications.13 A compendium of chapters by
The resulting problems are:
many authors which serves as an introduction to
• the accuracy of the resource estimates for solar radiation measurement.
flat-plate photovoltaics using the traditional (d) Listing of Solar Radiation Measuring
measures will depend upon the atmospheric Equipment and GLossary. 14 A listing of manufac
conditions at the time of use; and turers as of 1976.
• the accuracy of the resource estimates for (e) On the Nature and Distribution of Solar
concentrating photovoltaic systems will be Radiation. 15 An introduction to solar radiation
even poorer than those for flat plate systems. and its atmospheric interaction.
Additional measures of the atmospheric char (f) Solar and Terrestrial Radiation. 3 A text
acteristics are needed to improve the accuracy with emphasis on radiation instrumentation.
of the knowledge of the resource for these (g) Numerous solar radiation workshops
concentrating systems. have been held in the U.S. These have been
sponsored by the U. S. Department of Energy,
The increased development, testing, and
and most have been organized by one or more of
application of mathematical models of the
the eight University Meteorological Research
spectral characteristics of atmospheric trans
and Training sites.16
mission are due to the more widespread availa
(h) There have been periodic review meet
bility of computers and the decreasing cost of
ings of the U.S. Department of Energy con
their use. These improved models are also show
tractors in the field of solar radiation resource
ing us where improved instrumentation is
assessment. These meetings have provided a
needed and assisting in the definition of new in
center for information exchange and researcher
struments and measures.
interaction in the U.S. since 1975.
Another trend is the decreasing use of the
bimetallic strip type of solar radiation sensors.
RESEARCH FACILITIES
The general reason here is that these instruments
A number of research facilities have recently
tend to have poor accuracy.
been established in the U.S. which have pro
vided, and will continue to provide, advances in
EDUCATION, TRAINING, AND the knowledge about solar radiation and its inter
DISSEMINA TION OF KNOWLEDGE action with the atmosphere. Four of these are:
The recent interest in solar energy has created a (I) The Solar Energy Research Institute
much greater demand for solar radiation data (SERI), which has one entire division dedicated
than previously existed. More people are mea to solar radiation and solar energy resource
suring solar radiation, more people are using the evaluation. SERI is located in Golden, Colo.,
data, and there is a demand for more and better and was established in 1976.
quality data. (2) The eight University Meteorological Re
The methods of measurement and the prob search and Training sites, which were estab
lems in using solar radiation data are not lished in 1977.1<; These are located at universities
immediately obvious to the untrained user. A with atmospheric science units, as follows:
4