Criteria for Location of SERI 25

(except possibly the first), a field station may be desirable in order to

(a) Help verify techniques for detailed resource evaluation over time and space;

(b) Assemble and test elements and technical-evaluation models of SERI solar-energy prototypes;

(c) Provide a field station that could be shared with non-SERI government, university, industrial, and nonprofit organizations for their test and evaluation activites;

tion.

(d) Provide a support base for SERI evaluation of a demonstration by another organiza

The dimensions for selection of a field station site should be as follows:

1. Availability of the solar resource. A field station for exploration of wind energy obviously should be sited where there is a substantial wind. Similarly, the exploration of ocean thermal-gradient energy sources will require initially a land site and then a floating evaluation site near substantial supplies of warm and cold natural ocean water.

2. Commitment of a local technical institution to provide support, shops, libraries, etc. SERI itself would be large enough that it could provide the support required for a first-rate institute charged with research, analysis, and interaction with universities, industries, and nonprofit laboratories. In choosing a site for a field station located remotely from SERI, careful consideration should be given to the need for a congenial and supportive environment so that the station would not have to provide all of its own technical or administrative support.

3. Utility for non-SERI field-station work. A field station for SERI experimentation could also be valuable as a site for work by other organizations in the solar-energy field. The long tradition of NACA (and now NASA) with the construction and operation of wind tunnels for industry and other research organizations is a good example. It would be inappropriate to locate a field station within a highly classified military facility.

4. Existence of vacant facilities, or the acceptability of temporary or mobile buildings. To allow for the economic phasing and adjustment of the various SERI programs, the field stations should preferably have no permanent facilities. Thus, existing vacant facilities would be an asset in the selection of a field station, as would local codes and customs that permit the use of temporary or mobile buildings to avoid the expense and rigidity of permanent construction.

5. High displaceable energy cost to maximize utility of the field station as a support facility for SERI involvement in evaluation of a demonstration program. Other things equal, a field-station location would be more desirable if the immediate locality were not only rich in the particular solar resource but much in need of solar power. Thus, if the solar-energy approach would in a few years move to the demonstration or large-scale exploration phase, the field station would be an appropriate site at which to base personnel and resources involved in the evaluation of large-scale prototype or even demonstration activities.

The specialized nature of field stations and their much smaller size in comparison with the central SERI thus impose strikingly different criteria for selection of field-station locations.

6

Mechanics

of

Selection

The Committee has considered several alternatives in regard to the procedure to be followed by ERDA in establishing the Solar Energy Research Institute.

Essentially the tasks are two:

1. A corporate structure must be found or created to which ERDA can contract the management of SERI. The criterion for selection of that structure is simply the degree to which the public can be confident that it will carry out its responsibilities as outlined in Chapter 4 to create and operate a Solar Energy Research Institute whose purposes are sketched in Chapter 4 and whose structure is described in Chapter 3;

2. In addition, ERDA must choose sites for SERI and its field stations according to criteria such as those that we have outlined in Chapter 5.

We believe that the interests of the nation are best served by completely separating these two processes-by moving ahead independently but simultaneously with the site selection process for SERI and with the negotiations for its management. In this way ERDA can maximize separately the value of the site and of the management structure, thereby creating a SERI of better quality than obtainable from any prepackaged combination of management and site.

The selection of locations for field stations, as noted, is different from the site selection for SERI because the former should be strongly influenced by the availability of the solar resource that the field station has the task of exploring. Furthermore, the activities of the field station must be integrated with the SERI program. Thus we suggest that ERDA undertake only an exploratory solicitation for field stations to be concerned with wind power, ocean thermal-gradient exploitation, and solar thermal-electric power. The definitive selection process should take place as the SERI Director defines the Institute program.

Appendix A
Staffing
and

Program Content

This appendix outlines our consideration of individual SERI programs. The headings and suggested numbers of personnel do not imply that SERI projects (page 10) are one-for-one coextensive with the approaches to solar-energy exploitation. Some projects may initially be so, but others could beneficially cross the boundaries between such approaches-for example, a project on solar tracking and concentrators, applicable to both solar thermal-electric and some solar photovoltatic approaches. The number and type of scientists, engineers, economists, and the like should not be sensitive to the particular organization into projects.

POSSIBLE SERI PROGRAM IN HEATING AND COOLING

The technology of use of solar energy for heating and cooling of buildings is well understood in principle and has been demonstrated in a variety of applications. Despite this, solar heating is not yet generally regarded as competitive with heating based on oil and natural gas, so that a substantial amount of research and development remains to be done even on the principal candidates for solar heating systems and components, particularly on solar collectors. Some of this R & D may need to be of a basic nature, seeking novel materials and combinations. There is only limited experience in the application of solar energy to the cooling of buildings. Many ideas for such systems exist, but most require further development and evaluation and probably additional research.

In addition to the development of basic technology, extensive analysis of system economics needs to be carried out. This is needed to help guide technological research as well as to define market needs and opportunities. The types of economic studies that need to be made include a detailed array of technology versus market implications for residential heating; residential heating, but including aggregation of housing units into larger units, such as heating a block of houses or a subdivision; and commercial structures. In each case, the study should be made for a series of postulated costs of solar collectors, to help determine market sensitivity to basic component costs. These studies should then be expanded to include the costs and benefits of cooling, with various assumptions as to the cost of cooling. Such work would help provide a basis for determining the size of the market for various kinds of solar heating and cooling, including nocturnal cooling in appropriate climates, and hence the costs themselves.

28

ESTABLISHMENT OF A SOLAR ENERGY RESEARCH INSTITUTE

Standards and Measurements

Since solar heating is not fully developed, the methods of measurement of performance of basic components are often uncertain and unreliable. As promptly as possible, SERI should develop meaningful, relevant, reliable standards for determining the performance of basic solar-heating components (mainly collectors). Such standards and measuring techniques should be promulgated by ERDA and used in all future ERDA-HUD demonstration projects.

Basic to many of the solar-heating systems is the development of materials and their testing for performance and reliability. This includes development of plastics for less costly collectors, development of better "selective" absorber surfaces for collectors and novel methods for reducing heat losses from them, and the study and reduction of maintenance and service requirements. The study of energy storage, of corrosion of various systems, and of adaptive control systems are important to the economics and the market penetration of solar systems.

Professional manpower in systems analysis, collector and cooling component development, measurement development, and systems design and test for solar heating and cooling would total 52. There is considerable overlap with SERI work on low-temperature process heat, for which another 10 professionals would be needed.

SOLAR-ELECTRIC (PHOTOVOLTAIC)

Several laboratories have reported solar-photovoltaic power conversion efficiency in the neighborhood of 20 percent, and there is indication that further work can increase efficiency to 25 percent or more. The compounds that show this promise are gallium arsenide (GaAs) or more generally III-V compounds. These compounds merit continued exploration and experimentation; opportunities and problems are both abundant in this field of new materials and structures. Other photovoltaics with lower efficiency include cadmium sulfide/copper sulfide and polycrystalline silicon.

The major thrust in ERDA is to get single-crystal silicon solar cells (with an effiency in the neighborhood of 15 percent) into production and use. This requires close coupling between the fabricators of silicon solar cells and people who are knowledgeable in those aspects of the technology that have the greatest impact on cost, yield, and efficiency. Each manufacturer has his own method and style in cost reduction, depending on, for example, the amount of automation, hand labor, and overhead charges. Thus, it is unlikely that SERI work in the silicon area would benefit equally all those involved. On the other hand, a strong SERI solid-state group having many skills could be helpful to the fabricators in the course of workshops that SERI could

convene.

In the CdS/Cu2S, polycrystalline silicon, and GaAs areas, SERI can play a large and important role. The actual participation would depend on the work in progress in several groups across the country. A minimum role for SERI is to be aware of what is going on and to be able to extrapolate to the future to provide a basis for an ERDA judgment as to when and whether it is desirable to replace silicon with one of the materials listed above. In addition, life and mass producibility must be determined. Systems analysis is necessary to compare the potential of flat plates with the potential of photovoltaic systems using concentration of the sunlight and to determine the economic gain of increased efficiency of the cells, improved reflectivity, mirror tolerance, tracking, and the like. Thus, SERI will need an experimental, theoretical, and analytical capability in solid-state technology and fabrication.

While manufacturers and other developers may be motivated to raise the efficiency and reduce the cost of photovoltaic systems, SERI's role is not only to help those working actively in the field but especially to understand the limits and expectation of all of this effort. What if there is success

Appendix A 29

in photovoltaic conversion? The electrical power thus produced could initially be used for fuel sparing, as long as appreciable amounts of fossil fuel are being used and as long as periods of intense sunlight are high consumption periods as well. Thus it is important to have a considerable effort by solid-state application engineers, in power conversion, integration with utility grids, safety, protection, and reliability. The results of this effort can serve as a guide to industry and government in the early application of a technically successful solar photovoltaic program.

Somewhat further out in the period when much electrical power is supplied by nuclear energy, solar energy will be uneconomical in displacing nuclear fuel costs alone. They will be competitive only if they can displace generating capacity and capital costs as well. Thus, solar photovoltaic systems with storage will assume a greater importance. In fact, storage, power conversion, and transmission are so important to the economics of several approaches to solar-energy utilization that we discuss them as a separate project later. In the SERI solar-photovoltaic area we estimate that 50 professionals would be required.

SOLAR-ELECTRIC (THERMAL-TO-ELECTRIC)

Solar-thermal conversion systems concentrate solar radiation and convert it to thermal energy. This thermal energy is transferred to a working fluid for use in a Rankine-cycle turbine (or gas turbine) to drive a conventional generator. Power production is thus similar to that of nuclear or fossil fuel power plants. The "waste heat" energy from the turbine can further be utilized for space or hot-water heating and space cooling in so-called total energy systems.

Solar-thermal conversion alternatives being considered include central receivers and distributed collectors. The central receiver system employs a large array of two-axis tracking mirrors to focus energy on a heat exchanger located on a central tower. First-generation systems using pressurized water/steam with water cooling are under development, and second-generation gas-cooled (closed-cycle helium and open-cycle air) systems are being analyzed.

Distributed-collector system options include two-axis tracking paraboloidal dishes, single-axis tracking parabolic-trough and "slat reflector" concentrator collectors with fixed concentration and single-axis-driven collectors, and, finally, fixed concentrator systems. Each of these systems would use a large number of collector modules to heat a working fluid to temperatures in the range of 200°C to 540°C, depending on the degree of concentration.

Solar-thermal conversion is primarily in the conceptual design stage today, although a few engineering model concentrators have been built and tested and a 1-MW(thermal) solar furnace (predecessor of the central receiver) is in operation in France, and a 100-kW(th) steam generator cavity receiver is in operation in Italy. Recently, ERDA has awarded four contracts to perform R & D on heliostats, receiver configurations, and thermal storage, which may be used in a firstgeneration 10-MW(electrical) pilot plant.

A total-energy system test facility based on parabolic-trough collectors is in operation at Sandia Laboratories in Albuquerque. This system utilizes an organic working fluid to generate electrical energy, and the reject heat will be utilized to heat and cool an office building. An alternative design concept has also been formulated to provide electricity and space conditioning for a military barracks complex.

With these present efforts under way, what need is there for R & D at SERI?

1. The total R & D effort to date on solar-thermal conversion systems has been a few million dollars; thus the efforts have been primarily analytical and performance has not been experimentally verified.