These projects will be conducted in various climatic regions of the United States consistent with the overall program plan.

About eight early demonstrations on Federal facilities have been initiated in FY 1975 in cooperation with several Federal agencies. A number of these will be completed in FY 1976. These demonstrations will provide valuable design and operational experience with solar heating and cooling systems in Government-owned facilities.

Another area of particular interest is the application of solar heating technology to agriculture. Projects are underway in crop drying this year with plans to expand into animal shelters and greenhouses in the immediate future.

Solar Thermal Conversion

The goals of the Solar Thermal subprogram are: 1. to provide a full technology base for the production of thermal and electric power in the mid-1980s to meet electric utility requirements for load-following or intermediate load electric power generating systems, and

2. to provide a full technology base for total energy systems for Federal installations, urban complexes, rural communities and industrial parks.

To achieve the goals of the Solar Thermal subprogram area the following objectives have been established:

1. design, fabrication, and testing of prototype components and subsystems that are critical to the success of the central receiver concept for solar thermal electric plants;

2. design, fabrication, and utilization of test facilities to determine performance of components and subsystems of solar thermal electric systems and total energy systems; 3. evaluation of total energy system applications for Federal installations, urban and rural communities, and industrial parks;

4. investigation of critical interface problems and issues associated with the implementation of solar thermal electric systems and total energy systems;

Research will continue on the requirements, use, and scale of solar thermal electric power plants; parametric studies of the technical and economic variables of a variety of solar thermal conversion concepts; and system point designs for central receiver concepts and for distributed collector concepts involving, for example, parabolic trough collectors. Subsystem and component research activities will continue on the fabrication and test of new approaches to collectors, development of high efficiency solar absorption coatings, and studies of components required for less conventional cycles and energy storage.

Advances in second generation components, subsystems, and systems are expected to improve the economic viability of solar thermal conversion. Efforts directed towards improved component performance will include studies of environmental degradation processes, interference films, surface geometry, and techniques for large-scale, low-cost deposition of coatings. Thermal storage subsystem research for power plant applications will include studies utilizing sensible heat, change of phase, and chemical processes in the storage system. Some emphasis will be placed upon studies of unconventional cycles for conversion of collected heat to electricity.

Initiation of construction of a 2 MWth solar thermal test facility for testing and evaluating components and advanced conceptual designs is planned for FY 1976. Assessment of solar thermal systems and their economic viability will be continued. Studies of the environmental and social impact of solar thermal systems will be pursued including plant site location studies that involve institutional constraints such as land use requirements. The insolation data base will be improved. The design of a 10 MWe pilot plant will be initiated; and preliminary cost estimates for this facility will be obtained.

A systems analysis of a 100 MWe central receiver power plant will be initiated. The system configuration chosen for implementation is based on optical transmission using heliostat arrays focused upon a central receiver supported by a tower. Information developed through the system definition studies, subsystem and system analyses and component testing will be used to establish a set of feasible alternative approaches. Interface requirements between the sun energy resource, the energy demand, and all subsystems will be

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identified and tradeoff benefits analyzed to determine the most cost-effective configuration possible using first generation subsystems and components. The problem of scaling up from the 10 MWe power output level will be studied. The preliminary design schedule will be formulated so that a 100 MWe power plant can be in operation by the mid-1980s.

The development of non-focusing solar collectors which do not require daily tracking will be investigated carefully for their potential for increased collector performance and reduction in system costs for a distributed collector solar thermal power plant.

Solar total energy systems are designed to produce both thermal and electrical energy, with the by-product condenser thermal energy used for heating space or as process heat. Solar thermal conversion projects include initial assessments of such systems for applications meeting the thermal and electrical energy requirements of communities, Federal installations, industrial parks and rural areas. The preliminary design studies for two solar total energy plants will be initiated in FY 1976.

5. to insure the continued involvement of potential users and manufacturers as part of the overall effort to optimize the marketability of this technology;

6. to perform carefully planned experiments and demonstrations to assist in focusing systems technology and in evaluating problem areas; and

7. to identify and address environmental, legal, social and institutional issues relevant to PEPS. The immediate goal of the photovoltaic program is to reduce the price of photovoltaic arrays to about $500/KWe (peak) by the mid-1980s. Continued emphasis will be placed on development of low-cost, single-crystal silicon (Si) device and array technology and on analysis of photovoltaic conversion power system designs to determine the most effective ways to apply this technology. The low-cost, single-crystal Si effort includes projects for cost reduction of polycrystalline silicon feed material, continuous production of single crystal Si sheets, automated fabrication of solar cells and arrays, and the production scale-up for low-cost solar cells. These improvements will be incorporated into early systems tests. The further development of techniques for continuous drawing of silicon ribbon will be emphasized. Efforts will be directed toward obtaining advanced designs for single-crystal Si solar cells.

Research on photovoltaic conversion devices that have large potential for low-cost, high-production volume will also be carried on along with research on low-cost arrays such as those fabricated from thin films of cadmium sulfide, copper sulfide, and silicon. Feasibility of arrays costing less than $500/peak KWe is expected to be established by the early 1980s.

Analysis will continue on the requirements for power conditioning, energy storage, interfaces with solar heating and cooling systems, tie-ins to power grids, and total energy systems. System economics, institutional problems, and environmental impact will continue to be evaluated based upon progress in technology and system designs.

Accelerated environmental testing will be initiated to determine the long-term effects of particular terrestrial environmental conditions on electrical performance characteristics as well as on physical and chemical properties of photovoltaic conversion devices and systems.

Wind Energy Conversion

The goal of the research and development subprogram for Wind Energy Conversion is to accelerate the development of reliable and cost-competitive wind energy conversion systems as alternative energy sources.

The specific five-year objectives of the Wind Energy Conversion subprogram are:

1. to operate and evaluate 100 KWe wind energy systems at selected sites and improved units at user sites;

2. to utilize operational data obtained on 100 KWe-scale systems for application to future MWe-scale systems;

3. to design, construct, operate and evaluate MWe-scale single and multi-unit wind energy systems;

4. to operate and evaluate MWe scale second generation advanced systems in a user

environment;

5. to complete the preliminary design of a 100 MWe system;

6. to complete the system analysis and assessment of a future offshore hydrogen producing system;

7. to operate and evaluate a series of systems in a farm environment; and

8. to assess wind resource data over the United States.

Program objectives include design and development of improved subsystems for future systems; test and evaluation of several innovative and experimental types of wind energy concepts; and development of extensive operational data in user environments (on 100 KWe-scale systems) for use in second generation design studies. Initial answers to legal, environmental, public acceptance, institutional, and user interface issues will be developed. Technological capabilities and wind data will be assessed for rapid and inexpensive estimation of wind fields and their short- and long-term spatial and temporal variations as candidate wind system sites.

The series of regional application analyses initiated in FY 1975 will be expanded to other regions. Regions composed of utility, district, state, or larger geographical areas will be analyzed to determine user requirements, wind potential, projected costs, user economic parameters, and system performance and interface requirements. Variations in wind characteristics will be measured