Solar Total Energy Project

Georgia Power commitment				condenser. Control and Instrumentation
Georgia Power Company has a history of support				Subsystem: STEP control subsystem provided a
for nonconventional renewable energy technology,				range of operations from minimum operator
investing millions of dollars in initiatives for				control to extensive monitoring and data collection
development of solar thermal, solar photovoltaic				for subsequent analysis as part of DoE test
(PV), wind, and biomass. Significant investment				operations requirements. The subsystem
began in the 1980s with STEP and construction of				partitioned control functions between a
a new corporate headquarters in Atlanta, which				minicomputer [state of the art in 1982] and
included active and passive solar energy systems.				peripheral equipment and micro-processors
GPC also supported a major PV project to				installed throughout the project infrastructure. The
provide energy for the natatorium on the Georgia				control subsystem received information from the
Tech campus, used for the 1996 Olympic Games.				sensors and provided signals to field devices such
GPC continues to support development of				as drive motors on the tracking collectors and
residential and commercial solar systems and				valves throughout the heat transfer system. It
energy conservation measures that make a				also alerted operators to anomalies that might
difference to its customers.				damage the collectors or tracking system.
Information sources				System Loads: STEP was designed according to
The information in this project summary, including				electrical, air conditioning and process steam loads
scanned photos, is extracted from technical				already established by the knitwear factory, which
reports, project summaries and presentations				began operations during STEP design phase.
produced and widely distributed by GPC during the				These parameters, which represent the facility
early 1980s as part of STEP information				relatively constant peak load profile, were used
dissemination and technology transfer initiatives,				for system design.
an important element of the contract work scope				Load Type
[DoE Task 6]. As part of the deliverables				Peak Load Requirement for Plant
associated with this government-financed project,				STEP Capacity
the material is neither confidential nor restricted				Electrical
by special copyright requirements beyond source				161 kW
acknowledgment.				400 kW
Project history				Cooling
In 1977, DoE selected a joint proposal by GPC				1,420 MJ (113 tons[vague])[citation needed]
and the Westinghouse Advanced Energy Systems				3,260 MJ (257 tons[vague])
Division from a field of 16 competitors from 14				Process steam at 177 C (350 F)
states for STEP site and commercial application.				626 kg/h (1,380 lb/h)
Design work was completed between 1978 and				626 kg/h (1,380 lb/h)
1980 under DoE sponsorship (with GPC				Meteorology Station: During its operational period,
cost-sharing support) through the construction and				STEP monitored weather and insolation data via a
test operations phases. The project was formally				meteorology station at the northeast corner of
dedicated and began test operations in May 1982.				the collector field, operated and maintained by
GPC assumed full responsibility for STEP				Georgia Tech faculty and students, it fulfilled a
commercial operation in 1984 and continued the				vital role by cross referencing operational data
project beyond 1987. The project was conceived				with weather statistics to obtain an accurate
by Edward J. Ney, a Westinghouse energy				performance database for future solar project
physicist who later became a nationally-recognized				designers. The original weather station, at ground
expert on solar energy systems. Ney was the				level, consisted of eight solar radiation and surface
Project Integrator while with Westinghouse, later				weather instruments, support structures and
joining GPC as Manager of Solar Operations and				digital data loggers. The original STEP Weather
STEP Project Manager. He brought the involved				Monitoring Station contained these instruments,
parties into a joint-venture agreement and				which monitored the specified variables.
subsequently oversaw design, construction, test				Instrument
operations, commercial operations, and eventual				Variable
decommissioning and disassembly of the Project.				Horizontal Pyranometer
Site				Global Radiation
The site for the five-plus acre project was Solar				Pyrheliometers
Circle, along Amlajack Boulevard, in a commercial				Direct Normal Radiation
park within the planned community of				Resistance Thermometer
Shenandoah, Georgia (now part of the city of				Dry Bulb Temperature
Newnan). The location is 35 miles southwest of				Humidity Cell
Atlanta, on the west side of I-85 at Exit 47 (GA				Relative Humidity
Hwy 34 and Bullsboro Drive): 33 24 15.84 N and				Cup Anemometer
84 44 49.33 W.				Wind Speed
While STEP was shut down and dismantled by				Wind Vane
1991, the site of the collector field is still visible				Wind Direction
from the air, albeit with brush growing through the				Pressure Transducer
crumbling pavement. The overall site includes a				Barometric Pressure
renewable energy education center (between the				Performance highlights and conclusion
former collector field and Amlajack Blvd.) that has				As might be expected with a first-of-a-kind
accommodated classes from the University of				project, STEP encountered numerous electrical
Georgia and other educational institutions.				and mechanical anomalies during startup and test
Industrial application				operations, each of which was resolved and made
The industrial application for the Project was a				part of the record for future designers. For
knitwear factory operated by Bleyle of America				instance, the original motors and potentiometers
Inc. STEP provided a large part of the electricity				for all 114 collectors had to be removed and
for the facility, displacing fossil fuels normally used				waterproofed due to high failure rates in Georgia
to generate power to run the factory. STEP also				rainy environment. Overall, STEP achieved these
provided process heat for absorption air				objectives as listed in the 1983 project report:
conditioning within the building, as well as steam				1. A significant number of engineers, scientists and
(downstream from the turbine) for pressing the				students were trained and validated as system
knitwear products. The building was designed with				operators and data analyzers.
a series of features for energy efficiency,				2. All major thermo dynamic components met
including reduced height to minimize wall area and				their design values, including the steam turbine
interior volume, a 4-ft insulating earthen berm				generator, collectors, absorption chiller, and
around the building, north-south orientation,				high-temperature fluid storage system.
heavily-insulated roof and walls, high-efficiency				3. Solution of anomalies related to small mechanical
fluorescent lighting, energy-efficient production				components (motors, pumps, potentiometers, and
equipment, and an air conditioning system with an				valves) provided invaluable information for future
economizer cycle. According to GPC, which				system designers.
monitored the facility energy requirements as part				4. Additional checkout time and effort applied to
of the STEP design process, energy conserving				the hardware and software aspects of the
features alone reduced the factory energy				control and instrumentation system provided a
consumption by 46 percent.				significant base for more efficient designs and
Technical description				checkout procedures for future systems.
In general, a olar total energy system captures				5. Formal processes were determined for a
solar radiation [insolation] to supply high-grade				variety of test modes, providing a manual of
electrical and mechanical energy and low-grade				demonstrated procedures for application to other
thermal energy for a given application, with any				solar thermal systems.
excess electrical power being fed into the power				6. Both DoE and Bleyle, STEP two primary
company grid. As described in the technical				ustomers, documented their satisfaction with the
reports, TEP was a fully cascaded total energy				Project and reported that all their objectives and
system with parabolic dish solar collectors and				requirements were met safely and efficiently. DoE
steam Rankine cycle power conversion system				benefited from the wealth of data collected during
capable of supplying 100-400 kWe output with				operations, and Bleyle benefited as the beneficiary
process steam extraction. Technical specifications				of the electrical power and thermal energy
in this section are extracted nearly verbatim from				provided by the Project.
interim project reports published and distributed				Subsequent to the end of the 10-year contract
by GPC. Supporting information is available in this				period in 1987, operations were continued for
document in section 16.2.3.				another year until a failure of the steam turbine
STEP utilized a field of 114 parabolic dish solar				and the need for other high-value replacement
collectors, each 23 feet in diameter, arranged in				components proved too costly for continuation of
alternating rows of 9 and 10 units (12 rows total).				the Project. STEP was subsequently
STEP's 23-ft diameter collectors tracked in two				decommissioned and dismantled during 1990.
directions: east/west daily and north/south				Project participants
seasonally.				STEP had a large cast of participants during its
Tracking the sun east to west daily, and north				first six years, comprising design, development,
south during the seasons, the collectors				construction, test operations and data monitoring
concentrated solar energy onto a receptacle at				assessment. During this period, funding was
their focal points, heating a circulating				provided primarily by DoE with support from GPC.
silicone-based heat transfer fluid (HTF) to 750F.				The final four years of commercial operation and
The HTF was then pumped to a heat exchanger				subsequent shut-down were supported exclusively
in the generating facility, where the heat was				by GPC.
used to boil water to produce superheated				Design team
(high-pressure) steam, which in turn drove a				General Electric Co. (Valley Forge):
turbine generator and alternator to produce				Lockwood-Greene Engineers (A&E):
electricity. Medium-pressure steam (350F) from				Scientific Atlanta:
the turbine was then used for pressing the				Dow Corning Corp.:
clothing, which required 1000 lb/hr for normal				Mechanical Technology Co.:
operations. The remaining low-pressure steam				Construction team
was used to produce chilled water (absorption				Dow Corning Corp.:
process) for air conditioning or released through				L.B. Samford Co. [Defunct]
an air-cooled condenser.				B&W Mechanical Contractors: (link
Solar Collector Subsystem (SCS): The parabolic				nonfunctional)
dish collectors were fabricated in the field from				Joe North Inc.: [Defunct]
die-stamped aluminum etal segments laminated				General Electric (Daytona Beach):
with aluminized acrylic reflective firm. Each				Solar Kinetics:
collector tracked the sun independently in both				Site operations team
polar and declination axes to remain focused from				Georgia Power Company:
sunrise to sunset throughout the year. The				Georgia Institute of Technology:
receiver at the focal point of each collector was a				Heery & Heery Inc., A&E: [now Heery
avity type, capable of receiving an incident				International]
concentrated solar flux equal to 235 suns. he				Shenandoah Development Co.: [Defunct]
concentrated solar flux impinges upon the receiver				Owens-Corning Insulation:
coil absorptive surfaces enclosed within the				Westinghouse Electric Corp.: [Heritage
insulated cylindrical shell to heat the circulating HTF.				Westinghouse now Defunct]
The field piping network consisted of welded pipes				Bleyle of America:
in the main manifolds, and steel tubing with flexible				Sandia National Laboratories:
joints in the branches connecting to the tracking				U.S. Department of Energy:
collectors. The entire HTF piping system was				References
thoroughly insulated. Power Conversion				1. Ney, E.J. (Manager, Solar Operations), Georgia
Subsystem: This consisted of three-piece				Power Company. olar Total Energy Project,
pool-type boiler with preheater, boiler and				Shenandoah, Georgia Site: Summary Technical
superheater, a steam turbine-alternator rated at				Progress Report (July 1, 1980 through June 30,
500 KVA, an air-cooled condenser and condensate				1982). Prepared for the U.S. Department of
storage tank, make-up demineralizer, deaerator,				Energy, Division of Solar Energy under
and pumps. In normal operation, steam at 720F				Cooperative Agreement DE-AB04-77ET20216.
and 700 psig was generated in the				2. Ney, E.J. (Manager, Solar Operations) and W.H.
boiler-superheater and delivered to the turbine				Weidenbach (Industrial Marketing Manager),
inlet.				Georgia Power Company. evelopment of the
Thermal Utilization Subsystem: This was the				Solar Total Energy Project (STEP) at Shenandoah,
condensing medium for the steam and the heat				Georgia (U.S.A.). Paper for the International Solar
source for the cooling of the knitwear plant.				Energy Symposium, Palma de Mallorca, Spain;
Exhaust heat from the steam turbine was				October, 1983.
recovered through this subsystem during power				3. Ney, Edward J. (Manager, Solar Operations),
generation; however, when the turbine was not				Georgia Power Company. olar Energy Training
operating, steam from the boiler was used				Program: Overview and Course Guide. June, 1984.
directly as the heat source. Steam from the				Prepared under U.S. Department of Energy
turbine or turbine by-pass was routed to the				Cooperative Agreement DE-AB04-77ET20216
absorption air conditioning system to cool the				[Task 6: Technology Transfer and Information
facility, with excess heat routed to an air-cooled				Dissemination].

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Solar Total Energy Project