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| Solar Energy | |
In the mid-1970s, the Engineering Experiment Station, now the
Georgia Tech Research Institute (GTRI), got in on the ground
floor of solar energy with programs in high temperature solar
thermal energy conversion, and liquidification and gasification
of biomass using solar thermal energy. A decade later, as
research funding interests changed, the focus of solar energy
studies at Georgia Tech moved to photovoltaic devices, which
convert sunlight directly into electricity.
Led by the U.S. Department of Energy-funded Solar Thermal Test
Facility managed by GTRI's Dr. Tom Brown, early studies at GTRI
demonstrated the ability to store solar energy for nearly an
hour. The next advancement was a method for creating high-grade
synthetic fuels with solar thermal energy.
In 1980, Brown and researchers from Princeton University
announced a breakthrough in pyrolysis, an established process for
producing liquid and gaseous fuels from biomass materials, such
as wood and corn cobs. Highly concentrated solar energy, rather
than burning of biomass, provided the heat necessary for
pyrolysis reactions. The method's advantages were conserving the
biomass feedstock and producing a higher quality fuel.
Subsequently, GTRI senior research engineer Jim Walsh and
others were instrumental in developing standards for several
different types of biomass fuels through the American Society for
Testing and Materials (ASTM). The organization named Walsh a
fellow in 1995 for his work on the project.
Two years later, researcher Doug Neale and other GTRI
engineers at the Solar Thermal Test Facility produced directly
usable electricity with a Swedish-built external combustion
engine whose pistons were driven by helium heated by intense
sunlight.
At the time, the engine was three times more energy
efficient than photovoltaic panels. The engine's manufacturer
later marketed it to supply the power needs for irrigation and
desalination in Third World countries.
By the mid-1980s, utility companies shifted their interest to
photovoltaics (PV), as the efficiency of PV devices increased and
the cost of making solar cells decreased. A research program led
by electrical engineering professor Dr. Ajeet Rohatgi studied new
semiconductor materials and designed innovative devices.
In 1992, Rohatgi's work garnered Georgia Tech a Department of
Energy contract to operate the
University Center of Excellence
for Photovoltaics Research and Education (UCEP). Its goal is to
help make photovoltaics a leading contender in the search for
clean, renewable energy sources.
One of its working research
laboratories is the 340-kilowatt PV system installed in the
Georgia Tech Aquatic Center, which was built for the 1996
Olympics. At the time, this was the world's largest rooftop grid-
connected PV system. The system produces about 400 megawatt hours
of electrical energy per year and has already produced close to
1,000 megawatt hours of energy. It is providing significant,
long-term data on how to build and maintain large-scale PV structures.
In 1997, Rohatgi's research team reported on a process called
rapid thermal processing (RTP), through which they cut in half
the time it takes to make a silicon solar cell without
diminishing its performance. They produced a solar cell with the
same efficiency rating — 18 percent — as one made by
conventional furnace processing. They created the cells in 8-1/2
hours, compared with the 17 hours needed for a furnace-processed
cell.
More recently, researchers have combined RTP with screen-
printed (SP) contact technology to reduce the cell processisng
time to less than two hours. This RTP-SP rapid technology has
produced silicon solar cells with greater than 17 percent
efficiency, and further improvements are expected with process optimization.
As their research continues, Georgia Tech's UCEP scientists
are compiling an impressive list of achievements. They hold
patents for seven production techniques and have applied for
several others. They've published more than 150 papers in
peer-reviewed journals and both
refereed and non-refereed conference
proceedings.
Photo by Stanley Leary
Electrical engineering professor Dr. Ajeet Rohatgi (front)
fabricates cheaper, more efficient solar cells in Georgia Tech's
University Center of Excellence for Photovoltaics Research and
Education.
Photo by Gary Meek
Georgia Tech scientists continue to collect data from the solar energy system atop the Tech Aquatic Center, built for the 1996 Atlanta Olympic Games.
For more information, contact Tom Brown, Georgia Tech Research Institute, Georgia Tech, Atlanta, GA 30332-0816. (Telephone: 404-894-0834)
(E-mail:
tom.brown@gtri.gatech.edu);
or Dr. Ajeet Rohatgi, School of Electrical and
Computer Engineering, Georgia Tech, Atlanta, GA 30332-0250. (Telephone: 404-894-7692)
(E-mail:
ajeet.rohatgi@ee.gatech.edu)
Contents
Research Horizons
GT Research News
GTRI
Georgia Tech
Last updated: October 25, 1999