P ROTOTYPE D EVELOPMENT AND T ESTING OF I NFLATABLE C ONCENTRATING S OLAR P OWER S YSTEMS Drs....
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Transcript of P ROTOTYPE D EVELOPMENT AND T ESTING OF I NFLATABLE C ONCENTRATING S OLAR P OWER S YSTEMS Drs....
PROTOTYPE DEVELOPMENT AND TESTING OF INFLATABLE CONCENTRATING SOLAR POWER SYSTEMS
Drs. Mithra & Usha Sankrithi RIC Enterprises
[email protected] ricenterprises.org
SOLAR POTENTIAL
2010 world power consumption ~ 17,000 GW
Solar radiation at Earth’s surface ~ 90,000,000 GW
Recoverable solar power
~ 1,000,000 GW
far exceeds humankinds needs
CENTRAL RECEIVER SOLAR THERMAL POWERPLANTS ARE AN ATTRACTIVE SOLUTION FOR UTILITY SCALE SOLAR POWER
Current Central Receiver Powerplants use Expensive Mirrors (Heliostats)
CENTRAL RECEIVER SOLAR THERMAL POWERPLANTS ARE AN ATTRACTIVE SOLUTION FOR UTILITY SCALE SOLAR POWER
Heliostats are the largest cost element for Central Receiver Powerplants
HOW COULD COST OF HELIOSTATS BE SUBSTANTIALLY REDUCED?
Insights & Hypothesis:
Most current heliostats use heavy steel and glass mirrors for wind and storm resistance and precise pointing control
A very light and inexpensive membrane mirror can reflect sunlight as well as a heavy and expensive steel and glass mirror
Could such a light inexpensive membrane mirror be protected for wind and storm resistance using “sandwiching” light inexpensive inflated chambers?
INFLATABLE HELIOSTAT RESEARCH OBJECTIVES Conduct trade studies and component / subassembly tests to
evolve a preferred subscale prototype design for a lightweight, low-cost inflatable-structure heliostat
Refine the design then construct a prototype
Test the prototype for: ability of the heliostat pointing system to accurately aim the heliostat ability to form beam shape and concentration on a simulated target ability to function / survive in winds and gusts and precipitation
Develop a preliminary design for a production heliostat
Develop and document conclusions and recommendations
INFLATABLE HELIOSTAT V1.0
REFINED INFLATABLE HELIOSTAT DESIGN GOALS Provide a simple drive system using only two motors, and
having low torque requirements
Design for inertia and aerodynamic loads to act directly through the support system (no overhanging moments)
Design for low aerodynamic loads from winds and gusts using a near-spherical shape
Use differential pressure to focus / defocus the membrane mirror
Use “sandwiching” inflated domes to protect mirror from exposure to weather
Combine the use of direct load paths and the inherent efficiency of inflated structures to yield a lightweight, low-cost design
INFLATABLE HELIOSTAT V2.0
Patent 5,404,868
Additional Patents Pending
INFLATABLE HELIOSTAT FEATURES
INFLATABLE HELIOSTAT TESTING
PHOTOVOLTAICS AND CONCENTRATING PHOTOVOLTAICS (CPV) ARE ATTRACTIVE SOLUTIONS FOR SMALLER SCALE APPLICATIONS
High efficiency silicon solar cells are the largest cost element for PV
http://solarpanelsguides.com/wp-content/uploads/2009/05/solar-panels.jpg
INFLATABLE CPV MODULE RESEARCH OBJECTIVES
Evolve a preferred design for an inflatable CPV module that leverages the inflatable heliostat design
Enable much reduced per-watt cost for high efficiency silicon solar cells through the use of modest (5 – 15 sun) concentration
Design and test a full-scale proof-of-concept prototype for: ability of a 1-axis heliostat pointing system to accurately aim the
heliostat ability to form a linear focus beam shape on a linear CPV receiver ability to adequately cool the linear CPV receiver ability of inflatable chambers to protect the reflective membrane in
winds and gusts and precipitation
Develop and document conclusions and recommendations
“SURYA” CONCENTRATING PV MODULE FEATURES
Patents Pending
BUILDING THE SURYA PROTOTYPE
BUILDING THE SURYA PROTOTYPE
BUILDING THE SURYA PROTOTYPE
SURYA SET UP
SURYA SET UP
SURYA INSTALLED
SURYA INSTALLED
SURYA INFLATABLE CONCENTRATING PV MODULE
SURYA AT WORKEffective linear focus of 8+ suns concentrated sunlight reflected by the reflective membrane
SURYA IN THE MORNINGDew covering the ETFE transparent membrane
SURYA AT WORK VIDEO: SUN SENSOR TRACKING
SURYA AT WORK VIDEO: INVERTED STOW
SURYA POTENTIAL APPLICATIONS Private Homeowners, ground mount Private Homeowners, roof mount Private Homeowners, grid-connected & net-
metering Private Homeowners, off-grid Commercial buildings, roof mount, grid-
connected & net-metering Rural and agricultural area integrated
applications Variants suitable for floating applications
on ponds, reservoirs, lakes etc.
CONCLUSIONS
Prototype efforts have validated that:
Lightweight, low-cost reflective membranes can be effectively utilized for concentrating solar power
Sandwiching inflatable chambers can effectively protect a reflective membrane under adverse conditions
Inflatable heliostats with 2-axis tracking for central receiver solar thermal powerplants are technically feasible
Inflatable linear concentrating photovoltaic modules with 1-axis tracking are technically feasible
RECOMMENDATIONS
Additional design and manufacturing refinements will be needed for production low-cost inflatable solar energy harvesting devices, building on lessons learned from the prototype efforts
The next step for inflatable heliostat R&D is design, manufacture and test of full-scale prototype or pre-production units
The next step for Surya inflatable CPV modules is manufacture and in-service evaluation of pre-production units, leading to certification and commercial production
ACKNOWLEDGEMENTS
The authors acknowledge with gratitude the dedicated and skilled work of Gary Reysa and Lloyd Hagan in fabricating the prototypes of the inflatable heliostat and inflatable CPV module, respectively. Funding from the US Department of Energy for the inflatable heliostat research is also gratefully acknowledged.