Applications of Electrochromic Materials in Greenhouses

1. Applications of Electrochromic Materials in Greenhouses By: Divya Arcot Monarch High School

2. Background • Electrochromic devices are composed of metal oxide substances which vary optical and thermal properties in response to changes in voltage. (change opacity and emissivity) • Optical properties are reversible, meaning the original state of the device can be restored by changing the polarity of the voltage. • These characteristics grant user-operated dynamic control over: • Amount of light allowed to pass through • Amount of heat allowed to pass through Basic Structure of an Electrochromic device, depicting transport of ions under an electric field [Granqvist].

3. Current Applications • Energy efficient “smart windows” • Informational displays • Variable-reflectance mirrors • Variable-emittance surfaces

4. Research Goals • As the market for Electrochromic materials is on the rise, research is being conducted to discover other areas in which these materials are applicable. • The goal of this research : • To determine whether the controlled variability of opacity offered by Electrochromic materials would increase the effectiveness of Greenhouses.

5. FutureApplications • Energy efficient greenhouses for impoverished villages located in areas with harsh climates • Urban gardens • Future spaceflight , when astronauts must grow food on the spacecraft, simulating Earth-like conditions on lengthy missions (to Mars and beyond)

6. Hypothesis If light is key to photosynthesis, and the amount of light which a plant receive is varied by the opacity of the Electrochromic material shielding it from the light source, photosynthesis, and hence the growth rate of the plant will be impacted.

7. Controls Test Plants Methods • A Thermal Radiation Sensorand PASCO’s calibration curve will beused to determine the amount of light received by the plants. • To determine the impact of the varying transparency on the plants: • Vertical plant growth will be measured • Amount of leaves will be recorded • Plant progression through stages of development will be monitored • If the plants are not responding well, variable opacities will be changed and retested. A layer of transparent glass will be placed between the plants and the light source. Electrochromic material with varying opacity will be placed between the plants and the light source.

8. Methods Greenhouse Experiment Setup Control Test 1 Test 2 Test 3 ECD ECD ECD

9. Methods • Unfortunately, I was not able to acquire the Electrochromic Devices (ECD) • As a result, I changed my experiment in the following manner: • Control = Simulation of outdoor conditions • Test 1 = Simulation of clear ECD state (Plexiglas frame) • Test 2 = Simulation of darkened ECD state (Plexiglas frame covered w/ window tint) Alternate Experiment Setup Test 2 Control Test 1

10. Methods • All Arabidopsis thaliana Wild-type plants received: • 16 hours of light under the constant light source of fluorescent bulbs. • 8 hours of dark • All were grown in agarose gel

11. Data • All data collected for the Arabidopsis thaliana Wild-type plant was rendered unusable due to a severe mold infestation of all plants White Mold

12. Data • However, an interesting pattern was forming: Arabidopsis were dying and mold infestation was occurring more rapidly in the control plants than the test plants Control - Arabidopsis Test Chamber 2 - Arabidopsis

13. Methods Matrix Morpheus (Pansy) • I then began collecting data on Matrix Morpheus flowers • The following characteristics have been observed: • Stem length • Amount of leaves • Leaf color and general appearance • Amount of blossoms • Blossom color and general appearance

14. Data • From observations of the Matrix Morpheus plant, I have determined that: • Plants in Test Chamber 2 are developing lighter green spots on their leaves, but plants overall are healthier than those in Test Chamber 1 or the Control Chamber: Light green patch developing on a Test Chamber 2 Plant Test Chamber 2 Plant – full color transformation

15. Data • Plants in Test Chamber 1 are green, but dehydrated. • Plants in the control chamber are drier than plants in both test chambers: Test Chamber 2 - Plants Test Chamber 1 - Plants Control - Plants

16. Data • Additionally, I continued to observe the mold from the Arabidopsis plants. • After the Arabidopsis died, the mold began to follow the same pattern of death: Control - Mold Test Chamber 2 - Mold

17. Analysis • The increased survival rate of the Arabidopsis in Test Chamber 2 (w/ window tint) vs. the Control demonstrated that additional protection did contribute to the plants immunity to mold infestation. • The fact that the mold followed the same pattern of death shows that when the light sources acts as a stressor, it is beneficial to have some form of protection. • However, Chlorophyll production was impacted in Test Chamber 2 (w/ window tint) because the constant shade proved to be too dark, and hence photosynthesis was also affected.

18. Conclusions • The Arabidopsis thaliana, Mold, and Matrix Morpheus plants have demonstrated that protection from an intense light source is helpful to plants. The Matrix Morpheus experimentation has also shown that too much protection can also cause harm. • Therefore, the controlled variability of opacity offered by Electrochromic materials should increase the effectiveness of Greenhouses by providing different levels of protection. • However, this needs to be tested by further research.

19. Further Research • Biometrics/ LabVIEW – Programming to manipulate greenhouse environment in order to maintain suitable living conditions for the plants • Potential hindrances: • Size specifications – still in development • Cost • Variability, created by the fact that each ECD manufacturing company has its own unique patent on the device

20. Bibliography • Granqvist, C. G., “Electrochromic tungsten oxide films: Review of progress 1993-1998”, Solar Energy Materials & Solar Cells, Vol. 60, 2000.  • Granqvist, C. G., “Handbook of Inorganic Electrochromic Materials”, Elsevier, 1995. • Mortimer, Roger J., “Electrochromic Materials”, Chemical Society Reviews, Vol. 26, 1997. • Human Spaceflight Mission Analysis and Design. New York: McGraw-Hill, 2000. Print. • "How Smart Windows Work"" HowStuffWorks "Home and Garden" Web. 17 Oct. 2009. <http://home.howstuffworks.com/home-improvement/energy-efficiency/smart-window.htm>.

21. Acknowledgements Thanks to Jonathan Metts for his guidance and Mrs. Kristin Donley for her resources and instruction!