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* Water demand reduction was achieved by reduction in incident radiation due to the shading effect. | * Water demand reduction was achieved by reduction in incident radiation due to the shading effect. | ||
* Water use efficiency was found to increase for some varieties of lettuce in the shade | * Water use efficiency was found to increase for some varieties of lettuce in the shade | ||
====[http://pubs.acs.org/doi/ipdf/10.1021/es404950n Tradeoffs and Synergies between Biofuel Production and Large Solar Infrastructure in Deserts]<ref>Sujith Ravi, David B. Lobell, and Christopher B. Field. Environmental Science & Technology 2014 48 (5), 3021-3030</ref>==== | |||
'''Abstract:''' | |||
The paper discusses the setting up of agrivoltaic schemes in arid regions with limited water resources. It discusses about the use of land between panels for growing biofuel plants like Agave which can thrive in dry and arid climate thanks to its water efficient photosynthesis process. The limited water resources can be used to clean the PV panels as well as watering the plants by directing the water onto the PV panels which would drain off on the agave plants resulting in efficient usage of limited resources. The Agave plants are used in the production of ethanol fuel. | |||
'''Summary:''' | |||
* Revenues from the solar PV per unit of water used was 100 times greater than that of traditional crops. Combination of solar PV and agave resulted in the highest returns per cubic meter of water used. | |||
* Competition for land for growing biofuel and food crops is reduced and the agave crops can help in reduction of dust collection on the PV panels. | |||
=== References === | === References === | ||
Revision as of 08:31, 28 January 2015
Introduction
This literature review is for a project which involves using the same piece of land for setting up a PV farm and performing agriculture/livestock grazing on it. By doing this, the same piece of land can be used to generate electricity and food crops, thus, increasing land use. This setup can prove to be a as it would not only be a steady source of income for farmers but also allow a small area in the vicinity of the PV farm to become self sustaining in terms of electricity.
Initially, this topic would cover the growth of lettuce on a farm having PV panels mounted and the influence of PV panels on the growth pattern of lettuce.
Literature Review Page for "Dual Use of Land for PV farms and agriculture literature review"
Selected Papers and Literature
Combining solar photovoltaic panels and food crops for optimising land use: Towards new agrivoltaic schemes [1]
Abstract:
Extracting fuel from biomass was put forth as an alternative energy source to dwindling fossil fuel resources. However, this would involve the widespread use of food crops for producing biomass resulting in food shortages as the existing cultivable land on the planet cannot cope with the demand for crops used for food and biomass at the same time. A solution to this problem is an 'Agrivoltaic' system i.e. a combination of PV panels set up on an existing farmland, thus increasing land use. Simulations have shown an increase in land productivity by 60-70%.
Summary:
- Optimized solar panel orientation is determined by PVsyst software to ensure maximum amount of radiation is tapped by the panels.
- Panels are mounted at a certain height over the crops to allow mechanical farming equipment to underneath the panels.
- Difficult to predict the behavior of crops under the shaded area of the PV panel.
- Experiments have shown that electricity and crop yield of a 100 hectare farm with an agrovoltaic system in place is greater than a 170 hectare farm having separate production.
Productivity and radiation use efficiency of lettuces grown in the partial shade of photovoltaic panels. European Journal of Agronomy[2]
Abstract: Converting crop lands into PV farms would aggravate the competition for land between food and energy production. Setting up PV panels on top of crop farms shades a part of the crops. In spite of the shading effect, lettuce yields were higher by improving the Radiation Interception Efficiency. The effect of the shade on the lettuce plantation was a reduction in the number of leaves but and increase in the leaf area. This was the adaptation bought about by lettuce to thrive in the shade. A framework is defined based on the adaptive characteristics of crops that thrive in the shade to optimize agrovoltaic systems.
Summary:
- Lettuce has the ability to adapt to lower light conditions by increasing its capability to harvest light.
- Similar experiments were done using cucumber, french beans and durum wheat to study the effect of crop rotation on an agrivoltaic system.
- Agrovoltaic systems can be optimized by plant breeding and making adjustments to PV panels to find the best way to co-produce electricity and food on the same piece of land.
Solar Farms for livestock
- Report released by the BRE and National Solar Center of UK stating that PV farms can be set up on lands reserved for livestock grazing.
- PV farms gives the farmers an economic boost and at the same time does not affect his existing farming practices.
- The farmer does not need to cut down on the number of grazing animals nor does he have to adjust the grazing frequency of livestock as 95% of the grazing land is unaffected by the PV panels.
- A PV farm with an output of 4.2 MW was set up in Axminster, Devon, UK. This farm provides electricity as well as fodder for livestock.
To mix or not to mix: evidences for the unexpected high productivity of new complex agrivoltaic and agroforestry systems[3]
Abstract: Agrivoltaic schemes are profitable, environment friendly and have high levels of production. These schemes have higher volumes of production due to higher land equivalent ratios. Land equivalent ratio(LER) determines the efficacy of a piece of land. It is calculated by the relative yields of the components on the piece of land in question. LER for an agrovoltaic(AV) systerm was the sum of the relative yield of the crop and the relative yield of electricity by the PV panels.
Summary:
- LER for a 100 hectare AV farm was in the 1.3-1.6 range. Methods to optimize LER were suggested like having a North-South orientation for the crops.
- PV panels provide constant shading over crops which affect winter crops more as compared to summer crops due to the sunlight demands of such crops. However, the PV panels acts as a protective measure for the crops in the summer from excessive heat and evaporation.
- More research is needed on the PV panel density depending on the light demands of various crops.
Assessing the land equivalent ratio (LER) of two corn varieties intercropping at various nitrogen levels in Karaj, Iran.[4]
Abstract:
LER is the ratio of yield of the individual crop in the intercropped land to the yield of each crop in a monocropped land. LER value of 1.0 indicates the same yield from an intercropped and monocropped land. If LER>1.0 indicates a higher yield from the intercropped land and if LER<1.0, the yield of the monocropped land is higher than that of the intercropped land.
Summary:
- Experiment was conducted to study the effect of two different varieties of corn on land use efficiency with different nitrogen levels
- LER's for an intercropped land was observed to be 1.066.
- At different levels of nitrogen content in the soil, LER's were always greater than zero.
How does a shelter of solar panels influence water flows in a soil–crop system?[5]
Abstract:
Crops can achieve a higher yield under the fluctuating sunlight of an Agrovoltaic system. Under dry climatic conditions, the climatic conditions below the PV panels suggest that the PV panels help in alleviating the water demand by the crops. Water use efficiency can be increased by selecting crops with a rapid soil covering which contributes to a higher amount of light being captured with decreased soil evaporation.
Summary:
- Shading due to the PV panels resulted in water savings by 14-29% depending on the level of shading.
- Water demand reduction was achieved by reduction in incident radiation due to the shading effect.
- Water use efficiency was found to increase for some varieties of lettuce in the shade
Tradeoffs and Synergies between Biofuel Production and Large Solar Infrastructure in Deserts[6]
Abstract: The paper discusses the setting up of agrivoltaic schemes in arid regions with limited water resources. It discusses about the use of land between panels for growing biofuel plants like Agave which can thrive in dry and arid climate thanks to its water efficient photosynthesis process. The limited water resources can be used to clean the PV panels as well as watering the plants by directing the water onto the PV panels which would drain off on the agave plants resulting in efficient usage of limited resources. The Agave plants are used in the production of ethanol fuel.
Summary:
- Revenues from the solar PV per unit of water used was 100 times greater than that of traditional crops. Combination of solar PV and agave resulted in the highest returns per cubic meter of water used.
- Competition for land for growing biofuel and food crops is reduced and the agave crops can help in reduction of dust collection on the PV panels.
References
- ↑ Dupraz, C., Marrou, H., Talbot, G., Dufour, L., Nogier, A., & Ferard, Y. (2011). Renewable Energy, 36(10), 2725-2732.
- ↑ Marrou, H., Wéry, J., Dufour, L., & Dupraz, C. (2013).44, 54-66.
- ↑ Dupraz, C.
- ↑ Dariush, M., Ahad, M., & Meysam, O. (2006). Journal of Central European Agriculture, 7(2), 359-364.
- ↑ Marrou, H., Dufour, L., & Wery, J. (2013).European Journal of Agronomy, 50, 38-51.
- ↑ Sujith Ravi, David B. Lobell, and Christopher B. Field. Environmental Science & Technology 2014 48 (5), 3021-3030