M.P. Hayes

Louisiana continues to progress toward renewable alternatives for energy with offshore wind structures and urban solar installation projects, which are also known as photovoltaic systems. For the agricultural landscape, this often means a large acreage conversion from crops to solar infrastructure. The diverse landscape of Louisiana offers additional opportunities for solar energy production in noneconomic waterbodies, which include ponds used for industrial oxidation, municipal wastewater treatment and agricultural irrigation. Incorporating a floating photovoltaic (FPV) system into your pond is a feasible form of on-site energy generation while maintaining natural resources. LSU and LSU AgCenter researchers are learning more about floating photovoltaic systems through a yearlong demonstration at the AgCenter Hammond Research Station.

Land-based photovoltaic (LPV) is a highly studied area with swift growth anticipated over the next few decades. The implementation of LPV has many benefits, including energy independence, long-term savings and decreases in nonrenewable resources. It also faces many challenges, such as land constraints, permanent infrastructure to host panels and environmental or economic impact in selected regions. Some communities are pursuing creative solutions to land challenges by sharing land space for solar and crop production, a system called agrivoltaics. Agrivoltaics are limited to certain types of crops and are most beneficial for areas with a specific microclimate (soil temperature, moisture, crop temperature and other factors), and there are limited opportunities for Louisiana farms. As a permanent installation, the construction of large solar farms must consider the ever-changing dynamic of Louisiana’s landscape due to hurricanes, subsidence and land loss.

These uncertainties yield an opportunity for a novel approach to energy through floating photovoltaic units. Though floating photovoltaic has a higher estimated cost and a negative impact on recreational space, it has many benefits, which include increased efficiency from water cooling, decreased evaporation for the water body, reduced maintenance cost and a lack of a permanent structure. These benefits provide potential incentives for Louisiana communities. The AgCenter research study addresses the two challenges of FPV by using noneconomic inland water bodies with shallower depths, lower wind profiles and reduced vertical water movement. These sites are also unsuitable to support wildlife, which reduces environmental habitat concerns, and are isolated from public areas to reduce exposure. A common complaint about solar panels is that they harm the aesthetics of the community, and FPV in wastewater ponds will be hidden from sight.

Louisiana has a unique solar radiation profile averaging 5.31 kWh/m2/day across the entire year, with the peak month for energy in May. This number represents the average amount of energy per square meter per day, which can be used to calculate areas of land or water for solar installation projects. The National Renewable Energy Lab (NREL) PVWatts Calculator, which estimates the energy production of grid-connected photovoltaic systems, was used to assess the potential energy footprint of Louisiana's noneconomic waterbodies. The research study being conducted will compare the NREL PVWatt Calculator estimates to the field-collected data at the demonstration site to show accuracy and provide a template for future stakeholder technical assistance publications. Currently in the United States, the largest floating solar farm produced 8.9 megawatts on a 17-acre pond, which would power an estimated 1,400 homes annually.

This demonstration project will be located at the LSU AgCenter Hammond Research Station for 12 months to study the efficiency of LPV versus FPV. Studies have shown that water cooling on floating units increases the panel's ability to produce energy, thus increasing efficiency. The floating units are deployed in the research station's irrigation pond where water quality parameters, including temperature, algae, nitrate and dissolved oxygen, are being measured. The environmental impacts of the floating units are being closely monitored to show potential benefits in pond health from the panel's shading. In Louisiana, high temperatures can result in ineffective processing of pond nutrients leading to algae production. The resulting algae blooms can negatively affect operations, maintenance and native wildlife. The floating solar units will provide shading as a sunlight barrier, stabilizing the temperature, reducing algae production and mitigating evaporation loss from the pond, which increases the overall pond health. The decrease in evaporation is imperative to Louisiana agricultural irrigation ponds after recent harsh summers have had effects on water conservation.

With the availability of water resources across the state, floating photovoltaic units can be utilized in a wide range of applications. Whether it is increasing the aeration in your pond or producing power for irrigation systems, take stock of available pond space for energy production and added benefits for water conservation.

M.P. Hayes is a dual-appointed assistant professor in the LSU AgCenter School of Plant, Environmental and Soil Sciences and Louisiana Sea Grant.

This article appears in the fall 2024 edition of Louisiana Agriculture.

Video by Matt Faust

Researcher M.P. Hayes sets up a floating photovoltaic system at the LSU AgCenter Hammond Research Station. Photo by Mason Marcantel