Floating Solar-Powered Aeration System for Aquaculture

Technical Report · Wed Apr 27 00:00:00 EDT 2022

OSTI ID:1961164

Gilau, Asmerom; Sink, Todd; Beyene, Samson

Epsilon Innovation Group Inc., under SBIR Phase I award, sought to research, design, and pilot test an autonomous, floating solar powered aeration system for the aquaculture industry. The prototype system which included energy storage for night use, also included water quality testing instrumentation and field telemetry gateway that collected and sent water quality data to the cloud for ease of remote monitoring. The main objective of the project was aeration of fish farms during seasons, especially when low level of dissolved oxygen in water affects marine life health and production yield. Some of the critical milestones achieved include: • Performance of Floating Power System: An operational FSAS is designed that could be further refined. The FSAS automatically shutting down during the evening and starts during the morning hours. Despite an inefficient motor and short sunshine hours, our system managed to run at 50% of its designed capacity, which was expected considering the short sunshine hours in the winter. Though the system is designed to run for 20 hours with the assumption of about 9 hours sunshine hours, the performance of the FSAS is expected is during the short sunshine hours of 5.1h to 6.5h. We have identified areas where we need to make the system more efficient, and in Phase II, the time of the operation is expected to increase to more than 100% of the previously planned of 20 hours of operation, i.e., the system will run for mor than 20 hours per day. Another important point is that the FSAS is mainly needed during the summertime when the temperature is high and DO is very low. In Phase II, we shall address the technical challenges during the winter time (September – March 2022), pilot test the technology during summer time (May – September). Based on the results of our pilot test, we shall develop scalable FSAS that will be tested for the final stage of Initial Phase II during the months of March – July, which will be the end of Initial Phase II project activity. By then, we expect to have an efficient and scalable FSAS system that could be deployed to in an aquaculture farm to support interested industry clients. • Post-stocking and post-Aeration Dissolved Oxygen: Water quality monitoring in the pond began on 10/14/2021 prior to stocking fish by determining temperature, total dissolved salts (salinity), total ammonia nitrogen, nitrite, pH, alkalinity, and hardness weekly. The post stocking and post-aeration dissolved oxygen are: o Mean dissolved oxygen at the control location (Dock B) was 13.2 mg/L (SE±1.1 mg/L, range 10.2-15.2 mg/L). • Mean dissolved oxygen at the high aeration location (Dock A) was 13.4 mg/L (SE±1.1 mg/L, range 10.5-15.8 mg/L). • Mean dissolved oxygen at the intermediate aeration location (Dock A) was 13.3 mg/L (SE±1.1 mg/L, range 10.4-15.4 mg/L). • Mean dissolved oxygen at the low aeration location (Dock A) was 13.2 mg/L (SE±1.0 mg/L, range 10.2-14.8 mg/L). The results of the post aeration indicate the highest at the high aeration location decreasing toward to the low aeration location in Dock A. Compared to the Dock B, the level of mean dissolved oxygen in Dock A have shown minor improvements due to the cold weather of the winter season. • Fish Weight: Fish in all treatments lost weight numerically as is expected for this species in production during the winter, but losses were small and not statistically different from stocking weights. Final weights for each treatment are as follows: control mean 48.6 g (SE±2.7 g), high aeration treatment 49.1 g (SE±2.3 g), intermediate aeration treatment 48.6 g (SE±2.6 g), and low aeration treatment 48.7 (SE±2.7 g). • Statistical Analysis: An analysis of variance (ANOVA) was conducted to determine difference in dissolved oxygen among aeration treatment and the controls. There were no statistical differences among the control site or any of the aeration treatments. This is expected as the time of the year the study was conducted has continually high dissolved oxygen due to low water temperatures. Cold water holds more oxygen that warmer water, and aeration is rarely needed during winter months in commercial aquaculture in outdoor ponds. No statistical analysis on fish survival was conducted due to confounding factors arising from otter predation in the cages. As stated above, no significant differences in fish size or growth were found during the study period among the control or any of the treatments. • Levelized Cost of Electricity (LCoE) : Assuming the average capital cost of the FSAS of an in-efficient FSAS (Phase I) used to procure the materials, the levelized cost of electricity is about $0.51/kWh. In Phase II, addressing the challenges and increasing efficiencies could reduce the battery and PV requirement which can eventually reduce the levelized cost of electricity below 0.43 $/kWh. Please note this our rough estimate that could substantially decrease in Phase II. As the cost of the capital cost especially PV decreases, it is expected that the cost shall decrease. In conclusion, as indicated in the above results, despite several challenges that included delays to acquiring permits and shortage of critical components due to COVID pandemic related supply chain disruption, we managed to successfully complete the project and demonstrate the feasibility, and efficiency of floating solar power for aquaculture applications. Under SBIR Phase II grant, we plan to further refine our system using more efficient components and demonstrate scalability by installing the most efficient system for third party evaluation. In the second half of the Phase II project, we plan to focus on commercialization by installing our floating solar powered aeration systems in commercial aquaculture sites, who are the intended customer targets of the project. Epsilon’s FSAS will support sustainability goals of the U.S. aquaculture industry by providing clean and low-cost energy to aerate their farms which will result in healthy and higher yield food production.

• Research Organization: Epsilon Innovation Group Inc
• Sponsoring Organization: DOE Science Office
• DOE Contract Number: SC0021731
• OSTI ID: 1961164
• Type / Phase: SBIR (Phase I)
• Report Number(s): DESC0021731
• Country of Publication: United States
• Language: English