Assessing the social return on investment of an algae-salt mariculture polygeneration system in coastal communities

Milatul Wahyu, Fiki and Amir, Nizar and Kadir, Abdul and Bulo, Yulius S. and Fitra, Ermawan and Kheireddine Aroua, Mohamed (2025) Assessing the social return on investment of an algae-salt mariculture polygeneration system in coastal communities. IOP Conference Series: Earth and Environmental Science, 1542 (1): 012005. ISSN 1755-1307

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Abstract

Coastal communities are highly vulnerable to climate change yet play a critical role in mitigating global warming. However, many experience poverty due to limited income and inadequate access to clean water and energy. Although various assessment frameworks exist, studies on the social return on investment (SROI) for polygeneration systems in coastal communities remain scarce. Therefore, this study proposed a novel algae-salt mariculture polygeneration system to address these challenges, incorporating the SROI approach to evaluate its social value, with a coastal community in Pamekasan Regency, Madura Island, serving as a case study. The system integrates solar salt production and seaweed farming with solar energy–derived potable water production and pyrolysis technology within the saltworks area. The SROI methodology involves identifying key stakeholders, mapping outcomes, evidencing and valuing those outcomes, and establishing impact by accounting for deadweight, attribution, displacement, and drop-off, from which the SROI ratio is ultimately derived. This system produces solar salt, seaweed, clean water, and energy, benefiting local farmers. Excess electrical energy is supplied to the coastal community once the system’s energy needs are met, while the pyrolysis process produces bio-oil, biogas, and biochar as fuels. Furthermore, the system reduces CO2 emissions by 1,000 kg per year through seaweed absorption and renewable energy utilization. Financial proxy values were assigned to these outcomes, resulting in an SROI ratio of 10.28:1, indicating that every $1 invested in this system generates $10.28 of social value. Ultimately, this proposed system will shed light on how stakeholders can enhance the well-being of coastal communities, improve the saltworks model, and contribute to climate change mitigation while also enabling the implementation of an energy-self-sufficient village.