Freshwater use analysis of cassava for food feed fuel in the Mun River basin,Thailand

Purpose

This research aims to assess the current freshwater use in the cassava supply chain for food, feed fuel in the Mun basin, and the water scarcity impact and possible options to increase cassava production to meet the future demand following the Renewable and Alternative Energy Development Plan (AEDP) target.

Methods

This research analyzes freshwater use based on ISO 14046 water footprint assessment. The analysis was implemented based on a life cycle perspective that determines the impact on freshwater use from cassava products along their supply chain. Both direct water use and indirect water use that associated are analyzed. Midpoint impact of water use was assessed using water stress index (WSI) to calculate water scarcity footprint.

Results and discussion

The results show that in the current situation, total freshwater use of all cassava-related product in Mun basin in the base case is 1140 million m³/year. When WSI was applied, water scarcity footprint of all cassava-related products in the Mun basin in the base case was only 147 million m³/year. In the scenario 1, increasing irrigation to increase yield in the existing cassava cultivation area in the Mun basin has the largest water use compare to other scenarios. Scenarios 2 and 3, expanding cassava cultivation area in Mun basin and in other regions, have lower water and water scarcity impact than scenario 1. The benefit from transforming paddy rice (in unsuitable areas) to cassava cultivation was also good. However, more resources are required including land, energy, or fertilizer, and other environmental impacts such as greenhouse gas emission or eutrophication could be increased from the increasing resource use. Therefore, the decision-making process needs to consider the trade-off between those factors, and a more complete life cycle assessment (LCA) on the envisioned alternatives should be applied for further analysis.

Conclusions

The increasing demand of biofuels derived from cassava can increase stress on water in the Mun River basin. Increasing irrigation water use in the area as per requirement could possibly increase yield to meet the future feedstock demand but has large water scarcity impact. However, this could be alleviated by using groundwater from additional wells in the farm. Expanding cassava cultivation area could be another option having low water scarcity impact, but it requires more resources and could increase other environmental impacts that need to be further analyzed by a complete LCA.