In a recent publication from the MAGIC project, Serrano-Tovar and colleagues take a closer look at desalination, powered from renewable energy sources, used in water-scarce areas to support agriculture. The case study of reference is a project in the Canary Island of Gran Canaria, an island that depends on fossil fuel and food imports to supply its energy needs and food consumption. The case study reunites all the elements of the nexus: agricultural food production, its related water requirement met through desalination, and the energy required for water desalination. At first glance, the project seems to close the “nexus loop” by solving both the challenge of water supply in an arid region and of powering the desalination plant without fossil fuels. Upon closer inspection, it is far these specific solutions go and the answers that these technologies offer, due to the complexity of the environmental and socio-political problems encountered.
The study focuses on the company Soslaires Canarias S.L., which contributes to the irrigation of up to 230 ha of agricultural land pertaining to farmers of a local agricultural cooperative, which grow mainly fresh vegetables and fruits. The water derived from the desalination plant is stored in a reservoir, which acts as a strategic buffer element that allows for the use of wind energy (an intermittent energy source) by storing desalted water in periods when irrigation is not needed. Farmers have the option of combining the desalted water with other water sources. The water accounting is thus open: water from the desalination plant contributes to water supply to farmers, but does not cover 100% of the water requirement.
Figure: Contextualizing the representation of functional elements in relation to the socio-economic context (top) and environmental context (bottom).
The desalination system is connected to a wind farm, which contributes to the electricity demand of the desalination plant. The extent of this contribution is quite complex: wind power output depends on the strength and intermittency of the wind, which is variable. The wind farm does not provide power at maximum capacity year-round. Moreover, the desalination plant cannot use all the electricity produced by the wind farm at maximum power capacity. Hence, part of the electricity output of the wind farm is sold to the electricity grid and part of the electricity requirement of the desalination plant is obtained from the grid. Energy accounting is also open: the wind farm contributes but does not ensure the viability of the system.
Needless to say, the farmers only provide part of the fruits and vegetables used by the population of Gran Canaria. Therefore, the food flow is also open. In this case, the authors note that food production should be understood not only as contributing to food supply, but also as an economic activity that warrants access to the subsidies of the Common Agricultural Policy of the European Union, especially when food crops are exported to other EU countries. The food flow acquires interest in economic terms, more than with regard to its contribution to food security.
Overall, although the integrated wind farm-desalination-farming system seems to tie in the various components of the water-energy-food nexus, the analysis shows that many loose ends appear through this nexus system. The challenge is not just a matter of missing data or insufficient models. As the authors argue, “the analysis of the resource nexus is extremely complex and requires the consideration of many factors and functional elements operating at different scales. This makes it impossible to adopt simple standard models (of the type ‘one size fits all’) that identify ‘optimal’ solutions and eliminate uncertainty from the results.” In other words, the nexus presents some irreducible uncertainties. Uncertainties suggest that there are limits to the governability of “nexus solutions”.
Serrano-Tovar, T., Suárez, B. P., Musicki, A., Juan, A., Cabello, V., & Giampietro, M. (2019). Structuring an integrated water-energy-food nexus assessment of a local wind energy desalination system for irrigation. Science of the Total Environment, 689, 945-957. Available in OPEN ACCESS!