How can we measure the interrelation between Water, Energy and Food in Energy Production?

SVEN KOCK; ROXANA PIASTRELLINI; ALEJANDRO PABLO ARENA

Jena

Jornada; Tag Der Forschung EAH; 2023

Universidad Ernst Abbe (EAH)

Because of the growing scarcity of water, energy, and food and the three sectors' interconnections, the Bonn 2011 Nexus Conference has proposed to analyze them in a nexus approach to promote synergies and reduce trade-offs (Hoff, 2011; Rasul & Sharma, 2016). Especially because of the urgent necessity to replace conventional for renewable energy production, there is a lot of current development in the energy sector that causes sacrifices in the other sectors (de Fraiture et al., 2008; Sargentis et al., 2021; Späth, 2018; Velilla et al., 2021). While some approaches to indicators for the relationship between energy and water for Life Cycle Analyses already exist (Armengot et al., 2021; Pacetti et al., 2015), no indicators quantifying the relationship between energy and food could be found. In our study, we propose a new indicator for the relationship between energy and food called Food Impact per Produced Energy (FIPE). In addition, to consider all of the nexus sectors, we add an existing indicator from Pacetti et al, (2015) to the framework that we call Water Investment per Energy Return (WIPER) and that considers the trade-off of water for energy. FIPE calculates how much food could be produced with the same impacts on biodiversity as caused by the production of energy while WIPER measures the water scarcity footprint per produced energy. To implement the two indicators in a case study, we have carried out a cradle-to-gate Life Cycle Assessment of soybean biodiesel in Argentina, comparing the performance of the biofuels obtained from two different agricultural technologies called early and late soybean. We have found that in Argentina both early and late soybean biodiesel approximately have the same impact on water availability of 6 to 7 liters per megajoule and that about three-quarters of the impact comes from the industrial process.Applying the FIPE, we have also found that, causing the same impacts on biodiversity, food with a calorific value of 60 or 90 kilocalories could be produced instead of one megajoule of energy in biofuels, depending on the applied technology of soybean production. Analyzing the data, we have found that most of the impacts come from the physical occupation in the agricultural stage. Hence, the FIPE in our case study does not only give information on how much food could be produced causing the same impacts on biodiversity but also on how much could be produced using approximately the same space. However, this is not necessarily the case for every technology and every condition, hence future studies might do further research on that relation. The proposed indicators can provide a new perspective on the sustainability of different methods of energy production. However, especially in the FIPE, there are still considerable limitations. Firstly, the indicator only considers primary food crop production but not food processing and, because the processing increases the relative impact (Clark & Tilman, 2017; Steinhart & Steinhart, 1974), it does not reflect the actual average nutrition that could be provided instead of the energy. As well, we only consider the process’s energy output but not the energy use. So, both indicators only show the impact per energy contained in the product but not the impact per net acquired energy.