Renewability and emergy footprint at different spatial scales for innovative food systems in Europe

Food production is increasingly being challenged by limited resources of energy and land as well as bygrowing demand for food. In a future with less availability of fossil fuels, land area will become veryimportant for capturing the flow-limited renewable resources. Emergy assessment has been applied tocalculate scale dependent indicators, which account for the land area needed, if agricultural systems wereto be supported solely on renewable sources. These indicators are designated emergy footprints (EmFs)and expand the concept of support area defined previously in emergy accounting. The EmF (in ha) iscalculated based on renewable empower densities which convert resource use into area equivalents ableto capture renewable flows. The spatial division between on-site, local and non-local land areas appliedin this study, identifies where the support area is located in order to apply a site-specific renewableempower density. A new indicator applying the EmF is the emergy overshoot factor, which estimatesthe ratio between EmF and the geographical system boundary (in ha). We apply this approach on threeinnovative food supply systems in Europe located at farms characterised by combining high diversity,reduced use of resources, nutrient cycling and local sales. The question is whether this type of food systemmay be considered sustainable from a resource use point of view measured as resource use efficiencyby means of unit emergy value (UEV), renewability (R_on-siteand R_global), direct and indirect occupationof land on different spatial scales (EmF and Emergy overshoot factor) and productivity per ha of thedirectly observed areas and the EmF area, respectively. Labour inputs constituted between 13 and 80 % ofthe total emergy flow. The proportion of resource use from renewable sources was between 31 and 60% when excluding the inputs of direct labour. The food system with the lowest UEV, excluding direct labour,had the highest emergy overshoot factor, which even exceeded the global average of seven. However,this system had the highest productivity. The system with the highest UEV, excluding direct labour, hadthe lowest overshoot factor. In conclusion, each food system strategy has its pros and cons and it dependson the priorities, which is judged the most sustainable from an emergy point of view.© 2015 Elsevier Ltd. All rights reserved.