Life cycle assessment of the production of beet sugar and its by-products

Abstract

This work presents estimates of the emissions resulting from the production of white sugar and its by-products (molasses, pressed beet pulp and dried beet pulp) from sugar beet cultivation to the final product at the factory gate. The study covers the impact of global warming potential, eutrophication potential (freshwater and marine) and particulate matter. The analysis was based on detailed primary data provided by Nordic Sugar A/S, from the Örtofta Sugar Factory (southern Sweden). The results of this analysis are presented for the functional unit of 1 tonne (t) white sugar without allocation. Economic and energy allocations were also applied and compared for white sugar and its by-products. The allocation of emissions to the product and by-products reduced the emissions for white sugar by 9% in the economic allocation, and by 21% in the energy allocation. The low economic value of the by-products gave rather low emissions for all by-products when applying economic allocation. These results were compared with those in the literature for white sugar in terms of global warming potential (GWP), and the results showed the lowest impact for both allocations. Replacing fossil natural gas as the main process energy source with softwood chips reduced the GWP for white sugar (without allocation to by-products) from 623 to 342 kg CO2eq/t, illustrating the considerable potential for greenhouse gas emission reduction by replacing fossil fuels in the production process.