Life Cycle Assessment combined with Exergetic Analysis in cane sugar production analysis

Transcription

1 CENTRAL UNIVERSITY MARTA ABREU OF LAS VILLAS. CUBA GHENT UNIVERSITY. BELGIUM Life Cycle Assessment combined with Exergetic Analysis in cane sugar production analysis Authors: Ana Margarita Contreras Moya Elena Rosa Domínguez Jo Dewulf Herman Van Langenhove Maylier Pérez Gil Ronaldo Santos Herrero

2 Content 1. Introduction 2. Methodology to the Life Cycle Assessment (LCA) in the sugar cane industry combined with Exergetic Analysis 3. Application of the methodology 4. Conclusions

3 1. Introduction Sugar production is a complex system, it includes two stages (agricultural and industrial) and both generate significant environmental impacts Sugar Industry requires that together with the changes of today environmental problems will be analyzed Integral utilization of sugar cane by the industrialization of by- products and the use of waste streams leads to a more sustainable industry It has been widely studied from the techno- economic point of view, but the environmental contribution has not been assessed scientific and globally. This however is a requirement for the future sustainable society

4 Sustainability Techno- Economic Goals Environmental Goals Socio- Economic Goals Resource Depletion Ecological Impact Human Health Impact Life Cycle Assessment

5 Why Life Cycle Assessment combined with Exergetic Analysis (ELCA)? Life Cycle Assessment (LCA) is a tool for the systematic evaluation of environmental aspects of a product or service system through all stages of its life cycle Exergetic Life Cycle Assessment (ELCA) Calculation of Cumulative Exergy Consumption (CExC). It allows to quantify, in terms of exergy, the use of resources during the complete product life cycle

6 2. Methodology to the LCA in the sugar cane industry combined with Exergetic Analysis LCA Phases (ISO 14040) Goal and Scope Definition Inventory Analysis Interpretation Impact Assessment

7 START Goal and Scope Definition New Alternative Life Cycle Inventory Exergy consumption indexes Exergetic Analysis Impacts Assessment Environmental Profile of sugar production Interpretation Yes Improvement Introduction? Methodology for the Life Cycle Assessment combined with exergetic analysis No Final Results

8 Exergetic Life Cycle Assessment (ELCA) Calculation of Cumulative Exergy Consumption (CExC). (MJ of exergy for the production of a kg of sugar (Szargut et al., 1988; software exoinvent, De Meester et al., 2006) CE x C j = n ( ) X i i = 1 a ij CE C x j --- Cumulative Exergy Consumption of j th product (MJ ex ) Xi --- Exergy factor of the ith reference flow (MJ ex / reference flow unit) aij --- Cumulative amount of reference flows

9 3. Application of the methodology System Function and description Scheme of Alternatives Inputs from Ecosphere and Technosphere Emissions to water, soil and air Agricultural Stage ALTERNATIVE I Sugar cane Inputs Emissions to air Industrial Stage Product: Sugar Agricultural waste (Avoided product as animal food) Emissions to water (Waste water) Emissions to soil (Ash and filter cake) Molasses (Avoided product as animal food) Electricity (National network) By-product: Molasses (Avoided product as animal food) Inputs from Ecosphere and Technosphere Emissions to water, soil and air Agricultural Stage ALTERNATIVE II Sugar cane Inputs Industrial Stage Emissions to air Product: Sugar Agricultural waste (Avoided product as animal food) Waste water (as fertilizer) Ash and Filter cake (as fertilizer) Molasses (Avoided product as animal food) Electricity (National network)

10 ALTERNATIVE III Inputs from Ecosphere and Technosphere Emissions to water, soil and air Sugar cane Inputs Emissions to air Product: Sugar Agricultural Stage Industrial Stage Ash (as fertilizer) Filter cake Waste water Molasses (Avoided product as animal food) Electricity (National network) Agricultural waste (Avoided product) Sludge (as fertilizer) Waste water (as fertilizer and fresh water) Anaerobic Digestion Biogas (Avoided product as kerosene) Inputs from Ecosphere and Technosphere Emissions to water, soil and air Agricultural Stage ALTERNATIVE IV Sugar Sugar cane Emissions to air Ash (as fertilizer) Inputs Product: Sugar Industrial Stage Filter cake + Waste water Electricity (National network) Molasses Distillation Waste water Inputs Alcohol and yeast (Avoided product as gasoline and animal food, respectively) Agricultural waste (Avoided product) Sludge (as fertilizer) Waste water (as fertilizer and fresh water) Anaerobic Digestion Biogas (Avoided product as kerosene)

11 Functional Unit : 216 t of sugar Definition of System boundaries Allocation Methodology for the impact assessment Specifications and limitations

12 Example: alternative IV

13 Example of an alternative results Process Network for Alternative IV Daily sugar production Alt IV 6.83E4 Sugar cane Sugar 4.38E4 2.45E4 Diesel 2.41E3 Urea, as N 1.54E3 Combine harvesting 982 Irrigating Cuba 1.64E3 Use of agricultural wastes -9.38E3 Electricity Cogeneration with bagasse 2.95E4 Petrol, low-sulphur, -3.42E3 Biogas from sugar waste -2.1E3 Grain maize Electricity -9.7E3-2.35E3

14 Results of Alternatives comparison Impacts evaluation. Total Contribution of each alternative A- I A- II A- III A- IV HUMAN HEALTH ECOSYSTEM QUALITY RESOURSES Method: Eco-indicator 99 (H)

15 Results of ELCA Consumption of non-renewable exergy. Alternative I Exergy (MJ) Agricultural stage Industrial stage Avoided Products

16 Alternatives Comparison Net consumption of non-renewable exergy Exergy (MJ) Alternative I Alternative II Alternative III Alternative IV

17 4. CONCLUSIONS 1. LCA can be complemented with the ELCA to obtain more solid conclusions on the environmental performance of the cane sugar production process 2. Alternatives comparison shows: advantages in the integration of production processes of sugar, alcohol from the molasses and biogas from the wastes from both processes that agricultural stage presents the greatest impacts in the industrial stage: largest impact comes from PM emission during the co-generation of bagasse non-renewable resources can be saved by the implementation of the alternatives, especially alternative IV

18

19 Life cycle model for the conventional sugar production Land resources Energy resources Fertilizers Production Pesticides Production Diesel Production T AGRICULTURAL STAGE Sugar cane Emissions to Air Material resources HCl Production T Emissions to Water T Transportation Sub-system Ca(OH) 2 Production NaOH Production T INDUSTRIAL STAGE Sugar By- products Emissions to Land DISTRIBUTION AND CONSUMPTION