Life Cycle Assessment combined with Exergetic Analysis in cane - - PowerPoint PPT Presentation

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

CENTRAL UNIVERSITY “MARTA ABREU” OF LAS VILLAS. CUBA GHENT UNIVERSITY. BELGIUM

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

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

Sustainability

Techno- Economic Goals Environmental Goals Socio- Economic Goals Resource Depletion Ecological Impact Human Health Impact

Life Cycle Assessment

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

Why Life Cycle Assessment combined with Exergetic Analysis (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 Exergetic Life Cycle Assessment (ELCA)

• 2. Methodology to the LCA in the sugar

cane industry combined with Exergetic Analysis

LCA Phases (ISO 14040)

Goal and Scope Definition Inventory Analysis Impact Assessment Interpretation

Methodology for the Life Cycle Assessment combined with exergetic analysis Goal and Scope Definition Life Cycle Inventory

Environmental Profile of sugar production Exergy consumption indexes

Exergetic Analysis Impacts Assessment

Yes No Improvement Introduction?

Final Results START

Interpretation

New Alternative

Exergetic Life Cycle Assessment

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)

( ) ∑

=

× =

n 1 i i

X

a ij

j xC

CE

j xC

CE

• -- Cumulative Exergy Consumption of jth

product (MJex)

i

X

• -- Exergy factor of the ith reference flow (MJex/ reference flow unit)

aij

• -- Cumulative amount of reference flows

(ELCA)

System Function and description

Scheme of Alternatives

Agricultural Stage Industrial Stage

Emissions to water (Waste water) Emissions to soil (Ash and filter cake)

By-product: Molasses (Avoided product as animal food)

Agricultural waste (Avoided product as animal food) Emissions to air Molasses (Avoided product as animal food) Electricity (National network) Inputs from Ecosphere and Technosphere Emissions to water, soil and air Sugar cane Product: Sugar

ALTERNATIVE I

Inputs

• 3. Application of the methodology

ALTERNATIVE II

Agricultural Stage Industrial Stage

Waste water (as fertilizer) Ash and Filter cake (as fertilizer) Molasses (Avoided product as animal food) Electricity (National network) Product: Sugar Agricultural waste (Avoided product as animal food) Emissions to air Emissions to water, soil and air Sugar cane Inputs from Ecosphere and Technosphere Inputs

ALTERNATIVE III

Agricultural Stage Industrial Stage

Waste water (as fertilizer and fresh water) (as fertilizer) Product: Sugar Agricultural waste (Avoided product)

Anaerobic Digestion

Biogas (Avoided product as kerosene) Sludge (as fertilizer) Filter cake Waste water Emissions to air Emissions to water, soil and air Sugar cane Molasses (Avoided product as animal food) Electricity (National network) Inputs from Ecosphere and Technosphere Inputs

ALTERNATIVE IV

Alcohol and yeast (Avoided product as gasoline and animal food, respectively) Biogas (Avoided product as kerosene)

Agricultural Stage Industrial Stage

Waste water (as fertilizer and fresh water) Ash (as fertilizer) Product: Sugar Agricultural waste (Avoided product)

Anaerobic Digestion

Sludge (as fertilizer) Molasses

Distillation

Filter cake + Waste water Waste water Emissions to air Emissions to water, soil and air

Sugar

Sugar cane Electricity (National network) Inputs from Ecosphere and Technosphere Inputs Inputs Ash

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

Example: alternative IV

Combine harvesting 982 Grain maize

• 9.7E3

Urea, as N 1.54E3 Diesel 2.41E3 Petrol, low-sulphur,

• 3.42E3

Electricity

• 2.35E3

Biogas from sugar waste

• 2.1E3

Use of agricultural wastes

• 9.38E3

Sugar cane 4.38E4 Sugar 2.45E4 Electricity Cogeneration with bagasse 2.95E4 Irrigating Cuba 1.64E3

Daily sugar production Alt IV 6.83E4

Example of an alternative results

Process Network for Alternative IV

Results of Alternatives comparison

HUMAN HEALTH ECOSYSTEM QUALI TY RESOURSES

Method: Eco-indicator 99 (H)

Impacts evaluation. Total Contribution of each alternative

A- I A- I I A- I I I A- I V

• 6.0000
• 4.0000
• 2.0000

0.0000 2.0000 4.0000 6.0000 8.0000 10.0000

Exergy (MJ) Agricultural stage Industrial stage Avoided Products

Results of ELCA

Consumption of non-renewable exergy. Alternative I

Net consumption of non-renewable exergy

Alternatives Comparison

0.0000 1.0000 2.0000 3.0000 4.0000 5.0000 6.0000 Exergy (MJ) Alternative I Alternative II Alternative III Alternative IV

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

• 4. CONCLUSIONS

Life cycle model for the conventional sugar production

By- products

DISTRIBUTION AND CONSUMPTION AGRICULTURAL STAGE INDUSTRIAL STAGE Fertilizers Production Pesticides Production Diesel Production

T

HCl Production Ca(OH)2 Production NaOH Production

T

Sugar

T

Sugar cane Land resources Energy resources Material resources

T

Transportation Sub-system Emissions to Air Emissions to Water Emissions to Land