Life Cycle Assessment (LCA) © Colin Fitzpatrick. Life Cycle Assessment (LCA) As corporations seek to improve their environmental performance they require.

Life Cycle Assessment (LCA)

© Colin Fitzpatrick


As corporations seek to improve their environmental performance they require new methods and tools. LCA is one such tool that can help companies to understand the environmental impacts associated with their products, processes and activities.

LCA is controversial and still evolving as a methodology but the principles behind it are being adopted rapidly by organisations as a way of opening new perspectives and expanding the debate over environmentally sound products and processes.

The goal of LCA is not to arrive at “the answer” but rather to provide important inputs to a broader strategic planning process


Defined in Industrial Ecology as– The life cycle assessment is an objective process

to evaluate the environmental burdens associated with a product, process or activity by identifying, quantifying and assessing the impact of energy and material usage and environmental releases and to implement opportunities to effect environmental considerations.


Life Cycle Assessment is an environmental management tool. The International Organisation for Standardisation (ISO) defines LCA as– A compilation and evaluation of the inputs,

outputs and potential environmental impacts of a product throughout its lifecycle

Full Life Cycle Assessment (LCA)

Primary Resources

Emissions & Waste

Extraction & Processing Production Use

Reuse/Recycle Disposal


The LCA methodology is standardised by a series of ISO standards and includes the following phases– 1. Goal and scope definition (ISO 14041)– 2. Inventory Analysis (ISO 14041)– 3. Impact Assessment (ISO 14042)– 4. Interpretation (ISO 14043)

Goal and Scope Definition

The first phase of LCA includes definition of– The purpose of the study and its intended use– The system and system boundaries– The functional unit– Data quality, the assumptions and limitations of

the study


Purpose of the LCA– Internal– External


System Boundaries– Depends on scope of LCA– Depends on type of product and suitability for full

LCA


Functional Unit– Quantitative measure– Crucial for comparative LCA’s– Beverage Example


This phase also includes an assessment of the data quality and establishing the specific data quality goals. “Goal and Scope Definition” are constantly reviewed and refined during the process of carrying out an LCA as additional data becomes available.

Inventory Analysis

The purpose of the “Inventory Analysis” is to identify and quantify the environmental burdens in the life cycle of the activity under study. The burdens are defined by material and energy used in the system and emissions to air, liquid effluents and solid wastes discharged into the environment.

Inventory Analysis includes the following steps– Detailed definition of the system under study– Data collection– Quantification of the burdens

Inventory Analysis

A system is defined as a collection of materially and energetically connected operations which performs some defined function. The system is separated from the environment by a system boundary

Life Cycle Inventory Analysis

Materials Acquisition

Formulation, processing and Manufacturing

Product Distribution

Product use

Recycle, products, components, materials

Waste Management

Inputs

Materials

Energy

Water

Air

Outputs

Principal Products

Coproducts

Water effluents

Airborne emissions

Solid Waste

Other Environmentalinteractions


Detailed system characterisation involves its disaggregation into a number of interlinked subsystems. Depending on the data available, the subsystems can represent the unit operations or a group of units.


Inputs

Functional Outputs

Emissions/Wastes

Environment

System

Subsystems


Environmental burdens are then quantified for each subsystem according to the formula

– Where bcj,i is burden j from activity i and xi is a mass or energy flow associated with that activity

i

iiijj xbcB

1,

Calculating Environmental Burdens & Impacts in LCA - Example

The system in this example has one functional output and each activity i from extraction of raw materials to final disposal generates a certain amount of CO2 and CH4.

Extraction Production Use Disposal

CO2 = 0.2 kg/tCH4 = 0.1 kg/tx1 = 2t/tFU

CO2 = 0.3 kg/tCH4 = 0.1 kg/tx2 = 1.5t/tFU

CO2 = 0.1kg/tCH4 = 0.1kg/tx3 = 1t/tFU

CO2 = 0.1kg/tCH4 = 0.3kg/tx4 = 0.5 t/tFU

x1 x2 x3 x4

FU


Using the Environmental Burdens equation the total environmental burdens per functional unit related to the emissions of CO2 and CH4 are therefore

BCO2 = ∑bcCO2 . xi = (0.2)2+(0.3)1.5+(0.1)1+(0.1)0.5 →BCO2 = 1.0 kg/tFU

BCH4 = ∑bcCH4 . xi = (0.1)2+(0.1)1.5+(0.1)1+(0.3)0.5 →BCH4 = 0.6 kg/tFU

Impact Assessment

The environmental burdens quantified in “Inventory Analysis” are translated into the related environmental impacts. This is carried out within the following steps– Classification– Characterisation– Normalisation– Valuation

Impact Assessment

Classification– Involves the aggregation of environmental burdens into a

smaller number of environmental impact categories to indicate their potential impacts on human and ecological health and the extent of resource depletion. The aggregation is done on the basis of the potential impacts of the burdens so that one burden can be associated with a number of impacts; eg Volatile Organic Compounds (VOC’s) contribute to both global warming and ozone depletion. The approach used most widely for classification of the impacts is known as ‘problem oriented’, whereby the burdens are aggregated according to their relative contributions to the environmental effects they may have

Impact Assessment

The impacts most commonly considered in LCA are– Non-renewable resource depletion– Global warming– Ozone depletion– Acidification– Eutrophication– Photochemical oxidant formation– Human toxicity– Aquatic toxicity

Impact Assessment

Characterisation– Involves the quantification of the impact of interest

relative to a reference substance. In the example we examined we look at the Global Warming Potential of the Products life cycle relative to CO2 emissions. Takes place using the formula

j

jjjkk BecE

1,

eck,j represents the relative contribution of burden Bj to impact Ek

Classification Factors for Selected Burdens


EGWP = (ecCO2)BCO2 + (ecCH4)BCH2

= 1(1) + 21(0.6)

→ EGWP = 13.6 kg CO2 equiv / tFU

Impact Assessment

Normalisation– The impacts can be normalised with respect to

the total emissions or extractions in a certain area over a given period of time. This can help to asses the extent to which an activity contributes to the regional or global environmental impacts. Should be interpreted with care due to lack of reliable data.

Impact Assessment

Valuation– Each impact is assigned a weight which indicates

its relative importance. As a result the environmental impacts are aggregated into a single environmental impact function EI

k

kkEwEI

1

Where wk is the relative importance of impact Ek

Impact Assessment

Valuation– A number of problems at philosophical and

practical level in the realisation of this and there is no consensus on the best way to aggregate the environmental impacts into a single EI figure.

– Some people argue that valuation should not be carried out at all as it obscures information and that considering the impact in a disaggregated form enhances the transparency of the decision making based on LCA results

Interpretation

This phase is aimed at system improvements and innovation and it includes the following steps– Identification of major burdens and impacts– Identification of ‘hot spots’ in the life cycle– Sensitivity analysis– Evaluation of findings and recommendations

Interpretation

Sensitivity Analysis– Indicates the level of reliability of the LCA

Data availability and reliability Uncertainties Data gaps

Further Reading

Azapagic et al, Appendix Life Cycle Thinking & Life Cycle Assessment

Life Cycle Assessment (LCA) © Colin Fitzpatrick. Life Cycle Assessment (LCA) As corporations seek to improve their environmental performance they require.

Documents

lca slide

scope of lca

goal of lca

phase of lca

lca methodology

study slide

lca internal external

scope definition iso