Life Cycle Assessment (LCA)

Life Cycle Assessment (LCA)

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

Life Cycle Assessment (LCA)

LCA considers the following stages in the life cycle of an activity– Extraction and processing of raw materials– Manufacturing– Transportation and distribution– Use, reuse and maintenance– Recycling– Final disposal

Life Cycle Assessment (LCA)

Primary Resources

Emissions & Waste

Extraction & Processing Production Use

Reuse/Recycle Disposal

Life Cycle Assessment (LCA)

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

Goal and Scope Definition

In full LCA studies, the system boundary is drawn to encompass all stages in the life cycle from extraction of raw materials to the final disposal. However, in some cases, the scope of the study will demand a different approach, where it is not appropriate to include all stages in the life cycle. This is usually the case with commodities, for instance, which can have a number of different uses so that it is not possible to follow their numerous life cycles after the production phase. The scope of such studies is from “cradle to gate”.

Goal and Scope Definition

One of the most important elements of an LCA study is a functional unit. The functional unit represents a quantitative measure of the output of products or services which the system delivers. In comparative LCA studies, it is crucial that the systems are compared on the basis of equivalent function, that is functional unit

Eg comparison of different beverage packaging should be based on their equivalent function which is to contain a certain amount of beverage. The functional unit is then defined as “the quantity of packaging necessary to contain the specified volume of beverage”.

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– Allocation of environmental burdens in multiple-function

systems– Quantification of the burdens

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

Life Cycle Inventory Analysis

Inputs

Functional Outputs

Emissions/Wastes

Environment

System

Subsystems

Life Cycle Inventory Analysis

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

Calculating Environmental Burdens & Impacts in LCA - Example

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

Classification Factors for Selected Burdens

Calculating Environmental Burdens & Impacts in LCA - Example

EGWP = (ecCO2)BCO2 + (ecCH4)BCH2

= 1(1) + 21(0.6)

→ EGWP = 13.6 kg CO2 equiv / tFU

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

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