LCA: Cloth vs. Disposable Diapers Introduction

[1] Disposable Diaper Life Cycle Diagram [2] Figure 1: A general life cycle schematic.Disposable Diaper Life Cycle Diagram

This page summarizes life cycle assessment (LCA) studies that focus on how cloth and disposable diapers differ in cradle-to-grave impacts. Life cycle analysis follows resource consumption and environmental impacts from a product's "cradle to grave", meaning, from the product's creation to disposal (Figure 1).

Every diaper type has differing associated impacts for production, use, and disposal. Impacts are broken into four categories: water consumption, energy consumption, raw materials consumption, and solid waste. Raw materials consumption describes natural and man-made resources needed for production of the diaper type and solid waste describes specific impacts related to disposal of diaper type. These impacts are all related to production, use, and disposal of each diaper type.

One primary goal for this page is to communicate how complicated the relationships are between resources, environmental health, and product consumption. It is impossible to quantify all cradle-to-grave effects for a product. Hopefully, the reader (YOU!) will read this summary and not only understand how to make more informed decisions, but understand how a mundane item like a baby diaper can be involved in complex environmental impacts relationships related to diaper production, diaper use, AND diaper disposal practices.





Disposables: Throw-away and Compostable Diapers

Disposable diapers are composed of various wood and plastic products. The composition of a disposable diaper can be approximated as 43% wood pulp (Fluff pulp), 27% super absorbent polymer (SAP), 10% polypropylene (PP), 13% polyethylene (PE), and 7% tapes, elastics and adhesives (Figure 2; [3])

[3] Figure 2: Compositional constituents of a disposable diaper.

Life Cycle Overview

The LCA for disposable diapers must first account for resource impacts from production of diaper materials, which can become exhaustive. Figure 3 is a schematic diagram representing a disposable diaper LCA which begins with the five basic diaper components. All resource categories are needed for the production of the diaper components and for the assimilation of the diapers from the components. Resources must also be accounted for after diaper production: packaging, shipping, sales, use, and disposal. Depending on regional waste management resources, several types of disposal methods may be available.

[1]) Figure 3: Disposable Diaper life cycle,

Water Consumption

Disposable and compostable diapers consume less water than reusable cloth diapers. Production processes are designed to minimize water consumption in manufacturing. A break down of the water consumption in the life cycle analysis for one child is shown in Table 1, the data assumes there are 4.6 changes a day until the child is 2.5 years of age.

Table 1: Water uses associated with disposable diapers [4]

Process Water Use (kg) Manufacture 34,200 Retail and Transport to Retail 135 Consumer Transport Home 1 End of Life Waste Management 47



While the production of disposable diapers requires more energy than production of reusable types, disposable diapers do not need to be laundered. Laundering the reusable diapers requires additional energy for washing and drying that disposables do not, unless they are line dried. [2]

Energy Consumption

Energy consumption for disposable diapers is tied into the coal and crude oil used to create the energy needed to harvest the raw materials, manufacture, transport, and disposal of the diapers. Table 2 shows the amounts of crude oil and coal used in one life cycle stage.

Table 2: The coal and crude oil use for the life cycle of disposable diapers used for one child until the age of 2.5 years assuming 4.6 diaper changes were made per day. [4]

Process Coal (kg) Crude oil (kg) Raw materials, transport and nappy manufacture 60.9 93 Retail and transport to retail and to home 7.6 14 Electricity 27.3 0.7 End of life waste management -14.7 1

Raw Materials Consumption

Modern forest management processes include measures of sustainability such as replanting. Also, diaper wood pulp may come from forest waste products such as forest thinnings and sawmill waste.

Here is a breakdown of forest product usage [3]:

Of total timber harvest 47% is forest products (non fuel products).

Of forest products, 30% is pulpwood product.

Of pulpwood product, 9% is hygiene product.

Of hygiene product, 2% is diaper product.

The above breakdown can be used to estimate that diapers use 0.05% of total wood product (fuel and non-fuel).

Solid Waste

Solid waste has been the primary historical focus for disposable diaper environmental impact. Not only is the diaper product being thrown away, but untreated feces and urine as well.

Disposable diapers produce more solid waste than reusable diapers. Even if excreta are flushed before disposal of the diaper, the diaper itself still goes to the landfill. While most disposable diapers can decompose readily within five months, as they are just wood products and cotton, the absorbent gels and plastic components do not. Compostable disposable diapers however, generally decompose completely within five months of disposal.

Compostables, Another Viable Alternative?

Compostable diapers have just emerged into the commercial market, and offer another potential alternative to both disposable and reusable diapers. Compostable diapers are still easily disposed of, similar to conventional disposable diapers, and do not need laundering; this makes them very attractive to consumers. However, compostable diapers are not without their shortfalls. While compostable diapers do not generally last more than five months in a landfill, they require even more raw product consumption than conventional disposables. [2]

Cloth Diapers: Home Washed and Diaper Service Diapers

Cloth diapers differ from disposables in that they are intended to be reused, thus cloth diapers are viewed as the more environmentally conscious alternative than disposables. Cloth diapers are usually made with cotton or terry cloth. The water use and energy consumption associated with cloth diapers are in different phases in the life cycle than that of a disposable diaper. Cloth diapers are washed either at home or sent out to be washed commercially. Where available, information on the life cycle differences between these two use patterns of reusable diapers will be addressed.

Life Cycle Overview

[1] Figure 4: A reusable diaper life cycle,

The life cycle analysis of a reusable diaper starts with the raw materials and extends into the manufacture, transport, purchase, use, and final disposal.

Water Consumption

Due to the need to launder between uses, water consumption is much higher over the life of reusable diapers. A break down of the water uses associated with cloth diapers is in Table 3.

Table 3: Water uses associated with cloth diapers washed at home and commercially for one child until the age of 2.5 years [4]

Process Home Washed Use (kg) Commercially Washed Use (kg) Manufacture 47,200 31,800 Laundry Detergent 21,900 290 Mains Water Supply 15,300 16,100

Energy Consumption

Energy consumption is in general considerably less for reusable diapers when compared with disposable and compostable diapers. The primary source of energy usage associated with reusable diapers is from laundering, where disposables are primarily from manufacturing processes. Table 4 shows the break down of energy use for reusable diapers.

Table 4: Energy differences between home and commercially washed diapers [4]

Process Home Washed Commercially Washed Coal (kg) Crude oil (kg) Coal (kg) Crude oil (kg) Raw materials, transport, and nappy manufacture 19 3 5 22 Electricity use 118 3 79 2

It should be noted: if individuals launder their own disposables and line dry, rather than using a gas or electric drier, energy consumption would be reduced.

Raw Materials Consumption

Raw materials consumption for reusable diapers is generally lower than that of disposables. The primary component of reusable diapers is cotton; cotton use for cloth diapers is slightly higher for commercially laundered diapers than those laundered at home (diapers are replaced more often when laundered commercially).

Solid Waste

While the amounts of excreta are not different between reusable and disposable diapers, cloth diapers produce considerably less solid waste (from lack of being discarded in a landfill) than disposable types. Reusable diapers are often used for a period of two and a half before disposal; generally the amount of time a child spends in diapers. Commercially laundered cloth diapers have a shorter span of use, and therefore produce more waste than home washed.

Conclusions

To emphasize how complicated an LCA can be, and how the "golden" solution does not emerge for a more favorable choice between cloth and reusable diapers Table 4 shows the different impact topic comparisons.

Table 4: Life-Cycle Analysis of Disposable and Reusable Diapers (based on weekly diaper needs)[1]





Resource Category Disposable Diaper Reusable Diaper Raw Materials Consumption (lbs) 25.30 3.60 Energy Consumption (Btu) 23,290.00 78,890.00 Water Consumption (gal) 23.60 144.00 Atmospheric Emissions (lbs) 0.09 0.86 Waste Water Effluents (lbs) 0.01 0.12 Process Solid Waste (lbs) 2.02 3.13 Post-Consumer Waste (lbs) 22.18 0.24 Total Costs ($/week) 10.31 7.47-16.92



Infinite statements representing the above table can be made to represent the relationships between diaper type and resource impact. Here are two broad statements:

Disposable diapers create less atmospheric emissions, waste water effluents, and solid waste (feces processing) than reusable diapers.

Reusable diapers use less raw material for production and create less post consumer waste than disposables.

These statements do not necessarily present a clear solution to the question, "Which diaper type is better for the environment?". Assessing which resource is more valuable, or more sensitive to impact is difficult but suggested for further analysis.





References Cited