For questions or comments, contact Bruce Nordman
Do Reusable Diapers Use More Energy?
Parents make many decisions which affect energy use and the environment. One of the first is whether to primarily use reusable cloth or "disposable" diapers on their children. For many environmentalists, the amount of garbage created by using disposable diapers is symbolic of our culture's excessive consumption. Disposable diaper manufacturers counter that reusable cloth diapers use more energy and water. An issue which at first glance seems clear-cloth is better-is bogged down in weighing a variety of disparate environmental impacts and conveniences, with concerned consumers unsure what to do.
Most of the energy associated with cloth diapers is used by household appliances, which vary widely in their efficiency. The extra energy used by cloth diapers is not inevitable; in fact, one can use less energy with cloth diapers than with disposable diapers, or much much more. The average numbers so often quoted mask a huge range.
Diaper Impact Studies
Two recent studies were commissioned to examine diapers and energy use: Proctor and Gamble hired Arthur D. Little, Inc. (ADL), and The American Paper Institute, Diaper Manufacturers Group hired Franklin Associates, Ltd. (Franklin). Each of these examined the energy, water, wastewater, atmospheric, and solid waste impacts of disposable diapers, commercial (cloth) diaper services, and home laundering of cloth diapers. Their energy use results are summarized as follows:
The two studies are not comparable as they make many different assumptions, boundary decisions, and interpretations. However, they are similar in the conclusion that cloth diapers use significantly more energy (at least for home laundering). Unfortunately, the Franklin study does not explain enough assumptions to reproduce their results.
*This table refers to disposable diaper equivalents. Franklin assumes 1.79 cloth per disposable, while ADL assumes 1.9, and some critics suggest 1.4.
Apart from choosing between disposable and cloth diapers, parents make many other decisions affecting energy use and the environment. Disposable diapers are often not properly rinsed resulting in human feces entering the solid waste stream (which is not designed to accommodate them). Reusable diaper decisions are more complicated; factors which affect energy use include the following:
Many assumptions must be made to determine energy use. Space does not allow listing of all of them, but the following are a few key ones. A disposable diaper is assumed to replace 1.79 cloth diapers (Franklin). Electricity is converted to source energy at a rate of 11,500 btu/kWh, which is typical of what is required for generation and transmission. Cold water is assumed to be 50F. The efficient cases use 120F water and are filled close to capacity whereas the inefficient case assumes 120F and less than half full of diapers (but full of water). Solar water heaters are assumed to save 60% of the energy required by typical conventional heaters. Other assumptions were derived from equipment characteristics or the two studies. Remember that standby losses are not relevant.
The following numbers are in btu per disposable diaper equivalent (at 1.79 cloth per disposable) so as to be comparable to the first table, but can be prorated to reflect alternate ratios.
Table 2. Washing Energy (hot water and machine energy)
|Heat Pump (3.0 COP)||270||660||120|
|Gas (85%) Backup||150||350||70|
Table 3. Drying Energy (btu/disp.diaper)
The most striking result is the range of energy consumption possible. Water use can also be reduced by proper load settings and horizontal axis washers.
The two primary differences between these results and the studies are water heating efficiencies and the number of diapers per load. Franklin also calculates an additional 290 btu/disposable diaper equivalent for producing the diaper and accessories, and 500 btu/disposable diaper equivalent for detergent and bleach. Horizontal axis washers also reduce detergent needs.
Not all these energy savings are attainable. The weather precludes solar drying some of the time, and many architectural, economic, social, and institutional constraints limit people's options. Nevertheless, people can significantly improve on the average energy use usually cited for cloth diapers. Every option has its drawbacks, but the opportunities for individuals to control these are usually ignored.
These results suggest that the minimum-impact diaper is an efficiently home-washed cloth diaper, followed by a diaper service. The simplest methods of saving energy consumed by diaper use is to:
Chances are, this will not be the last word on diapers.
Arthur D. Little, Inc., Disposable versus Reusable Diapers: Health, Environmental and Economic Comparisons, Report to Proctor and Gamble, March 16, 1990.
Franklin Associates, Ltd., Energy and Environmental Profile Analysis of Children's Disposable and Cloth Diapers, prepared for American Paper Institute, Diaper Manufacturers Group, July 1990.
font color=red>Note: This is an unpublished discussion of real choices in diapering
For questions or comments, contact Bruce Nordman
Disposable diapers have evolved considerably since they were introduced in the 1960s. The result has been a significant reduction in their environmental impact, though this was done for manufacturing cost rather than environmental purposes. Disposable diaper manufacturers no doubt have more 'green' options available to them; it would be interesting to learn the costs and benefits involved.
Consumers have many choices in diapering, whether they consciously make them or not. The choices range from easy to more difficult, and some are linked to other consumption issues. The choice is also not absolute. Traveling causes many parents who use cloth at home to choose disposables, and some cloth users use a disposable at night.
For any kind of diaper, there is the choice of how water efficient the toilet is that flushes any feces in the diaper (readily available low-flush toilets are considerably more water-efficient than conventional toilets). Diaper services don't require flushing (their, laundry systems can handle them), and disposables can obviously be disposed of with the feces, though the solid waste system was not designed to handle human waste. Any kind of diaper can be changed only when really necessary.
For disposable diaper users, there is the choice to not litter them, and to buy them without making special trips to stores.
For cloth diaper users, 'organic' diapers are available that address concern over the intensive use of pesticides in growing cotton. Worn-out cloth diapers can be reused or recycled.
For diaper service users, one can choose a more energy and water efficient diaper service, and one that services other households in the neighborhood (to minimize vehicle travel).
For those who home-wash diapers, the choices are greatest, including to:
Not every consumer has all these choices, and there are barriers to others. Nevertheless, there are real opportunities for concerned consumers to reduce the environmental impact of their diapering needs. Public policy can affect diaper impacts in many ways, including regulations and incentives to:
These options available to consumers and policy involve either changing many of the assumptions of conventional LCAs, or taking advantage of the large existing variation to move the population average towards the lower-impact part of the range.