A life cycle inventory is a process that quantifies the use of energy, resources, and emissions to the environment associated with a product throughout its life cycle. An LCI of cotton versus disposable diapers, for example, would quantify the amount of pesticides and water used to grow cotton, as well as the water and energy needed for manufacture the diapers and transport them to stores and homes. Finally, it would consider the amount of water and energy used to launder the cloth diapers. An LCI of disposable diapers would take into account the environmental implications of cutting down and processing trees for wood pulp, along with the environmental burdens of extraction and refining of the petroleum required to produce the plastic backsheets. It would quantify the energy used in manufacturing and transportation, as well as how much solid waste was eventually sent to landfills.
Caution is advised for using life cycle inventory as a marketing tool.
Many life cycle inventories performed to date and leveraged for marketing purposes have been criticized for favoring the sponsor. This research conflicted with findings from an LCI commissioned by the National Association of Cloth Diaper Services which found cloth to be environmentally superior to paper disposables. Monsanto is one company that is using LCI strategically. While improvements are being made, additional data can be accumulated. According to Martin Wolf, a consultant on life-cycle inventory and green product development, LCI must be augmented with a holistic evaluation of a product's environmental impact.