seeks to optimize the cycle of virgin material to finished material, including components, products, and waste products (Jelinski et al., 1992).

The concept of industrial ecology, therefore, extends beyond the typical flow of materials in a process industry (such as an oil refinery) into the manufacturing industry, where separate companies with different processes, movements of material, and operations contribute to a final product. Manufacturing is a complex system with an almost unlimited number of different but related variables that can influence sustainability. The complexity is best illustrated by the fact that, depending on boundary conditions, a full life cycle analysis of a beer can include as many as 600,000 data items (Pomper, 1992).

Paradoxically, a systems-oriented and sustainable approach to the design of manufacturing and products means that the complexity needs to be simplified. Simplification can be achieved by limiting the number of variables to be tracked through a system or by organizing them so that consequences from different design strategies can be evaluated, such as in Volvo's Strategies in Product Design (Horkeby, this volume).

Hydro Aluminum, a fully owned subsidiary of Norsk Hydro, manufactures two classes of product: semifabricated products (such as aluminum sheets) and end products (such as aluminum cans). The company has approached industrial ecology by focusing on understanding its products.

Aluminum offers several benefits in its many applications in the economy. It has a positive strength-weight ratio, is noncorrosive, is a good conductor of heat, and is excellent for food and beverage packaging. In terms of its environmental impact, energy consumption is high for initial production and low for recycling. Typically, 35 kilowatt-hours (kwh) are required for processes leading to primary aluminum and 1.7 kwh are required for recycling. Most of the emissions arising from the extraction, production, use, and recycling of aluminum are from primary production.

These characteristics necessitate a proactive approach to all environmental, health, and safety (EHS) matters and the need to highlight the advantages of aluminum from a life cycle perspective. In 1991, Hydro Aluminum began its program of ecological responsibility, which is based on an understanding of industrial ecology as a systems-oriented approach to EHS management. Under this program, the process-oriented EHS functions are a part—but not of—industrial ecology

Two different dimensions of industrial ecology are important to the firm. One is related to information and education of the company's employees and the general public. The other is related to product, system, and process development defined by market needs and economic and technical feasibility.

Hydro Aluminum initiated several steps to increase awareness about the industrial