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Closed-loop system

Ecologists describe a closed-loop system as one that does not exchange matter with the outside world. Although the only genuinely closed-loop system may be the Earth itself. Some mechanical sub-systems approach as closed-loop and the concept is useful as an ideal for assessing and inspiring improvements in industrial sustainability. Loops may be closed, for example, by recovery, re-use or recycling (waste management), the energy that would conventionally waste recovered. The heat is going up a boiler flue captured with an economiser, and pre-heat returning condensate. Temperature discharged from compressor coolers can be used for process, water or space heating. Heat leftover from a production process used for district heating: to provide low-temperature heat for area buildings, both within and outside the fence line. Industry wastes so much heat that many energy experts see any heat-dissipating equipment, such as a cooling tower, as a sign of opportunity. See Earth system science


Reuse prevails as a strategy for packaging and shipping containers for incoming components and materials, with thousands of creative applications designed not only to reduce waste but to minimise other costs. When parts and materials packaging is reused instead of discarded or recycled, engineers can justify the cost of designing it. For higher shipping density (lower transportation and storage costs), better protection, and more comfortable – even automated – loading and unloading. The package optimised as part of the process. Many other resources might be made more sustainable through reuse, including water, surplus equipment, rebuildable components, and supplies such as shop wipes, gloves, and containers. But every potential application should be fully understood in terms of both cost and sustainability of each step in the re-use cycle (reduce, reuse, recycle, upcycle).


Recycling has become a familiar tool for sustainability, but don’t restrict yourself to conventional off-site, third-party approaches. Some of the most innovative and effective recycling programs we see are on-site, where packaging, waste or by-products from one step used as materials for another. For instance, auto manufacturers are following the inspiration of Henry Ford. Who specified that parts delivered, whose boards could use as Model T components, by recycling incoming packaging into sound-deadening panels. Let the concept of the closed-loop similarly inspire you to find cost-saving ways to reduce emissions, waste and raw materials requirements in your industrial operations.

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