Resource and energy efficiency – a challenge for plastics technology

Efforts to improve resource and energy efficiency in the plastics-processing industry are derived from ecological and economical targets. While ecological targets are defined by society and/or by legislation – and in some cases also by self-imposed commitments on the part of industry players – economic targets are exclusively business-oriented. The aim must therefore be to meet the ecological targets while also taking into account basic economic conditions. In this respect, it is up to every player involved in the value-adding process to optimise the benefit derived from the resources and energy used for the manufacture of products made from and with plastics in relation to the consumption of materials and energy, and naturally also in relation to the amount of labour involved. In this respect it will become increasingly important in practice to appraise not only the investment and operating costs but also the lifecycle costs.

It is natural that the consumption of material resources for the production of plastics products can only be minimised by avoiding every conceivable kind of wastage. Intelligent product design using integrative possibilities of plastics processing technology is key to solving this challenge. In a lifecycle cost appraisal, however, it quickly becomes clear that resource efficiency is achieved more through increased benefits in application than through the possible reduction of production costs.

Energy-efficient plastics processing means that the manufacturing processes must, with regard to their specific energy requirement (predominantly electrical energy), be improved firstly in the short term, and secondly in the middle and long term. The most effective measures for increasing efficiency in the short term should begin with processes that have the greatest potential for improvement. Thermoforming processes, for example, are nowadays very inefficient from an energy point of view. Injection moulding processes have enormous savings potential. Extrusion and compounding processes offer less potential for specific energy saving, but the plant outputs are comparatively high.

Improvement potential along the entire value/production chain first needs to be identified. Monitoring systems for energy and material flows will make an important contribution to this. Suppliers of machines and equipment will be confronted with an increasing need to compare specific consumption – and thus costs. Buyers will examine not only the quasi-stationary operating states of the plants, they will also take a closer look at the cost of product changeover phases. After all, unproductive process changeovers such as material and colour changes not only generate scrap and wastage, they also reduce capacity. Intelligent manufacturing and process control systems will help to reduce wastage of raw materials and energy.

Many studies show that faster processes can result in greater energy efficiency. For example, inline processes for the high-speed production of packaging articles can raise energy efficiency by a factor of 2. Optimised injection moulding cycles can result in improved efficiency if all causes of non-optimum cycle time are eliminated.

Consistent recirculation of stored energy in the form of mechanical energy in drive systems of cyclically operated plastics machinery (recuperation) can also contribute to this. So, too, can the use of existing possibilities for the direct recovery of heat from cooling processes for direct application in plastics processing. The production of cooling water from waste heat is one viable method.

It can generally be said that energy efficiency can be improved by 20 – 25 % through simple, non-cost-intensive measures. Such targets can be achieved in two to five years in virtually all areas of plastics processing. Efficiency increases that go further than that definitely require new concepts for the processing process, plants, machines and tools. Alternative drive systems with improved efficiency require capital expenditures for latest-generation machinery and equipment with much improved efficiency. This means a changeover phase in the production plants of at least five to ten years. On the other hand, it also means significantly higher savings of more than 50 %.

The targets now being set by many companies for increasing resource and energy efficiency in production mean that an improvement potential of 20 – 25 % can be regarded as feasible in the next five years, and 50 % in the next ten years up to 2020.

New and further development of machinery and equipment for plastics processing will be measured against the expected efficiency increases. Intelligent production will, wherever possible, avoid wastage and combine both ecological and economic targets.


Resource and energy efficiency – a challenge for plastics technology - Vita Prof. Dr.-Ing. Johannes Wortberg