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Sustainable manufacturing: the industrial ecosystem

What is sustainable manufacturing, how are companies doing it now, and what practices can you copy to save money? E&T finds out.

Environmentally-driven activity and greater resource efficiency is good business, as far as manufacturers are concerned. That's because the pressure on manufacturers to improve their processes and technologies is no longer merely a matter of economics and costs - now it comes from environmental legislation and the expectations of society, too.

Meeting those demands for a reduction in resource use requires behavioural and technological change and taking a systems view of manufacturing. Fortunately, leading-edge organisations are already showing the way here, and there is a lot that can be learnt.

This environmental activity is increasingly common in manufacturing businesses to address the triple bottom-line components of people, planet and profit: namely accounting for societal needs, the growing evidence for global warming, and the need to reduce costs. The drivers include both the opportunity costs of reducing the consumption of resources, and the requirements and punitive costs from increasing legislation.

Long-term predictions indicate that the need to reduce resource use will continue and even accelerate. The pressures come from rising energy costs as oil reaches peak output and demand outstrips supply, as well as from the cost and availability of materials and their subsequent disposal. Two examples of this are the increase in steel prices and material disposal costs in UK landfill.

Additionally, there are concerns over the security of material supply. Quite apart from the societal pressures to be cleaner, manufacturers must reduce the consumption of materials and energy, and the subsequent generation of waste, in order to remain competitive. Waste here must be interpreted in its widest form - not merely the clearly visible material, but also energy, water and other resources.

Defining sustainability

Sustainable manufacture is based on the principle of meeting the needs of the current generation without compromising the ability of future generations to meet their needs. Pre-dating sustainability research are the waste reduction principles embedded in the Toyota Production System. Interestingly, Toyota Motor Europe's focus on reducing volatile organic compounds and water and energy use since 1993 has resulted in a 68 per cent reduction per car so far, as well as zero waste to landfill.

This is from a company that was already known to be aggressive on waste, therefore many people would not have expected them to find such additional waste. If Toyota can do it, there must be significant savings to be made in other companies. But companies do not intend to be wasteful so, apart from switching off equipment, what can they do? To quote one facilities manager, you have to 'Dig, dig, dig to find there are still savings to be made'.

While there is a growing amount of information on sustainable manufacture, little is still known about how the components of low carbon and sustainable manufacture can be integrated. Most importantly, there are too few pragmatic, low cost and repeatable examples of manufacturers who have made significant savings.

Industrial ecologies

Few industries have considered their manufacturing system as an industrial ecosystem, using natural systems as a model. Yet this can be an extremely useful model, where materials and energy are used in an efficient and effective way to comply with the four system's conditions according to The Natural Step:

  • Do not deplete natural resources extracted from the ecosphere;
  • Do not accumulate waste produced by technosphere into the ecosphere;
  • Do not degrade the ecosphere by physical means;
  • Meet human needs worldwide.

A key part of this system is to draw a clear distinction between the ecosphere, associated with environmental science, and the technosphere, associated with environmental engineering (fig 1, overleaf). Material and energy inputs are 'consumed' in the technosphere with limited efficiency. By maximising the productivity of resource usage, the amount of waste output and related CO2 emissions can be minimised. By allowing the recirculation of what was previously lost or emitted to the ecosphere, efficiency is increased.

Emissions of CO2 can be used as a performance indicator, but this metric does not capture all the environmental impacts such as resource depletion. It is, however, the easiest measure to use when you want to quantify the consequences of human activities on the environment.

This view of an industrial ecology can be transformed into a view of the lifecycle of materials against their thermodynamic value (fig 2). As material is converted into components and those components are assembled into products, their value increases. The strategies of Reduce, Reuse, Recycle, etc. can be mapped onto this.

Any change of state will change the value of the materials. Under typical current recycling schemes, this change involves significant jumps, with the highest value loss and energy consumption occurring as the material is returned to a raw form. Companies are increasingly looking to reuse components rather than recycle, thereby holding the value and reducing costs.

The industrial ecology model also captures losses from the value stream, where high-value materials are recycled - or down-cycled - into lower value roles. Examples of this are recycling glass for road construction, and recycling plastic into picnic benches.

Change is coming

The pressures on manufacturers for change are many and varied. Some arise externally, such as legislative change, customer demands and pressures from wider society. A common example is customers who demand evidence of sustainable manufacturing activity.

Other pressures are associated with the key resource flows in and out of a business - that is materials and energy on the one hand, and product and waste (including CO2, of course) on the other. Although manufacturers are putting considerable work into becoming leaner, improving performance and efficiency, and removing waste, they are only now paying more attention to less visible forms of waste such as power and heat loss, leakage and inappropriate use of compressed air, and unnecessary water use.

Many of the practices that manufacturers are adopting are practical and simple, but that does not mean they should be undervalued. They are often relatively easy to implement, require little investment and produce significant savings. Here are some recent examples from manufacturers of all sizes and sectors of how to keep resources in the technosphere:

Materials and packaging:

Ordering materials in appropriate volumes and in appropriate packaging can reduce costs through lower packaging content and less wasted product. An example is a small liquids processor, which worked with its supplier on reusable packaging; this also enabled full liquid extraction with cost reductions for both supplier and customer. Another example is Farnell, which now distributes electronics in biodegradable antistatic packaging.

Energy:

In general, you should focus on reducing your energy consumption before considering the origin of the energy. However, one interesting example from Mars is its investment in piping methane from local landfill to significantly reduce energy costs.

Measurement:

Invariably, companies measure the consumption of resources to seek potential savings. Measurement can prompt for savings in absolute consumption terms, as well as comparisons between production areas or shifts. Companies following their consumption have made impressive savings. One best-in-class company, long known for its focus on waste, recently reduced its absolute energy consumption by nearly 10 per cent year on year for five years while still increasing its production volumes. Through its structured improvement process, Trelleborg Sealing Solutions Malta measured current consumption, set targets for improvement, and used display boards for communicating progress. Its improvements ranged from cutting demand, for example switching off equipment and lighting, reducing service provision to meet demand rather than exceed it, e.g. by reducing compressed air pressure and isolating some transformers, and using more energy efficient devices such as lightbulbs. These show a disciplined, cost-effective approach to energy reduction, rather than major investments.

Water:

Water conservation is perhaps an obvious area for attention, but sometimes investment in alternative sources such as rainwater harvesting suggests significant opportunity. One company invested in large water butts for collecting rainwater from its roofs. This has saved significant sums in water consumption for the cleaning of the yard. Similarly, condensers recover water from steam systems and return it to boilers, saving on energy use, while APW Electronics reduced demand in its existing facility by analysing water use and reducing its consumption in PCB manufacture.

Facilities:

Compressed air is known to be an inefficient form of shopfloor energy, made worse by line leaks and inappropriate use of air for cleaning. Basic maintenance can significantly save on compressor costs. Cooling is another opportunity - Toyota Motor Europe recently made significant energy savings by discovering that it was able to relax the operational tolerances on its chillers without affecting its production conditions.

Lighting:

The suggestion that lights should be switched off when not in use is an obvious one, but it is not always easy to do when running multiple shifts and balancing the risk of lamp failure. Disciplines are important here. Sensors can be installed for automatic lighting in more lightly used areas of a facility. One company reviewed its lighting levels and determined they were well in excess of requirements, so saved energy by removing every other lamp. Then there is removing the need for artificial light altogether - for instance, an automotive supplier acquired a new production area with sufficient skylights to avoid the use of daytime overhead lighting, and Airbus's new A350 final assembly line facility also has natural lighting as a key feature.

Machines:

Basic machine maintenance is a commonly cited approach to reducing costs, by maintaining machine life and reducing consumable consumption. Coolant systems can be changed or work carried out with suppliers. Shockingly, when many companies plot energy consumption against production there is a relatively small drop in energy consumption once production ceases. While it can be risky to switch machines off, they can be hibernated or powered down. CNC machines may tolerate pressing the emergency stop to reduce energy consumption without risking difficulties in restart. Clean room air handling can be reduced after the end of a shift providing doors are kept closed. Mars has measured the production and base loads of each of its production lines and uses a simple traffic light system: production staff must not exceed base load when production lines have stopped and must not exceed target KJ/tonne when lines are running.

People:

It is fundamental to involve staff in both improvement work and ensuring that new practices are adhered to. Regular audits, incentive schemes and participation in national awards have significant influence here. Leadership from the senior management team is essential to initiate and sustain momentum. For example, through the inspiration of its managing director, Framptons staff in two years have halved the company's carbon footprint, reduced waste-to-landfill by 80 per cent and saved over one million kWh of energy.

Waste:

Separation of waste streams minimises the loss of value of the waste, and either reduces the cost of disposal or increases the value of sale. For instance, Martin Baker keeps swarf types separate and ensures cleanliness, therefore maximising waste value while recovering coolant. Some waste is not obvious, such as water, as it is hard to visualise. One company found that calculating its use in terms of a number of imaginary tanker deliveries per hour, rather than abstract volume measurements, enabled it to better communicate its consumption, which soon fell!

Product or service?

While many manufacturers sell products, there are increasing examples of Product Service Systems in which the manufacturer sells a service based on a product that it owns. Retaining ownership of the product enables greater product performance insights, plus retention of valuable materials and a greater incentive to reuse. A classic example of this is Xerox, which manufactures copiers but sells them as a service rather than a physical asset. This can help customers reduce copy volumes, as well as enabling Xerox to reuse over 90 per cent of components via the remanufacture of returned copiers.

Value-add products:

Changing the product specification or its packaging can both save on direct costs and enable customers' machines to run faster or more accurately. One example is Fibercore, which changed its drum size to save on material and shipping costs, a change which also allowed customers to control their processes more easily.

Keeping it going

In many of the examples of sustainability programmes, manufacturers credit an external influence with initiating the activity, such as a key customer, or transferring onto a new energy tariff. However, once the programme has started it is clear that internal leadership is key, just as it is with lean manufacturing and other improvement campaigns. The leaders in these companies are relentless in promoting sustainable manufacturing and challenging all staff to reduce waste of all forms and thereby reduce costs.

While the pressures on manufacturing to become more sustainable are increasing, and so is awareness of this imperative, the techniques to support manufacturers are still developing. New technology allows energy to be generated more cleanly and enables processes to consume less material and energy, but these new technologies must be effectively combined with existing technologies and facilities.

By taking a systems view - for example, by modelling manufacturing as an industrial ecology or metabolism - there is significant potential to reduce net consumption. Yet even before we move to a closed-system approach, there are many simple ways of making changes to manufacturing systems that can reduce material and energy use as well as reduce waste.

 

Dr Peter Ball CEng MIET is a senior lecturer in manufacturing operations at Cranfield University.

Many individuals contributed to this article from the TSB-funded THERM project, including Steve Evans, Melanie Despeisse, Steve Hope and Andy Levers.

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