Sustainability: what does it mean to engineers?

At this point in time it's probably fair to say that in mechanical engineering sustainability has yet to be clearly defined. It has been variously described as company DNA, something that creates long term shareholder value or using natural and recycled materials. In the USA sustainability is described as an equation: 'sustainability = profitability' while others describe it as something that can be reused or recycled indefinitely.  The latter gets closer to my idea of sustainability. 

One of the most readily understood and durable definitions I have found was penned by an engineer, Professor Jeremy Purseglove who, in 2004, described sustainability as something that 'should meet the needs of the present without compromising the ability of future generations to meet their own needs'. Translating this into the contribution made by engineers requires application of the principle into the design and development of manufactured products. Sustainability is more than having a policy and taking steps to reduce carbon footprint; it is full blown culture change. It has to do with social sustainability, improving and preserving the quality of life. 

Generally the core benefits of producing sustainable products include improving the quality of life, energy efficiency, cost effectiveness, reliability, reduced CO2 emissions and reduction in waste going to landfill. WRAP, the Government's Waste & Resources Action Programme, works with local authorities, business and households to prevent waste, increase recycling and develop markets for recycled and sustainable products. Its declared aim is to create the case for change, support change and deliver change. A page on its website - www.wrap.org.uk - is dedicated to plastic in manufacturing and states that recycling plastic into end applications that displace virgin plastics can save on average two tonnes of CO2 for every tonne of plastic recycled.

Competitive advantage

Also it is important to recognise that sustainability can be a key differentiator against competitive products. Engineers who have taken the message onboard can use their knowledge to influence customers, help them to meet forthcoming legislative demands, enhance their products and add value. Do not harbour any preconceptions though. Sustainability does not necessarily mean products and services will cost less.  Although we want to save mother Earth we must also preserve our social structure and this means maintaining the economy.

How should engineers engage with sustainability? First, make sure you keep up to date with current regulations and requirements and if possible get involved in influencing the direction of these drivers. Consider the long term impact your design, processes and products will have on the environment. Discuss ideas and the opportunities presented with colleagues as well as customers and explore how they might benefit from it. Ask your suppliers what they believe sustainability means to them, what their policies are, what initiatives they have in place and how you can benefit from them. Explore renewable sources of energy, reduce waste and scrap and actively seek suppliers who offer recycled products.  Look at using recycled plastics, metals and natural materials.

Mark Ellis, Manager of Materials Design, Nissan Technical Centre Europe, uses recycled content compounds developed by Luxus and says: "We have a strategy for the environment called 'Green Purchase' which stipulates how Nissan works to ensure environmental compatibility is improved on future vehicles and part of this policy states that we should try to utilize recycled, recovered and bio based materials wherever possible."

Ideally the engineering industry needs a unified approach to sustainability and this may take time to evolve as there are many areas and routes to explore. For example; the impact of minimisation - ie make less in the first place, reuse through recycling, energy recovery and cost effective disposal of waste. Reducing weight has an immediate impact on the environment. A 3% weight reduction equates to a 3% cut in CO2. Every 20% of waste plastic recycled delivers a 10% reduction in carbon emissions.

Recycling options may play a major role in your consideration of sustainability. For example waste materials leaving your company might create a revenue stream. Establish a list of companies that can recycle plastics, metals, wiring products, printed circuit boards etc. Talk to them about collections, payments, landfill cost reductions and closed loop recycling options. Design and manufacture so you can facilitate the collection and separation of different polymer types. This will streamline future handling and recycling processes. Minimise the use of inserts as these have to be removed mechanically or by hand before processing. Consider using resources that can be renewed within the short term - one or two years - such as natural fibres. Think about sustainability at the concept stage of a project and be aware that requirements and approval systems might change over time. And look at the environmental outcomes of designing products that last longer or protect contents from deterioration because longevity reduces waste which in turn contributes to reducing CO2 footprint.  

Recycling has to be an integral part of any sustainability plan.  However, many engineering plastics are not degradable, or more precisely, they take hundreds of years to break down. Recycled plastic products may be fully recycled at the end of their life span. Recycling has therefore many advantages, not least of which is the conservation of non-renewable fossil fuels - plastics uses 8% of the world's oil production. The processing of recycled plastics generates 50% less CO2 than the production of prime materials. 

According to WRAP the UK uses over five million tonnes of plastic each year and consumption in the packaging, construction and automotive markets is increasing. Many uses for plastic are in products with a relatively short lifespan, yet it doesn't biodegrade and will last for decades. 

WRAP views plastic as a valuable and finite resource and says environmentally the optimum use for most plastic after its first use is to be recycled - preferably into a product that can be recycled again. Its latest figures show that the UK currently recycles or recovers approximately 19% of all plastic consumed but this is to increase to over 25% by 2010. Plastics and metals (precious finite metals as well as non-precious) can be retrieved and re-cycled to add value to the manufacturing process. In recent years many brands have started to introduce consumer products onto the market that address challenges to recycling through their design by using recycled materials such as plastics and by considering disassembly at the end of a product's life. For example over 23 million mobile phones were purchased in the UK in 2008 which is equal to nearly 3,000 tonnes of WEEE (Waste Electrical and Electronic Equipment) with the potential to be recycled into new products.

Cost-effective recycling

Recycling experts can often find the most cost effective recycling solutions. Luxus offers waste consultancy services and frequently open up new markets for plastics waste. As mentioned earlier sometimes it is even possible to turn a disposal cost into a revenue stream. Commonly used recycling processes used include the toll processing of plastics waste, closed and open loop systems. Toll processing is a comprehensive custom plastic processing service that delivers a cost effective way of turning a customers' plastic production scrap or regrind into high quality compound for reuse by the customer. Material is compounded with any additive that may be required to achieve specification and returned in packaging of choice, along with a Certificate of Analysis. 

Closed loop recycling allows products at the end of their useful life to be collected, recycled and returned their original application. Again, all materials are compounded to specification. Open loop systems convert end of end-of-life cycle products into materials that can be used to manufacture products that are not necessarily the same as the original application. The conversion of domestic heating oil tanks into reusable polymer is an example of how this process works and serves to illustrate how even 'contaminated' products can be successfully reused.

New materials and processes under development will broaden opportunities to create sustainable design and manufacturing practices. For example, nylon 11, an established engineering material, can now be made from castor oil. Scientists are continuing to investigate the use of polylatic or polyacitide (PLA), a biodegradable aliphatic polyester that is derived from renewable resources such as corn starch or sugar cane. The long term development outcomes are as yet undefined but these examples show that work is underway to develop new materials from sustainable resources.

As the use of recycled plastics increases due to quality and volumes rise, sales of virgin materials may fall and this will impact on prime manufacture and capacity. In this scenario CO2 emissions will certainly fall as fewer polymers would be produced assuming no overall growth in demand. Whatever transpires recycled plastics materials are already established as mainstream materials that can meet required technical performance parameters but with smaller carbon footprints.