Environmental aspects of stainless steel
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Recycling and the long term life of stainless steel
Today, where environmental issues are so important in saving and preserving our world, stainless steel can emerge as an excellent recyclable material.
“Did you know stainless steel is 100% recyclable?”
Stainless steel is theoretically 100% recyclability and its long term life makes it an ideal environmental performer much better than many other materials. Stainless steel products are designed to have a long life; often spanning over several decades. This long term life generally is the reason for choosing stainless steel in the first place. However of course there will be a time when the stainless steel does come to the end of its useful life. The end of life may be reached due to fashion changes, (product still functions but the design is out-dated), technological redundancy, (product is replaced by a more efficient technology) or the product reaches the end of its design life.
Even though the end of life is reached, this does not mean that the stainless steel is not useful as a recyclable product. The main alloying elements of stainless steel, (chromium, nickel and molybdenum), are all highly valuable and can be easily be recovered and separated from other materials.
“Did you know that any stainless steel object has an approximate recycled content of 60%”
In 2007, around 27 million tonnes of stainless steel were produced, taking approximately 16 million tonnes of recycled stainless steel and other materials to generate this quantity. The amount of recycled stainless steel in any stainless object is approximately 60%, this will increase however as the use of stainless steel expands as stainless steel produced today will not necessarily be recycled for 20-30 years.
“Stainless steel is made up of:
25% Old scrap such as end of life products
35% New scrap which is returning from production
40% New raw materials added”
Despite the very high recyclability properties of stainless steel, in some circumstances stainless steel will still find its way into disposal sites etc. Unlike many other metals, in this situation stainless steel will have no damaging effects on the soil and water.
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So how does stainless steel improve modern day life?
Stainless steel has many environmental and social benefits. Stainless steel products enable us to lead a healthier life and are cleaner for the environment as well. Even though it is impossible to demonstrate all areas where it is beneficial, below are some of the main examples where stainless steel is used.
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Improvements to air quality
Air emissions are always a problem in today’s moving world, where pollution is of such high importance. The greater influx of cars on the road, planes in the air and production factories all add to the problem. The effect of increased levels of ‘greenhouse gases’ on climate change is maybe the most debated example although pollutants which cause ‘acid rain’ are also worth noting. Ways in which stainless can help reduce this problem can be:
- New catalytic converters use stainless steel for the holding and transportation of catalytic substances. The newest versions are much lighter and stronger than traditional ceramic versions as well as being much more energy efficient. Catalytic substances are usually highly corrosive and are active within a high temperature environment, thus being the reason for stainless steel being the chosen material. These stainless steel converters help to decrease pollution on motor vehicles, generator sets, forklifts, mining equipment, trucks, buses and trains etc. The image below shows the inside of a catalytic convertor:
“Diesel filters can filter out 95% of black smoke and 85% of soot particles”
Diesel filters are designed to remove smoke and soot particles from the exhaust gas of a diesel engine. Newer versions can consist of up to 90% stainless steel. Diesel filters can filter out 95% of black smoke and 85% of soot particles from the gas produced. Stainless steels excellent temperature resistance, manufacturability and economic properties make it the best option for the filter.
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Reduction in the use of fossil fuels
We all know that it is important to save the worlds supply of fossil fuels. News headlines are always pushing the need for us all to do our part to save non-renewable energy forms. Stainless steel is now being used in many applications which can help to reduce the use of fossil fuels, these can include:
“Stainless steel condensing boilers have a 100% efficiency rating”
- Stainless steel can be used in the manufacture of condensing boilers. Condensing boilers are today’s most energy efficient heating method, with a 100% efficiency rating. Stainless steel is required because of the condensation that occurs during the process; therefore corrosion resistance is of high importance.
- Rooftop solar panels do not just reduce the use of fossil fuels they mean that renewable sources can be used instead. Stainless steel versions can account for a considerable part of the energy needed for the preparation of hot water and room heating. Solar panels can also be integrated into the buildings roofing or cladding possibly adding to its aesthetic appeal.
- Fuel cells are a source of energy for the future. Much like a battery the fuel cell converts chemical energy into electrical energy. Working from either natural gas or hydrogen, they generate heat and electricity with only one emission; water. Stainless steel is used for supporting the electrodes which are stronger, easier to manufacture and cheaper than ceramic versions. Fuel cells can be used in a variety of places including in cars and in domestic heating systems alike. The image below demonstrates a domestic fuel cell:
“Liquefied gas accounts for 10% of the Japanese energy supply”
Liquefied natural gas is considered as the worlds most environmentally friendly of the fossil fuels as it is a clean source of energy. In Japan it accounts for some 10% of their energy supply. The gas is transported at a temperature of -163°C, and this is the reason for stainless steel as it exhibits an increase in tensile and yield strength without loss of ductility at low temperatures. Typically 304 is used for this application, and thanks to its mechanical strength, a wall thickness of only 1.2mm is enough to give a comfortable margin of safety.
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Keeps water clean
It is so important that water is kept clean, not just for our health but for the environment as well. Stainless steel can be used to improve the cleanliness of water. The list below shows how stainless steel can help keep water cleaner:
- Stainless steel pipes for drinking systems help to keep water clean and quality standards high. Stainless steel guarantees lasting hygiene and prevents the formation of any medium on which bacteria can grow. Correct grade selection will minimise the risk of any localised corrosion, meaning there is practically no contamination of water in contact with the stainless steel. Leaching levels of nickel and chromium have also been proven to be less than the maxima permitted by the European Drinking Water Directive.For more information on stainless steels and drinking water Click here
- Waste water plants are using stainless steel in the transportation of waste water products, due to the possible corrosive nature of the water. Stainless steels durability and low maintenance also make it the best material to use. Therefore the reason for stainless steel is to maximise service life and to minimise malfunctioning.Below is an image from inside a waste water plant:
Stainless steels are also being used for piping which is needed to decontaminate waste water before it is filtered back into the rivers and soil. Due to the unpredictable nature of the contaminated water, stainless steel is needed to ensure the sufficient corrosion properties are in place. ISSF have assembled documents which provide further information on how stainless steel is used in a water context:
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Reduces waste
Stainless steel can be used to prevent the amount of waste gases and materials given off, as well as the disposal of waste products. The list below demonstrates some areas where waste reduction occurs:
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Further Information
For further information on the environmental aspects of stainless try the links below:
ISSF
The International Stainless Steel Forum (ISSF) is a non-profit research organisation, which serves as the world forum on various aspects of the international stainless steel industry. Founded in 1996, ISSF has its own Secretary General, Board of Directors, Committees and budgets. ISSF is legally a part of the International Iron and Steel Institute (IISI). To visit the ISSF home page click here
Pages of interest may include:
Nickel Institute
The Nickel Institute has an extensive range of literature on stainless steels and other nickel containing materials which can be ordered or downloaded directly from the site. This covers application market sectors which includes architecture and building, food processing and catering, environment, marine, oil and gas, power generation, chemical, petrochemical, automotive, water (supply, desalination, waste) and plumbing and swimming pool buildings. To visit the Nickel Institute home page click here
Pages of interest may include:
IMOA
The International Molybdenum Association (IMOA) is an association with scientific purposes. It is the focal point of promotion, statistical and technical activities for the worldwide molybdenum industry. The website provides information on where the element is mined, the reserves that are left, and product it is used in and their development. There are several publications discussing molybdenum and its applications. To visit the IMOA home page click here Pages of interest may include:
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