SUSTAINABLE STAINLESS STEEL
Stainless steel is playing an important role in sustainable design and alternative energy evolution. Ultimately, the most environmentally friendly materials are corrosion resistant and durable, have high-recycled content and recapture rates, provide long service life and reduce resource use. Stainless steel provides all of these benefits. If the correct stainless steel is selected and properly maintained, it will last the life of the project.
Two SSINA Designer Handbooks are available on this subject: Stainless Steel The Green Material and the Environmental Brochure on Stainless Steel. Additional information on the sustainability of stainless steel and application examples are provided in the following sections and from the International Stainless Steel
Both the U.S. and Canadian Green Building Councils recognize the environmental benefits of using high-recycled content materials and their respective LEED (Leadership in Energy & Environmental Design) Green Building Rating Systems™ award points for their use. Stainless steel is 100% recyclable into the same product with no reduction in quality. The metal’s high scrap value and recyclability ensures that it is diverted from landfills and recaptured for use in new stainless steel. A recent international study by the ISSF determined that about 92% of the stainless steel used in architecture, building and construction applications is recaptured and recycled at the end of service.
The ISSF (International Stainless Steel Forum) has developed a presentation titled, “The Recycling of Stainless Steel”. It describes the recycling process and contains international data on the recycled content of stainless steels and the typical post-consumer and post-industrial content. World Stainless has developed a video Stainless Steel Recycled for Lasting Value which provides more information on stainless steel's recycled content and high recapture rate. On average the recycled content of stainless steel is 60%. In North America and other parts of the world, which have historically used more stainless steel, recycled contents can
The stainless steel producing members of the Specialty Steel Industry of North America have indicated that the average recycled content of the 300 series stainless steel grades that are used in the architecture, building and construction market is approximately 75 to 85%. They have issued a statement covering the sheet, plate and reinforcing bars used for these applications, which can be downloaded here.
End-Of-Life (EOL) Recapture Rate
Specifiers have become increasingly aware that truly sustainable materials should not only meet the intended design life requirements but should also be recaptured at the end-of life (EOL) and either reused or recycled into new high quality products. The least sustainable materials are burned to produce energy or sent to landfills after service, which depletes natural resources.
At the EOL, stainless steel is recaptured and recycled into new metal at amazingly high rates. Researchers at the Center for Industrial Ecology, Yale University, New Haven, CT, and the National Institute for Environmental Studies, Tsukuba, Japan completed an in-depth study of the international life cycle of stainless steel, including the typical service life and EOL recapture rates by application.
In the industrial equipment and the building and infrastructure segments, 92% of stainless steel is captured at the EOL for use in new stainless or carbon steel. The EOL recapture rates for other common applications are as follows: transportation, 87%; household appliances and electronics, 70%; and other metal goods, 60%.
Researchers also noted that EOL recycling rates for stainless steel increased by 6.1% between 2000 and 2005. They have published their findings in the article "Global Stainless Steel Cycle Exemplifies China’s Rise to Metal Dominance", Environmental Science & Technology Magazine, April 2010.
When New York's Jamaica Station was expanded, Type 316 stainless steel was used for its large low maintenance roof.
Stainless steel’s role in resource conservation is not limited to its high-recycled content and reuse rate. It plays an important role in the production of alternative energy equipment and the generation of solar, biomass to energy, nuclear, geothermal, and wave power. Air scrubbing systems made from stainless steel are also making existing energy production technologies cleaner.
Stainless steel is used to store and transport potable water to minimize loss to the environment and to clean wastewater. Its extensive use in large public water and sewerage treatment facilities is well known, but it is also increasingly being used for small on-site water storage, treatment or filtration units. These small units clean building waste and grey water, so that potable water consumption is reduced. They are ideally combined with low run-off stainless steel roofs and drainage systems to maximize the capture and use of non-potable water sources and to minimize the structure’s overall environmental impact.
The high Solar Reflective Index (SRI) value of most bare stainless steel surfaces is high enough to reflect away and dissipate heat so that air conditioning requirements are reduced when it is used for high slope roofing, wall and sunscreen panels. Furthermore, this performance is not reliant on a coating that must be reapplied and the finish will not deteriorate over time if an appropriate corrosion resistant stainless steel is selected.
Stainless steel and other specialty alloys are playing an important role in the development of clean alternative energy technologies from renewable sources. These technologies and the need for stainless steel in their development are described in the following sections.
Researchers and utilities around the world consider the ocean to be an intriguing, new, source of renewable energy. Harnessing the power of ocean waves could provide a clean, efficient renewable energy source for coastal cities in the future. There are numerous potential ways to tap ocean tides, currents, salinity, and thermal features for energy. Wave energy may be the most promising source of ocean energy for the U.S. coastline, particularly in the Pacific Northwest. The NOAA (National Oceanographic and Atmospheric Administration) provides an overview of the unique benefits of this technology on their website.
Wave power technology is reliant on corrosion resistant materials that can be immersed and splashed in salt water and provide a long service life in this demanding environment. Corrosion resistant stainless steels are an obvious choice because of their proven performance in this environment. Learn more about this technology and the role of high performance materials by reading this Nickel Magazine article.
Biomass, Ethanol and Biodiesel
The production of liquid fuels (gasification) and electrical energy from crops, waste and residue materials from certain agricultural, forestry, and urban or industrial processes is an exciting emerging technology. These energy technologies use renewable resources, divert waste from landfills and have been identified as a potentially cost effective long-term option. The US Department of Energy predicts that they will become North America’s most significant alternative energy source during the next 20 years.
There are a variety of competing technologies, which require the use of corrosion and, in some cases, heat and erosion resistant stainless steels for production equipment. For example, biomass, industrial waste and sorted rubbish can be incinerated in industrial boilers to generate steam for electrical energy production. This process produces corrosive chlorides and sulfur dioxides in off-gases. Corrosion and erosion resistant stainless steel heat exchanger pipes, combustion chambers and other component materials are required to handle the corrosive dusts and gases.
The U.S. government’s incentive programs for gasification projects include plants for producing transportation-grade liquid fuels. Eligible feedstocks include coal, petroleum residues, and biomass. The inclusion of biomass is a relatively recent development. EISA2007 requires increased biofuel use in the transportation sector. Conversion of biomass to ethanol or diesel fuel in the industrial sector produces two types of energy. The liquid fuels produced have a lower Btu content than the biomass feedstock. This creates heat that can be used to power on-site equipment or to generate electricity for sale to the grid. More information about the importance of stainless steel in ethanol production can be found here.
Geothermal water, warmed by the natural heat of the earth's interior, can be a source of clean, renewable energy. These systems commonly use hot springs as their energy source. Many geothermal wells and hot springs contain large quantities of minerals and gases, which can cause corrosion or sedimentation in geothermal piping including salt brine and sulfides. To prevent this from happening, stainless steel piping, heat exchangers and other components are sometimes used.
The heat exchangers consist of a series of stainless steel plates with the geothermal water on one side and clean cold water on the other side of the plate. The geothermal water exchanges its heat through the plate to warm the clean water. The heated clean water can then be used in a building’s heating system or for heating water for swimming and whirlpools.
Photo credit: ATI Allegheny Technologies
A variety of solar technologies have been developed to take advantage of the sun’s natural energy. This exciting area holds tremendous promise and new innovations are continuing to emerge. These technologies use corrosion resistant stainless steels for the production of raw materials and for solar energy production.
Solar cells, also called photovoltaic (PV) cells by scientists, convert sunlight directly into electricity. PV gets its name from the process of converting light (photons) to electricity (voltage), which is called the PV effect. Today, thousands of people power their homes and businesses with individual solar PV systems and utility companies are using PV technology for large power stations. Renewable biogenic material, such as wood and rice chaff, is a raw material source for manufacturing PV cells. The production of the amorphous silicon oxide used for PV cells can be quite corrosive and requires the use of environmentally friendly high performance, high recycled content stainless steels and nickel based alloys in its production.
Concentrating Solar Power (CSP) is another energy production option that makes extensive use of stainless steel. The sun’s energy is captured and concentrated with mirrors to heat fluids that in turn heat water to make steam. Steam driven turbines then generate electricity. The two main CSP technologies are “solar troughs” and “solar towers.” Learn how stainless steel is being used to generate this type of solar energy here.
David L. Lawrence Convention Center
Chrysler /Socony building image, Credit: C. Houska, Nickel Institute
Although stainless steel only became available to designers in the mid-1920ís, it has had a tremendous impact on international design. Stainless steel has provided up to 80 years of service in high profile architecture projects without appearance deterioration or metal replacement. When properly selected, fabricated, and maintained, it should last the life of the structure, even if that life extends over centuries.
Building evaluation methods, like those developed by the World Green Building Council member countries encourage designers to ask questions about the potential environmental impact of construction materials. Material comparisons frequently include data on recycled content, potential for product reuse, durability, maintenance requirements, impact on energy and water consumption, and influence on indoor air quality and light. When these analyses are done, stainless steel is consistently one of the most environmentally friendly metals commonly used in construction.
Stainless steel is an ideal choice for exterior building applications. It has been used for many LEED rated buildings around the world that were designed for 50 or 100 year service. More information about stainless steel’s advantages in exterior applications and several case study examples can be found in the following articles and literature:
Stainless steel is also a sustainable choice for interior building surface applications because it produces no VOC emissions. This makes it ideal for buildings where control of the interior air quality is critical, such as museums, laboratories, archives, medical facilities, and but it is also ideal for any structure where low air volatile organic compound (VOC) levels are desired. When buildings require careful air quality control, stainless steel ductwork is specified, because it can be thoroughly steam sanitized and duct wall perforation due to corrosion in coastal and other corrosive environments is unlikely.
It is also widely used for transit and other public building interiors where a high level of scratch and impact resistance and excellent cleanability are required. These same characteristics also make it ideal for public restrooms and kitchens. Cleaning stainless steel requires no environmentally hazardous or dangerous chemicals.
There are many decorative and structural interior applications for stainless steel including slip resistant flooring, built in furniture, column covers and railings. These products can be obtained with a broad range of decorative finishes that produce no VOC emissions. Reflective stainless steel interior panels are used around skylights and on other interior surfaces to bring natural light into buildings.
SSINA’s Position On Climate Change
The member companies of the Specialty Steel Industry of North America (SSINA) are keenly interested in “climate change” policy and its potential effects on energy prices and industry competitiveness. For this reason, SSINA has voluntarily supported the Department of Energy’s Climate VISION program, including reporting on energy consumption since the U.S. steel industry joined the program in 2002. Read more »