Design Life-Cycle
assess.design.(don't)consume
Fiber Optic Cables
Amy, Cheng
Nathaniel Chow
DES 40A
Professor Cogdell
16 March 2023
Fiber Optic Cables Raw Materials
Introduction
Optical fiber is “a single, hair-fine filament drawn from molten silica glass” (“How Optical Fiber is Made”); multiple are combined to form a single optical fiber cable. These cables transmit medium in high-speed, high-capacity communication systems, which convert information to light. Fiber optic cables can transmit data at “10Gbps or more.” In contrast, traditional copper cables are limited to “a maximum bandwidth of 1 Gbps” (Babani et al. 60). Alexander Graham Bell, an American inventor, attempted the idea to communicate with light around 1880. Light wave communication was not feasible until the mid-twentieth century with advanced technology. In 1968, “researchers in England discovered” that silica glass fibers carry light waves without significant signal loss, and in 1970 the first optical fibers were produced commercially (“How Optical Fiber is Made”). As our world increasingly relies on digital communication and data transmission, the importance of fiber optic cables cannot be overstated. The production processes of raw materials such as silicon dioxide, pure oxygen, and petroleum-based polymers contribute to the environmental impacts of fiber optic cables through the emission of greenhouse gases, energy consumption, and waste generation. However, the entire life cycle process of fiber optic cables, including production, transportation, use, and disposal, also plays a significant role in their environmental impact and requires attention to promote sustainability.
Raw Materials Acquisition and Processing
Raw materials of optical fiber cables include quartz, pure oxygen, germanium, acrylic acid, and petroleum. These primary materials are further processed into functional components of fiber optic cables.
The most used material in the cables, quartz, must be extracted from “open pit mines” to produce the silica core as the center of the fiber. Quartz is a natural mineral found in rocks and sand. “China, Japan, and Russia” are the world’s primary producers of quartz; it contains “primarily of silica or silicon dioxide (SiO2)” and is the second most abundant mineral in Earth’s crust (“quartz”). Mining operations use bulldozers and backhoes to move soil and clay to “expose the quartz crystal veins in the rock” (McKenzie). Quartz is extracted and utilized by chemically reducing the mineral to produce silicon by “using carbon (carbothermic) at high temperatures (2400K)” in various methods. Silicon dioxide (silicon) with “a high level of purity (>95%) can be utilized for solar cells, microcomputer chips, electronics, semiconductors, and others. (Andriayani et al.).
Another component, oxygen (O2), a colorless gas that makes up 21% of the Earth’s atmosphere, is extracted by cryogenic air separation units, which separate oxygen by “liquefying air at very low temperatures (-300°F).” Ambient air is compressed in several stages with inter-stage cooling, further cooled in chilled water. The residual particles in the air, such as “water vapor, carbon dioxide, and atmospheric contaminants, are removed in “molecular sieve adsorbers” (“3.1 Commerical Technologies”). Oxygen is cooled to cryogenic temperatures through heat exchange with product gasses, after-coolers, and expanders. This air finally enters a cold box containing distillation columns with many stages and an argon column for additional purification. Pure oxygen in this process results in a high-purity product with low impurities. Impurities in the oxygen can result in defects in the silica, which can degrade the optical performance of the fiber.
A similar process is performed with germanium, making germanium into a gas form; germanium is a crucial raw material for producing fiber optic cables. It is “a silvery-white semi-metal” and “it is brittle” (“Germanium”). With properties between a “semiconductor in pure metallic form, transparent to most infrared light spectrum in crystal form, and has a high refractive index in glass form.” (Nguyen, Thi Hong, and Man Seung Lee.) Although germanium is contained in some sulfide ores, the byproducts reside from processing these ores and coal combustion, the primary resources for recovering this element.
Acrylic acid is another element, a precursor to a polymer called acrylate. Acrylic acid is produced through the vapor phase oxidation of propylene. This chemical compound is a gaseous byproduct obtained during petroleum refining. The process of forming acrylic acid involves two reactors in series using two catalysts. The first reactor converts propylene to acrolein, and the second converts acrolein to acrylic acid. Acrylates are prepared industrially by treating an acrylic acid with the corresponding alcohol with a catalyst. This reaction using lower alcohols “such as ethanol and methanol occurs at 212-392°F” using “acidic heterogeneous catalysts.” With higher alcohols, such as “n-butanol,” the reaction is “catalyzed in a homogeneous phase” with sulfuric acid. (Samudrapom)
Another component is petroleum-based polymers, which are compromised of oil. Most oil is trapped in underground reservoirs, in which petroleum bubbles to the surface of the Earth in some places. In Saudi Arabia and Iraq, porous rock allows oil to create small ponds. Drilling usually occurs where oil reserves have been found, called developmental drilling. Oil can also be extracted through oil rigs and platforms that are offshore and by the shore. (“Petroleum”) Petroleum is made into polymers through polymerization; this is a process where gasoline (monomers) are converted into “higher molecular weight hydrocarbons (polymers).” The process occurs when monomers are chemically bonded into chains (Baheti).
The amount of energy used in the manufacturing of fiber optic cables can vary depending on several factors, including specific materials used, the manufacturing process, and the location of the manufacturing facility.
III. Manufacturing
Fiber optic cables consist of five parts distributed into the core, cladding, coating, strength member, and outer jacket. The manufacturing involves several processes, including producing raw materials, fiber drawing, coating, and cable assembly. Silicon tetrachloride and germanium are filled into a giant silica container called the preform and melted at high temperatures creating a core. Silicon dioxide, composing the core and cladding, is further processed into a gas form which becomes silicon tetrachloride. Silicon tetrachloride chemical reaction can be manufactured by directly reacting hydrogen chloride with silicon. This reaction occurs in a heated chamber where the SiCl4 and O2 are introduced and heated to high temperatures. SiO2 is also deposited in the preform to form the fiber optic cable. While germanium is used in the core because it increases its refractive index and minimizes signal loss. This preform is drawn into fibers, which involves heating the glass and pulling it into a long, thin strand. This process is synthetic and is the main component of optical fibers. The fiber is then coated with an acrylate coating, which protects it from damage and improves its mechanical properties. After the fibers are coated, they are assembled into cables. The cable assembly process involves several steps, including standing the fibers together and applying the strength members to provide tensile strength, and applying a protective jacket to provide additional protection from the environment. During the manufacturing process, measures are also taken to ensure the quality of the fiber optic cables, and the fibers are inspected to ensure they provide adequate protection.
IV. Distribution and Transportation
The main modes of transportation for delivering fiber optic cables include trucks, trains, and ships, powered by fossil fuels such as diesel and gasoline. These fuels emit greenhouse gases and other pollutants into the atmosphere leading to climate change and air pollution. The packaging materials that protect fiber optic cables during transportation contribute to waste generation and environmental pollution. Spools are used for transporting fiber optic cables and are typically made of various materials such as wood, plastic, or metal. The spool material depends on the application’s requirements, including the cable’s size and weight, transportation method, and environmental considerations. Wooden spools are commonly used for heavier cables and provide greater strength and durability. Plastic spools are lightweight and easy to handle, making them suitable for smaller, lighter cables. Metals spools are typically used for specialized applications requiring high strength and durability.
V. Use, Re-Use, and Maintenance
Fiber optic cables are used for various applications, including high-speed data transmission, telecommunications, and internet connectivity. They are also used in medical equipment and military technology. Using fiber optic cables for high-speed data transmission can also reduce the need for physical travel and transportation, reducing carbon emissions. In order to ensure the longevity and efficiency of the cables, proper maintenance is crucial. Various equipment is required to use fiber optic cables, such as power meters and fusion splicers. These tools install, splice, test, and repair optic cables. Fiber optic cables may require regular cleaning to remove any debris or dust accumulation on the cables, as this can cause signal loss or distortion. Maintenance personnel who work on fiber optic cables require specialized training and certification. The exact maintenance process may vary depending on the specific application and installation. Fiber optic cables can be repurposed for different applications or installations, although this is less common due to the nature of the technology. Fiber optic cables are designed to last for decades, and their relatively low maintenance needs and long lifespan contribute to their sustainability compared to other types of cables.
VI. Recycle
Due to fiber optic cables’ long life span; they are usually maintained and not recycled. However, the recycling germanium used in the core of the fiber optic is vital because Ge does not exist in the free states and is commonly found in another mineral with a “concentration of 0.0007% in the Earth’s crust” (Nguyen, Thi Hong, and Man Seung Lee.).
VII. Conclusion
As the demand for high-speed data transmission in communication networks increases, fiber optic cables have become popular. However, their potential environmental impact throughout their life cycle has raised concerns regarding their sustainability. Thus, it is necessary to analyze the sustainability of fiber optic cables. A life cycle assessment of fiber optic cables indicates that the production, transportation, use, and disposal stages have notable environmental impacts. Therefore, addressing these impacts is vital for promoting a sustainable future. Developing more eco-friendly fiber optic cables is an ongoing process, and significant progress has been made in recent years. Manufacturers increasingly use more sustainable materials in cable construction, such as bioplastics and natural fibers, which are renewable and have a lower environmental impact than traditional materials. Also, the development of more efficient production processes such as 3D printing and automation is pushing the advancements of these cables being more renewable. These advancements are reducing waste and energy use during manufacturing. Improvements are being made to the end-of-life management of fiber optic cables. All of these initiatives are helping to make fiber optic cables more eco-friendly and sustainable.
Works Cited
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Nathaniel Chow
Amy Cheng
DES 40A
Professor Cogdell
Embodied Energy of Fiber Optic Cables
Introduction
Optic fiber cables have become an essential infrastructure in modern telecommunications, providing a reliable and efficient means of transmitting vast amounts of data over long distances. They are utilizing light to transmit data rather than pure electrical conductive materials like copper. They offer greater bandwidth, improved durability, and faster communication speeds than previous cable solutions. Despite their advantages, the energy required to fabricate, install, and maintain these cables is immense, with an energy-intensive specialized process needed at every step of their life cycle. This process raises concerns about the environmental impact of the optic fiber cable industry and the sustainability of its energy sources. This essay examines the life cycle of Optic Fiber cables and the energy sources used in each step to understand the environmental implications of their production and use. Examining Optic Fiber cable's environmental impact in its Life Cycle will show that the transport and installation of Fiber Optic cables contribute to most of its disruption to the ecosystem.
Raw Material Acquisition
The production of Optic Fiber cables involves acquiring several raw materials, each with its energy-intensive process. Silica, the primary component of the cable, is obtained from mining quartz and processing it. The mining process involves mechanical energy-intensive procedures, such as open-pit mining with heavy machinery, which consists of the use of fossil fuels through industrial vehicles. Open-pit mining methods using industrial vehicles are often used to extract quartz from the ground, “such as Jaw crushers, Cone Crushers, Impact Crushers and Hammermills” (Mclanahan). The mined quartz is chemically broken down into silica using sodium hydroxide and hydrochloric acid solutions (Andriayani et al.).
Pure oxygen is another material for both the fiber itself and heating elements in the manufacturing process. Oxygen gas can be obtained through various methods, the primary one being extraction machines that liquefy air at temperatures of -300°F ("Commercial Oxygen"). They are very energy intensive and require dedicated coal-powered energy plants to run the extractors. One of these plants was Tampa Electric, which generated more than 4.8 million MWh of electricity over 18,000 hours using 2,200 tons of coal per day ("Tampa"). Germanium is used to improve light efficiency in the cables, obtained through zinc and copper refinery-produced byproducts, specifically, “by processing zinc smelter flue dust.” ("Germanium"). Acrylate, one of the primary materials used in the coating process, is a chemically produced product from acrylic acid. Acrylate production requires batch reactors and distillation that utilize sulfuric acid (Mihai Daniel Moraru et al.). While many other materials are used to create fiber optics, there are too many to list, as each location-specific design uses specific materials during manufacturing to solve its environmental requirements.
Manufacturing, Processing, and Formulation of Optic Fiber cables
There are several manufacturing processes for Optic Fiber cables, many of which have several specialized steps, each with its own energy requirements. The energy sources used in manufacturing include electricity, natural and synthetic gas, and other fossil fuels. The processes generally include drawing a preform, coating, and testing the fibers before bundling them into cables. The main focus will be on the Modified Chemical Vapor Deposition process, the currently most widely used process, where silica, oxygen, and germanium are combined as a chemical gas into a large silicate glass cylinder preform. The glass is superheated to over 3600 °F in a chemical gas furnace and stretched by mechanical machines utilizing gravity into thin fibers; these fibers are coated with acrylate and recoated with special polymers. (“Optical Fiber”) Hundreds of miles of fibers are spooled by machine to be distributed to assembly factories by truck, where dozens to hundreds of fibers are weaved into a single cable depending on the use case. The cable is then rigorously tested for imperfections before being distributed.
Compared to previous cable solutions like copper, the manufacturing process of Optic Fiber cables is more energy-intensive as there are more steps. However, when installed, the cables are more durable and effective at transferring data.
Distribution and Transportation of Optic Fiber cables
The distribution and transportation of Optic Fiber cables require significant energy to move them from manufacturing facilities to installation sites. The energy sources used in distribution and transportation include trucks, ships, and airplanes, which rely on fossil fuels. According to the International Energy Agency, the transportation sector of goods accounts for approximately 27% of global greenhouse gas emissions from fossil fuel combustion like gasoline and diesel, which are petroleum-based ("International Shipping"). The transportation of Optic Fiber cables also requires packaging and insulation, which further increases the environmental impact of the distribution process. Cables have specifications for varying uses, from consumer-grade business solutions between buildings to commercial distribution between countries. Network providers like AT&T and Google Fiber ("Providers of Fiber Internet Service") have to distribute cables from the manufacturer to installation companies that install cables indoors and outdoors in dug cable tunnels or ceiling spaces ("Fiber Optic Cable Installation").
Commercial-grade submarine Fiber optic cables are used for inter-continental communication. Currently, there are over 300 of these cables spanning “550,000 miles (885,139.2 kilometers)” ("The 550,000 Miles of Undersea Cables That Power the Internet"), all of which were installed by “cable laying ships” that are over 150 meters long. They carry “thousands of tons of fiber-optic cable by spooling it into large tanks onboard the vessel.” ("Submarine Cables - Fiber Link Internet") The laying process is also energy-intensive and involves specialized equipment and machinery. While a specific percentage of greenhouse gasses caused by fiber optic distribution cannot be found, global shipping accounts for 2% of global CO2 emissions. It is not on track to be zero emissions ("International Shipping").
The transportation and distribution of Optic Fiber cables require significant amounts of energy, mainly derived from fossil fuels. Using more energy-efficient transportation methods and biodegradable or recyclable packaging materials could help reduce the distribution process's environmental impact. Furthermore, installing and maintaining fiber optic cables requires skilled technicians to do this safely and efficiently.
Use, and Maintenance of Optic Fiber cables.
Optic Fibers installed in buildings theoretically could last for decades. Low light sources in “the milliwatt range (0.001 watts)” ("Fiber Optic Cable Installation") are sufficient to power them. However, to ensure efficient data transfer, technicians use battery-powered handheld meters to check for imperfections. Sometimes imperfections are found, and cables are returned to the distributors for replacement, which accounts for some fossil fuel usage. Damage to the cable can also occur over time; there are various methods of repairing damage, and one of the methods is to cut the damaged section off and replace it with connectors. While repair is theoretically simple at smaller scales using specialized equipment, submarine cables, which have amplifiers that use up to 16.5 Kw (Kaneko et al), require divers with oxygen tanks to use vacuum-sealed apparatus to initiate repairs; these are intensely energy intensive as they require teams of ships to complete. (Fluctus) Currently, methods of recycling damaged cables are being researched.
Recycling
The recycling of Optic Fiber cables is an important step in reducing their environmental impact. The recycling process involves separating the various materials used in the cables and reprocessing them for use in new products. Germanium is a rare earth metal used in the base fiber optic, a process to recover it using “hydrometallurgical methods” (Chen 2017) has been published. However, the scale of implementation of the process is unknown. While the recycling of Optic Fiber cables can reduce their environmental impact, it is still a relatively new process and requires further development to become more energy-efficient.
Waste Impact of Optic Fiber cables
The environmental impact of Optic Fiber cables is significant, particularly in the manufacturing and installation stages. The energy required for these stages relies heavily on fossil fuels, contributing to greenhouse gas emissions and other environmental impacts. However, compared to previous cable solutions, Optic Fiber cables have a lower environmental impact during their use and require less maintenance and replacements due to their high durability and future-proofing, as they have an “estimated life span of 20 to 40 years” (Yaméogo et al.)
Conclusion
In conclusion, while optic fiber cables have become an essential infrastructure in modern telecommunications, they have a significant environmental impact. The energy required for their production, installation, and maintenance is immense, and the environmental implications of their life cycle are substantial. The raw materials required for their production involve energy-intensive processes, including open-pit fossil-fuel mining. The manufacturing process of optic fiber cables is also energy-intensive, including several specialized steps. The distribution and transportation of the cables make up most of the energy usage, using fossil fuels for trucks, ships, and airplanes. While optic fiber cables offer greater bandwidth, improved durability, and faster communication speeds, their environmental impact is an important consideration. As the world continues to demand faster and more reliable communication systems, it is essential to consider the energy sources and environmental impact of the infrastructure that supports them.
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