Design Life-Cycle

Daniel Medina

Professor Cogdell

DES 40A

22 November 2021

The Embodied Energy of Hard Disk Drives

Since the development of the first external hard drive by IBM in 1956, a monstrous machine the size of two refrigerators, decades of innovation have significantly reduced the size of hard drives to just a few inches and turned them into one of the most ubiquitous forms of mass data storage globally. The rapid data access and lower power consumption of solid-state drives have increased their popularity as secondary storage systems in personal computers. Despite the appeal of solid-state drives, hard drives are still prominently used in large-scale applications such as businesses and remain favored due to their lower cost and superior storage capacity potential. Moreover, the steadily increasing digitalization throughout the world means that hard disk drives remain large contributors to energy consumption in almost all stages of their lifecycle. Despite efforts to improve their power efficiency, hard drives’ embodied energy consumption shows the massive energy costs that go into their manufacture, usage, and disposal.

Hard drives use a wide assortment of raw materials, of which a few are notably used in high levels and may be particularly difficult to acquire. Rare earth elements (REEs) are essential minerals used in various digital electronics. In hard drives, neodymium is used in neodymium-iron-boron (NdFeB) magnets that make up a part of the actuator assembly that reads and writes data on hard drive platters. Most minable deposits have been found in China’s Bayan Obo region, making China the world’s leading producer with 90% of the world’s supply of rare earth metals, with smaller sources located in Australia, India, Malaysia, Brazil, and the United States (Peiró and Mendéz 1327). The energy used for the mining and processing of rare earth metals depends on the location, the processes involved, and the type of ore. This discussion will focus on the mining process in Bayan Obo, the world’s largest source. According to Peiró and Mendéz, the extraction process can be divided into mining, beneficiation, and separation of rare earth. During mining, ore is blasted, crushed, and grinded into small particles. The beneficiation process helps purify the ore by removing gangue and the energy consumption during beneficiation on average consumes a minimum of 12.06 GJ/tonne of rare earth metal. The separation phase can separate the different rare earth elements, such as neodymium, and uses between 15.60 and 22.70 GJ/tonne of REM. Final steps involved in pure rare earth metal production includes metallothermic reduction and electrolysis which can consume between 38 and 48 GJ/tonne. The overall mining and reduction process is estimated to consume roughly 58.51 GJ/tonne (Peiró and Mendéz 1328-1338). Illegal mining accounts for 30% of rare earth metal mining, which leads to significant environmental impacts and unnecessary energy consumption (Jin et al. 2). Hard drives also require base metals like aluminum, iron, and copper, precious metals like gold and platinum, and non-metallic materials like glass-ceramic, silicon, and fiberglass. According to PC Plus, the disk platters, where information is magnetically stored, are largely made up of either aluminum or glass-ceramic and use several other metals in the data storage layers (PC Plus). The full process of bauxite mining and aluminum processing consumes about 279 GJ/tonne (Cushman-Roisin and Cremonini 1).  Glass ceramics use 10-11 GJ/tonne while the mining and separation of platinum can consume between 275,000 and 284,000 GJ/tonne (Cushman-Roisin and Cremonini 5-13). The printed circuit board (PCB) controls all hard drive operations and contains many components including prepreg, a type of fiberglass, and copper (“Printed Circuit Board (PCB) Materials”). Fiber glass is estimated to have an embodied energy between 107 and 118 GJ/tonne, epoxy between 127 and 140 GJ/tonne, and copper a total of 130.3 GJ/tonne after mining and refining (Cushman-Roisin and Cremonini 2-14). These are only some of the raw materials used, and these have major energy impacts in the production of hard disk drives. Following raw material acquisition and processing, it must next be transported.

After mining and processing, materials are transported to different manufacturing facilities by plane, ship, or trucks across global supply chains. Transportation can take place several times over the lifecycle of a hard drive: from raw materials to manufacture, manufacture to retail, retail to consumer use, and then to disposal. In the case of Seagate hard drives, for example, neodymium is first transported from China to Japan where neodymium magnets are made, then to Malaysia where the magnet assembly or actuator assembly is produced, and then to Thailand where the full hard drive is manufactured (Jin et al. 5). This sequence of events doesn’t include the actuator arm and read/write heads which also go into the assembly. Each component and subcomponent is usually produced in a different country. For example, Western Digital operates manufacturing facilities in the United States, Japan, China, Malaysia, and Thailand, but these locations do not account for all manufacturing and material processing (“Western Digital ESG Data Download”). The extensive international transportation that is required relies on ships and planes, primary energy consumers which consume massive amounts of fuel. The hard disk drive supply chain on its own exemplifies the main energy inputs that go into overseas transportation during the lifecycle of a hard drive. After transportation, raw materials and other subcomponents are used in specialized manufacturing facilities for the generation of specific hard drive parts.

A significant portion of the embodied energy of a hard drive is derived from the manufacturing of the hard drive and takes place in various facilities across the globe. According to Western Digital’s Environmental, Social, and Governance Report, during the 2020 fiscal year the total electricity consumption of every development and manufacturing facility was around 6716 trillion joules, with only about 522.4 trillion joules coming from renewable sources (“Western Digital ESG Data Download”). This value accounts for the manufacturing of all products made by Western Digital, not just hard drives. According to both PC Plus and Lamelot, the most notable manufacturing processes for a hard drive are the production of the magnetic disk platters and the read/write heads because of their complexity (PC Plus 1; Lamelot 1). According to PC Plus, the disk platter manufacture process starts with the addition of magnetic recording layers onto aluminum alloy disks. Ingots are rolled into thin sheets from which the disks are punched out and subsequently “precision-ground” and given a hard coating made up of a nickel and phosphorus alloy. Disks are polished with silicon carbide, diamond, and aluminum oxide and then cleaned with acidic and alkaline solutions and washed with soapy solutions and deionized water. Several magnetic layers with unique properties are then deposited on the disks through magnetron sputtering, the first of which is a soft underlayer usually of a cobalt, nickel, and iron alloy. The next few layers are for data storage and made of a cobalt, chromium, platinum alloy. The last layers are a diamond-like carbon layer to give protection against corrosion and a lubricant layer (PC Plus 1-3). The complete process involves many complex deposition processes which frequently varies between different manufacturers. The manufacture of hard drive disk platters therefore uses many other elements beyond aluminum or glass-ceramic, and each of these requires another energy-consuming process for incorporation into the disk platters. The process of manufacturing the read/write heads is highly complex and comparable to the manufacture of silicon chips or semiconductors. According to Lamelot, the production of these heads begins with wafers made of slices of a “high-performance ceramic called aluminum titanium carbide (AlTiC)” instead of silicon. Manufacturing occurs in a class 100 cleanroom and begins with photolithography and etching to imprint different patterns. Between 30 and 40, magnetic and protective layers are added by deposition and reaches a thickness of less than two Ångströms, roughly the diameter of an atom. Platinum, cobalt, nickel, iron, platinum, and magnesium can be used during this process. Though these components are small, the machinery used to apply these materials in each microscopic layer uses significant energy. Moreover, the cleanrooms are estimated to use around 0.22 kWh (Frost et al. 5). Unfortunately, research is very limited on the manufacturing processes of specific hard drive components and information about their individual energy consumption is not readily available. After manufacturing, hard disk drives are transported to warehouses and then distributed to retailers or companies.

As a common part of personal computers, hard drives require power to perform their read and write functions on magnetic data and spin their disk platters at extremely high speeds. HDD manufacturers have focused their efforts on improving the energy efficiency of hard drives for the daily use of average consumers. The power consumption varies greatly between manufacturers and hard drive models. According to Hylick et al., power to hard drives is typically received via a 12-Volt supply line that powers the spindle motor to spin the disk platters and a 5-Volt supply line that powers the read/write heads along with other smaller parts. Hard drives have four power states: active, idle, standby (spin-down), and sleep.   During standby mode, all mechanical parts of the hard drive stop moving including the disk platters, so most energy consumption comes from the electronic components. In tests run by Hylick et al., the Seagate ST380215A (80GB) hard drive electronics were measured to consume about 7J/min while in standby mode, whereas the mechanical parts consumed less than 1J/min. The Western Digital WD500AACS-00ZUB0 (500GB) hard drive’s electronics consumed about 12 J/min while its mechanical parts also consumed less than 1J/min in standby mode. During idle mode, several mechanical parts inside the hard drive including the disk platters are moving but not performing any read/write actions. In this mode, the electronics from the Seagate drive consumed around 108 J/min and its mechanical components used about 160 J/min while the Western Digital drive’s electronics consumed about 108 J/min and its mechanical components consumed around 140 J/min. Energy consumption during read actions depends on the location being read on the disk platter, with reads closer to the center consuming more energy, up to 110J. Write actions consumed about the same amount of energy (~50J) regardless of location on the disk platter (Hylick et al. 3-7). Power consumption of hard drive use by average consumers depends on daily computer usage, manufacturer, model and make of the hard drive. Either way, there is certain room for improvement in energy efficiency when a hard drive is in idle or standby mode. Hard drives reach their “end-of-life” after several years, when they either no longer function properly or are preventatively replaced, and can be disposed in various ways.

The disposal or recycling of hard disk drives has improved over the years and is an area of focus for rare earth element recovery and carbon emission reduction, with varying impacts on energy costs. Currently, most hard disk drives and most other electronics are improperly disposed of in landfills or exported to developing countries (Sabbaghi et al. 560). Problems that interfere with recycling processes include “insufficient recovery infrastructure, low level of consumers’ participation, and lack of environmental regulations” (Sabbaghi et al. 560). Even though hard drives heavily require rare earth elements, particularly neodymium, their recovery rates through recycling are estimated to be lower than 1% (München and Veit 373). In light of rare earth ore shortages leading to economic and political crises and extraction processes causing detrimental environmental impacts, recycled hard drives may be one of the best sources of neodymium (München and Veit 373). According to Jin et al., there are five primary hard drive recycling methods. The first option, currently the most popular but providing little reuse potential, is hard drive shredding and aluminum recovery which involves data wiping, using about 0.17 kWh per hard drive, followed by shredding and dust collection which consumes about 0.01 kWh per hard drive. The second option is to wipe the data and reuse the hard drive entirely for a second, albeit shorter, lifespan before being shredded. Reusing hard drives extends their lifetime by about 10% (~6 months) and eliminates 10% of the need to make new hard drives and shred them. A third option involves reuse of the hard drive’s neodymium magnet assembly, which requires a cleanroom and robotic removal of the hard drive’s top cover, extraction of the magnet assembly, and transport to a manufacturing facility for reuse (Jin et al. 3-4). The total energy consumption of this process is estimated to be around 0.287 kWh (Frost et al. 5).  According to Jin et al., the fourth option for recycling is magnet-to-magnet recycling in which the neodymium magnet is recovered, cleaned, and then put through powder metallurgical processing. The benefit of magnet-to-magnet recycling to produce new magnets is the elimination of the massive energy costs associated with melting metals and rapidly cooling into alloys since the recycled material is already alloyed. The fifth method of hard drive recycling involves different hydrometallurgical, pyrometallurgical, and electrochemical processes to recover different base, precious, or rare earth metals. Unfortunately, these recycling methods are associated with significant environmental waste production and often large energy costs (Jin et al. 4-6). Hard drive disposal can vary from direct landfill disposal to various increasingly popular e-waste recycling processes, each with their own energy benefits and tradeoffs.

Since the invention of the hard disk drive, hard drive function and efficiency has greatly increased. Unfortunately, analysis of the hard drive lifecycle from raw materials to its end of life and disposal reveals that hard drives consume vast quantities energy even beyond their time in computers. While it is unlikely that we will see the dominance of hard drives in mass data storage wane in the near future or their manufacturing cease entirely, solid state drives have begun to present themselves as costly yet faster and less energy-intensive alternatives. For now, it is important to recognize the energy-related costs that come with producing hard drives at every stage of the lifecycle, so that we can be more cognizant of their environmental impacts the next time we are using a computer.

Bibliography

Cushman-Roisin, Benoit, and Bruna Tanaka Cremonini. “Chapter 1 - Materials.” Data, Statistics, and Useful Numbers for Environmental Sustainability, edited by Benoit Cushman-Roisin and Bruna Tanaka Cremonini, Elsevier, 2021, pp. 1–16. ScienceDirect, https://doi.org/10.1016/B978-0-12-822958-3.00012-1.

Frost, Kali, et al. “Environmental Impacts of a Circular Recovery Process for Hard Disk Drive Rare Earth Magnets.” Resources, Conservation and Recycling, vol. 173, Oct. 2021, p. 105694. ScienceDirect, https://doi.org/10.1016/j.resconrec.2021.105694.

Hylick, Anthony, et al. “An Analysis of Hard Drive Energy Consumption.” 2008 IEEE International Symposium on Modeling, Analysis and Simulation of Computers and Telecommunication Systems, 2008, pp. 1–10. IEEE Xplore, https://doi.org/10.1109/MASCOT.2008.4770567.

Jin, Hongyue, et al. “Life Cycle Assessment of Emerging Technologies on Value Recovery from Hard Disk Drives.” Resources, Conservation and Recycling, vol. 157, June 2020, p. 104781. ScienceDirect, https://doi.org/10.1016/j.resconrec.2020.104781.

Lamelot, Matthieu. “Where Do Hard Drive Heads Come From?” Tom’s Hardware, 20 Nov. 2008, https://www.tomshardware.com/picturestory/476-seagate-hard-drive.html.

München, Daniel Dotto, and Hugo Marcelo Veit. “Neodymium as the Main Feature of Permanent Magnets from Hard Disk Drives (HDDs).” Waste Management, vol. 61, Mar. 2017, pp. 372–76. ScienceDirect, https://doi.org/10.1016/j.wasman.2017.01.032.

PC Plus. “How the Humble Hard Drive Is Made.” TechRadar, 31 Jan. 2010, https://www.techradar.com/news/computing-components/storage/how-the-humble-hard-drive-is-made-667183.

“Printed Circuit Board (PCB) Materials.” Printed Circuits LLC, https://www.printedcircuits.com/printed-circuits-materials/. Accessed 25 Nov. 2021.

Sabbaghi, Mostafa, et al. “The Global Flow of Hard Disk Drives: Quantifying the Concept of Value Leakage in E-Waste Recovery Systems.” Journal of Industrial Ecology, vol. 23, no. 3, 2019, pp. 560–73. Wiley Online Library, https://doi.org/10.1111/jiec.12765.

Talens Peiró, Laura, and Gara Villalba Méndez. “Material and Energy Requirement for Rare Earth Production.” JOM, vol. 65, no. 10, Oct. 2013, pp. 1327–40. Springer Link, https://doi.org/10.1007/s11837-013-0719-8.

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Ulane Eng

DES 40A

Professor Cogdell

26 November 2021

Wastes and Emissions of Hard Drives

Hard drives are one of modern society’s most important digital devices, allowing us the capability to provide storage for terabytes of computer data in a small and portable machine. With such high level technology, many may consider what harms and wastes comes out of creating a hard drive. Hard drives, like most products, go through the life cycle process of acquisition of raw materials, manufacturing/processing/formulation, distribution/transportation, use/re-use/maintenance, recycling, and waste management. Each of these phases follow with wastes and emissions that vary depending on the product. Throughout the life cycle of a hard drive, the majority of wastes and emissions produced as well as the amount of impact they have on the environment comes from the acquisition of its raw materials, distribution and transportation, and the usage of the device.

Beginning with the acquisition of raw materials, mining and extracting for the rare earth elements used in hard drives produces a considerable amount of radioactive wastes, toxins, acids, and greenhouse emissions. Hard drives are made of elements such as neodymium, dysprosium, aluminum, magnesium, silicon, zinc, copper, nickel, and phosphorus to name a few. The process of extraction of rare earth elements commonly requires them to be separated from radioactive elements, uranium and thorium, which produces radioactive wastes. These radioactive wastes pose a dangerous amount of harm to not only the humans that mine for them but also the environment, especially if they are handled poorly. Mining also generates cyanide and other toxic metals that pollutes surrounding waters that is eventually brought to the lakes and oceans, contaminating drinking water and harming sea life. Acquiring raw materials also produces greenhouse gases such as carbon dioxide, or CO2. For example, Seagate’s Momentus HDD (Hard Drive Disk) generates a total of 7.34 kg of carbon dioxide equivalent emissions (CO2e) per product. Acquiring raw materials and pre-processing contributes the most to the total compared to the other life cycle stages － standing at 42% of the Momentus HDD’s total climate change contribution. 

Along with the acquisition of raw materials being a main contributor to the wastes and emissions of a hard drive, the manufacturing, processing, and formulation of hard drives also involves carbon dioxide emissions. In the packaging summary of Seagate’s Backup Plus hard drive, the material production and assembly of it make up 37% of the hard drive’s total average greenhouse gas emissions, which is 2.92 kg CO2e per packaging product. Although I could not find specific information on what other wastes come out of the manufacturing process of hard drives, I would assume that scrap metals, plastics, and overproduction of hard drives leading to wastes can be added to the list of wastes during this life cycle process.

Following the manufacturing process, the distribution and transportation of hard drives also produces CO2 emissions that are a close comparison to having the most impact on climate change compared to the other life cycle phases. For Seagate’s Backup Plus hard drive, the transportation and end user life of the hard drive stands at the top of having the most CO2e impact on climate change, being 58% of the average total emissions (2.92 kg CO2e per packaging product) produced through its life cycle. From the data collected on Seagate’s packaging of hard drives, the production and use of fuel from air transportation is 57%, contributing the most to the total greenhouse gas emissions between the rest of the life cycle stages. These other stages include: external carton at 12%, ESD bag at 10%, internal product protection at 9%, scored pad at 3%, and others at 9% of contributions to the packaging’s impact on climate change. In general, the manufacturing process of acquiring materials and processing them are one of the life cycles that produce the most pollution that affects the environment along with the other main phases in the life cycle.

Although hard drives are usually long-lasting, user use and re-use/maintenance also produces CO2, eWaste, otherwise known as electronic waste, and other toxins that impact the environment. Going back to Seagate’s Momentus HDD, the use stage of its life cycle is an estimated 12% of its total CO2 emissions (7.34 kg CO2e per product). For Western Digital’s WD Blue HDD, its use phase contributes a whopping 62% to its life cycle’s total carbon footprint impact on climate change. This effect is due to the amount of energy consumed by the product during its useful life. Hard drives can also be re-used and maintained by wiping out the stored data from them to store new information, but this does not always happen, as whatever is not reused or recycled is thrown into the trash, becoming eWaste. Various pieces of the hard drives are then burned and melted down for scraps, causing toxins to be released into the air, land, and waters, damaging the environment. 

However, as the concern towards eWaste’s impact on the environment increases, efforts to recycle and reduce waste of hard drives are being made among manufacturing companies like Western Digital and Seagate. From an article by Wired titled “Can You Recycle a Hard Drive? Google Is Trying to Find Out”, “Typically, when a data center operator swaps out old drives for new ones—as they do every three to five years—the discarded drives are unceremoniously shredded” (Stone). After shredding and crushing hard drives, materials can be separated out, such as light metals from aluminum, magnets, and circuit boards. Other materials include steel, copper, plastic, electronic connectors, glass, and ceramics. Hard drives also contain magnetic dust made out of various elements, with some main components including aluminum, barium, calcium, iron, magnesium, manganese, nickel, and zinc. Dell also launched a program with Seagate and Recontext in 2019 that harvested magnets from computer hard drives by crushing them, extracting their rare earth metals, and making new magnets out of them. “To date, some 19,000 pounds of rare-earth magnets have been harvested for recycling via this collaboration” (Stone). Hard drives can also be reused multiple times by wiping the information in them out or transferring them into a different computer data storage system. 

As for how the waste from hard drives is managed overall, they either end up in landfills as eWaste or properly recycled with some materials recovered for reuse. Hard drives that are not reused or recycled are dumped in the trash and shipped to dump sites in places like Ghana. Local people may look through the area for extractable raw materials and valuable parts. According to a study done in Economic Assessment for Recycling Critical Metals from Hard Disk Drives Using a Comprehensive Recovery Process, rare earth metals: steel and a rare earth oxide mixture (REO) of praseodymium, neodymium, and dysprosium were able to be recovered from hard drives. Other materials that are able to be recovered were copper scraps, silver, gold, and palladium elements. Methods for physically destroying hard drives include crushing it, hitting it with a sledgehammer, burning, and drilling holes into it. To ensure that the data inside is completely destroyed, hard drives can be given to professional hard drive disposal sites where they use a series of destruction methods to annihilate it. There are also many places available that encourage people that want to destroy their hard drives to recycle their eWaste and hard drive parts by giving the wastes to them. 

Overall, essentially, every phase of the life cycle of a hard drive produces waste and emissions involving greenhouse gases, mainly being carbon dioxide. The main contributions to the wastes and pollution in the life cycle of hard drives come from its acquisition of raw materials and manufacturing, transportation of materials, and use until its end of use. Although which phases impact the most vary for different types of hard drives and their manufacturers, in general, the transportation, gain, and use of the materials and products are generally what affect the environment the most due to its wastes and pollution from greenhouse gas emissions. These overall affect many aspects of climate change, with some major ones being due to freshwater pollution, marine ecosystem toxicity, and human toxicity.

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