Table 4.

Current applications and initiatives

Application/initiative	Description
ITRENEW [16]	ITRENEW is based in Silicon Valley and has been optimizing the lifetime benefit of data center technologies for more than two decades through creative circular economic models and a robust range of resources for decommissioning and network protection, computing and storage solutions on a rack scale. They have collaborated with some of the largest hyper scale data centers in the world. They have also built a new circular data center model to open up ways to increase the efficiency of the infrastructure and boost sustainability. By seeing the true promise of the data center equipment lifecycle, from network architecture to the remanufacture of complete systems after decommissioning
Amazon [17]	Amazon’s commitment to fighting climate change, with the goal of reducing carbon emissions to be carbon–neutral by 2040. The companies’ plan is to be run solely on renewables by 2030. Amazon currently gets 40% of its energy from renewables, such as solar and wind farms. “Our research shows that delivering a typical order to an Amazon customer is more environmentally friendly than that customer driving to a store,” an Amazon sustainability representative had written
Google data centers [18][19]	The strategic collaboration between Google and the Ellen MacArthur Foundation assists Google in expanding on current strategies and integrating circular economic concepts into the architecture of Google’s technology, operations, and community. Maintenance, renovation/remanufacturing, redistribution/secondary sector selling, and recycling. These activities combined with Google’s circular approach to managing server end-of-life based on the concept of total cost of ownership (TCO) culminated in expense avoidance of hundreds of millions of dollars per annum •Google is the product manufacturer in Google’s server supply chain. Google performs an excess and obsolescence (E&O) project that analyses the life cycle of products and their overall ownership costs compared to new equipment and compares demand and supply to assess E&O rates •Google’s data center maintenance process helps the servers to have a longer life expectancy. When servers malfunction and collapse into maintenance, the faulty parts are replaced with refurbished components •When data center servers are decommissioned, they are transferred to the main repository. At the core servers, their functional components (central processing unit (CPU), motherboard, flash drives, hard disks, ram modules and other parts) are removed and de-kitted. Once all components are in Google’s inventory, both refurbished and new equipment are considered equivalent •Memory modules, hard drives, and original equipment manufacturer (OEM) networking equipment are examples off access equipment; therefore, they are sold in the secondary market •Finally, all equipment that cannot be resold or reused is recycled. This is done by crushing the equipment and is then converted into reusable materials
Facebook [20]	Facebook’s data centers are among the world’s most modern and energy efficient facilities. Electricity supply has been replaced by clean and renewable sources. Their sustainable hardware design approach is done by looking at the entire life cycle (raw material extraction → manufacturing → transport → use → end of use → reuse or recycling) with the goal of reducing fossil fuel inputs and emissions. Natural fiber-filled polypropylene (NFFPP) is being used as replacement for many of their materials, thereby reducing the carbon footprint
Microsoft [21]	Microsoft’s Carbon Negative Pledge — not only to become carbon free by 2030 but also to offset its past carbon emissions by 2050. One solution is to use 100% renewables by 2025, as well as to work with supply chains and partners to reduce carbon emissions
European Union (EU) Circular Economy Action Plan [22]	Makes Europe less dependent on primary materials. A “Circular Electronics Initiative” to encourage longer life cycles on a variety of equipment for the data center. Acts include server and storage regulatory initiatives under the eco-design mandate to ensure systems are designed for energy consumption and reliability, reparability, upgradability, repair, reuse, and recycling
Infrastructure masons (IM) [23]	Infrastructure Masons’ Sustainability Committee have come up with several approaches on how data center designers and managers can reduce the industry’s detrimental impact •Using “waste” heat in district heating systems, comfort heating, heating swimming pools, spas, greenhouses, or industrial processes •Power sharing is being integrated into the power grid to provide back-up power to the community when it is not needed by the data center •Turning waste such as biofuel into power •The use of other materials to construct data centers; one example is wood •Managing equipment life cycles; this is done using LCA, LCIA, and LCC
Circular Economy for the Data Center Industry (CEDaCI) [24]	The data center industry has evolved fast and creates a significant amount of e-waste. The present infrastructure for dealing with this waste is inadequate, and as a result, there is a clear and pressing need to solve this issue right away. CEDaCI will create a Circular Economy for the Data Center Industry by bringing stakeholders from all stages of the equipment life cycle together to transform waste into a usable resource and support the industry’s continuous fast expansion. CEDaCI will create a Circular Economy for the Data Center Industry by increasing the sector’s reclamation and reuse of critical raw materials, extending product life through equipment reuse and remanufacture, reducing the use of virgin materials, waste, and environmental impact caused by the increase in redundant equipment, and developing a secure and economically viable supply chain. At the moment, only 10% from the sector is recycled and recovered, but this will climb to 19% and 24% 5 and 10 years after the project finishes; reuse of equipment will also increase to 65% and 75%, respectively, and overall product “waste” will be reduced to 35% and 25% at end-of-life
EcoDataCenter [25]	Situated in Falun, North of Stockholm, which is made up of 8 MW 3600 m2 extension framework going up in a beautifully engineered “wood.” It is a product called “Glulam,” an engineered timber created by cross-laminating and gluing, under high pressure. Better fire resistance capability than steel frames due to the surface build-up of carbon limits the oxygen supply to the wood below and acts as an insulator. Glulam also has a much lower embodied energy than reinforced concrete or steel. And importantly a reduction in the carbon footprint
InfraPrime	A pure play start-up provides affordable 24 × 7 clean energy infrastructure for global data centers to align with the United Nations Sustainable Development Goals and enact Climate Action Plan. Arctic Prime data centers are located at the Arctic Circle, deliver net zero in carbon, emission, waste; each data center is resilient using the power duality architecture to utilize hydroelectric renewable energy grid supply, outside air cooling, waste heat reused for district heating to the Nordic communities, applications including green house for agriculture, and fish farming for salmons. EcoPrime Power Clean Energy module is a Carbon Free Energy (CFE) module which generates 24 × 7 carbon free energy on premise at any data center location. Its resilient design provides 99.999% uptime with a performance guaranteed to the data centers, uses renewable gas, fuel cells as the primary energy source using the fossil fuel grid as a backup without the need of a conventional diesel generator. The design has been selected by the European Union “Fuel Cell for prime power in data centers” ID-FCH-02–9-202 and is in operation at Microsoft Research Lab, Seattle, Washington achieving 99.999% uptime when the electric grid has a downtime failure
Santa Clara [26]	Silicon Valley is one of the largest data center markets in the US. Santa Clara has been the data center capital of Silicon Valley. The main reason for this location is due to the lower power pricing. Santa Clara boasts a number of well-known data centers. With this comes sustainable and efficiency requirements for the data centers The California Environmental Quality Act (CEQA) mandates that city and state officials weigh a project’s possible environmental impacts before determining if they approve it. The aim of the CEQA is to expose the possible impacts of a project, recommend strategies for mitigating such impacts and explore alternatives to the project so that decision-makers have complete knowledge on which to base the project One company, Vantage Data centers, had recently constructed another data center, designed to meet sustainability requirements. They have used new cooling systems which use less water than normal. This is done by using recycled water and modular chillers and dry-cooler technology
UNICA data centers	Use of access or wasted heat to heat 2 million households by 2030. As well as the use of LCC in their data center designs
Cloud data centers (CDC) [27]	Cloud computing has gained popularity in recent times. These facilities are hosted by CDCs. There is research being done for sustainable CDCs and reductions in emissions. Solutions such as renewable energy, reductions in heat waste, and modular data centers are used
CERN openlab2 and used by CERN [28]	Growing power prices and aging data centers are forcing many companies to rethink their computing infrastructure’s energy efficiency. CERN has been grappling with this problem for many years, due to its huge processing demands and 35-year-old data center, and is taking a holistic path to achieving the best possible output per watt. CERN has replaced older servers with single-core processors with newer servers built on the newest 45 nm Intel Xeon processors, which have four cores per chip. This approach, according to the company, has added almost 2 years to the life of its data center, and potential multi-core Intel processors could extend it by another 6 months. CERN’s tendering process, data center architecture, power and cooling methods, and software development techniques have also been changed. Both of these modifications are aimed at improving overall efficiency while using less total resources