Global trends, performance metrics, and energy reduction measures in datacom facilities

Over the last decade, the demand for data center and network services has increased dramatically. To meet this demand, global average rack power density has risen from 2.4 kW/rack in 2011 to 8.4 kW/rack in 2020 with the aid of technological advancements. About 36% of global data centers have racks above 30 kW/rack. Average Power Usage Effectiveness (PUE) dropped from 2.5 in 2007 to 1.65 in 2013, but has been almost flat since then, at 1.59 in 2020. The depletion of finite fossil fuel reservoirs, adverse impact of greenhouse gas emissions on global warming, recyclability of electronic waste, and the rising cost of energy are pushing the datacom industry toward more energy-efficient and sustainable technologies including renewable energy, highly efficient elec-tronics cooling, waste heat recovery, passive cooling systems, and energy storage, which are broadly reviewed in this paper. Use of renewable energy resources through power purchase agreements rose by 346% from 2.4 GW in 2017 to 10.7 GW in 2020. Air-side economizers can reduce PUE by 30-50% and water-side economizers by 10-30%. The server/rack outlet is an ideal spot for waste heat recovery and can be coupled with a multi-stage heat pump to save significant energy if coupled to a district heating system. Active and passive deployment of thermal energy storage can save more than 20% of cooling energy and reduce temperature fluctuations by more than 60%. Edge computing, decentralization, and virtualization can lead to lower latency, higher scalability, and reliability during failure.