Most ICT gear - core facilities, communications infrastructures, and edge devices - runs on DC power. Converting AC to DC within a building is inefficient, on-site renewable power generation is usually DC to begin with, and super-efficient LED lighting is also DC. So DC power distribution has been a attractive option, but there have been vigorous arguments for and against. Recent events suggest the tide is turning in favor of DC distribution, although skeptics continue to press their case. The growing use of solar-generated electricity might be providing the latest boost DC.

Image courtesy IEEE Spectrum

Most Green ICT focuses on hardware. That make sense, because hardware lifecycles encompass everything from environmentally responsible sourcing of its raw materials through energy efficiency of its use to sustainable disposal at its end-of-life. Special utility software such as desktop power-saving plays a central role in Green ICT, but less attention has been given to the application and system software in the gear, itself. Now, projects are looking at how to create more sustainable software.

There is a rich global mix of advanced concepts and technologies emerging from research labs that may improve the future sustainability of ICT equipment and infrastructures. We'll regularly update this post with technologies to watch. (You can see all the technologies which hold the promise of greener ICT in the future by clicking the 'FutureTech' tag, above.) Our latest are two from IBM: the possibility of a liquid transistor and the the demonstration of a very high speed optical communications link.

Wearable tech is of interest to Green ICT because it can drive miniaturization and energy efficient. Miniaturization can reduce resource consumption in the creation of ICT gear and reduce e-waste in its disposal. Miniaturization combined with energy-efficiency can enable a host of applications ranging from "smart building" sensors to compact assistive technology. Is more wearable tech all positive? We look at a number of technologies, including one developed in Kenya which allows shoes to charge mobile phones.

What is a battery? A device to store energy and convert it to electricity on demand? This is an important question as ICT facilities and infrastructure elements increasingly rely on sophisticated battery-based systems such as UPS. Potentially greener alternatives are emerging to chemical batteries, with flywheels appearing to have the most momentum for ITC facilities going into 2013.

Let's start by reviewing the role energy storage devices play in ICT. A 2011 APC white paper lists three applications:

Supercomputers manufacturers have always vied to build the most powerful machine. Now, they routinely increase energy efficiency, as well. Recent additions to this ongoing article include the Titan supercomputer and the Supercomputing in Small Spaces project.

Liquid cooling was once a staple of large-scale computing, but has largely been replaced by air cooling. We identified several efforts to bring liquid cooling to the server world in our first version of this post a year and a half ago. Here is an update featuring a UK company.

Microsoft has announced plans to spend $5.5 million to build a zero-carbon data center pilot project in Wyoming. A source of very low carbon electricity is key to such projects. Microsoft's power generation fuel? Municipal sewage!

Companies and individuals are advancing innovative ideas for more sustainable. These range from products we can buy today to futuristic concepts for tomorrow. Our most recent addition to this post a pc with a cardboard case.

We've covered the issue of 'vampire devices": excessive standby power consumption in consumer electronics and other ICT components. As integrated circuits become more power-efficient during operation, their standby power consumption becomes an issue, too. A research group at Japan's Center for Spintronics Integrated Systems and Research Institute of Electrical Communication of Tohoku University together with NEC Corporation (NEC) has developed a standby-power-free large-scale integrated circuit (LSI).