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:

1. Power stability – When the power supply coming into the data center is unstable (e.g., power surges and sags), stored energy can be used as needed to balance out disturbances and assure a clean power supply to the load.
2. Power bridging – When switching from one source of power to another (e.g., utility power to generator power), stored energy can be used (from seconds to hours) to assure consistent power.
3. Energy management – This is the cost-optimizing strategy of charging stored energy when energy cost is low, and using stored energy when energy cost is high.

Chemical batteries are pervasive in ICT, as they are in in our homes, cars, and e-devices, but non-chemical options are emerging. These are are positioned as 'greener' due to reduced use and disposal of toxins, lower CO2e footprint, and/or more energy efficient operation.

Ultracapacitors: Maxwell Technologies products are used in telecom infrastructure. We are not aware of any current use of ultracapacitors in a data center.

The APC white paper characterizes compressed air and superconducting magnetism as "technologies not economical or not mature enough to be practical". While true for data center use in 2010, I expect to see existing and new companies bring compressed air products to market for ICT in the next two years. Superconducting magnetism for ICT appears to be further out.

(This type of product should not be confused with products like Bloom Box fuel cells. The latter are energy generation devices, rather than energy storage devices; both can play a role in greener ICT power systems.)

UPS supplier Eaton's white paper "Emerging UPS Standby Power Sources - Four Promising Alternatives to the Lead Acid Battery" "explore[s] the strengths, weaknesses and future prospects of four…technologies: Flywheels, ultracapacitors, fuel cells and lithium ion batteries."

Pike Research reports, "Uninterruptible power supply (UPS) systems, which use a built-in energy storage source such as a battery, flywheel, or other device to supply clean and sufficient power during grid power outages, have demonstrated their value in preventing undesirable downtime, data loss, or even catastrophic failures…In particular, as green IT becomes an important goal for many IT vendors and users, UPS systems that can fit into and augment existing IT infrastructures to support the vendors’ overall green IT objectives will be in increasing demand…these trends, along with significant growth in emerging economies, will lead to strong growth for the UPS sector in the next few years. The global market for UPS systems will expand from $8.2 billion in 2011 to $9.4 billion in 2012, a year-on-year growth rate of 14%…Going forward, the market will grow to $13.2 billion by 2015."

California is working on energy storage requirements for utilities as an alternative to new generation for peak capacity. This might well result in spin-off technology for ICT facilities and infrastructure nodes. EcoSeed notes that "…storage devices such as compressed air, flywheels and fuel cells are all in the pilot stage. PG&E, for example, has launched a pilot project to store electricity in the form of compressed air."