Power to the Internet

The high commercial demand and mission-critical applications of the Internet has also spawned an extraordinary level of dependence. As a direct result, downtime, for whatever reason, is simply not tolerated, either by Internet service providers (ISPs) or their customers.

Protecting the Internet
With large numbers of ISPs competing for a limited number of sites within easy reach of the optical fibre routes, suitable locations are at an absolute premium.

To accommodate the ISPs' demand, third party developers have established colocation sites (or server farms) in each of the UK's four key fibre location centres.

A colocation site is a purpose-built facility that offers a highly secure environment in which to house ISP servers. The companies which own these sites (colocation companies) rent space to various customers and typically operate as facilities providers. More recently, the telecoms companies have expanded their services to provide complete colocation turnkey project management solutions.

In Frankfurt, for example, the demand for suitable premises is so high that four independent colocation companies currently lease and share space within the same secure building.

Under pressure
With such high concentrations of colocation sites in London's West End, Docklands, Park Royal and Heathrow regions, there has been an incredible surge in the localised demand for electricity.

Each colocation site, serving multiple customers, typically draws around 20 MVA of power, 24 hours per day, seven days per week. With power generation facilities operating at virtually full capacity before the most recent wave of ISPs opened for business in the UK, the situation is fast becoming critical.

Richard Phillips of E-Commerce reports that recent events in California, involving these same issues, are sounding an ominous warning for UK authorities and businesses. "Exploding demand for electricity from Internet hotels and users has pushed parts of the supply grid close to meltdown…[and] officials have had to declare a Stage Two Emergency, which is one step away from a complete blackout," he warns.

Few would disagree that the UK's 'e-revolution' is still in its early stages and many industry experts forecast that the current ISP growth cycle will continue for another three to five years.

The London Electricity Board (LEB) conservatively estimates that the demand for power will rise by 20% in the next four years, mainly as a result of the growing telecommunications and ISP markets.

With such high demand for power in such a small concentration of geographic regions, the quality of supply will inevitably start to deteriorate. And with the time required to establish a colocation site being far shorter than that needed to develop and implement alternative energy sources, the problem can only worsen.

Many ISPs have already considered generating their own power using gas turbine or combined heat and power processes.

To exacerbate the pressure on the utilities, ISPs' power requirements are of a non-linear nature, causing problems with old substations.

Guaranteeing power
Due to the critical nature of on-line business operations, companies demand constant Internet availability. To maintain this high level of systems integrity, all ISPs have incorporated uninterruptible power supply (ups) systems as standard.

A ups system serves two main functions: first, it provides constant and clean power; and second, it ensures power back-up in the event of mains failure.

It is estimated that around 90% of colocation centres have opted for static ups systems. These offer far greater flexibility than their more generic, rotary counterparts, as they can be installed in the most appropriate position in the building. They do not require special reinforced flooring or exhaust gas emission planning and control.

Generally they are 40% more competitive than rotary units, they offer better value for money, and they have a considerably smaller footprint. The units' batteries can also be located separately (eg in the basement) allowing more floor space for server rooms.

It is a battery bank that holds the mains stored energy for every ups system, and provides back-up power of between 10 and 30 minutes (depending on the system requirements). The battery bank is connected via a circuit-breaker to the dc link and is always available in the event of poor mains or failure. Within ISP applications, it is common to use multiple strings of batteries with ten-year design lives, to BS 6290 Part 4, providing optimum reliability and long-life.

Given the reliability issues, colocation centres invariably opt for dual-feed power configurations for servers with ups supply and static transfer switches. Because of the high systems integrity demanded by ISPs, the colocation sites are not only using parallel redundant systems but also 100% redundant ups configurations, ensuring zero downtime.

Power consumption
As a general 'rule-of-thumb', the ups systems installed at colocation sites are sized on 1200 W/m2 of power consumption of server room footprint. With this guide, the average site drawing 20 MVA would consume approximately 16 MW.

As well as considering the power requirements of the servers, it is necessary to evaluate the power requirements of all support systems such as the air conditioning and lighting. As colocation facilities become larger, more hardware is installed and, as a consequence, more heat is generated. The flow-on effect is that more air conditioning is required to control the ambient temperature, therefore more power is consumed.

In Amsterdam, for example, another strategic site for colocation facilities and ISPs, authorities have tried to manage the problem by allocating an energy budget to new ISPs due to limitations on utility capacity to support excessive demand.

Given the sensitivity of the server equipment, power quality is as equally important as continuity. ISP equipment requires a clean, uniform power supply, free from any surges or spikes in the feed supply.

The harmonic filter, integral to the design of most modern ups units, reduces the reinjected harmonics down to 5%.

With the inherent non-linear loading of colocation sites, there is no standard solution, and consultants must carefully consider application of active harmonic conditioners, over-sized neutrals and isolation transformers. It is also important to not overlook elementary matters such as the 'skin effect', due to high harmonic frequency currents flowing in the cables and busbars.

An industry overview
As colocation sites boom, so too does the demand for associated technologies. This has become particularly apparent within the ups sector.

Most ups suppliers are now operating at near 100% of their production capacity, as a result, the demand for basic ups components is soaring. The lead times for many of these raw materials, such as drawn copper, batteries, microchips and semi-conductors, are increasing. At the same time, ISP and colocation delivery schedules are being compressed due to commercial reasons.

This incongruent relationship between demand and supply is also drastically affecting the construction of colocation sites at the primary and secondary fibre access points. This situation means that meticulous planning is necessary from the outset of a site's design, otherwise colocation operators may have an empty building on their hands, with no way of protecting their potential customers.

To facilitate the delivery of reliable, 24 hour, seven days a week Internet services, ISPs are turning to colocation sites to house and protect their business-critical servers.

Due to the massive power demands of these sites (often in excess of 20 MVA), environmental controls and power protection are critical considerations. To ensure continuous power protection, the much maligned and often overlooked ups is playing an integral role in supporting the new Internet economy.

Providing power protection at 100% redundancy, ups systems ensure that all electrical equipment, including ISP servers, continues to operate. Coupled with providing constant power protection, active harmonic conditioning ensures that power distortions are virtually eliminated, thus providing mission-critical hardware with harmonic-free, clean power supply.