As heavy power users, IT departments have a key part to play in reducing greenhouse gas emissions. And apart from the environmental impact, they need to make sure they don't exhaust their capacity. A recent Gartner report notes that 50 percent of data centres will have insufficient power and cooling capacity by 2008.

IT companies need to tread carefully if they want to compete in the new carbon economy.

Virtualize and centralize

Most IT departments still use independent servers for discrete systems. That means lots of hardware sitting at low utilization. As a result, scaling is expensive and power use is inefficient.

Meanwhile, virtualization technology has matured and lets you squeeze more value out of the same hardware.

The same applies to storage. Consolidate with a robust SAN device rather than less reliable and less efficient local drives.

Look at your processors

High-performance processors can take a lot of power to run. Then budgets are hit a second time by the extra cost of cooling them.

To mitigate the impact of high-density computing, look at phasing in the new low-power, low-heat chips made by AMD and Sun.

Servers powered by AMD Opterons use significantly less power and Intel is now offering low-power variants of its Xeon Chips.

Use what you need ...

While excess capacity used to induce feelings of misty-eyed bliss in IT managers, many have realized that it's better to use what they need, and no more.

Dropping a NIC's connection speed from 1000Mbps to 10Mbps can lower the device's power consumption from 4W to .60W Scale that across an organization and the savings add up.

Overbuilding cooling capacity is no longer critical because modern units are modular, and in-rack cooling is mature.

Careful planning of hot aisles, cold aisles and air return mechanism can save power, and delay that expensive upgrade to a larger air conditioner.

... and recycle what you don't

As hardware lifecycles grow shorter and shorter, it's more important than ever to recycle old systems responsibly.

Some recyclers distribute old machines through a social structure. Others recycle individual components into their base elements to limit the environmental impact of their manufacture.

Whichever recycling method you choose, be sure to explore data-destruction software like KillDisk or DiskDeleter.

Choose green suppliers

Choose suppliers that work to limit or offset their greenhouse gas emissions. Aside from the environmental benefits, this can make a strong and motivating marketing statement on behalf of your brand.

A growing number of technology companies such as Dell and Salesforce.com are working actively to sell carbon neutral products and services.

Finally, do your bit for the global good

It may cost a little more, but [buying renewable energy] from your power company will help trigger investment into more wind farms, solar power plants and hydro/geo-thermal generation.

For a small outlay reduce your carbon footprint further with [carbon offsets] to offset staff travel and office waste.

Matt Mulligan is the director of product development at ilisys, Australia's first carbon neutral Web hosting company.