Will a switch to light speed cut power use at data centres?

"I think we're at the end of copper," says Chris Sharp, the chief technology officer at data centre operator Digital Reality.

He's not saying that we are running out of copper, instead Sharp, and many others in the data centre industry, are betting that it will be used less.

Data centres use vast amounts of the metal: around 400 tonnes , external will go into typical facility of around 100MW (data centre size is measured megawatts, a unit of electrical power).

Most of that copper is used in the electrical infrastructure needed to power the datacentre and for cooling systems. But up to 70 tonnes is used by the computer servers that do the work of processing data in that 100MW facility.

Meanwhile, up to 20 tonnes is used for the network wiring connecting up those computer servers.

It's here, in the spaghetti-like wiring which snakes through a data centre where copper is targeted for replacement.

"The wires between these GPUs, CPUs, and all this compute are what's slowing us down," says Sharp.

Data is shunted around data centres in the form of electrons, which travel efficiently in copper wiring.

Many think there's an even better way of doing that, using light in the form of photons.

Light has been used for decades for long-distance communications over optical fibre - the data for this article probably travelled down a fibre optic cable at some stage.

But researchers and companies want to extend fibre's use to inside the data centre.

It involves intricate engineering, where optical components are connected directly to electrical ones, sometimes on the computer chips themselves.

The technology is called photonics and the big benefit is that light does not have the heating effects of electricity. Less heat means less energy is needed to cool data centre systems.

"You can save so much energy," says Callum Littlejohns, deputy director of silicon photonics foundry Cornerstone Labs.