Earlier this week, a prominent Weibo defence blogger posted an image that appeared to be a Chinese naval warship carrying an electromagnetic railgun.

Key points: The gun uses the power of a neighbourhood to fire one shot at 2.5 kilometres per second

The gun uses the power of a neighbourhood to fire one shot at 2.5 kilometres per second China appears to be testing railgun technology on warships

China appears to be testing railgun technology on warships Previous prototypes have been too large and energy-hungry to be practical at sea

The velocity of railgun projectiles allows them to slice through ships. ( US Department of Defence: Jessica L Tozer )

This gun, oft-touted as a super-weapon, does away with the use of conventional explosives to fire a projectile, instead using an incredibly powerful electric circuit to launch a projectile.

The technology forms part of a suite of "next-generation" weapons that global powers have touted over recent years, such as Russia's hypersonic glide missiles announced in December.

Proponents of the railguns praise it for a number of reasons: It makes ships safer as you don't have to carry explosive ammunition, it's incredibly fast, and — depending on calculations — the shot can be incredibly precise.

Tests have shown that projectiles from railguns can be fired at 2.5 kilometres per second, over distances of up to 200 kilometres.

Put simply, this kind of weapon would be the equivalent of a ship in Sydney firing a projectile faster than the Concorde, striking a target somewhere past Newcastle within a minute and 20 seconds.

'It's like an electrician being blown off a chair'

The rails need to carry enough power to service an average neighbourhood to launch just one shot. ( ABC News: Jarrod Fankhauser )

The railgun essentially functions as an incredibly powerful electric circuit that consists of three elements: a power source, conductive rails, and a moveable bridge — also made out of conductive metals — sitting between the rails housing the projectile (known as the armature).

The rails are made out of conductive metals (such as copper) which are fed with whopping amounts of energy from a generator — one side positive, the other negative — to propel the armature at great speed and distance via magnetic force.

This kind of magnetic force is known as the Lorentz force, where the force is directed perpendicular to the magnetic field.

"I like to think of it as similar to when a dodgy electrician is trying to change a lightbulb who gets blown off their chair," said Dr Jai Galliott, Leader of the Values in Defence & Security Technology Group within the University of New South Wales's School of Engineering and Information Technology at the Australian Defence Force Academy.

"The science is pretty straightforward, but the issue is that the railgun calls for huge energy generation, and of course, power is pretty scant at sea," Dr Galliott said.

"The systems that the US were looking to deploy were somewhere between 15 and 25 megawatts which is enough to power a reasonably-sized neighbourhood if not more — so it's a whole lot of energy for just one shot," he said.

"The benefit of a normal projectile is that, if you've got enough on hand, you can pump out tens if not hundreds of rounds per minute depending on the weapon you're talking about."

Will the railgun suffer the same fate as the Concorde?

The sheer size of railgun generators has been an impediment to their introduction to navy fleets. ( US Navy: John F Williams )

The sheer amount of power that a railgun uses generates incredible heat during operation, and previous US railgun tests have seen rails melt during launches.

Over the past decade, the US has pulled away from railgun research toward Hyper Velocity Projectiles (HVPs), which are equally as fast but can be added to existing US and select allied fleets with a few tweaks.

"It's a lot cheaper to invest in HVPs because you don't have to retrofit a ship with a whole new weapons platform," Dr Galliott said.

"So there's a question of: 'Why should we make such a big investment in the technology when the capability enhancement isn't that great'?"

As global powers return to more conventional forms of warfare, defence strategists across the US and its allies are all vying to create agile forces that can be quickly deployed.

While US railgun research is in its second phase, it is a while away from being able to be deployed at a mass scale — BAE systems has been concurrently developing HVP and railgun technology for the US Office of Naval Research since 2013.

US President Donald Trump has not been a fan of electromagnetic technology, rubbishing its use in catapult systems on aircraft carriers to a US Navy Officer in November:

"Steam is very reliable, and the electromagnetic, I mean, unfortunately you have to be Albert Einstein to really work it properly," Mr Trump said.

Chinese railgun might be a bit of a fizzer

Ballistics experts have questioned the firing efficiency of current railgun efforts. ( US Navy: John F Williams )

In March 2018, a Chinese engineer working with the People's Liberation Army (PLA) claimed to have developed the "largest repeating power supply system in the world".

At present, it is unclear if China's railgun is able to fire multiple rounds, at what rate per minute it can fire, and what exactly they are going to do with the gun.

Dr Galliott believes it is all a bit of a fizzer.

"The thing with Chinese technology is that it might look like something on the outside but actually be hollow on the inside," Dr Galliott said.

"From what I've seen it doesn't look like anything special, and it doesn't look like it would be a readily deployable weapon — it might be more for PR purposes than anything else."

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But Dr Galliott added that there's plenty of other items in the Chinese armoury that already exist to wipe a potential adversary out.

"China already has missiles that could reach Australia relatively easily," he said. "The bigger problem is that countries like Australia are always 10 to 30 years behind the US and certain European players."

"And even if Australia worked toward getting 80 decent ships, the PLA Navy's sheer size will be our main issue."

The Australian fleet consists of 48 ships, boats and submarines compared to about 220 combat ships in the PLA Navy's favour (they plan to increase to 351 by 2020).

But in the case of the railgun, officials at the Australian Navy will not have to fret just yet, as China's touted "ship destroying" technology is even viewed with scepticism back home.

A Chinese senior editor from a prominent defence publication told the ABC anonymously that the widescale threat of Chinese railguns is not on the horizons.

"As we have seen, the US electromagnetic railgun is so big that it's unable to be carried by a warship," they said.

"So I don't see how the technology will be practical despite the reported technological developments."

The Chinese Foreign Ministry and Chinese Embassy were contacted for comment but the ABC has yet to receive a reply.

Additional interviews by Michael Li