Some of the world’s most famous celebrities are now choosing to travel virtually, as three-dimensional, high-definition holograms. Last week Prince Charles was beamed live to Dubai to address the World Future Energy Summit. Instead of racking up thousands of air miles and producing the estimated 15 tonnes of CO2 that his US trip last year generated, the Prince was able to address an audience in Abu Dhabi without leaving Clarence House.

And he’s not the only one. Sir Richard Branson, Madonna, David Beckham and the green evangelist Al Gore have all used the Eyeliner projection system, made by the British company Musion, to be in two places at once.

Although its lifesize, lifelike holograms look futuristic, the inspiration for Eyeliner is a stage trick more than a century old. The “Pepper’s Ghost” illusion used smoke and mirrors – or, rather, a sheet of glass – to summon up spectral phantoms in Victorian theatres. Its 21st-century incarnation is far more sophisticated, of course. “Our system tensions a polymer screen up to five metres tall,” says Ian O’Connell, one of Musion’s directors. “This is illuminated by a hidden projector to create a 3-D image that looks as solid and realistic as a roaring fire.”

The challenges involved in creating convincing, interactive holograms are immense, according to O’Connell. “We used a powerful full-HD projector and the latest TelePresence technology from Cisco to transmit HD signals over the internet.”

The high-definition projection of Prince Charles used a secure broadband connection to deliver sound and video that is said to have looked better than a Blu-ray movie.

One advantage of an internet-based system is that you’re not limited to appearing in just one place. In Musion’s Virtually Live project, starting next week, a pop band will be performing “live” in five nightclubs simultaneously.

Unsurprisingly, given its Alist clientele, the Eyeliner system isn’t cheap. While Cisco’s chief executive, John Chambers, aims to bring a two-dimensional high-definition TelePresence system to homes within three years for not much more than £500, Musion’s holographic setup currently costs £70,000. But a more affordable virtual doppelganger was recently unveiled by the American company iRobot, whose $500 (£207) ConnectR robot has wheels, a video camera and a two-way audio link, all of which can be controlled from a web-connected computer anywhere in the world.

That means travelling parents or distant relatives can still play a part in family life, driving their ConnectR round the house, swapping gossip or reading bedtime stories.

ConnectR, which is currently being trialled in the USA and should be on sale by the summer, needs a home wi-fi network to function, and has the drawbacks that it doesn’t look human and can’t climb stairs.

These new technologies can’t be faulted for their efforts to reduce carbon footprints, travel time and stress. But whether granny will appreciate a robot or hologram instead of an invitation to stay next Christmas is another matter.

SLEIGH ’EM IN THE AISLES

Porsche Kinderbob €77 (£58) tinyurl.com/29kjy2 0049 711 9117 8823

Aspiring Le Mans drivers have to start young these days, and wintry weather should never be an excuse for them to miss their training. This super-swish downhill sled should have junior drivers (weighing up to 60kg, or about 9½ stone) steering and cornering like true professionals, thanks to the integration of a shock absorber, the use of metal runners and – that essential Porsche feature – a very loud horn.

DOCK AND LOAD

Creative Xdock HD $399 (£210) www.creative.com

Apple’s iPod and iPhone are great for enjoying music, photos and videos on the move but are far less impressive when linked to a TV or hi-fi. This docking station has an HDMI socket for connecting it to an HD-ready television and claims to “upscale” videos bought from Apple’s iTunes online store, although upscaled videos will not look as good as real high-definition digital downloads. It also boasts of improving the sound of digital music stored on the iPod to exceed CD quality. It comes with an RF-based wireless transmitter to beam tunes to speakers around your house. You also get remote control of your docked iPod via smart on-screen menus. Available in the US soon.

JUST ADD WATER

HydroPak Portable Power $400 (£205) www.millenniumcell.com; 001 732 542 4000

The HydroPack combines two processes to generate 270 watt hours (ie, it could power a 25W bulb for more than 10 hours) from a lightweight cartridge costing $20 (£11). You add water to trigger a chemical reaction that produces hydrogen, which is then consumed in a fuel cell to generate electricity. There are no toxic chemicals or waste products, and the unit is completely silent. The Hydropack has a standard American AC socket and two USB ports and is capable of delivering enough power to charge a laptop, run a mobile phone or provide overnight lighting. HydroPacks go on US sale this summer, aimed at campers. Unlike most battery systems, HydroPacks don’t lose their power over time.

gear@sunday-times.co.uk