physics4me

physicsgg

Posts Tagged ‘energy

Internet responsible for 2 per cent of global energy usage

leave a comment »

How much energy does the internet use? It’s hard to know where to start. There’s the electricity consumed by the world’s laptops, desktops and smart phones. Servers, routers and other networking equipment suck up more power. The energy required to manufacture these machines also needs to be included. Yet no one knows how many internet-enabled devices are out there, nor how long they are used before being replaced.

That hasn’t stopped Justin Ma and Barath Raghavan from trying to answer the question. The pair, researchers at the University of California, Berkeley and the nearby International Computer Science Institute respectively, estimate that the internet consumes between 170 and 307 GW. Which, of course, raises another question: is that is a big number, or a small one?

Raghavan and Ma came up with their total by conducting a rough internet census. By drawing on previously published research, they estimate that our planet is home to 750 million laptops, a billion smart phones and 100 million servers.

They also put figures on the energy that it costs to produce each of these devices (4.5 GJ and 1 GJ for a laptop and smartphone respectively) and the period for which each is used before being replaced (three years for a laptop, two for a smart phone). Estimates for the energy that cell towers and optical switches use when transmitting internet traffic, plus similar calculations for wi-fi transmitters and cloud storage devices, helped complete the picture.

Their final answer sounds big. A gigawatt is a billion watts, so running and maintaining the internet is a like illuminating several billion 100W bulbs simultaneously. But it’s a small number compared with global energy use across all sectors. That figure is 16 terawatts, so the internet is responsible for less than 2 per cent of the energy used by humanity.

Raghavan and Ma suggest that attempts to create more energy-efficient internet devices, while worth pursuing, will not do much to lower global energy consumption. Instead, they propose that we should think about how the internet can replace more energy-intensive activities. Their calculations show that a meeting that takes place by video-conference uses an average of one hundredth as much energy as one in which participants took a flight so that they could sit down together. Replacing just one in four of those meetings by a video call, they add, would save as much power as the entire internet consumes.

The research will be presented next month at the Workshop on Hot Topics in Networks in Cambridge, Massachusetts.

newscientist.com

Written by physicsgg

October 26, 2011 at 12:43 pm

Posted in TECHNOLOGY

Tagged with ,

A renewable energy generator for all seasons

leave a comment »

GREEN power may no longer be as fickle as the weather, thanks to a device that can generate electricity in any conditions – be it sun, wind or rain.
Most forms of renewable energy are intermittent, says Elias Siores at the Institute for Materials Research and Innovation at the University of Bolton in the UK – the wind doesn’t always blow and the skies aren’t always cloud-free. “What we wanted was something that can take energy from different elements,” he says.
So, together with his colleagues, Siores has done just that. First, he created 20-centimetre-long flexible ribbons made of a piezoelectric polymer that generates electrical currents when perturbed, either by wind or when rain drops fall on it. The team chose a polymer called polyvinylidene fluoride over ceramic piezoelectric materials because in wind tunnel tests and simulated rain it deformed more, creating higher peak voltages. That means more energy per rain drop or gust of wind, says Siores.
Next, the team coated the ribbons with a flexible photovoltaic (PV) film, and attached a pair of electrodes with which to harvest this solar-induced current. Siores says that 10 square centimetres of the PV film can generate 1 to 2 watts of solar energy at its peak. The work will appear in Smart Materials and Structures.
It makes sense to combine different forms of renewable energy because they complement each other so well, says Hod Lipson at Cornell University in Ithaca, New York. But such hybrid generators would likely be limited to small-scale applications, because piezoelectric materials aren’t very energy-dense. “Their benefit would be more for powering very low power devices,” he says.
Siores agrees that each hybrid ribbon would only generate a few milliwatts consistently, perhaps enough to charge a cellphone. He envisages building pine cone-like structures made up of many flat “needles” that oscillate with the wind and rain, while simultaneously having a high surface area to harvest the sun’s energy.
A similar technique using standard nylon could also be used to make energy-generating clothing, Siores says: “We can turn nylon into piezoelectric nylon.” His team achieves this by extruding it into fibre form in the presence of a strong electric field. The fibres are then coated with a conducting electrode material, followed by a PV layer and then another electrode layer. The result, says Siores, can be woven into fabrics to make garments that generate energy as we move or soak up sunshine.
http://www.newscientist.com/article/mg21028156.100-a-renewable-energy-generator-for-all-seasons.html

Written by physicsgg

June 10, 2011 at 9:21 am

Posted in TECHNOLOGY

Tagged with