FIDDLY cables, incompatible plugs and
sockets, and the many adaptors needed to fit
them all together used to be the travellers’
bane. But the USB (Universal Serial Bus) has
simplified their life. Most phones and other
small gadgets can charge from a simple USB
cable plugged into a computer or an adaptor.
Some 10 billion of them are already in use.
Hotel rooms, aircraft seats, cars and new
buildings increasingly come with USB sockets
as a standard electrical fitting.
Now a much bigger change is looming. From
2014, a USB cable will be able to provide
power to bigger electronic devices. In the long
term this could change the way homes and
offices use electricity, cutting costs and
improving efficiency.
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The man who invented the USB, Ajay Bhatt of
Intel, a chipmaker, barely thought about
power. His main aim was to cut the clutter and
time-wasting involved in plugging things into a
computer. The keyboard, mouse, speakers and
so forth all required different cables, and often
drivers (special bits of software) as well. The
USB connection’s chief role was to help
computers and devices negotiate and
communicate.
Mr Bhatt did not think he was creating a new
charging system. Indeed, the trickle of
electricity (up to ten watts on the existing
standard) is still barely enough for devices
such as an iPad. Yet USB charging is now the
default for phones, e-readers and other small
gadgets. Some mobile-phone manufacturers
are already shipping their products without a
power adaptor. Ingenious inventors have eked
out the slender USB power supply to run fans,
tiny fridges and toy rocket-launchers.
The big change next year will be a new USB PD
(Power Delivery) standard, which brings much
more flexibility and ten times as much oomph:
up to 100 watts. In his London office Simon
Daniel, founder of Moixa, a technology
company, charges his laptop from a prototype
souped-up USB socket. The office lighting,
which uses low-voltage LED (light-emitting
diode) lamps, runs from the same circuit. So
do the monitors, printers and (with some
fiddling) desktops. Mains power is only for
power-thirsty microwaves, kettles and the like.
Current affairs
That could presage a much bigger shift,
reviving the cause of direct current (DC) as the
preferred way to power the growing number of
low-voltage devices in homes and offices. DC
has been something of a poor relation in the
electrical world since it lost out to alternating
current (AC) in a long-ago battle in which its
champion Nikola Tesla (pictured, left) trounced
Thomas Edison (right). Tesla won, among other
reasons, because it was (in those days) easier
to shift AC power between different voltages. It
was therefore a better system for transmitting
and distributing electricity.
But the tide may be turning. Turning AC into
the direct current required to power transistors
(the heart of all electronic equipment) is a
nuisance. The usual way is through a mains
adaptor. These ubiquitous little black boxes
are now cheap and light. But they are often
inefficient, turning power into heat. And they
are dumb: they run night and day, regardless
of whether the price of electricity is high or
low. It would be better to have a DC network, of
the kind Mr Daniel has rigged up, for all
electronic devices in a home or office.
This is where USB cables come in. They carry
direct current and also data. That means they
can help set priorities between devices that are
providing power and those that are consuming
it: for example, a laptop that is charging a
mobile phone. “The computer can say ‘I need
to start the hard disk now, so no charging for
the next ten seconds’,” says Mr Bhatt. The new
standard, with variable voltage and greater
power, enlarges the possibilities. So does
another new feature: that power can flow in any
direction.
This chimes with another advantage. A low-
voltage DC network works well with solar
panels. These produce DC power at variable
times and in variable amounts. They are
increasingly cheap, and can fit in windows or
on roofs. Though solar power is tricky to feed
into the AC mains grid, it is ideally suited to a
low-voltage local DC network. When the sun is
shining, it can help charge all your laptops,
phones and other battery-powered devices.
Such a set-up would benefit an individual
home or office. It works even better if the
network has a biggish central battery hooked
up to the mains grid, which can charge itself
up at night when power is cheap. But the real
prize comes when several buildings combine
such DC networks. Pooling supply, demand
and storage gives you the makings of a “smart
grid”—an electricity supply system which is
more resilient and thrifty than the existing set-
up.
Emergency planners like the idea: in a power
cut, devices such as phones are vital. Those
trying to manage ageing power grids welcome
anything that flattens the peaks in electricity
consumption.
Mr Daniel’s company has already set up a
dozen prototypes in Britain, including at a
London theatre and in a neighbourhood in
Southend-on-Sea. Another project is at
Nupharo, a technological park in the Czech
Republic. A conference held there this month
looked at how to bring low-voltage DC power
networks to people in poor countries who have
scant chance of hooking up to the AC mains
grid. A system that stores solar power and
shares it among those needing to charge
mobile phones or read at night meets a big
need.
Electricity-lovers are excited. Low-voltage DC
power is cheap, safe and green. Big companies
are working on rejigging chips and logic to fit
the new standard. The first USB PD devices will
come to market in 2014, with a “big roll-out”
in 2015, says Brad Saunders of Intel. Gregory
Reed, of the Swanson School of Engineering at
the University of Pittsburgh, calls the new USB
standard a “game-changer”. Big data centres,
with their huge, humming arrays of servers,
are already using DC circuits. Homes and
offices will follow, he says.
The shift comes just in time for the “internet of
things”—the idea that devices and gadgets can
talk intelligently and automatically to each
other online. That will mean many millions of
new bits of equipment, all needing their own
power supply and means of communication.
The new USB standard provides both.
Mr Bhatt, who invented it 20 years ago, is
delighted. His next plan is to make the USB
cable “flippable”—so that the plug fits the
socket whichever way it is inserted (for now it
works only one way round). That tiresome flaw
is because an original design priority was to
make manufacture as cheap as possible: few
believed his idea would really catch on.

Ubercool!