* New cable system doubles power flow
* May make renewable energy projects cheaper
* Hopes will make DC power grids more feasible
By Caroline Copley
ZURICH, Aug 21 Swiss engineering group ABB
has developed technology that can double the power
flow of underground cables, making it cheaper to integrate
electricity into the grid from distant offshore wind farms.
The innovation means a single high-voltage direct current
(DC) cable can now transmit up to 2.6 gigawatts (GW) of power --
enough energy to power two million homes, or serve the
electricity needs of Paris, ABB said on Thursday.
Being able to pump more power through underground cables
should make it easier to transmit electricity through
densely-populated or environmentally-protected areas and even
reduce the need for unsightly overhead power lines, said Claes
Rytoft, ABB's chief technology officer.
He also hopes the new cable system, which uses a new
polyethylene insulation material, can be deployed underground or
beneath the sea, will encourage utility customers to invest in
more big-ticket renewable energy projects due to lower
"Germany is installing a lot of offshore wind farms at the
moment with a typical capacity of 1 GW. This means for every GW
they have to install a separate cable system to the shore,"
Rytoft said in an interview.
"With this technology they have the option to connect two
offshore wind farms and only have one cable to the mainland."
Rytoft sees a further application in long-distance power
corridors, such as Germany's "SUED.LINK" project, announced in
February, to carry surplus wind energy from northern regions to
the industrial heartland of Baden-Wuerttemberg in the south.
ABB, which makes products used by oil, mining and utility
companies, hopes Germany's shift to renewable energy as it weans
off nuclear power will help drive demand for green energy.
GREEN POWER GRIDS
Its latest technological achievement follows on from the
development of a circuit breaker two years ago that makes it
easier to send electricity through high-voltage DC lines into
the grids that link power stations to consumers.
While Rytoft conceded this latest development was more
"incremental" than the high-voltage DC circuit breaker, he
believes it will help pave the way towards what ABB hopes will
be a multi-billion dollar market for DC grids.
Conventional grids use alternating current (AC), but it is
less efficient at transferring power over long distances and
less compatible with some forms of renewable power generation.
AC and DC power have been at odds since their proponents,
Nikola Tesla and Thomas Edison, battled for supremacy in the new
technology over a century ago.
Edison even electrocuted an elephant to highlight the
dangers of Tesla's AC power, but his rival's system took off
because it could transmit electricity further. At the time, DC
power couldn't carry power beyond a few city blocks.
High voltage DC can transmit 30 to 40 percent more energy
than conventional overhead lines carrying alternating current,
making it a better for bringing power from distant sources.
ABB said its new 525 kilovolt high-voltage DC cable system
could now reach distances of 1,500 kilometres (932 miles), up
from less than 1,000 km.
"The two inventions put together make it more feasible to
build a DC grid," Rytoft said.
(Editing by David Evans)