How do
you power
Kristiansand
using salt?
A
quiet revolution is
taking place in the
sleepy Norwegian
village of Tofte.
Statkraft, Europe’s
largest renewable energy company,
has constructed a prototype device
here that uses freshwater and
seawater to generate energy in a
process known as osmotic power.
“
If we succeed with this technology
we’ll be the first in the world to utilise
this source of energy,” says Stein Erik
Skilhagen, Statkraft’s head of osmotic
power. “It’s based on the flow of water
running from the river to the ocean,
where saltwater meets freshwater.
What’s so attractive is that, unlike
other forms of renewable energy
such as wind power and solar power,
this process is continuous and not
dependent on the weather.”
The initial discovery that osmosis,
the movement of water through a
semi-permeable membrane, could
generate power was made at an Israeli
university in the 1970s, but Statkraft
is the first company to invest in its
long-term development. “The key is to
put a membrane between freshwater
and seawater,” Skilhagen explains.
“
The freshwater is drawn towards the
seawater and the membrane prevents
the salt molecules from passing. This
creates a pressure on the seawater
side used to drive a turbine.”
For now, Statkraft is working with
a relatively small prototype unit that
generates enough power to operate
a coffee-making machine. The goal,
however, is to one day open a full-
scale osmotic power plant, a facility
as big as a football stadium capable
of generating 166 gigawatt hours of
electricity a year – that’s enough
to supply 30,000 households with
power, the equivalent of a medium-
sized Norwegian town such as
Kristiansand or Fredrikstad.
There are still hurdles to be
cleared – for one, more efficient
membranes are needed to succeed
on a far larger scale – but the
company has proven the technology
works and is confident it will one
day be replicated outside Norway.
“
As long as countries have access
to freshwater and saltwater they
should be able to invest in osmotic
technology,” says Skilhagen.
In the battle against climate
change, osmotic energy may be
more than merely desirable – it may
become necessary.
statkraft.com
We ask the man behind the
world’s first osmotic power
plant in Tofte, Norway
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