POWER August 2015 - 10

cooling system. Engineers also reduced
the oil needed by the valve actuators with
the use of a compact hydraulic system.
In Siemens' new design, the position
of the rotor is registered by sensors and
controlled by a system that adjusts the
magnetic field. Then, a Siemens SIMOTICS
system compensates for all the weights
and process forces acting on the rotor. " Because
of this technology, active magnetic
bearings also open up the possibility of
monitoring rotors online, " says Siemens.
In general, the magnetic bearing technology
is appropriate for Siemens steam
turbines with rotor weights of up to ten
metric tons, which corresponds to an output
of between 45 kW and 40 MW. Oil-free
steam turbines also operate more efficiently,
because there is almost no rotational
friction, Siemens says.
" Depending on the design of the turbine,
efficiency gains of up to 1% are realistic, "
the announcement noted.
Statkraft Shelves Wind
Projects in Norway, Cites
Unprofitability
Lower power and electricity certificate
prices in the Nordic region have made two
wind power projects in Central Norway-
with a combined capacity of 1 GW-
unprofitable, Statkraft said in June as it
announced it would scrap them.
Norway produces the bulk of its power
from hydropower (Figure 3), but the country's
government has encouraged wind
farm installations to help save water reserves
for dry seasons. In 2012, Norway
and neighboring Sweden made a pact to
jointly develop renewable energy projects,
including an estimated 6 GW of wind capacity
across both countries.
But in 2013, while Norway had installed
just 62 MW, Sweden added 677 MW. The
country's wind industry group says the
difference has resulted from different
depreciation rules that allow developers
in Sweden to cover costs of wind within
five years, compared to 12 to 15 years in
Norway. Norway's government in February
floated a legal amendment that could increase
the return.
But for Europe's largest generator of
renewable energy, Statkraft, more needs
to be done. " The authorities have contributed
by facilitating wind power development,
for example through improving
the depreciation rules. Unfortunately, the
market development is such that it is still
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not commercially responsible to invest in
these projects, " said President and CEO
Christian Rynning-Tønnesen in June.
Statkraft estimated the Fosen and Snillfjord
windfarms would produce 3.25 TWh
annually, but their development would
cost about $1.36 billion.
The Emergence of
Evaporation Energy
Dr. Ozgur Sahin, an associate professor of
biological sciences and physics at Columbia
University, who has helped develop a
floating, piston-driven engine that generates
power, most succinctly describes the
impetus that makes it work: " Evaporation
is a fundamental force of nature, " he said.
" It's everywhere, and it's more powerful
than other forces like wind and waves. "
Sahin, who is the lead author of a paper
published in the online June 16 issue
of Nature Communications, last year found
that when bacterial spores shrink and swell
with changing humidity, they can exert
force. Sahin, who reported the finding in
a paper published in Nature Nanotechnology,
said they pack more energy, pound
for pound, than other materials used in
engineering for moving objects.
That finding led researchers at Columbia
University to develop devices that could
be powered by the force of swelling bacteria
spores. Along with the piston-driven
3. Norway's 2013 power mix (in
MW). According to Norway's statistics agency,
the country's total capacity in 2013 stood at
33,486 GW, most of which was hydropower.
The agency also noted that operating profit
from the power industry totaled $3.62 billion-
about 10% higher than in 2012. Norway saw
a 21% increase in wind power generation in
2013 compared to 2012, and a nearly 10% decrease
in hydro production. Source: Statbank
■ Hydro power ■ Thermal power
■ Wind power
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