The English translation is not so good. The essence is that they are using the heat from the underground server rooms to heat 500 homes in Helsinki.
Helsinki already has "town heating" - a network of hot water pipes that take heat from the power station cooling systems into many houses and buildings, and even a couple of streets in the city are heated to prevent ice. This system feeds into that.
In my home town Kuopio (pop. 93 000) 90% of all real estate is connected to district heating.
In Finland we've even had discussions about using heat from nuclear plants to town heating. But connecting Loviisa or Eurajoki (where our plants are located) would require building of heat transfer pipes. Helsinki - Loviisa is 87 km. Projected cost would be 700 million euros or 10 million euros / km. 500 million euros for building heat transfer infrastructure at the plant.
Rough estimates for 1000 MW reactor: Produces 3000 MW of heat of which 1000 MW can be converted to electricity. Remaining 2000 MW of heat is currently dumped into ocean.
They've estimated that with current heat transfer technologies they would be able to put 1500 MW of wasted heat to good use.
"In 2007, co-generation produced 74 percent of the heat needed for district heating and generated 29 percent of the Finland's electricity supply and 34 percent of production.
Manhattan does something similar - waste steam from power plants is piped through to customers who use it for hot water, heating, and AC (most likely via absorption refrigeration: http://en.wikipedia.org/wiki/Gas_absorption_refrigerator ).
I read once that some buildings use the steam to run backup generators in case of power failure, but I can't seem to find that source anymore - so take it with a grain, so to speak.
No it wouldn't, since there already is a functioning heat transfer network and the server room heat will be lead into it.
District heating has been functional in Helsinki since 1953.
"Helsinki district heating covers more than 93 percent of the heating energy demand. More than 90 percent of buildings are heated with co-generated district heat."
Helsinki already has "town heating" - a network of hot water pipes that take heat from the power station cooling systems into many houses and buildings, and even a couple of streets in the city are heated to prevent ice. This system feeds into that.
Corrections from Finns welcome.
Edit: Some more info - http://www.helen.fi/energia/konesali.html