The City of Helsinki has announced the winners of its million-euro Helsinki Energy Challenge.
An international jury selected four winners out of ten finalists at an awards ceremony that marked the end of the year-long challenge.
The competition attracted 252 proposals from teams based in 35 countries. The winning solutions all focused on the city's district heating system, which accounts for more than half of Helsinki's carbon emissions.
The city has committed to becoming carbon neutral by 2035.
Two of the winning concepts, HIVE (siirryt toiseen palveluun) and The Hot Heart (siirryt toiseen palveluun), would use water from the Baltic sea as a source of carbon-free warmth and energy storage for Helsinki's heating needs.
The Hot Heart's proposal also featured an artificial island dome covered with tropical plants and warm pools, which the team claimed could be a "new, global attraction for the city."
Moving to a more sustainable future
"We did not expect the competition to yield one solution, which solves the whole puzzle. Instead, we now have in our hands a very wide range of solutions, which will help not only Helsinki, but also other sustainable and innovative cities looking for heating solutions," said Helsinki's Mayor Jan Vapaavuori.
Winning entrant Beyond Fossils (siirryt toiseen palveluun) proposed a model to transition Helsinki to clean energy through an auctioning system for energy producers, while Smart Salt City (siirryt toiseen palveluun) would use AI and a new form of limestone-based energy storage to meet the city's demands.
"We addressed a significant question with the challenge competition model and it generated thinking and discussions, both within the city and outside it, which may not have occurred otherwise," said Project Director of the Helsinki Energy Challenge Laura Uuttu-Deschryvere.
"The energy revolution and the fight against climate change require innovative and exceptional ways of finding solutions," she added.
More than half of Helsinki's heating energy is currently generated by burning coal, which will be banned in Finland as of May 2029.
The Hanasaari coal-fired plant will be closed by 2024, with coal use at the city's other main generating plant, Salmisaari, to end by 2029.