Helsinki Energy Challenge leads the way into a carbon-neutral future with Savosolar being part of the winning consortium

To tackle the climate crisis also cities are taking the lead in driving the global shift towards a low-carbon economy of the future.

The city of Helsinki has set an ambitious goal of becoming carbon neutral by 2035, a challenging task considering that more than 50% of the cities heat is produced by coal in 2020. To identify the right methods for carbon neutrality the city launched the Helsinki Energy Challenge, a competition to answer the question: How can we decarbonize the heating of Helsinki, using as little biomass as possible?

The competition was hugely successful globally, with 252 entries submitted on the first round, with 1,528 experts from various fields participating. For the final round, 10 consortiums were selected to compete for the one-million-euro prize.

To answer the call for renewable and carbon neutral heat solutions Savosolar teamed up with two expert consortiums selected for the competition final:

  1. The HIVE, a consortium with Engie (France), Storengy, Newheat (France), Savosolar, Planenergi (Denmark) and AEE  Intec (Austria)
  2. The Sustainable Heat Coalition, a consortium with EIT InnoEnergy (Sweden), Heliac (Denmark), Savosolar, Ecovat (The Netherlands), HeatVentors (Hungary) and ConnectPoint (Poland).

Both consortiums submitted proposals that were aligned with the objectives of Helsinki, to eliminate fossil fuel use by 2035 and to drop green house gas output by 78% by 2035. Energy technologies used in the proposals included heat pumps, solar thermal plants and large scale thermal storages, and even gamification for citizen engagement stimulation was proposed.

The HIVE-consortium selected as the winner

The jury announced the winner on Tuesday 16th March 2021 and the HIVE consortium was among the 4 winners.

HIVE’s solution means no more coal or gas to heat the city, so a better air quality for every inhabitant and much less CO2 emissions for the planet.

The HIVE proposal provided a solution enabling the end of coal burning by 2028, no fossil fuel burning beyond 2035 and a drop in biomass use to 50% of the 2024 needs. This plan will decrease GHG emissions by 78%, aligned with Helsinki’s targets.  

HIVE’s energy plan for Helsinki, based on proven solutions, is composed of a combination of sea water heat pumps, solar thermal, electrical boilers and large heat storage. The mixed asset portfolio of mature technologies further boosts the system reliability. 

The published prize of one million euro is to be distributed between the winners, with the HIVE consortium receiving 350 000 € to be distributed between the team participant companies.

The individual HIVE team participants:

Storengy (France): Philippe Aubry
Newheat (France): Julien Metge
Engie (France & Belgium): Romain Donat  – Sandrine Bosso – Valentin Gavan – Jean-Baptiste Débonnaire – Albin Popot
PlanEnergi (Denmark):  Daniel Trier
AEE Intec (Austria): Ingo Leusbrock
Savosolar (Finland): Laurène Mejean

This what our team members had to say about participating:

“ Participating in the consortium work was extremely interesting, and being able to work with international leading experts from various fields of energy industry gave me incredible insight into the future of energy infrastructure “ – Laurene Mejean, Technical Sales Manager at Savosolar and member of the HIVE consortium

” Creating the proposal with innovative energy experts from six countries was very interesting. It was great to notice how the different technical solutions from the participating companies were combined together seamlessly to build the proposed solution ” – Miika Kilgast, Solar Energy Expert and Sales Manager at Savosolar and member of the Sustainable Heat Coalition.   

You can find links to the finalist proposals below:

  1. The HIVE –
  2. The Sustainable Heat Coalition

More Resources:

Link to the Press release of  EIT Innoenergy – participant of the Sustainable Heat Coalition

Read below the press releases and proposal summaries of the both finalist teams:


HIVE’s team awarded by the city of Helsinki as one of the ten most effective solutions to decarbonize its heating network by 2035. 

16:00, March 16, 2021 

The world is increasingly urban. By 2050, 70% of the global population will be living in cities. And, with 50% of CO2 emissions produced in urban areas, cities have a crucial role to play in the much needed energy revolution. 

Helsinki is aiming to be one of the leading cities in the transition towards a sustainable future, with the goal of becoming carbon-neutral by 2035. To achieve this target, the city has decided, in February 2020, to launch a competition to meet the challenge of decarbonizing its heating network by using as little biomass as possible.  

shared ambition to move forward towards a carbon-neutral economy 

HIVE’s team, a European team composed by ENGIE & its subsidiary STORENGY, NEWHEAT, SAVOSOLAR, PLANENERGI and AEE INTEC join forces to propose a solution enabling the end of coal burning by 2028, no fossil fuel burning beyond 2035 and a drop in biomass use to 50% of the 2024 needs. This plan will decrease GHG emissions by 78%, aligned with Helsinki’s targets.  

Selected technologies offering the best use of Helsinki’s assets: 

HIVE’s energy plan for Helsinki, based on proven solutions, is composed of a combination of sea water heat pumps, solar thermal, electrical boilers and large heat storage. The mixed asset portfolio of mature technologies further boosts the system reliability. 

 Tuning down the operating temperature of the district heating grid for better energy efficiency and larger thermal need coverage through the selected technologies  

  • Taking advantage of the incredible natural resource that Helsinki offers to harvest heat from the sea with heat pumps, up to 50% of the city’s heat needs. Heating will not rely on imported fuels or commodities. Baltic sea water balanced by large local storages will become the main heat source. 
  • Freeing space in the city-centre, especially in Salmisaari and Hanasaari neighbourhoods where coal plants will be gradually decommissioned and replaced by smaller-sized heat pumps. 
  • Minimizing as much as possible the combustible use and  thus achieving a better air quality  
  • Providing a cheaper heat supply. 
  • Promoting territorial anchoring and creating local jobs over the 15 years of the master plan’s implementation and beyond 

 HIVE – a scalable, adaptable and ambitious solution, to reduce the city’s footprint. 

HIVEs solution meets the city’s expectations, including demand side management measure and a strong support throughout the implementation. Its energy plan is flexible and capable of integrating new technologies or new heat sources if and when these emerge, and the roadmap (“baseline scenario”) until 2035 can be updated several times as new opportunities arise over the years 



EIT InnoEnergy (The Netherlands): Johan Söderbom, Sofia Gonçalves

Heliac (Denmark): Jacob Jensen

ConnectPoint (Poland): Marek Zając

Ecovat (The Netherlands): Ruud van den Bosch

HeatVentors (Hungary): Zoltan Andrassy

Savosolar (Finland): Jari Varjotie, Miika Kilgast

The transition to a 100% renewable, decarbonised energy system is possible – even for cities exposed to cold Nordic climates. Through  the proposal of Team Sustainable Heat Coalition – including six European companies and their complementary technologies – Helsinki will be the first to showcase this with their district heating (DH) network. We will deliver 1039 GWh of CO2-free, non-hazardous, and environmentally friendly solar thermal energy per year to the citizens of Helsinki, while maintaining existing levels of indoor climate comfort.

The project will provide solar thermal heat with flat plate collectors and concentrated solar heat. Using large-scale storage, up to 33% of the total solar thermal energy collected per annum will be stored, allowing the system to operate year-round. Decentralised heat storage facilities will add day-to-day flexibility to the system and reduce peak demands, achieving an annual cumulative system demand reduction of up to 8.9%. A real-time intelligent district heating platform will allow Helsinki’s DH network to be smartly and remotely managed and citizen engagement will be stimulated through gamification. By adopting these proposed measures, Helsinki will be able to reduce its DH network’s CO2 emissions by an impressive 78% by 2030 compared to current levels.

This no-regret solution can be implemented, integrated and financed in a modular and scalable manner. Starting implementation with an entry-level system will allow for rapid deployment, economies of scale and a project management strategy that mitigates any technical, financial, or governance risks.

The proposed solution is highly sustainable, cost competitive, technically feasible and has a high degree of social acceptance. Helsinki will be able to significantly decrease its import dependency on fossil fuels and provide a much higher degree of certainty for future operational costs. Through this front-running project, Helsinki will serve as an example of sustainable urban heating for other cities worldwide.




In a solar district heating system a large field of solar heat collectors supply heat to the local district network. The system is supported by a heating centre that generates additional heat to cover all heating needs in every situation. Two Solar thermal plants, each with a peak capacity of 25 MW, are part of the HIVE proposal. They will cover a significant part of the energy needed for supplying the city with hot water in summer. Solar collectors can be sourced locally.
Thermal storages are a proven storage technology, with a number of sites in operation. Existing sizes are typically smaller than what is proposed in the HIVE solution (up to approx. 200,000 m3 but larger cases are upcoming. In Aalborg, Denmark a turn-key project of 2 x 500,000 m3is currently (January 2021) in the tendering phase). HIVE proposes to build similar sized units in Helsinki,
In Europe, approximately ten times more heat is needed in winter than in summer. From May to August, the sun covers the entire heating demand and the district heating boiler can be shut down, significantly extending its service life. Excess heat from summer can be stored in seasonal storage for winter use.