Helsinki Energy Challenge outcomes: an artificial island, salt and a HIVE will help decarbonise heating

Key lessons include involving citizens, market forces and combining existing technology with local resources


The city of Helsinki organised an international projects competition to find future-proof solutions to heat the city and meet its goal of becoming carbon neutral by 2035. Helsinki heat is today produced mainly with coal (53%) and natural gas (35%). The city aims to decarbonise it using as little biomass as possible to preserve Finland’s forest carbon sink.

Awarded projects

This unique challenge received 252 proposals from 35 countries and selected 10 finalists. The jury of this one-year competition announced the results on March 16th. They distributed 1 million euros among the following winner projects:

  • HIVE: this plan uses Helsinki’s coastal location and is based on existing technologies such as seawater heat pumps, electrical boilers, solar thermal fields, thermal energy storages and demand side management measures. Among its selling points; the plan will create local jobs and aims to be flexible in order to integrate new technologies if and when these emerge.
  • Beyond fossils, an energy transition model based on open and technology neutral clean heating auctions. It will ensure that investments in clean heating solutions will be cost effective in rapidly developing low-carbon energy markets. This market-based solution aims to ensure the implementation and financing of existing technical solutions as well as the integration of future solutions.
  • Smart Salt City, is based on the integration of electric heating technologies (heat pumps and electric boilers) with wind and solar energy installations. The solution uses innovative thermochemical storage solutions and artificial intelligence to design and optimise this new heat system.
  • Helsinki’s Hot Heart, is an innovative project that would contain an artificial island: a flexible storage system consisting of 10 floating tanks filled with warm seawater that can be powered by different energy sources and seawater heat pumps. The structure would be enclosed by inflatable roof structures to create a new leisure attraction.

The City of Helsinki also grants a recognition award to the team “CHP Consumers to Heat Producers” for an eye-opening description of the diversity of the heating challenge and relevant stakeholders.

Outcomes of the competition

The different market and technology-based projects propose a range of different innovative solutions focusing on energy efficiency, waste heat utilisation, electrification and storage and even hot water supplies by ship produced with low carbon energy in isolated tankers. We can learn a few lessons from all the projects:

  1. Many projects underline the need to involve citizens in this systematic change. The Carbon Helsinki project has proposed the creation of a knowledge centre to make the people aware of and understand their city’s heating changes.
  2. The projects have all shown that decarbonised heating on a city scale is not composed of a single solution but of partial solutions, as well as of multiple actors that need to work together. Most of the projects are based on the use of renewable energy or wasted heat, heat pumps coupled with seasonal storage solutions and some market measures.
  3. The projects have shown that solutions already exist and that decarbonisation of large cities, even in cold climates, is possible. The future-oriented projects also emphasise the need for flexibility to integrate future solutions.

Finally, the solutions proposed by the teams of innovators are adapted to the local context and the geographical situation, especially the coastal situation of Helsinki. Nevertheless, these projects can be replicated by adapting them to other local contexts, matching the heating local needs and the resources available. That is why Helsinki Mayor Jan Vapaavuori concluded that “the biggest winner of the challenge is Helsinki itself and also other cities around the world that can benefit from the knowledge and insights gathered here”. The Finnish capital is convinced that “the change is in the hands of cities” and wants to show the way. Helsinki wishes to share its experience and the knowledge gathered here and will make the details of each project available on the Helsinki Energy Challenge website.