39 Hot Heart
For pioneering an AI-powered renewable energy solution that doubles as an urban playground
When government leaders in Helsinki dangled a €1 million prize for "radically new energy solutions," Carlo Ratti Associati (CRA) went bold. The Italian design firm conjured up Hot Heart, a floating archipelago of basins that act as giant thermal batteries—and a recreational destination.
The project cracks a major conundrum for sustainable storage: how to keep energy until it’s needed. With Hot Heart, excess renewable energy will be converted to heat, stored in 10 seawater-filled basins and rerouted into the city’s heat distribution channels as demand dictates.
In an era of offshore wind and solar farms, Hot Heart’s tech advantage is an AI-fueled system designed to synchronize production and consumption. The CRA team achieved this by working with a global cohort of experts from Ramboll, Transsolar, Danfoss, Schneider Electric, OP Financial Group, Schlaich Bergermann Partner and Squint/Opera. For a city that gets more than half of its district heating from coal, the project would mark a significant step toward reinforcing the national energy grid. When project leaders unveiled Hot Heart in January, they said it will cover the full heating demand of Helsinki (an estimated 6,000 gigawatt hours) by 2030. And it will do it without carbon emissions—bolstering the city’s goal to be carbon-neutral by 2035—and at a 10 percent cost reduction compared to conventional methods.
Along with the sustainability and economic benefits, Hot Heart will also function as an oasis for urbanites looking to escape subzero Nordic temperatures. LED technology will help turn four of the basins into domed forests that mimic tropical ecosystems from the world’s rainforest zones, with dedicated spaces for beaches and other recreational spaces.
What was the guiding vision for the project?
We proposed affordable, reliable thermal energy storage at an unprecedented scale—taking a proven technology principle and scaling it up to solve a bigger, more-pressing challenge.
Another reason Hot Heart can be a game changer is how it proposes a merging of experience design and infrastructure. We strongly believe that infrastructure should not just be performing its functional task hidden in the background somewhere, but rather should be front and center, inviting the public to engage with it and understand it. Why not raise awareness and knowledge about climate change in addition to actually fighting it with technical solutions?
What was the biggest obstacle the team encountered during planning?
The initial vision was like a hypothesis that we verified by testing through numerous feasibility studies. From the initial vision, CRA and our consultant team would zoom in to make sure the details work, adjusting premises as needed along the way, and then we’d zoom out again to ensure the initial vision was still intact.
The team has specialists from a wide range of technical disciplines. How did you keep everyone aligned, especially during the pandemic?
We never actually met the team of collaborators in person. While this created some challenges, it enabled us to have a more geographically diverse team. We created a series of conversation tools, such as weekly all-team meetings and a shared document that everybody could update in real-time as a platform for discussion and review. We also synchronized the latest updates into a PDF every week that was distributed to the whole team for review.
How did the team encourage new ways of thinking?
Open-source management. We had a core team of collaborators who were with us from the beginning, but whenever we had a new idea or felt the project needed an extra push, we readily invited new collaborators to join the team. We did that even toward the end of the process, as new ideas were emerging and new needs for specific expertise became evident. The team was free to grow to tackle new issues or develop new levels of detail.
How might Hot Heart influence other renewables projects?
I hope we can inspire people to think big—do the engineering to be as forward-thinking and innovative as possible but also think beyond engineering to what public impact you can make with your infrastructure.