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  • Friederike

11: Winning the 100m USD carbon removal XPrize - Interview with student initiative CircularHorizon

Updated: Aug 10, 2022

In this episode, I am talking with Stella Harper and Darius Stulz. Darius co-founded the student initiative Circular Horizon with the goal of developing a scalable carbon removal project based on biochar.

They are participating in the 100m USD XPrize Challenge by Musk Foundation. To win the grand prize, teams must demonstrate a working solution at a scale of at least 1000 tonnes removed per year; Stella Harper is an ETH Environmental Sciences Student and joined the team later in the communication team.

The student initiative already has 40 student members, and they are actively searching for companies to support them with expertise and financing.

This will be a short episode to present the CircularHorizon initiative.

You can listen to this new episode on Spotify:

You can also listen to this podcast at Apple Podcast, Google Podcast or other major podcast distributors.

What is Biochar?

Biochar is defined as a carbon-rich material produced during pyrolysis process that is a thermochemical decomposition of biomass with a temperature about ≤700°C in the absence or limited supply of oxygen. Source: Science Direct

Under low oxygen conditions, biomass does not combust, but rather thermally decomposes. The result is a porous and stable form of organic matter. A number of biomass materials are used as feedstocks for biochar, including wood and wood waste, agricultural residues, and other organic wastes.

For much of the last 2,500 years, people of the Amazon Basin have produced and used char to enhance low quality soils to sustain agriculture, creating soils known as terra preta (“dark earth”). Modern scientists and land managers are evaluating the potential for biochar as a soil amendment to reclaim and remediate disturbed or contaminated soils, enhance agricultural productivity, and possibly mitigate climate change through carbon sequestration and reduction of emissions of nitrous oxide (N2O), a powerful greenhouse gas. Source: BANR

How Biochar removes CO2 from Air

In this episode, we are addressing the following questions:

  • Can you please explain to my listeners what Circular Horizon is and why you started it? 1:40

  • It is part of the Musk Foundation Project / Challenge Xprize - Can you explain that a little bit more? 3:18

  • Can you explain what Biochar is? 6:27

  • Which projects will you submit? 7:56

  • What makes your solution different and more scaleable? 10:16

  • What are the limits to using biomass and how would you overcome them? 11:41

  • How far in the project are you? 12:56

  • What have been your roles in this project? 14:37

  • How do you finance your projects? 16:53

  • If someone wants to support you, how can they do that? 18:25

  • What kind of support do you need from the community? 20:40

Timeline of the project


Instagram: @circularhorizon2021


Download PPTX • 2.93MB



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