Jun 10 2022

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To all of the teams who competed in the Milestone Round of XPRIZE Carbon Removal:

Thank you! One year ago, we launched the largest privately-funded incentive competition in history to address the greatest threat to human society. When we launched, we had no idea who would rise to the challenge: Would we only see familiar faces, or would we see new and exciting concepts, individuals, and organizations come to the table?

You did not disappoint. In addition to many of the existing Carbon Dioxide Removal (CDR) companies joining the competition, we saw hundreds of new projects come to life. Over 1400 teams registered for the competition by December 1, 2021, and 453 submitted proposals for the Milestone Award Round on February 1, 2022, making this not only the largest XPRIZE to date but also the world’s largest technical review of CDR concepts. So thank you for your dedication, sweat, and tears in service of our climate.

Since the announcement of our Top 60 List and 15 Milestone Award Winners on Earth Day, we have received many questions about the evaluation process. In addition to the individual team feedback that XPRIZE gathered and shared with you from the Expert Reviewers and Judges,  we wanted to take the opportunity to answer a few questions about how the selection process worked and what to expect next. Two things are important to emphasize before we get into more generalized feedback and things to consider for the Finals of the prize. First, there was no deviation from the published Milestone Awards rules in terms of requirements to be in-scope and in terms of the basis of evaluation. Second, any team is still eligible to win the grand prize. We hope the following general feedback can be useful as you continue to develop your carbon dioxide removal systems for the next round of the competition and beyond.

1. How were the prize winners chosen? 

Throughout the process, the contents of each proposal were judged against the three major criteria described in the Prize Guidelines and Milestone (Phase 1) Competition Rules:

  • Operational criteria 
  • Sustainability criteria
  • Solution cost

The selection process included three rounds of review and evaluation. First, our team of 70 Expert Reviewers screened proposals against the competition’s technical definition of carbon dioxide removal and the basic demonstration requirements. Each proposal was then scored based on the scientific and engineering principles described in the submission and the overall feasibility of the concept, including consideration of the team’s process documentation, demonstration details, and strategy to assure durable carbon dioxide sequestration.

Second, we forwarded the 60 highest-scoring teams to our 12 Judges, who provided a more comprehensive review of the full proposals, including reviews of the emissions analysis and cost analysis that the teams completed.

Third, the highest scoring teams among the top 60, as determined by the Judge review, were discussed in detail at an in-person Judge Summit in Los Angeles, where the 15 Milestone Winners were selected.

2. Why was my team not selected?

There are a number of reasons teams were not selected for a milestone prize. Of the 453 submissions received on February 1, 93 (~20%) were incomplete. Given the size and complexity of the submission, this number was actually much lower than we expected. Another 73 (~16%) were flagged as being out of scope or of insufficient quality to be considered for a milestone award. It must be noted that the scope of this competition is very broad but also very specific to carbon dioxide removal. This means that very good, very impactful ideas were not able to advance beyond this point because they simply are not carbon dioxide removal. Proposals were screened out for some of the following reasons:

Out of Scope:

  • Emissions-avoiding, emissions-reducing, or emissions-offsetting technologies, but not durable nor net negative carbon dioxide removal (e.g., lower-carbon products or fuels, energy efficiency, alternative energy sources, non-CO2 emissions reduction etc.)
  • Nothing to do with direct carbon dioxide management (e.g., sensor technology, software, vehicles, etc.)
  • Captures post-combustion carbon dioxide from fossil sources (e.g., CCS on CO2 sources which burn coal, natural gas, etc.)
  • Carbon dioxide cannot be expected to remain durably sequestered for 100 years under any circumstances (e.g., selling CO2-derived liquid fuel) 

Poor Quality:

  • Reliance on non-science or pseudo-scientific concepts
  • Obvious catastrophic health, safety, or environmental issues (e.g., uncontrolled dumping of known toxins into the ocean)
  • Unable to discern sufficient content or meaning from the written proposals materials
  • Not written in English

The judges scored each submission against the operational and sustainability criteria and on the solution’s estimated cost. Within each of these major criteria, the competition rules laid out a number of requirements. The real challenge the judges contended with was to determine whether or not a team’s claims on each of these detailed points were credible. Some common issues included:

  • Missing or under-developed technical details: In many cases, teams proposed a multi-stage process where one stage was explained in detail while the other stages were not. While this can be expected at the proposal stage, the judges required enough detail for all stages in the process to lend credibility to the cost and emissions analysis, both of which depend on accurate inventories of the full cradle-grave system. For example, we received several proposals from teams whose key innovation is in the capture step of carbon dioxide from ambient air and/or shallow ocean. This is completely fine; each team has a core focus. However, proposals that did not describe a long-term, durable sequestration and management plan for the carbon dioxide were not looked upon favorably by the Reviewers and Judges. Casual allusion to a future plan or partnership was insufficient. Teams that did well all had detailed future plans, if not a formal partnership already established, for the sequestration step and/or a management plan to ensure net durability of removed carbon dioxide over at least 100 years. 
  • Uncertainty in the durability of sequestered carbon dioxide: In some cases, there is limited scientific consensus to date on the inherent durability of sequestered carbon dioxide. Some teams spoke to this issue directly and articulated significant understanding of the durability of their specific solution, while others did not substantiate their durability claims. Uncertainty in the durability has a significant impact on the overall design basis and long-term performance of the system, and so these claims were scrutinized by the judges very closely.
  • Issues that will hamper sustainable scalability: One of the key objectives of this round of the competition was to ensure that teams are able to identify and develop strategies for overcoming challenges to the sustainable scaling of solutions to a gigatonne and beyond. While many teams acknowledged some of the challenges that would need to be overcome as the solutions scale up, the teams who were successful in the judging process were able to show that they had a superior understanding of the issues and clearly articulated strategies beyond just a conceptual level. One issue which emerged for many teams was the availability of key feedstocks (this included availability of critical minerals used in enhanced weathering projects, and nutrient availability for nature based approaches, as two examples) or the management of hazardous byproducts (acidic byproducts, for example) at huge scale.
  • Uncertainty in the cost calculation: The judges approached the team's cost calculations with great skepticism. Cost estimates, especially those that rely on huge extrapolations of nascent technologies, are extremely difficult to do well. At a bare minimum, teams needed to present inventories of the costs involved in their solutions that were detailed enough to be considered complete. Successful teams clearly articulated the assumptions underlying the performance of their solution at the required megatonne scale (for example, assumptions around energy or production efficiencies). Capital expense estimates in particular were commonly underestimated, in some cases by orders of magnitude. Very few teams provided cost estimates that the judges felt confident in.

Ultimately, the judges were tasked with identifying the teams that could be deemed to have met all the criteria outlined in the rules and ranking those teams in consideration of the uncertainties present in each team’s proposal. As a result, since the prize is  fundamentally a competitive process with only 15 awards available in this round, some proposals that may have met all the requirements enumerated in the rules were simply outdone by others.

3. I still think that my solution will have the greatest impact at scale!

The Milestone Round of this competition was intentionally designed to reward teams who not only have potential for great impact, but have demonstrated progress to support their impact goals. The existence of some kind of demonstration, and the quality of the demonstration, were both as important as the quality of the concept. Many teams presented good ideas with insufficient real-world data to convince the judges of their ability to execute their proposal. On the other hand, even teams with sophisticated demonstrations were expected to make a compelling case for the sustainability of their solutions up to the Gigatonne scale. As this was a competitive factor, some teams with great ideas and impressive demonstrations were simply outranked by other teams with even better ideas, demonstrations, and scale-up plans.

4. Can I still participate in the next phase of the prize?

YES! The good news is that even if you were not recognized as a milestone winner or on our Top 60 list, you are still eligible for the $80M still up for grabs. The best part about the next round of the competition is that the winners must actually build working demonstrations of their solutions. So the challenge is really – prove it! Show us your solution in action, and demonstrate how your innovation can truly remove carbon dioxide from the atmosphere.

5. So what do I do now?

First, please re-read the Competition Guidelines. The guidelines remain unchanged and fully in effect for the remainder of the competition. If you registered for the Milestone round, your registration remains active and in effect for the Grand Prize round.

Please also watch out for emails from us with additional information about the competition. We will publish details on the submission requirements for the remainder of the competition, including details on the verification and due diligence processes that XPRIZE will conduct in the final year of the competition.

Then, the only thing left to do is to keep working on your carbon dioxide removal project. The next submission deadline is on February 1, 2024, where you will be competing for one of 20 site visits, a firm requirement to win the grand prize. In that submission, you will be required to show that your project is up and running, with evidence and data to show that you are on track to remove and durably sequester at least 1000 tonnes of carbon dioxide from the air or ocean in the final year of the competition.

Thanks again for your dedication in the fight against climate change and for your support of XPRIZE Carbon Removal. If you did not participate in the Milestone round of the competition, registration is still open through December 1, 2023. You can register here.


The XPRIZE Carbon Removal team