I enjoyed David Friedman’s Odd Applications of Economics
Spartacus, an app for collective action. Anyone can start a campaign and followers join anonymously. Once a preset threshold is reached, everyone is deanonymized simultaneously “exchanging the safety of anonymity for the safety of numbers, instantly!” Pretty cool, seems like a useful tool for economic catalysis.
Worldcoin. A cryptocurrency to be distributed freely to as many people as possible.
Also: Seawater seems like a great source of CO2 for a fuel from air system. Pulling CO2 from the ocean also removes CO2 from the air indirectly, whereas pulling it from the air induces leakage from the ocean back to the air. I looked into seawater CO2 extraction recently, focusing on approaches which extract CO2 rather than produce minerals and ignoring approaches which use rare inputs like as desalination brine or wastewater. These papers seem like a good starting point for further research: