Thanks Andrew, Olivier, Bala, and everyone else for diving in with critiques here. I'm a cofounder of Make Sunsets and want to clarify a few things:
*Honesty: * We have no desire to mislead anyone. If we make a mistake (which we will), we'll correct it. *Radiative Forcing:* I didn't make this "gram offsets a ton" number up. It comes from David Keith's research: "a gram of aerosol in the stratosphere, delivered perhaps by high-flying jets, could offset the warming effect of a ton of carbon dioxide, a factor of 1 million to 1." <https://keith.seas.harvard.edu/news/whats-right-temperature-earth> and, again: "Geoengineering’s leverage is very high—one gram of particles in the stratosphere prevents the warming caused by a ton of carbon dioxide." <https://longnow.org/seminars/02015/feb/17/patient-geoengineering/> By stating "offsetting the warming effect of 1 ton of carbon for 1 year," I was trying to be more conservative than Professor Keith. I am correcting "carbon" to read "carbon dioxide" on the cooling credit description right now, and I'm adding a paragraph at the start of the post stating that estimates vary, but a leading researcher cites a gram offsetting a ton. For the several hundred dollars of cooling credits we've already sold, I'll be providing evidence to each purchaser that I've delivered at least 2 grams per cooling credit. Olivier, or anyone else: I'd be happy to post something by you to our blog explaining what you estimate the radiative forcing of 1g so2 released at 20km altitude from in or near the tropics will be and why. I will include language of your choosing explaining that you in no way endorse what we are doing. I very much hope to get suggestions from this community on instrumentation we should fly to improve the state of the science here. Again, I'm happy to do this with disclaimers about how researchers we fly things for are not endorsing our efforts. Or even without revealing who the researchers are: we'll fly test instruments and provide data, no questions asked:) *Telemetry: * My first 2 flights had no telemetry: in April, this was still in self-funded science project territory. After burning some sulfur and capturing the resultant gas, I placed this in a balloon. I then added helium, underinflating the balloon substantially, and let it go. There is technically a slim possibility that neither of these balloons reached the stratosphere, as I acknowledged to the Technology Review reporter. I will add Spot trackers to my next flights. These cut out at 18km, so I'l be able to confirm that I achieve at least this altitude. If (and this is a big if) I'm able to recover the balloons, I'll have a lot more data from the flight computer <https://www.highaltitudescience.com/collections/electronics/products/eagle-flight-computer>. I will eventually switch to Swarms <https://www.sparkfun.com/products/19236?utm_campaign=May%206%2C%202022&utm_medium=email&_hsmi=212205037&_hsenc=p2ANqtz-9EyQOQ6C-9XuSOHa7CggOC8Pf2tEow_Fppo5pXgTHO8-7gV-aHrrYpnPcliws6Ju8j2PBAX3Tkog0oVpwk8XqWX2xo0w&utm_content=212206499&utm_source=hs_email>, which should let me transmit more data regardless of balloon recovery. *Pricing: * Bala, you're totally right that this should be priced much lower. We're trying to make enough with our early flights to stay in business until we get meaningful traction with customers, and we plan to eventually drop prices to $1 per ton or less. *Reuse: * We are not yet reusing balloons, and Andrew is correct that latex UV degradation will limit our ability to do so with weather balloons. Given that balloon cost is our main expense per gram, even a few uses per balloon will dramatically improve the economics here. I expect to disagree with some of you, but I hope we can do so politely and assuming good intentions. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/550ec54e-4b36-4b6e-b4be-834229c870cen%40googlegroups.com.
