| Andrew, I used Hydrogen for 20 years to use for weather balloons. No problem , even when one exploded fir a colleague in a balloon shed ( he has the doors firmly closed and there was a leak , which he knew about). Probably millions of radiosondes were launched with hydrogen. We had a fusion lab where hydrogen was piped around the facility. However, in the Falklands they had a hydrogen making device … ( solid + water). Now that was dangerous. There was one hole in the ground in africa where a hydrogen plant as above had been sited, but using the stuff is a safe. obviously , if you plant a bomb nearby , little is safe ( what was the actual cause of the hind disaster?)
i predict trains / trucks / cars will soon be using the stuff. Far greener than Li batteries and I think safer. Never mind the Co2 output. An electric car costs more to produce as regards Co2 than a small petrol car does ( + 70,000) miles of petrol. i should have bought an H2 car, but the problem is there are / were on 11 charging stations in the YK and 8 of them were in the M25 A. T --- Alan Gadian, UK. Tel: +44 / 0 775 451 9009 T --- On 29 Dec 2022, at 11:05, Andrew Lockley <andrew.lock...@gmail.com> wrote:
Large weather balloons don't have much over pressure relative to volume, so venting is a challenge. Valves and pumps add weight. Hydrogen has ground handling risks, due to flammability (Hindenberg), and any leaks risk buoyancy loss and the canopy descending loaded. The most extreme scenario is that an out of control failed balloon descends into an enclosed building through an open door, skylight, or Courtyard. In windy conditions, drift into a small industrial unit is perfectly possible, through the roller shutter doors - which could be automatically or accidentally closed behind, trapping the balloon and its flammable payload. This could allow a loaded canopy to leak out into a fully enclosed space, with ignition risks.
While such scenarios appear outlandish, with thousands or millions of launches, they become real risks.
Andrew
Hi
I do not understand the bit about bursting. Control of a venting valve protects the balloon and allows release at the chosen altitude.
Helium is irreplaceable and needed for super cooling. Is there a reason not to use hydrogen?
Stephen
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I will keep finding this rather murky as long as you keep being so hand-wavy about your numbers and then claiming you can offset a “substantial amount of warming” in your homepage.
Weather balloons have different bursting altitudes depending on 1) payload 2) amount of helium used to inflate 3) material.
You can find an example here with a calculator down below that lets you calculate max bursting height based on inflation
Which balloons did you use?
How much did you inflate them?
Did you check with the producer if the mix of SO₂ and He in the balloon would affect their calculations, and if so how?
The forcing we’re talking about changes depending on altitude of release as well: at 19 it’s different than at 25 (and depending on your definition, sometimes the tropopause is above 18km..), and above 29km sulfate aerosols evaporate because
temperatures are too high to form liquid aerosols. If the balloon doesn’t burst at the right altitude, what would happen to the oxidized S is not so simple - frankly I don’t know the answer off the top of my head, there are a few factors that could influence
this. Do you have studies showing what would happen there based on lack of water vapor and different temperature and OH levels?
If you don’t - and you don’t have any tools to measure it yet - maybe you should at least tone down the claims already present on your website?
For some ranges of stratospheric releases of sulfate we have some numbers for SAI we can be somewhat confident about - not just in term of the forcing but in terms of downstream effects on the stratospheric composition - but this may not
be true for what you are proposing or claiming you are doing.
Lastly, in your Twitter account you claimed in a post 2 days ago that there are “supporters and scientists who believe in you”. I would avoid claiming you have the support of scientists if you don’t - or show proofs if you do. As far
as any scientist I know is concerned they don’t seem particularly impressed - and your lack of clarity goes against any of the calls for open and transparent research (not to mention inclusive decision making) this community has asked in previous public statements.
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:
We have no desire to mislead anyone. If we make a mistake (which we will), we'll correct it.
I didn't make this "gram offsets a ton" number up. It comes from David Keith's research:
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:)
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. I will eventually switch to Swarms,
which should let me transmit more data regardless of balloon recovery.
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.
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.
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