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Why are there so many methane satellites?

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Re: Why are there so many methane satellites?

#31

Post by leetcodesucks »

codeflo wrote: post #17
trompetenaccoun wrote: post #7

Earlier quoted context omitted.

That's a misunderstanding. The methane stays in the atmosphere a few years until it reacts with oxygen to CO2. So first you have the multiple times worse effect of CH4 and then you're left with CO2, which is still a greenhouse gas. You're left with CO2 either way, even when you burn the methane. That's why it's so bad. And that's why actually when companies or politicians tell you about "clean" gas, it's very mislead…

Sure, but the question is still whether that carbon came from a fossil source or was part of the cycle to begin with. Let's say a cow eats grass, produces methane, the methane gets converted into CO2, the grass grows back. No net increase in CO2. If, on the other hand, the methane came from natural gas, you have permanently added carbon to the cycle.

[dead]

Re: Why are there so many methane satellites?

#33

Post by perrygeo »

jessriedel wrote: post #16

Putting aside the climate aspects and just concentrating on companies that are trying to identify methane leaks: If I have a device that can accurately see methane leaks, I am very surprised it's really more economical to put them on satellites than to operate them locally. Yes, I get that you can have one device in orbit that can do the job for multiple companies, but satellites are just fantastically expensive. Unl…

> satellites are just fantasically expensive

Are they? A CubeSat can be launched for less than $100k, and their payload can contain off-the-shelf consumer hardware. That's what some upper-middle class families pay for an extra car. I think you're overestimating the cost of satellites.

At the same time, you're underestimating the challenges of operating a ground sensor network. How would identify which sites to survey from the ground without a broader search? Would the oil industry get to regulate itself? What about temporal variability or detecting flares? How would you detect new leaks and add new sensors? What about large-scale natural leaks that spread over many kms in inaccessible terrain?

Even assuming you could pinpoint the location of every active methane source ahead of time, how would you get a sensor there? How would you secure access for installation and maintenance? How would you ensure connectivity? How would you monitor in areas controlled by hostile governments?

Each of the hundreds of thousands of sites has its own logistical challenges which explode the cost. And because you need to keep the sensor network up to date, it's a constant operational battle, not a one time expense. Compare that to a satellite: the one-shot launch, then lower cost, lower operations, and superior temporal detection abilities and global coverage - not hard to understand why satellites are preferred.

Re: Why are there so many methane satellites?

#34

Post by codeflo »

Scarblac wrote: post #29
codeflo wrote: post #3

I get that methane has a strong greenhouse effect, and that climate models need to account for its concentration to make accurate predictions. But in terms of climate activism, isn't worrying about methane mostly a red herring? My understanding is that it only stays in the atmosphere for 12 years or so. It doesn't accumulate over centuries the way CO2 does. This means even if we manage to permanently reduce the amoun…

The half life is 12 years. So after 24 there's still a quarter, after 36 still an eighth, etc. It's worse than CO2 for a very long time, and then it is CO2.

I just looked it up to be sure. It seems like the mean lifetime is 12 years, which is the figure one uses for calculations. The half life is shorter.

Re: Why are there so many methane satellites?

#35

Post by codeflo »

metaphor wrote: post #28
trompetenaccoun wrote: post #7

Earlier quoted context omitted.

That's a misunderstanding. The methane stays in the atmosphere a few years until it reacts with oxygen to CO2. So first you have the multiple times worse effect of CH4 and then you're left with CO2, which is still a greenhouse gas. You're left with CO2 either way, even when you burn the methane. That's why it's so bad. And that's why actually when companies or politicians tell you about "clean" gas, it's very mislead…

> So first you have the multiple times worse effect of CH4 and then you're left with CO2, which is still a greenhouse gas. In case anyone else was wondering, the EPA[1] puts a layman figure on that notional multiple: >> Methane's lifetime in the atmosphere is much shorter than carbon dioxide (CO2), but CH4 is more efficient at trapping radiation than CO2. Pound for pound, the comparative impact of CH4 is 28 times gre…

But note that at the end of that century, the CO2 is still there and will continue to heat the atmosphere indefinitely. We really need to stop adding carbon to the cycle; optimizing the form of that carbon can only ever be a secondary goal.

Re: Why are there so many methane satellites?

#36

Post by Denvercoder9 »

jessriedel wrote: post #16

Putting aside the climate aspects and just concentrating on companies that are trying to identify methane leaks: If I have a device that can accurately see methane leaks, I am very surprised it's really more economical to put them on satellites than to operate them locally. Yes, I get that you can have one device in orbit that can do the job for multiple companies, but satellites are just fantastically expensive. Unl…

> satellites are just fantastically expensive

This has become less and less the case over the last decade or so. There are more or less mass-produced satellite buses now, and a SpaceX rideshare puts 150kg into orbit for less than a million. If you go small, you can probably procure, launch and operate a satellite for less than $1000 per day of usage.

Re: Why are there so many methane satellites?

#37

Post by chris_va »

jessriedel wrote: post #16

Putting aside the climate aspects and just concentrating on companies that are trying to identify methane leaks: If I have a device that can accurately see methane leaks, I am very surprised it's really more economical to put them on satellites than to operate them locally. Yes, I get that you can have one device in orbit that can do the job for multiple companies, but satellites are just fantastically expensive. Unl…

(disclaimer I work on climate/methane mapping)

Companies do survey from the ground, and for large facilities there is often permanent monitoring.

Detecting methane from the ground still requires an expensive instrument, and it covers a very tiny area.

Having said that, a lot of methane leaks are from abandoned well heads, and in many places there just are no economic incentives to care about it.

Anyway, satellites are not cheap from a capex standpoint, but they are surprisingly cheap in terms of $/m^2. A camera moving over the earth at 7km/s mapping a 200km swath can cover a million square km for O($1000). Getting a team with expensive equipment into the field for a day on one site could easily be more than that.

Re: Why are there so many methane satellites?

#38

Post by angiosperm »

etrautmann wrote: post #6
codeflo wrote: post #3

I get that methane has a strong greenhouse effect, and that climate models need to account for its concentration to make accurate predictions. But in terms of climate activism, isn't worrying about methane mostly a red herring? My understanding is that it only stays in the atmosphere for 12 years or so. It doesn't accumulate over centuries the way CO2 does. This means even if we manage to permanently reduce the amoun…

That’s exactly why it’s also worth targeting. Its short residence time means that addressing methane emissions could make a meaningful impact. It’s not zero sum - we should address the low hanging fruit of methane emissions while also decarbonizing.

There is a project to get transcontinental ships to add emitters of FeCl3 to their exhaust stacks, to catalyze oxidation of methane. It seems to be getting enthusiastic uptake from shipowners for reasons unknown to me. 10,000 ships emitting 100kg a day would be enough to bring atmospheric methane in line.

(Fe seeded to the ocean surface is negligible. This is not a thing to trigger algae production.)

https://en.wikipedia.org/wiki/Atmospheric_methane_removal

Re: Why are there so many methane satellites?

#39

Post by angiosperm »

alwa wrote: post #13
cabirum wrote: post #9

Because these are either spy sats or even weapons in space disguised as "methane detectors".

“Many” seems to mean only a dozen-odd. Which seems like an awfully small number to image the entire earth at meaningful levels of resolution or frequency. Which also seems to be the article’s lesson. FWIW, it looks like Starlink alone is up to 5,942 satellites in orbit [0] these days [0] https://planet4589.org/space/con/star/stats.html

If SpaceX cared, the Starlink fleet (both satellites and ground stations) could be the biggest, most sensitive radio telescope in the world, without compromising its usefulness as a network. It points in all directions at the same time. With such sensitivity, a very short "exposure" time is plenty.

Each node records a few cycles of analog waveform at a certain atomic-clock time determined by its position, and forwards that to a common collection point to correlate with the others.

Re: Why are there so many methane satellites?

#40

Post by mturmon »

jauntywundrkind wrote: post #14

With permafrost thawing and arctic warming releasing methane clathrates, methane has been on my mind for a while. I wonder if these satellites will also be useful in detecting dispersed wide-area releases like these? The current publicly available tools like https://methane.jpl.nasa.gov/ seem to focus on showing methane plumes. Which is good & something we are better positioned to do something about. But I wonder if…

The OP touches on the question of "why the focus on plumes and not on tundra or wetlands", and has a quote from Andrew Thorpe hinting at an answer.

>> “These types of emissions are really, really important and very poorly understood,” [Andrew] said. “So I think there’s a heck of a lot of potential to work towards the sectors that have been really hard to do with current technologies.”

I try to keep touch with work in this area. I think it's a combination of SNR and resolution/coverage. The CH4 from a gas leak is very concentrated and so it puts a strong imprint on the spectrum of light passing through it. The natural sources are more diffuse and have less contrast with the surroundings.

(For earlier airborne experiments, the JPL team [which included Andrew] was using a simple matched filter aligned with the methane absorption bands - now they may be using something more complex. This was able to run on a computer on the airplane holding the sensor as it flew over regions of interest.)

Anyway, for sources with a lower CH4 concentration, there will be a much weaker spectral signature. It will be hard to distinguish from other influencers like water, aerosols/dust, etc., or from instrumental effects that may be correlated with location. (E.g., "sometimes high water concentration has spectral effects that appear as high CH4 concentration, so our CH4 values over moist areas are sometimes too high.")

You can improve the effective SNR by accumulating results over a larger area (of space or time). As noted in OP, the ability to get large-area, frequent coverage is quite new.

And also, CH4 moves, so to combine measurements taken at different times, you need to account for transport. This is the difference between measuring "concentration" (a quantity we're more-or-less directly measuring) and "flux" (an emission rate over time, which we don't get to measure directly).

As noted in OP, the plumes were a low-hanging fruit (or as they say, a fruit lying on the ground. ;-)

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