[belorn]

The start of the carbon cycle is one which I have found to be very unpopular to discuss, and it has a direct connection to methane in the atmosphere. Artificial fertilizers is produce through a process which takes in natural gas as its primary ingredient. The process is also a major source for methane leaks, with a large variance in claimed contribution for the global methane pollution.

For a large portion of the global Methane pollution from cattle, the carbon cycle started out with natural gas being used to produce artificial fertilizer. If we wanted to address methane pollution it would make sense to start there in order to address both leaks and the introduction of carbon into the system, but this is where politics comes in. Artificial fertilizer is not just the building block for most cattle farmers, it is also the building block for most meat alternatives and the so called "renewable and carbon free" biomass industry.

On my free time I often spend time diving in the Baltic sea, and every time I go below the surface I see the effect that artificial fertilizer has. The excess nutrient is killing the whole area, which in turn release more methane from the ocean bottom. Currently the area is around of 60,000 km2, but the effect can easily be seen in nearby "healthy" areas.

[epistasis]

It will be fairly straightforward to decarbonize fertilizer production, using electrolyzed hydrogen rather than natural gas. As the industry matures, it's likely to be even cheaper than naturals gas derived ammonia. Here's a pilot project in Spain, for example:

https://www.bloomberg.com/news/articles/2020-10-28/spain-cou...

However, misapplication of fertilizer, and the resulting destruction of aquatic ecosystems, will take other fixes, and strong penalties on farmers that do this sort of damage.

[iamthemonster]

You are right, in the longer term, but hydrogen from electrolysis comes at a levelised cost approximately four times grey hydrogen. Of course that is comparing apples and oranges a bit (the grey hydrogen externalises some of its costs) but I think it is still over double as expensive as blue hydrogen. I would be delighted if electrolysis becomes two to four times cheaper than it is today but for a relatively mature chemical process I'm just not sure I see it happening in the next couple of decades.

[sdenton4]

Or else make the natural gas based fertilizer 4x more expensive through taxes...

[Ericson2314]

This is why the Carbon and other externalities taxes always have to come as soon as possible. They are not just good ideas in themselves, but the resulting price corrections will make further investigation and planning easier.

No only is trying to do all subsidy non tax embarrassingly weak politics, it's a stupid game of whac-a-mole a market can just route around.

[Doji]

This is a very insightful comment, thank you!

[ZeroGravitas]

That fertilizer accounts for about 2% of global carbon output, but it does seem on track to be replaced with ammonia made from green hydrogen rather than steam reformed from fossil gas.

Probably won't help with runoff issues though, as it'll be chemically identical, just with a lower carbon footprint.

[xyzzy21]

Does that include all the supply chains required? You have to deal in EROEI not specific process steps.

[heavyset_go]

Fertilizer runoff has absolutely decimated the fresh and brackish water systems that I'm familiar with, even in protected areas.