←back to thread

147 points rbanffy | 1 comments | | HN request time: 2.929s | source
Show context
dizzant ◴[] No.42728125[source]
The comments here are focused on how much energy it would take to turn this into fuel. The real story here is decentralized fertilizer production, buried at the end of the article:

> this innovation could fundamentally reshape fertilizer manufacturing by providing a more sustainable, cost-effective alternative to centralized production

The high energy cost of Haber-Bosch, plus the additional cost of transportation from manufacturer to farmer could potentially be eliminated by distributed, passive fertilizer generators scattered around in the fields.

I'm no expert, but assuming sufficient local production, low concentration could potentially be overcome by continuous fertilization with irrigation throughout the growing season.

Let's find out. Some quick fiddling with a molarity calculator and an almanac:

-- 100 uM ammonia -> 1.7 mg / L ammonia

-- 82% nitrogen -> 1.4 mg / L nitrogen

-- My lawn needs around 1 lb / 1000 sq ft, or around 5 g / m2

-- So my lawn needs about 3500 L / m2 of fertilized irrigation total for the season

-- Ballpark farming irrigation is around 0.2 inches per day, or around 5L/m2

I would need to water my lawn about 700 days in the year, or more realistically up my irrigation rate by about a factor of 4, AND source all of the water from the fertilizer box.

I'm a little skeptical that I can allocate space for enough production and still have a lawn left to fertilize. The tech probably isn't ready for the big time on an industrial farm yet, but for research demo, this seems like a promising direction! Much more than concentrating it for fuel.

replies(6): >>42728262 #>>42728385 #>>42729985 #>>42731375 #>>42732368 #>>42754286 #
cogman10 ◴[] No.42728385[source]
Interesting idea.

So, farms are definitely setup already to accomplish this. Most farms have moved to central pivots for irrigation, and they already inject fertilizer into the pivot [1]. If fertilization could be generated onsite, then you could theoretically have everything plumbed together to "just work" without much intervention or shipping of chemicals.

[1] https://www.farmprogress.com/farming-equipment/chemical-fert...

replies(1): >>42729819 #
bluGill ◴[] No.42729819[source]
Rain will wash nitrogen away (down to streams, rivers, and then the ocean creating lots of problems) so you want to apply nitrogen with an eye on when it will rain so your fertilizer stays on the field where you want it. Your link doesn't specify what fertilizer is being applied, I would guess nitrogen is not one.

Ammonia should be applied to the soil - in the air it is a hazard that can kill people and harm the plants (farmers wear lots of protective gear when working with ammonia, with more other things they don't bother).

As such I'm not convinced that is the right answer. You want a system that will apply nitrogen

replies(3): >>42730685 #>>42732470 #>>42740612 #
1. Suppafly ◴[] No.42740612[source]
Farmers use anhydrous ammonia that bounds with water in the soil and then bonds to the soil.

I don't know that farmers wear anything special when applying it, but there are safety procedures. I work with a farmer and he was telling me about one time he forgot to switch one of the valves off and when he disconnected a hose, the fumes knocked him out. Luckily it was just the fumes from the hose and not the whole tank or he likely would have died instead of just being knocked out.