Using moss to combat CO2 emissions

[HankDorsett]

I came across a few different articles and social media post that claim moss is far better at absorbing CO2 and other pollutants then trees. The article from the link below claims that a relatively small planter is the equivalent of 250 trees. Is this accurate? If it is, why isn't this more common?

https://www.forbes.com/sites/trevor...rbs-more-air-pollution-than-a-grove-of-trees/

 

[HankDorsett]

Please ignore this reply, I forgot I could edit my post.

 

[gleem]

Is this accurate? If it is, why isn't this more common?

When a plant absorbs CO2 it converts it into plant material, carbohydrates mainly. To my knowledge most mosses do not grow very fast as the same for trees. The data in the article is inconsistent. It says each "city tree" absorbs 240 tonne of CO2 each year. It say it is equivalent to 275 trees where a tree absorbs 0.022 tonnes of CO2 each year. So 275 trees absorb about 6 tonnes according to that figure. So something is wrong. Grass however at least in my lawn seems to double its mass every week. So I would say grass sucks up more CO2 than that moss.

If the "city tree" absorbed 240 tonnes of CO2 that would be 657 kg per day. In the production of carbohydrates each carbon is accompanied by two hydrogen and an oxygen atom. The 1 tonne of CO2 should produce about 0.7 tonnes of carbs and that's a still a lot more moss that you should see each day. So where is all this CO2 going. At that rate you should actually see it grow I would think.

Disclaimer: Not much knowledge of plant metabolism.

 

[BillTre]

@gleem, your description is a lot like particular technologies used in maintaining aquariums.
In particular, tuff scrubbers in salt water aquarium systems.
Mostly, the problem in closed/partially closed water systems for fish is a build up of nitrogenous compounds in the water.
Normally, bacterial filters are used to move the nitrogen to less toxic compounds (nitrate vs. ammonia), but even those compounds can build up to troublesome levels. Bacterial filters just grow bacteria (plus other in filter organisms) while processing the nitrogen compounds for energy.

An alternative, I am mostly aware of from salt water aquarium systems, is an algal turf scrubber type of filter.
Water containing fish wastes, flows over an illuminated bed (lights if inside) where turf scrubbing algae are anchored.
The algae grows fast and accumulates mass (made as the result of photosynthesis) out of materials it gets and removes from the water. The mass is largely composed of the elements: C, N, P, O, H, S.
The filters are designed so that it is easy to remove the accumulated mass, thus taking those chemicals out of the water system.
In water systems it is easy to measure amounts of dissolved chemicals in the water, as well as how fast things in the water system are growing. There is a lot done with it.

https://enst.umd.edu/research/research-centers/what-algal-turf-scrubber: (ATS + Algal Turf Scrubber)

The ATS system consists of an attached algal community growing on screens in a shallow trough or raceway through which water is pumped. The algal community provides water treatment by uptake of inorganic compounds in photosynthesis. Water is pumped from a waterway onto the raceway and algae remove the nutrients through biological uptake for growth as the water flows down the raceway. At the end of the raceway water is released back into the waterway, with a lower nutrient concentration than when it was pumped up onto the top of the raceway. The nutrients that have been removed from the waterway are stored in the biomass of the algae growing on the screen. The algae are harvested, approximately once per week, during the growing season thus removing nutrients from the waterway in their biomass. Because of the fast growth rate of algae on the ATS, this technology can remove nutrients at a high rate. Harvesting is important since this action rejuvenates the community and leads to high growth rates. In fact, biomass production rates of ATS are among the highest of any recorded values for natural or managed ecosystems.

 

[willem2]

If the "city tree" absorbed 240 tonnes of CO2 that would be 657 kg per day. In the production of carbohydrates each carbon is accompanied by two hydrogen and an oxygen atom. The 1 tonne of CO2 should produce about 0.7 tonnes of carbs and that's a still a lot more moss that you should see each day. So where is all this CO2 going. At that rate you should actually see it grow I would think.

This is indeed completely ridiculous. It would take 6GJ to convert 657 Kg CO2 into glucose. (2800 Kj/mol enthalpy of combustion of glucose, which produces 6 mol CO2.).
The power needed for that is 70kW, even with 100% efficient photosynthesis. (more like 1-2% in practice)
The surface area is 12m².
The website of the producer Green City Solutions, doesn't mention CO2 absorption at all. This appears to be a case of circular reporting. Someone confused the absorption of particulates with that of CO2, and everyone copied this.

 

[HankDorsett]

Thanks for the replies.

 

[gleem]

Like many threads this sent me looking on the web for relevant information. Indeed there is an endeavor to find the best plant to sequester CO2.

https://www.ozy.com/fast-forward/the-search-for-a-perfect-plant-that-could-stop-climate-change/92396

The plant related to the mustard plant Arabidopsis is being studied at the Salk Institute. It is the first plant to have its entire genome mapped. The plan would be to bioengineer a variety with bigger, deeper root system while increasing the amount of suberin the waxy substance in cork that is particularly resistant to decay.

In the mean time trees still offer a good method of sequestering CO2 because they live for decades and decay slowly, provide shade, habitats for animals, control soil erosion as well as building materials for structures that can last for centuries.

 

[Rive]

The original claim there is about air pollution, not about CO2. In this regard, it might be correct: the surface and filtering efficiency what that wet moss bench providing may be comparable to several big trees, since trees has only leaves with very low filtering efficiency as the wind flows through them easily.

It worth noting tough that a big bench of HEPA filter with forced air circulation would be even better...but maybe less of a sensation