Currently [pun intended..?] such batteries use graphite as their anode, which material has its own environmental concerns. Searching for a greener alternative, Jialiang Tang and Vilas Pol demonstrate the potential for pollen – particularly that from cat-tail (Typha sp. presumably, though not specified in the paper!) – to be used as a source of carbon that could substitute for graphite. I can just see the advert for an army of ‘cat-tail wranglers’ needed to harvest the amount of pollen required to satisfy the demands of the lithium battery industry!
Exhibit 2, spruce cones as CO2 scrubbers. We’re probably all aware of concerns about excess CO2 in the atmosphere (global warming/climate change, that sort of thing…) and attempts to remove what’s already there and to reduce what’s being added. As good botanists, we’re also aware of the value of living plants in drawing down some of that CO2 during photosynthesis and locking it away within cellular components. It’s also the case that dead plant material can help to remove atmospheric CO2, as discovered by Bingjun Zhu et al.
Although described as pine cones, they peeled and washed cones of Norway spruce, burned them at 600°C for an hour (one does wonder how much CO2 that released..?), then ground them into smaller particles which were treated with potassium hydroxide and nitrogen. The resultant high surface area material was able to take up approx. 21 % of its weight in CO2, which admirable performance matches that of costly, state-of-the-art engineered metal-organic frameworks(!). But what do you do with the CO2-enriched product? You can’t exactly burn it…
Exhibit 3, air pollutant-degrading peanut shells. In this case it’s not the ‘shells’ of peanut (Arachis hypogaea) that do the purifying, but microbes housed within them. The microbes, which include the fungus genus Fusarium and bacterial genus Brevibacterium, utilise methanol and other air-borne solvent products of industrial processes for their own growth. In that way, the biofiltering population increases and air pollution decreases.
The system, designed by Raul Pineda Olmedo et al. at the National University of Mexico (UNAM), is at an early stage of development* , but it is hoped that it could prove to be a popular way to exploit what is otherwise considered to be a worthless agricultural residue. Which only goes to show that, in the right hands, there need be no such thing as waste.
* It seems that this work builds upon earlier studies by Elsa Ramírez-López et al., which gives some insight into the time it can take for ideas to become reality. Would a call for crowd-funding be in order to progress this worthwhile project?