Don't dump your coffee grounds: use it as supercapacitor coffee grounds for fuel

Energy circle is a coffee lover, bought a set of homemade coffee tools, and can enjoy the fragrant homemade coffee in the office from now on. But every time there is a pile of coffee grounds left, and it seems that there is no other way to deal with it but to pour it into the trash can.

The world produces more than 9 million tons of coffee beans every year, and once brewed, a large pile of rubbish is made, most of which are landfills.

However, the latest research shows that coffee grounds is a high-quality fuel, and it is too wasteful to dump it.

(the following text is compiled by Wang Diudou and fried with eggs)

Researchers in South Korea have found a way to use discarded coffee grounds as a more literal fuel, in a study in Nanotechnology. they reported the use of coffee waste to produce a carbon material full of tiny pores to increase the surface area, known as activated carbon. The new material can absorb and store methane and hydrogen, both of which can be used as fuel.

While the ability to store these fuels with this cheap material is a big step forward in making the technology more feasible, it also has an environmental advantage: methane is a harmful greenhouse gas.

This is by no means the only use of abandoned coffee grounds. As a relatively pure and essentially free waste logistics, scientists, engineers and entrepreneurs have studied various ways to take advantage of it.

Burning coffee as a low-cost fuel for several years, Nestl é has been using discarded coffee grounds from his home's instant coffee as thermal fuel. It currently uses coffee to cook its food in more than 20 factories around the world, replacing more than 800000 tons of coffee grounds that would otherwise be landfill.

In a more specific effort, London-based Bio-beans is trying to turn waste from local instant coffee producers (nearly 200000 tonnes in London and south-east England alone) into biomass particles for power generation and to heat homes with trendy biomass burners. These beans burn cleaner and contain 50% more energy than traditional wood particles. Unlike Nestl é, however, Bio-bean first removes oil from coffee, which brings us to the next point:

Turning coffee into liquid fuel Coffee beans, like most plant seeds, contain large amounts of oil that can be extracted or chemically extracted, which can then be converted into biodiesel with properties similar to conventional diesel.

The fuel can be used in standard diesel engines. Paul Joseph, CC BY

Coffee-derived biodiesel is not affected by where the coffee is grown, the type of beans or how the coffee is brewed, which is a big advantage, which means that coffee-derived fuels provide predictable and consistent energy values when burned.

Coffee grounds can also be fermented to produce ethanol or to apply extreme temperature and pressure to create bio-oils similar to crude oil. however, both processes are expensive. Biodiesel seems to be the only fuel that works on a larger scale, so Bio-beans is struggling to commercialize it.

Coffee contains a lot of valuable chemicals that can be separated and purified for very special uses, such as chlorogenic acid, a food additive that slightly lowers blood pressure; fenugreek alkaloids, which help prevent and treat diabetes and central nervous system diseases; polyhydroxyfatty acid esters used in the manufacture of bioplastics And a wide range of antioxidants that can be used medically or added to fuels and lubricants to extend their life.

Coffee compost?

This Hawaiian coffee farm has the right idea. Scot Nelson, CC BY-SA

Coffee grounds are rich in nitrogen, an important nutrient for plant growth, and some coffee shops know that they will give used coffee to their customers. This reduces their waste and can be turned into organic fruits and vegetables. what barista would say no?

Absorption of heavy metals

Coffee grounds can even effectively absorb harmful heavy metals such as chromium, copper, nickel or lead, which are often leaked from chemical plants and cause heavy losses. Under specific laboratory conditions, it has been reported that waste coffee can remove 91% heavy metal ions from the solution-a good example of potential environmental benefits.

Does anyone have coffee grounds on hand? There was a major leak at the Polishan copper mine in Canada last year. Reuters

Coffee making supercapacitor

The most complicated thing is that researchers use coffee to make supercapacitors, which can maintain more power and more charging cycles than traditional batteries, and ultra-thin porous carbon nanosheets with excellent electrical properties have been produced.

Whether it's composting in the garden at home, research in the laboratory, or even in industrial fuel production, discarded coffee obviously has a lot of uses. One thing is certain, of course we should not just lose it.

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