Those damp, spent coffee grounds languishing in your compost bin may be more than just waste — they may actually help save the planet from global warming.
That's the word from a paper published in the journal Nanotechnology, in which researchers from the Ulsan National Institute of Science and Technology in South Korea have figured out a way to soak and heat used coffee grounds, turning them into the grittiest, most delicious methane storage source ever.
Methane is the second most abundant greenhouse gas that humans are spewing into the atmosphere after carbon dioxide. During a 100-year period, it's about 25 times worse for climate change than CO2.
Methane pollution comes from a variety of natural sources, including our wetlands, natural gas systems, and livestock, but more than 60% of total methane emissions worldwide result from human activities like agriculture, industry, and waste management.
Greenhouse gases as a whole are the major contributor to climate change. In fact, president Obama is tackling this problem with new rules aiming to cut 32% of greenhouse gas emissions from fossil fuel-fired power plants by 2030.
The new technique is promising because our current methods of capturing methane from the air are dangerous, expensive, and heavy. Our traditional way of compressing methane gas into cylinders subjects workers to sudden explosions, fires, and toxic gases, if the cylinders are not handled and stored correctly.
And this new coffee technique may be a cheap, easy, and quick way to help take a bite out of the problem.
Carbon-based materials, like coffee grounds, are ideal candidates for methane capture and storage because they're light, cheap, and durable.
Researchers mixed 1/2 cup of used Kirkland brand dark roast Colombian coffee grounds with sodium hydroxide for 24 hours, and then heated the mixture to between 1,300 and 1,700 degrees Fahrenheit in a furnace, producing a stable material that's able to absorb methane from the air around it. This process took only a day — a fraction of the time it normally takes to produce methane-absorbing materials.
Then they measured how much methane the treated grounds were able absorb from the air, and found that they were able to absorb up to 7% of its weight in methane. While that's lower than other methane-absorbing materials this coffee mix is faster and cheaper to produce.
Christian Kemp, an author of the paper from Pohang University of Science and Technology in Korea, got the idea while discussing a different project with colleagues over a cup of coffee, according to a press release.
"We were sitting around drinking coffee and looked at the coffee grounds and thought, 'I wonder if we can use this for methane storage?'" he said in the press release.
The technique is extremely cheap. "The waste material [used, ground coffee] is free compared to all the metals and expensive organic chemicals needed in other processes. In my opinion, this is a far easier way to go," Kemp said in the press release.
It also may be used one day to capture methane for use as a clean energy fuel alternative to fossil fuels.
As if we needed more reasons to be thankful for coffee.
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