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Coffee Biochar Concrete Carbon Sequestration

Posted on January 2, 2024January 8, 2024 by dishanth

Coffee is one of the most popular drinks worldwide; on average, 400 billion cups of coffee are consumed each year. As a result, approximately 18 million tonnes of coffee grounds are produced annually. Coffee grounds can be used for a variety of purposes. It can be used to fertilize your garden or added to compost. Coffee grounds can neutralize odors, can be used to exfoliate your skin, tenderize meats, and many other uses.

Despite all of these amazing uses for coffee grounds, the reality is that most of the coffee grounds produced actually end up in landfills; about 75% in fact. Rotting coffee grounds generate methane, a powerful greenhouse gas contributing to warming. Rotting coffee grounds also emit carbon dioxide, nitrous oxide, and ammonia. While there have been programs from coffee shops that will donate their coffee grounds to customers to use in their gardens (Starbucks has been part of the Grounds for Your Garden program since 1995), but most coffee shops are not implementing these initiatives.

Researchers from the Royal Melbourne Institute of Technology University in Australia have found a way to use coffee grounds on a larger scale and to eliminate the risk of them ending up in landfills. And that is to use coffee biochar concrete in the construction industry.

The researchers have developed concrete that is almost 30 percent stronger than traditional concrete by mixing in coffee-derived biochar. The coffee biochar was created using a low-energy process called pyrolysis. The organic waste is heated to 350 degrees Celsius without oxygen to avoid the risk of generating carbon dioxide. Under pyrolysis, organic molecules vibrate and break down into smaller components, creating biochar. This is a similar process that is used to roast unused beans to enhance their taste, except without the use of oxygen.

In coffee biochar concrete, about 15 percent of the sand they would use to make concrete is replaced with the coffee biochar, thus creating new concrete. The coffee biochar is finer than sand, and its porous qualities help to bind to organic material. Reducing the total use of sand in concrete will minimize the construction industry’s environmental footprint. It is said that over 50 billion metric tons of natural sand are used annually in construction. Sand mining significantly stresses ecosystems, including riverbeds and riverbanks, coffee biochar concrete can relieve some of that pressure on the environment.

The cement industry is the third largest source of industrial air pollution, including sulfur dioxide, nitrogen oxides, and carbon monoxide. Moreover, cement currently accounts for around 8% of global carbon dioxide emissions. Turning coffee- biochar into concrete will reduce the construction industry’s reliance on continuous mining of natural resources, making the industry more sustainable.

When introduced into concrete mixtures, the coffee biochar concrete was found to act as a microscopic carbon repository within the concrete matrix. The alkaline conditions within hardened concrete enable biochar to mineralize and firmly bind carbon dioxide into its structure over time. Concrete containing even a small percentage of spent coffee biochar was shown to sequester meaningful quantities of CO2 from the curing process and surrounding environment.

Utilizing waste coffee grounds to synthesize biochar for carbon sequestration could offer a sustainable way to offset concrete’s sizable carbon footprint while giving new purpose to spent grounds. With further research, coffee biochar concrete could provide a feasible carbon capture pathway for the construction industry.

The researchers estimate that if all the waste grounds produced in Australia annually could be converted into coffee biochar, it would amount to roughly 22,500 tonnes. Compare that to the 28 million tonnes of sand that are required to produce over 72 million tonnes of cement concrete in Australia. Just think: Australia has over 13 thousand coffee shops, whereas the United States has over 38 thousand coffee shops. If this project expands outside of Australia, coffee biochar concrete could significantly impact the environment and waste.

The research on coffee biochar concrete is still in the early stages; there is still a lot of testing to be done, but it shows that there are innovative and unique ways to reduce and repurpose organic landfill waste. Once the researchers can account for things like durability, the researchers will collaborate with local councils on future infrastructure projects, including the construction of walkways and pavements. Just think, we are one step closer to adding sustainability into the construction industry and one step closer to walking on coffee biochar concrete!

Source Happy Eco News

What is the carbon footprint of space tourism?

Posted on July 22, 2021July 26, 2021 by dishanth

Amazon founder Jeff Bezos does not appear best pleased with Richard Branson stealing some of his thunder with the Virgin Galactic launch: Branson went 53 miles (85 kilometers) into suborbital space on Sunday while Bezos has a self-funded trip to space planned for July 20. Bezos published a document comparing his Blue Origin to Branson’s Virgin Galactic, including its impact on the ozone layer.

Virgin Galactic

Virgin Galactic has only said that it is equivalent to a business class return ticket on a transatlantic flight, which the Financial Times calculates to be 1,238 kilograms of carbon dioxide per person.

A much earlier article in the Wall Street Journal suggests that it is higher:

“According to the U.S. Federal Aviation Administration’s environmental assessment of the launch and re-entry of Virgin Galactic’s spacecraft, one launch-land cycle emits about 30 tons of carbon dioxide, or about five tons per passenger. That is about five times the carbon footprint of a flight from Singapore to London.”

For something that isn’t going to happen very often, that isn’t such a big deal, even if it is nothing more than an expensive joyride. But as in everything else these days, you have to go beyond just the fuel burn.

The Virgin Galactic plane burns HTPB (Hydroxyl-terminated polybutadiene) and nitrous oxide, sometimes referred to as rubber cement and laughing gas. HTPB is the main ingredient of polyurethane and is made from butadiene, a hydrocarbon extracted during the steam cracking process used to make ethylene. The heat needed to make the 900 degrees Celcius steam comes from natural gas, and one study estimated there is about a metric ton of CO2 emitted for every metric ton of ethylene, so it probably is about the same for butadiene.1 So that would mean that emissions including upstream manufacturing emissions of the fuel are double, or about 60 metric tons of CO2.

This doesn’t include the fuel used for the big plane that carried the craft up, and of course, it doesn’t include the embodied carbon from building the whole operation.

Blue Origin

Bezos’ New Shepard is a rocket, not a space plane, and needs a little more oomph to get off the ground, so it is running on liquid hydrogen and liquid oxygen. The products of combustion are water and a tiny bit of nitrogen oxide.

However, hydrogen has a big carbon footprint of its own. Most of it is “grey” hydrogen made by steam reformation of natural gas, a process that releases 7 kilograms of CO2 per kilogram of hydrogen. Compressing it and cooling it into liquid hydrogen is also energy-intensive; in an earlier post, the company making it said it took 15 kilowatt-hours of electricity per kilogram of hydrogen. A lot of liquid hydrogen is made in Texas, where according to the U.S. Energy Information Administration, the electricity emits 991 pounds of CO2 per megawatt-hour, or 0.449 kilograms per kilowatt-hour, or 6.74 kilograms per kilogram of hydrogen.2 That totals roughly 14 kilograms of CO2 per kilogram of liquid hydrogen.

Compressing and liquifying oxygen is energy intensive too: according to engineer John Armstrong, to produce one metric ton of liquid oxygen (LOX) you need about 3.6 megawatt-hours of electricity. Applying Texas electricity, you get 1.61 kilograms of CO2 making 1 kilogram of LOX.

Bezos hasn’t released any details on the amount of fuel it takes to launch his rocket, but a Redditor did some estimates and came up with 24,000 kilograms of fuel. At a 5.5 mix ratio (hydrogen is really light, 1/16 the weight of oxygen) you get:

4363 kilograms of hydrogen X 14 kilograms of CO2 = 61 metric tons of CO2
19637 kilograms of oxygen x 1.61 kilograms of CO2= 31.6 metric tons of CO2
Totalling 93 metric tons of CO2 per launch

None of this includes the incalculable upfront carbon emitted making all the prototypes and infrastructure and the rockets and planes themselves, a Life Cycle Analysis of the whole enterprise would be mind-boggling, but that is another story.

So What’s the Big Deal?

In the larger scheme of things, it’s not much, with Virgin Galactic at 60 metric tons of CO2, Blue Origin at 93 metric tons. After all, a full 777-200 going from Chicago to Hong Kong pumps out 351 metric tons and that kind of flight happens many times per day. It’s carrying many more people many more miles, but the total CO2 emissions from flying dwarf that of these rockets.

It looks even less dramatic when you compare it to the average footprint of the billionaire who could afford a $250,000 ticket; he probably already has a carbon footprint of 60 to 80 metric tons per year flying private between multiple residences.

In the end one can probably conclude that we don’t need fewer rockets and less space tourism, we need fewer billionaires.

Source Treehugger