1st Sep 2017

From villain to good gas: CO2 can produce food, shelter and energy

1st Sep 2017

Curated by Anna Firsova

Researchers are building machines to capture carbon from atmosphere
Algae, plankton and artificial foams can absorb a lot of carbon dioxide (CO2), which can be turned into useful products from food to bricks. And this in turn is good for the planet.

In 10 seconds? It turns out we should not fear, but embrace CO2. Not only can it help create sustainable foods based on algae, but it can be turned into bricks and power zero-emission plants as well. (Read the science here)

Say it slowly? Now we should love CO2?! Well, plants need CO2 to photosynthesise. And algae too. Since we have so much of the climate change-inducing stuff, why not turn it into something useful? Researchers have found that algae grown in bioreactors can remove CO2 from the flue gas of power plants. The resulting biomass contains up to 51% protein and can be used as a food source. That’s a win-win!

Hmm, that’s food for thought! Indeed, according to the UN's Food and Agriculture Organisation: “1-2 grams/day of high protein Spirulina [an algae] can totally end malnutrition in children”. This means CO2 helping to grow algae can be put to use for a good cause.

And what are the other uses of CO2? Believe it or not, it could replace water in zero-emission power plants that would be much more energy efficient than current ones, and can also be used in the production of concrete. The cement industry has so far been one of the world’s major CO2 emitters, with a tonne of CO2 released with every tonne of concrete produced. But with carbonation activation, half of the CO2 is locked away instead. Currently though, most of carbon-dioxide is used to help recover crude oil from depleting fields… which is not so good in terms of climate goals.

But can CO2 become a more popular commodity and if so, how do we transport it? Priced between $3-26 per metric tonne, depending on what state it is in (gaseous, liquid or solid), CO2 is mostly being transported in pipes. However, a new method of capturing it in reusable foam that sucks up 3 times’ its own mass in CO2 can make transportation and future use far easier. (Read more here)


How does the CO2-run gas plant work?

Net Power’s plant (planned opening: 2017) uses ‘supercritical’ state CO2 which has the properties of gas and liquid under high pressure and temperature.

In the first step of the cycle, oxygen, carbon dioxide and natural gas are used to ignite the gas in a combustor, producing hot water and supercritical CO2. The CO2 drives the turbine, generating electricity. This CO2 then goes through a number of devices, to capture the heat and then the gas is returned to the beginning of the cycle.
 
Using this super-hot CO2, the plant is reliant on significantly less fuel for the initial combustion step. The plant can rake in further profits by selling by-products, including CO2! (Read more here)

And, a ground-breaking Swiss carbon capture plant can suck CO2 directly out of the air and supplies it to a nearby farm to use is as fertiliser. (Find out more here)


(Psst, Anna distilled 26 research papers to save you 317.5 min)

Curated by

Anna Firsova

Anna Firsova is a Sparrho Hero, independent researcher and consultant working for academic institutions and private companies.

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