Thursday 23 April 2020

Carbon Capture Technologies

April 22nd, 2020 marked the 50th anniversary of Earth Day. Every year, activities focused on environmental issues are organized all over the world. Although this year all the events will be online (You know the reason, right?). But you know, days come and go. And who cares about the environment anyway? Or probably they think that we live in the Marvel Cinematic Universe where heroes will come and save us.

You would have seen a lot of examples of how industrialization and development of human civilization have affected our home. But today we will give you a new example.



The picture you are seeing is the picture of Peppered Moth before and after the industrial revolution began in England. Initially, the black colored one was rare, but human's influence on the environment grew, so did their numbers. After 80 years since they were first sighted, 98% of the Peppered Moths in Manchester were black.

Now you will say, "Ok. So, what are the solutions to this problem?" Well one of them is Carbon Capture and Storage Technologies.

IPCC (Intergovernmental Panel on Climate Change) released its special report on global warming in October 2018 which stated that some form of carbon dioxide removal is needed in order to keep the global temperature below 1.5-degrees celsius and also to avoid the worst effects of climate change. IPCC also estimates that carbon capture and storage has the potential to make up between 10% and 55% of the total carbon mitigation effort until the year 2100.

So, today we will look into some of these Carbon captures and Storage Technologies and how they will shape our future.


The Carbon Eating Fuel Cell


At an Alabama power plant, FuelCell Energy and ExxonMobil aim to capture 90 percent of the CO2 emissions. And they are doing this with the help of fuel cells.

In a molten carbonate fuel cell, carbon is an integral part of the equation. At the cathode—also known as the air electrode—carbon dioxide and oxygen are fed to the cell, and they react to form charge-carrying carbonate ions suspended in a molten salt electrolyte. The ions migrate through the electrolyte to the anode— or fuel electrode—where they react with hydrogen (which is formed from a hydrocarbon fuel like natural gas or biogas) to produce water, CO2, and electrons. The electrons then go into an external circuit to do useful work before returning to the cathode, while the carbon dioxide produced in the reaction gets recycled back to the cathode. The high temperature makes them less susceptible to poisons like carbon monoxide (created by processing carbonaceous fuels), which can damage the innards of lower-temperature fuel cells.

Against the backdrop of climate change, the company’s engineers realized that the fuel cell’s pumping action could be used to concentrate and collect carbon dioxide at the anode. To replenish the carbon dioxide needed to keep the fuel cell running, they could use pollution— industrial exhaust, that is. The concentrated CO2 can be stored deep underground or used as an industrial feedstock.

Unlike the conventional amine-based method of carbon capture, which consumes electricity, the fuel cells will generate their own electricity to drive the process.


The Power Plant that runs on CO2


The natural-gas-fired plant’s novel design, from Durham, N.C.–based NET Power, uses a fuel mix that is 95 percent carbon dioxide at the point of combustion. What’s more, it captures and sequesters carbon dioxide at virtually no additional cost. According to NET Power’s calculations, once the company scales up and rolls out the technology commercially, its plants should cost no more to construct and operate than a traditional natural-gas plant, which simply vents its exhaust into the atmosphere.

Above a certain temperature and pressure—31.1 °C, or a summer day in Phoenix, and 7.39 megapascals, or about 80 percent what you find on the surface of Venus— carbon dioxide turns supercritical. In that state, it can expand like gas and yet still move with the density of a liquid; it can even dissolve things the way a liquid can. (In fact, it’s used to decaffeinate coffee.) Supercritical CO2 can be pumped, compressed, and driven to spin a turbine with an efficiency that steam may never reach. Consequently, supercritical CO2 has been proposed and developed for decades as a credible replacement for steam in all sorts of power generation, including nuclear power and concentrated solar towers.
  • An air separation unit strips oxygen from the air and sends it to the combustor.
  • Natural gas combines with oxygen and hot, supercritical carbon dioxide to burn in a combustor. 
  • The resulting in very hot CO2 and water drives a turbine to generate electricity. 
  • A heat exchanger extracts energy from the turbine’s hot exhaust and delivers it to the stream of supercritical CO2 further down the cycle. The cooled water drains away. 
  • The cooled CO2 is pumped and compressed up to high pressure.
  • A fraction of the CO2 is siphoned away to be sequestered or used to pump oil out of wells. 
  • Energy from earlier in the cycle heats the high-pressure supercritical CO2 for a return trip to the combustor.
After almost a decade of development, NET Power is putting the finishing touches on its US $140 million, 50-megawatt power plant there. The grid-connected plant is being tested this year, and its backers hope to scale up to commercial deployment by 2021.


Methanol-fueled cars could drive us toward an emission-less future


Carbon Recycling International (CRI), whose engineers have developed a novel method of using renewable energy to produce methanol fuel from waste streams of CO2 and electrolyzed water. Methanol generated this way, CRI is betting, could have a real impact on climate change. Over the past decade, CRI engineers have been refining and vetting their process at the plant, which is named for the late Nobel Prize-winning chemist George A. Olah. A pipeline carries about 5,500 metric tons of CO2 per year from Svartsengi, which also supplies the electricity to split water into hydrogen and oxygen. The hydrogen and CO2 are then combined to form water-laden methanol, which is distilled into pure methanol. Opened in 2012, the plant now produces 4,000 metric tons, or 5 million liters, a year.

 Of course, in an ideal low-carbon world, the roads would be filled not with methanol cars but with electric vehicles charged by renewable energy. We’re still well short of that goal, however. Today, EVs make up a tiny fraction of cars in every country where they’re sold. Even under the most optimistic assumptions, it may be a mid-century before a majority of cars on the road are all-electric. In the meantime, methanol is among the most promising alternatives for significantly shrinking our cars’ carbon footprint.

If you power a methanol plant with a renewable energy source and capture the CO2 coming from the exhaust of, say, a steel plant, you can halve the total carbon being released into the atmosphere. So even though burning methanol in a car’s internal combustion engine does release CO2, along with some water vapor, you’re first capturing CO2 from the steel plant. That is, you’re basically recycling the carbon and extracting some useful work before it gets released. In contrast to carbon capture and storage, which aims to permanently sequester CO2 deep underground, this type of cycle is known as “carbon capture and utilization.”

Carbon Engineering


In Squamish, British Columbia, there’s a company that wants to stop climate change by sucking carbon dioxide out of the atmosphere. It’s called Carbon Engineering, and it uses a combination of giant fans and complex chemical processes to remove carbon dioxide from the air in a procedure known as Direct Air Capture.

Direct Air Capture isn’t new, but Carbon Engineering says its technology has advanced enough for it to finally make financial sense.

This type of direct air capture starts with an air contractor, where the air is sucked in at high volumes. This structure “wet scrubs” the air by using a strong hydroxide solution to capture CO₂ and convert it into carbonate. The hydroxide solution reacts with carbon dioxide to form carbonate ions(CO32−) This occurs within a structure that is much the same as an industrial cooling tower.

The next step involves a “pellet reactor” where the carbonate ion reacts with calcium(Ca2+) to form calcium carbonate, in the form of dried pellets. Then, a circulating fluid heats the calcium carbonate pellets to decomposition temperature, breaking them apart to release the carbon dioxide as a gas and leave behind calcium oxide (CaO).

Finally, the carbon dioxide is combined with hydrogen and converted into liquid fuels, including gasoline, diesel, and jet fuel, using the Fischer-Tropsch process. This is a process where a mixture of carbon monoxide and hydrogen are converted into liquid hydrocarbons. These reactions occur in the presence of metal catalysts and typically at temperatures of 150–300 °C.

This means the company can produce carbon-neutral hydrocarbons, meaning if you were to burn this fuel in your car, you would release carbon-dioxide pollution out of your exhaust and into the atmosphere. But because this carbon dioxide came from the air in the first place, these emissions would not introduce any new carbon dioxide to the atmosphere, and no oil would need to be extracted from the earth to power your car.

The company has tested the technology and has proved that it will cost between 92 dollars to 232 dollars to convert a single metric ton of carbon dioxide which is much less than the estimated 600 dollars per metric ton of carbon dioxide.

The company is backed by Bill Gates and also by the oil giants Chevron, BHP, and Occidental. These partnerships will bring Carbon Engineering’s tech to market by using the captured carbon to make synthetic fuels and help extract more oil from the ground.

Our world is developing everyday. New inventions and research every other hour and we are getting laced with technologies but as it is always said, “Every coin has two face”. If we are gaining, we are losing too but we can’t afford our coming generations to lose nature completely in a distressed form. That's why we need technology to coexist with other technologies so that we can grow without losing our environment, just like the concept of Sustainable Development. Our Earth is our mother and we are her sons and daughters and it is our responsibility only to take care of her. Let’s pledge to take care of her from today!

Thanks for reading. IEEE SB NITP would like to once again remind its readers to obey the guidelines as issued by the Government and WHO. Stay home and stay safe. Please drop your views in the comment section.

1 comment:

  1. Thank You. We hope for your reviews and suggestions ahead as well.

    ReplyDelete