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Suck CO2 out of the air as global warming solution: Research

Model DAC Plant
A model plant designed to pull carbon dioxied out fo the air. Credit: Carbon Engineering

In a race against time to come up with solutions for global warming, a group of researchers have come up with a detailed financial analysis that suggests directly capturing and storing carbon dioxide (CO2) might be a possible and economic solution.

While the idea of direct capture of carbon dioxide is not new and the technology has been around for at least a decade, it was always deemed to be too expensive to sustain and a worst case scenario option.

The case study published by Carbon Engineering, which operates a carbon extraction plant based out of Canada. The analysis is based on the economics of the plant, which operates on the principle of Direct Air Capture (DAC), one of many carbon capture and storage (CCS) technologies being used today.

Carbon Engineering claims that the cost of extracting one tonne of CO2 is between US$94 to US$232, depending upon several factors, which is a 60%-85% reduction on the previous estimates by researchers from American Physical Society in 2011 which estimated the cost to be at US$600/tonne.

What is direct air capture?

Suck CO2 out of the air as global warming solution: Research 1
A Model Direct Air Capture (DAC) Plant

Direct Air Capture (DAC) is a method of Carbon Capture for Storage which is used to process atmospheric air, remove CO2 and purify it.

The captured air then can be processed to create a range of products, including clean-burning liquid fuels.

Is Direct Air Capture science-fiction or reality?

DAC Technology
How the DAC Technology Works
Credit: ClimeWorks

A decade ago, DAC was regarded as hypothetical, and more of a science-fiction than actual reality.

Even today, the viability is questioned, which is why Carbon Engineering’s cost reduction is being noticed by researchers and industry alike.

Carbon Engineering already has a prototype plant that operates in Squamish, British Columbia in Canada since 2015, that captures 350 tonnes of CO2 annually and produces 350 barrel of fuel using its AIR to FUELS technology at the cost of US$94 – US$232 per tonne.

ClimeWorks, another major player in this space, claims that its first commercial factory that costs US$23 million, can capture 900 tonnes of CO2 annually, at the cost of $600 per tonne. The second such plant is expected to be built in Iceland.

What are the challenges?

Researcher regard Direct Air Capture as a definite solution to global warming, however, questions have always been raised about its economic viability.

Energy requirements

The question is related to the power requirements of running such a project and, two of the biggest companies that used Direct Air Capture method, ClimeWorks and Carbon Engineering, haven’t traditionally published their energy requirements. Though ClimeWorks states it uses low-grade/waste heat for the majority of its energy requirements.

Scientists estimate one tonne of CO2 extraction requires up to 45 Gigajoules of energy.

Water Requirements

DAC also has significant water requirement. According to a study, a large-scale implementation capable of extracting 3.3 gigatonnes of carbon per year will require 300 cubic kilometres of water, that is 300 trillion litres of water. For reference, that is equal to about 5% of water used for crop cultivation globally.

Other methods using sodium hydroxide would use far less, however, they produe highly caustic and dangerous by-product substances.

What other options do we have?

A few, but none of them are as impactful as CCS methods.

Solar Photovoltaics

Solar photovoltaics (PVs) are array of cells that converts solar radation into electricity. This is a type of solar energy, but different from what we typically imagine.

Solar Power

Concentrated Solar Power (CSP) uses sunlight focused on mirrors to capture heat. However, only 30% of the heat is converted to electricity using current technologies.

Same as what we typically see on media whenever someone talks about solar energy.

Wind energy

Energy is generated from wind by using large turbines that can convert the kinetic energy of the wind to electricity. These turbines are capable of converting only 33% of the kinetic energy in wind to electricity.

Geothermal energy

Geothermal energy is extracted from hot water and steam from below Earth’s surface. This is already widely used to provide heat for buildings, industrial processes, and domectic water.

Hydroelectric energy

Hydroelectric energy is the worlds largets renewable source of electricity. It accounts for almost 20% of total electricity produced. Most hydroelectric plants are situated at dams and uses falling water from the dam to generate electricty.

Oceanic and Tidayl Waves

Oceanic waves can also be used to create electricty, however, this technology is only at the prototype stage.

Nuclear energy

Nuclear power plants produce electrity by nuclear fission, once regarded as the alternative to thermal plants, has seen a reduction in adoption due to dangers associated after the Japan Fukushima nuclear power plant disaster.

Image result for fukushima disaster
Fukushima nuclear disaster has changed the adoption of nuclear energy.

Biofuels

Biofuels can be solid, liquid, or gaseous fuel that is derived from organic matter, usually dead plants or excrements.

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