Want to understand carbon capture? Read this series

Carbon capture can be counted on to consistently accomplish one thing: spark passionate debate.

On the one hand, there are those who say that every dollar spent on this climate technology is a waste. From this point of view, carbon capture is a smokescreen for the efforts of oil companies to preserve their profitable franchises at the expense of the health of the planet.

On the other hand, there are those who think that between point capture (capturing concentrated emissions from a chimney) and direct air capture (capturing very diluted emissions directly from the atmosphere), the humans can completely reverse the progression of global warming and live happily ever after. After.

Both sides are wrong.

For those who are anti-capture, it’s time to wake up. A phenomenal amount of carbon is present in everything that citizens of developed countries touch. Suddenly stopping hydrocarbons would set civilization back several hundred years.

For those in favor of capture, try counting how many point source capture systems and DAC plants you will need to return atmospheric carbon to pre-industrial levels. Who will pay for this? How much will it cost to bring extinct species back to life and refresh the oceans?

Huge amounts of money are currently being invested in carbon capture technology, and the approaches can be confusing.

This article provides an investor-level overview of the three technologies used for point source capture and the following describes the strengths and weaknesses of each from an investor’s perspective. I’ll delve into direct air capture in a follow-up.

How does carbon capture work?

Carbon dioxide present in combustion exhaust gas is difficult to capture because it is diluted. There are two general approaches to capturing carbon: increasing the concentration of CO₂ in exhaust gases and find a chemical compound that effectively captures even dilute concentrations.

The easiest way to increase CO concentration₂ in an exhaust flow involves changing the input fuel. Burning coal generates about twice as much carbon dioxide as burning natural gas. Burning biomass releases less CO₂ than coal but more than natural gas.

A harder way to increase CO₂ concentration involves changing the equipment and processes used to burn the fuel.

Oxycombustion, the method that generates the most CO₂ concentration in exhaust gases, burns organic fuels using pure oxygen rather than ambient air, producing exhaust gases containing approximately two-thirds CO₂ and a third water vapor, plus some impurities, depending on the type of fuel burned. Capture CO₂ using an oxycombustion system is simple: filter out the impurities, dehydrate the exhaust stream and you end up with almost pure CO₂.

Pre-combustion capture, the other technology that boosts CO₂ Concentration involves two steps: first, the hydrocarbon fuel is split to produce “syngas” (carbon monoxide + hydrogen gas). Second, the syngas is blasted with steam, converting carbon monoxide to carbon dioxide and creating a higher concentration of hydrogen gas. These linked processes create two exhaust streams: one rich in CO₂ and another rich in hydrogen.

The carbon dioxide present in a pre-combustion system has a concentration between 15% and 60%, depending on the initial hydrocarbon used, and can be easily captured by dissolving the CO.₂-air loaded into a tank containing organic compounds. The hydrogen-rich stream is burned to produce nearly carbon-free heat or electricity (burning hydrogen is carbon-free, but only about 85-90% of the syngas is converted in the “reforming” process steamed “). The National Energy Technology Laboratory has a good explanatory video on gasification-before-combustion technology.

Final capture technology is the most widely used in modern industry and, unlike oxy-combustion and pre-combustion, it aims to capture CO at low concentrations.₂. These systems use one or more compounds that readily bind to carbon dioxide molecules chemically or trap them mechanically (i.e., without forming chemical bonds).

A class of chemicals called amines are often used to chemically bond to CO₂. Amines bind to CO₂ at low temperature and release it when heated. Specific salts or a class of chemicals called zeolites can trap CO₂ mechanically.

This process is called “post-combustion capture” and the concentration of CO₂ in the hot exhaust stream is between ~2% and ~15%, depending on the fuel burned to create the exhaust. About a year ago, I wrote about an innovative carbon capture company called Carbon Clean, which has developed a particularly effective chemical blend for post-carbon capture.

The planet needs carbon capture

Unless everyone reading this article wants to learn how to make their own soap and spin their own fabric, our civilization must continue to burn carbon-based fuels. However, we must not only stop releasing carbon dioxide into the atmosphere, but also reduce the amount of carbon dioxide already present.

Changing the way we farm – using regenerative methods and local food chains – is the first initiative we should pursue. Changing agriculture is necessary and might be enough to solve our climate crisis, but I doubt we can change attitudes, business models and supply chains quickly enough.

Carbon capture, part of what Energy Secretary Jennifer Granholm calls a “silver buckshot strategy,” is the second initiative we need to pursue…yesterday. Pushing this technology is also necessary but insufficient.

My next article will examine the strengths and weaknesses of each of the three carbon capture technology pathways and explain why carbon capture is so difficult.

Smart investors take note.