Climate Crisis: Direct Carbon Capture Solution

By Robert Bernstein

The Intergovernmental Panel on Climate Change (IPCC) just released its latest report emphasizing the urgency of the Climate Crisis. Scientists have been warning of disaster for decades and the result has been endless delay and inaction. The longer we delay, the more expensive are the solutions and the more catastrophic are the impacts.

A company called Carbon Engineering is working on one piece of solving this crisis by actually removing carbon dioxide (CO₂) from the atmosphere by Direct Air Capture. Their representative Lori Guetre gave an informative talk recently to the Science and Engineering Council of Santa Barbara all about this.

Here Lori Guetre has kindly shared her slides for us.

Guetre started with a background on how we got to the current crisis. Fossil fuels are cheap and abundant.

I learned in my physics training to look at these situations in orders of magnitude terms. Fossil fuels are the accumulation of 100 million years worth of carbon compounds in dead living things. We have burned them and put that 100 million years of carbon in the atmosphere in the course of just 100 years. What could possibly go wrong?

People think of the Earth as so huge that humans cannot have much effect. But the atmosphere is not huge. Think of the skin of an apple. Our atmosphere is 20 times thinner than that relative to the Earth.

Scientists have known for decades that the safe limit for carbon in the atmosphere is about 350 parts per million (ppm). We have already passed that limit.

We have only seven years left in the “carbon budget” to avoid a level of 450ppm which would cause a two degree Celsius rise in global temperature.

The IPCC has said that halting dumping more carbon into the atmosphere is no longer enough. We have to actively remove what we have already dumped there.

How big is the challenge that we are facing? Goldman Sachs offers a “Carbon Abatement Curve” that is her favorite demonstration of the facts.What is needed to get to “Net Zero” added carbon to the atmosphere? As shown in that graphic, some solutions are cheap and easy. Some even have a negative cost as they save money. Solar and wind is already cheaper than fossil fuels in many applications.

But to get to that last bit of carbon is very expensive. The last bit can cost over $1,000 per ton of CO₂ to eliminate. Burning a gallon of gasoline produces over 20 pounds of CO₂. At this rate, it would cost $10 to eliminate the equivalent of burning that gallon of gasoline.

The area under that curve now represents about 8% of the world’s GDP. That is unaffordable. Yet the problem has to be solved or the price is even more unaffordable.

Direct Air Capture (DAC) of carbon from the atmosphere is essential.

Apollo 13 is Guetre’s favorite movie. The engineers are heroes. They had to remove CO₂ to survive. They came up with an air scrubber. This is done in submarines, too.

But using traditional techniques costs $600 per ton of CO₂. We need to get this down to $100.

Carbon Engineering is partnering with Occidental Petroleum to build plants to remove millions of tons a year; the first plant will be operational by 2024.

What to do with the carbon that is captured? Guetre estimated that over 10 billion tons per year of carbon can be put to industrial use. To make synthetic fuels or to mix into concrete or use in other construction materials.

But about 36 billion tons per year could go into stable geological formations for permanent storage.

She went into some detail on the chemistry and logistics of the process. They want to make modular systems that are on the order of about one million tons of CO₂ removal per year for each module. There is a potassium loop and a calcium loop.

They did not want to have to start from scratch with new technology. Instead, they are using four key building blocks that already exist on that scale for their modules. Using off the shelf building blocks is essential to scaling up this process to remove vast amounts of CO₂ from the atmosphere.

First is an Air Contactor that brings in air; this is taken from existing industrial cooling towers. Atmospheric CO₂ is captured using an aqueous solution of potassium hydroxide.

Next is a Pellet Reactor that comes from water treatment technology. CaCO3 pellets are precipitated out of the solution, and the KOH solution returns to pick up more atmospheric CO₂. 

Third, a Calciner that releases the CO₂ from the calcium carbonate. These units already exist for mining and ore processing.

Finally, a Slaker is used to re-hydrate the CaO, completing the calcium loop.  Slakers are standard equipment for converting calcium oxide to calcium hydroxide.

Here you can find more detailed information about this process.

What does she mean about making synthetic fuels? Well, people have been advocating using biofuels for many years as a way to remove carbon from the atmosphere and then create liquid fuels that can be burned in planes, trains and automobiles.

But “natural” biofuels are very inefficient in many ways. They use large amounts of land and water and mean competition between biofuel crops and food crops.

The trademarked “Air to Fuels” project of Carbon Engineering claims to have 100 times less land and water consumption than biofuels to achieve the same result.

This would use solar photovoltaic and wind power to fuel their machines. They would combine “clean” hydrogen produced from this clean energy with CO₂ taken out of the atmosphere.The resulting fuel is drop-in compatible for use in airplanes and other transportation that needs liquid fuels. Such fuel has an energy density 30 times higher than the best batteries. This density is essential for such applications as aviation where weight is so important.

The idea is to place these Direct Air Capture plants in places that are optimum for wind and solar energy. The fuel is then easily transported using existing fuel distribution systems. Unlike existing fossil liquid fuels, these synthetic fuels would have no contamination with sulfur or other pollutants.

This chart shows how Direct Air Capture saves three trillion dollars a year vs known alternatives to reducing CO₂ emissions. This assumes a cost of $150/ton for Direct Air Capture. It gets better as that cost goes down.For me, the elephant in the room is who is going to pay for this? California is one of the few states that has a government mandate to reduce carbon emissions.

Guetre claims that there are voluntary actions already happening in private industry. Bill Gates is already paying for Direct Air Capture to offset his personal carbon emissions as well as planning to expand that to all of Microsoft.

She said that Shopify is also voluntarily buying carbon removal to offset their carbon emissions.

Her view is that voluntary actions like these will encourage governments to make carbon removal mandatory.

I would argue that without such mandatory requirements a responsible business is at a disadvantage to one who uses our atmosphere as a garbage dump.

And we need to remove a trillion tons of CO₂ already dumped into the atmosphere over the past 100 years just to get us back to a safe level of 350PPM of CO₂.

It was good news to see that the technology exists now to remove carbon from the atmosphere and to dispose of it and/or make good use of it.

But the political and economic challenges still remain. It is up to the people to demand that the Climate Crisis is an urgent and important problem to solve.

Spending the money to solve the problem is a lot cheaper than the massive devastation that will result from inaction.

Here you can find more information about the Science and Engineering Council of Santa Barbara. And here is the web site of Carbon Engineering.