Category: CO2 Removal

40 Gigatons

Pilate Questioning Jesus
Pilate Questioning Jesus, “What is truth?”

In the discussions at this site we have suggested that we need to develop a theology that is suitable for the times that we are entering: an Age of Limits. We have further suggested that a foundation for such a theology is that, “We understand and tell the truth”. This is not easy. In this context, telling the truth goes beyond simply not lying — it means taking the time and effort to understand and analyze the immensely complex systems that provide the background to our modern lives. Telling the truth also means that we need to avoid wishful thinking and giving in to “hopium” — a belief that “they will come up with something”.

As an example of wishful thinking, consider the following chart. It shows the concentration of CO2 in the atmosphere. The value has risen steadily from 310 ppm in the year 1960 to its current value of 420 ppm.

CO2 concentrations in the atmosphere with overlays of dates of COP meetings and IPCC reports

Overlaid on the chart are the dates of the IPCC (Intergovernmental Panel on Climate Change) reports and the COP (Conference of Parties) meetings. These reports and meetings have been warning us for 30 years that, unless we do something to stop the increase in CO2 concentrations, we are facing a climate catastrophe. We see how effective those efforts have been. No wonder young people are angry.

So we face an uncomfortable truth: We will continue to burn fossil fuels regardless of the consequences. As we saw in the post Two Triangles, moral admonitions are of limited effectiveness.

If we are unable to stop adding CO2 to the atmosphere then the next logical step is to find some means of removing it. (Intuitively, this approach does not make sense. It is always better to avoid catching a disease than to have treatments for the disease once caught.) So we need to investigate the technologies that are grouped under the general heading of Carbon Capture and Sequestration (CCS). But that statement brings us to another uncomfortable truth, and that is to do with scalability and project management realities — an issue that we have already discussed in The Slow Train.

As is to be expected, this is a complex topic, involving many different potential technologies. But we have to start somewhere, so let’s use the following parameters.

  • Human activities emit about 40 gigatons (40 billion tons) of CO2 per annum.
    Roughly half of that CO2 comes from point sources such as power plants and industrial facilities. The other half comes from transportation (gasoline, diesel, bunker fuel and jet fuel) and from residential.
  • We need to reduce the emissions of CO2 to zero within the next 20 years.
  • There are various carbon capture technologies that can be used. Many of these have been demonstrated on a small scale, but none of them are established as an industry standard. The technology is still in the development stage.
  • CO2 can be removed either from point sources (the stacks of power plants and industrial facilities) or from the atmosphere.
  • The concentration of CO2 in the flue gas leaving a power plant stack is about 20%.
  • Currently the largest CCS facility can extract 10 megatons (10 million tons) of CO2 per annum from a point source.
  • The CO2 that has been removed is then stored in a subsurface facility, such as a depleted oil well. the power plant and a suitable geological formation in the same location.

There are lots of assumptions and simplifications in the above statements, but they do at least provide a sensible starting point in our quest for finding the truth.

Power plant stack annotated showing CO2 emission

Based on the above assumptions, we can develop the following calculation.

  • We start the program with point source emissions because that is the most cost-effective approach.
  • This means that we aim to remove 20 gigatons of CO2 per annum. This is only half of what needs to be done, but, at least, it’s a start.
  • Given a capacity of 10 megatons per annum per facility, this means that we need (20 * 109) / (10 * 106) = 2,000 facilities in operation.

But CCS technology is still in the development stage, with many unresolved issues such as, “Where do we put the CO2 once we have removed it?”. If it takes say ten years to fully develop this technology, then we need 4,000 of these facilities to be fully operational by the year 2030. Such a program would require an unparalleled, worldwide commitment of financial, engineering and project management resources.

But it becomes even more complicated. There are at least 50,000 power plants throughout the world, most of which use fossil fuels (coal or natural gas). So, maybe we need more than 4,000 CCS facilities.

There are so many unanswered questions and so many assumptions. Nevertheless, when it comes to reducing atmospheric CO2 concentrations our first-pass answers to Pilate’s question are,

  • It is very unlikely that we will voluntarily reduce our CO2 emissions.
  • The technology, financing and political will to implement carbon capture technology needs to be created within the next ten years. There are no signs of this happening.

Which leads us to the second of the theological points that we present, “Accept and adapt”.

Essential Petrochemicals

Ruthenium — Used to convert CO2 to methane

A theme of the posts at this site is that society will have to reduce its use of energy and raw materials. There is no way of getting around an Age of Limits. This leads to a subsidiary theme that our faith in technology is misplaced. In spite of our best hopes, they will not “come up with something”.

Nevertheless, it is worth keeping an eye on technological advances that can help us reduce the impact of the predicaments we face, or that can slow down the speed with which they are taking place. In particular, it is worth looking at developments in “carbon sequestration” — the removal of carbon dioxide (CO2) from the atmosphere. This CO2 can then either be stored, or converted to another chemical.

I am dubious about such proposed technological advances because they cannot get around the basic of the Second Law of Thermodynamics. No system is truly sustainable; all the actions that we take will lead to an overall increase in system entropy. Nevertheless, this is an area we should keep an eye on.

Given this background my attention was caught by an article published in this month’s Chemical Engineering Progress magazine. The title of the article was Transforming a Carbon-Based Economy. It discusses the use of a rare element, ruthenium (Ru), as a catalyst to convert CO2 in the atmosphere to methane (CH4). I was particularly caught by the following two quotations in the article,

We are a hydrocarbon-based economy, and we have been for 100-something years . . . So, at least as a bridge to technology for the next generation, we’re going to have to stay largely with hydrocarbons.

We still need plastics, carbon materials, and other commodity chemicals that are carbon-based.

What proponents of programs such as the Green New Deal fail to recognize is that about 10% of a barrel of oil is used as a feedstock used to make the thousands and thousands of chemicals that are essential to modern life. The list includes plastics, detergents, lubricants, packaging, carpets, structural foam, rubber, clothing, penicillin, chemotherapy drugs, food preservatives, fertilizers, pesticides, dyes, clothing, contact lenses, and so on and so on. Even if it were realistic to run our society on clean, renewable sources of energy within the next 20 years (which it isn’t), we would still need fossil fuels to make those chemicals.

The authors of this article recognize this dilemma. Their research is pointing toward a solution whereby we can use CO2 in the atmosphere as a petrochemical feedstock.