Instructors looking for a good climate geoengineering reading should consider a new article in the Proceedings of the National Academy of Sciences on one of the potential carbon dioxide removal options, air capture, by Klaus Lackner, one of the pioneers in this field. The study’s discussion of cost issues and motivations for geoengineering could generate some excellent class discussion. Among the findings of the piece:

1. A primary rationale for air capture is the challenge that climate change poses. If we’re to reduce emissions by 30-85% by 2050 to stabilize carbon dioxide concentrations in the atmosphere at between 350-450ppm, we would have to cease emissions from coal by 2050, substantially reduce other emission sources, and ultimately reduce carbon dioxide emissions to virtually zero to fully stabilize CO2 concentrations. Given the fact that carbon-free renewable sources and nuclear power sources face serious questions in terms of speed of deployment and social-political obstacles, air capture should be considered as a complementary option;
2. All currently discussed methods of air capture use absorption or adsorption on collector surfaces. Methods include liquid sorbents, membrane processes using electrochemical systems, and partial pressure-driven techniques that release carbon dioxide to a vacuum;
3. While estimates of future cost for air capture range from $30-1000/t CO2, the key is to assess “ultimately achievable costs” for mature version of these technologies. Lessons can be drawn from the precipitous drops of other technologies, e.g. solar panels (100-fold drop in cost since 1950s), sulfur emission trading (10x cheaper than anticipated). Demanding assurances of economic viability for a technology at the outset “stifles innovation, favors incrementalism and keeps game-changing ideas from consideration;”
4. If air capture costs can be reduced to $50/t CO2, it would be a strong contender among various options to address carbon dioxide emissions;
5. Mass production of small air capture units could be a viable model. Production of 1 million units per year could capture approximately 10% of current emissions; production of 10 million units cost capture more than current rates of emissions;
6. Without air capture, non-point sources of emissions will have to be phased out over the next few decades to avoid passing critical climatic thresholds;
7. Air capture could operate storage sites and eliminate the need for eliminating need for transporting carbon dioxide over long distances, reducing “NIMBY” effects;
8. Air capture could also help us to avoid an overshoot scenario, which we are probably already in, i.e. current atmospheric concentrations of carbon dioxide are already above optimal levels.

Among potential questions for classroom discussion:

1. Does air capture potentially threaten a “moral hazard,” i.e. could deployment reduce our commitment to reduce greenhouse gas emissions, and if it did, would this be problematic? Is the moral hazard issue in this context different than what may be posed by some other geoengineering options, e.g. solar radiation management?
2. Are there opportunity costs associated with investing in geoengineering technologies that may never bear fruit, e.g. air capture? Should governments invest in such technologies?;
3. Is air capture a more benign option than other geoengineering approaches?

Related posts:

1. Good summary of Air Capture Geoengineering Approach
2. New Article on Air Capture Geoengineering
3. Methane Capture Geoengineering?
4. Another Geoengineering Approach: Air Capture
5. New article: Geoengineering and the pursuit of 350ppm