Last month I spent a delightful day at the Carbon Dioxide Removal / Negative Emissions Technology workshop at Berkeley, put on by Wil Burns, one of our original members. He had a crowd of 130 people there from all over the country, with presentations on various technologies for carbon dioxide removal (CDR).
The key take-aways were that we have lots of options now for CDR that can scale up to 50 GT / year, at a cost of less than 1% of global GDP.
Can your technology scale up to remove 50 GT CO2 / year?
- DAC- Global Thermostat, Inc. (Menlo Park): Yes
- DAC-Carbon Engineering, Inc. (Vancouver): Yes
- DAC-CDR trees (Ariz. State Univ): Yes
- Marine Permaculture Arrays (Brian von Herzen): Yes
- Ocean Alkalinization (Santa Cruz): Yes
- Ocean Iron Fertilization: Yes
- OTEC (Alan Miller): Yes
We spent the morning of the conference looking into BECCS (Bio-Energy and Carbon Capture and Sequestration). This is an area of CDR which is receiving a lot of attention in the last few years. Getting energy from biological sources, such a corn, switchgrass, sugar cane, and even trees has obvious appeal. In fact almost half of the US corn crop is now used for this purpose, growing corn for ethanol used to replace some usage of gasoline.
With all that positive attention, the downside of BECCS is that it cannot scale beyond about 2 GT CO2 / year—just 5% of what we need. In addition, achieving even that CDR potential requires giving up large areas of agricultural area to energy production—potentially at the cost of growing food for the world’s expanding population. The fundamental reason for the limitation is that plants are at best 1/100 as efficient, per acre, at producing energy as are solar panels. And solar panels don’t require water, fertilizer, planting, and harvesting.
Another popular technology, biochar got an excellent mention from Brian von Herzen (one of the Healthy Climate founders). Biochar, like BECCS has great potential in certain situations, especially for reducing pollution by shifting the burning of rice chaff from in the fields, to biochar ovens which are clean, produce energy, and then provide biochar (sort of like charcoal) which is used as a very effective soil enhancer. Biochar doesn’t make it on the list above because its global potential is about 1 GT / year of CO2.
In summary, we have seven excellent candidates for doing CDR at scale. Yet the two CDR technologies now getting the most public attention, BECCS and Biochar, are valuable and attractive, but simply don’t scale, mainly because they are limited to the amount of the earth’s surface area that we’d be willing and capable of committing to that purpose.
We are making great progress—just in the last month!