Updated: Aug 6, 2021
If you have paid attention to the arguments in “Drawdown”, you realize there is no silver bullet for global warming (aka climate change). It will take modification to a variety of human activities to reverse the impact of hundreds of years of extraordinarily high CO2 emissions generated by a multitude of human actions. Electric cars, reducing food waste, etc. etc. are great and worthy ideas for reducing CO2 emissions. But, even if we reduce our emissions to zero, there is so
much human generated, residual CO2 and other green house gases (GHG) already in the atmosphere (referred to as the legacy load), that the planet will continue to heat up for decades to come. We must drawdown this legacy load of GHG if we are to stabilize the planet’s average temperature at an acceptable level. Planting trees and regenerative agriculture are great, but the maturation rate and sequestration rate of CO2 is slow and will require billions of trees and acres of farm land. But it appears we will need to withdraw many gigatons of CO2 from the atmosphere and store it safely for the foreseeable future.
One developing technology that can help with the drawdown of atmospheric CO2 is Direct Air Capture (DAC). This is a process by which atmospheric air is drawn into a huge cooling fan-like apparatus and through a series of chemical reactions the CO2 is removed from the air and the remaining air is returned to the atmosphere. The captured CO2 is concentrated into a gaseous form and available for storage, conversion into low carbon fuels, and other commercial applications. The plant is powered by renewable energy sources to keep the overall process carbon negative. For more information, see here.
A similar, somewhat more mature technology is biomass generation. During its life cycle, the source of the biomass, various vegetative “crops”, extract CO2 from the atmosphere through the process of photosynthesis. When the biomass is burned it is used to produce steam which drives a turbine and its attached electrical generator. Scrubbers are used in the smoke stacks to remove the CO2 and store or use it. For any process along these lines there has to be a commercial incentive to continue. Storing huge amounts of CO2 in tanks is impractical and expensive. Just treating it as a waste product by sequestering it underground, especially considering the large investment required to build and maintain the CO2
extraction facilities would provide a negative financial incentive. But if we can find a practical commercial use for the CO2, one that would turn a profit, then these processes would be sustainable without government support.
Excess CO2 already has several commercial uses, such as an inert gas in certain chemical processes, carbonation of various beverages, fire extinguishers, and greenhouses (ironically enough), to name a few. But these uses may not result in long term sequestration of the CO2. A recent refinement of the ancient practice of using CO2 to produce a superior grade of concrete would not only provide a commercial application for excess product but also would result in the long term and even permanent sequestration of the gas. As it turns out, the Romans used this process some 1900 years ago in building Hadrian’s Wall in northern England. They mixed calcium oxide with water and let it absorb CO2 from the atmosphere turning the wall into calcium carbonate also known as limestone. Unfortunately, this crude process may take decades to complete. A Canadian company, Concrete Cure, has devised a method to inject CO2
directly into their wet concrete mix, forming nano-sized calcium carbonate particles, which they claim greatly increases the strength of their concrete and permanently sequesters the captured CO2. They have been able to successfully market their “superior” concrete to the building trade. Still, it will require some government incentives to enable manufacturers of concrete products to ramp up the use of this technology rapidly enough to make a significant impact on climate change. As the innovation continues, other means of sequestering and uses for CO2 are emerging.
- Frank Fazekas November 16, 2020