This article published in ‘Frontiers in Climate’, 21 May 2019, by Phil Renforth (School of Engineering and Physical Sciences, and Research Centre for Carbon Solutions, Heriot-Watt University, Edinburgh, UK) and Jennifer Wilcox (Worcester Polytechnic Institute, Worcester, MA, USA).
The article presents an easy to read figure showing the range of Negative Emission Technologies (NETs) that have been proposed, the key routes being:
- Terrestrial management growth (trees and biochar)
- Marine management growth (marine organic carbon and ocean sedimentation)
- Silicate materials dissolution (transformation of minerals to bind with CO2)
- Carbonate mineral dissolution (calcium bicarbonate solution and lime addition to the ocean)
- Direct air capture (liquefying CO2 to inject underground or deep under water)
The article very neatly identifies all the major pathways available to sequester CO2, most of which involve mimicking natural processes.
A next step must involve an open discussion of the relative merits of each pathway, including the relative scale of each with estimates of the likely achievable sequestration rate (tonnes/year) and ultimate capacity limit of each pathway; the energy balance – how much energy is consumed per tonne of CO2 sequestered; the capital and operating costs/tonne; the management and human effort required/tonne; and the start/ramp up rate for each pathway (e.g. we can plant trees today)
HCS is providing some answers to these questions in our whitepapers to help you, our readership, to better understand what can be done to avert the looming climate catastrophe.