It is technically possible to capture CO2 from air at industrial scale. Indeed, technologies for industrial air capture were commercialized in the 1950s for pretreating air prior to cryogenic air separation. The cost of air capture is, however, uncertain and disputed. Some have argued that the costs would be prohibitively high (Herzog, 2003) or that investing funds into research on air capture is a mistake because it diverts attention from more important areas (Mark Jacobson as quoted in Jones, 2008). In sharp contrast, others have argued that air capture might be comparatively inexpensive and that it could play a central role in managing carbon dioxide emissions (Pielke, 2009).
Our view is that air capture is simply another large chemical engineering technology. Its cost will depend on the technology employed, as well as the cost of materials, labour and energy. The economics of the process will determine its feasibility but will not be well defined until more work has been done on specific processes. As with other significant climate-related energy technologies it will not be possible to determine the cost with precision by small-scale academic research. Instead, costs will only become clear through pilot-scale process development and through costing by contract engineering firms with relevant expertise.
In our view, such development is justified for three reasons. First, early estimates suggest that the CO2-abatement cost of air capture is less than other technologies that are getting very large research and development investments. For example, the cost of cutting CO2 emissions by displacing carbon-intensive electricity production with roof-mounted solar photovoltaic panels can easily exceed 1000 $/tCO2. We are confident that a straightforward combination of existing process technologies could achieve air capture at costs under 1000 $/tCO2. Indeed, neither we nor others working in this area would be commercializing these approaches if we were not able to convince investors that we could develop technologies to capture CO2 from air at costs many times less than 1000 $/tCO2.
Second, air capture offers a route to making carbon-neutral hydrocarbons fuels (CNHCs) for vehicles by using captured CO2 and clean energy sources to make synthetic fuels with desirable handling and combustion properties. Deep reductions in emissions from the transportation sector will require a change in vehicle fuel. Each of the three leading alternative fuel options - electricity, biofuels and hydrogen - face technical and economic hurdles which preclude near-term, major reductions in transportation emissions by using these technologies. Carbon-neutral hydrocarbons represent a fourth, fundamentally different alternative, a method for converting primary energy from sources such as solar or nuclear power into high-energy-density vehicle fuels compatible with the current vehicle fleet. As stated in Zeman and Keith Chapter 7, this volume:
We argue for the development of CNHC technologies because they offer an alternate path to carbon neutral transportation with important technical and managerial advantages. We do not claim that CNHCs are ready for large-scale deployments or that they will necessarily prove superior to the three leading alternatives. We do argue that they are promising enough to warrant research and development support on a par with efforts aimed at advancing the alternatives.
Finally, air capture allows negative global CO2 emissions. While the prospect of achieving negative global emissions is distant, it is important because it represents one of the few ways to remediate human impact on climate. Without the ability to take CO2 out of the air, the climate change arising from current emissions is essentially irreversible (Solomon et al., 2009).
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Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.