Climate Intervention Carbon Dioxide Removal and Reliable Sequestration (2015) / Chapter Skim
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2 Carbon Dioxide Removal
2 Carbon Dioxide Removal
Pages 29-38
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From page 29... ...
To put these rates and totals in context, Table 2.1 summarizes human emissions of CO2 and the associated increase of CO2 in the atmosphere and CO2 sinks since 1750 and in a recent 10-year period. Over the past decade, human activities have produce approximately 34 GtCO2/yr annually with about 16 GtCO2/yr, or about 2 ppm/yr, accumulating in the atmosphere (more recent estimates of annual emissions sources are ~39 GtCO2/yr: 36 GtCO2 from fossil fuel combustion and cement production and ~3 GtCO2 from land use changes [Global Carbon Project, 2014]
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From page 30... ...
Using his energy budget model, he estimated that a 50 percent increase in CO2 would raise global temperatures by about 3°C to 3.5°C, while a reduction of CO2 by one-third would lower temperatures by roughly the same amount. His was in essence a geological model, used to examine the onset of ice ages and interglacials, in which he considered volcanoes and not coal burning to be the "chief source of carbonic acid for the atmosphere." However, since he estimated that burning the world's annual production of coal -- at that point in time approximately 500 million tons -- produced about one-thousandth of the total atmospheric concentration of carbon dioxide, he realized that humans could have a major influence over the course of a millennium (Arrhenius, 1896; Fleming, 1998)
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From page 31... ...
. to operate in tandem with the carbon dioxide scrubbers." Over the course of recent history, as knowledge of the role carbon dioxide plays in climate change has been developing, so too there have been many grand ideas about how to alter the carbon cycle (Fleming, 2010)
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From page 32... ...
An additional challenge is the continued appetite of modern society for energy fueled by carbon-based sources. Efforts by developed nations to cut their emissions through conservation and increased reliance on renewable energy sources have been more than offset by growth in energy demand by developing nations, which has largely been met by fossil fuels (IPCC, 2014b)
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From page 33... ...
combined with the capture and sequestration of the CO2 generated during oxidation and gasification; this is referred to as bioenergy with carbon capture and sequestration (BECCS) .3 Chemical separation methods that directly capture CO2 from ambient air combined with long-term CO2 disposal is referred to as direct air capture and sequestration (DACS)
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From page 34... ...
Red arrows and numbers indicate annual anthropogenic fluxes averaged over the 2000-2009 time period. These fluxes are a perturbation of the carbon cycle during Industrial Era post-1750.
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From page 35... ...
, the middle panel shows the components involved in direct air capture and sequestration (DACS) , and the bottom panel shows the components involved in bioenergy with carbon capture and sequestration (BECCS)
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From page 36... ...
. A more thorough assessment that could inform prioritization of future research and development efforts would in addition assess risks, costs, and efficacy, as well as the potential for research and development to reduce barriers to widespread deployment.
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From page 37... ...
• Ocean -- available cheap alkalinity Ocean 1d ~ 100 50-100f Ocean iron fertilization 1-4g 90-300 500h E • nvironmental consequences and potential co-benefits U • ncertainty in net carbon sequestration Bioenergy with capture 15-18i 100-1,000j ~100k S • equestration of 18 GtCO2/yr requires (Theoretical) ~1,000 million acres of arable land (1,530 million acres available worldwidel; actual amount of arable land available Capture for bioenergy production will likely be significantly less because much of arable land area is required for food production)
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From page 38... ...
m If fueled from solar, assuming an estimate of ~11 acres per MW electricity used for powering direct air capture (DAC) , and based on the range of energy requirement estimates in the literature, ~31,000 acres required to remove emissions associated with one 500-MW power plant (i.e., 11,000 tCO2/day)
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