Saturday, August 18, 2018

Cost of Carbon Capture:  Can Young People Bear the Burden? - by James Hansen & Pushker Kharecha

It feels as if the world is almost sleepwalking into a tragedy for humanity and many other species on our planet.  Estimates for the dangerous level of global warming have declined, as recognized in the United Nations Paris Agreement, which aims to “strengthen the global response to the threat of climate change by keeping global temperature rise this century well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5°C.”  Yet global fossil fuel emissions, the principal cause of global warming, continue at a high level, even rising (Figure 1).

The Intergovernmental Panel on Climate Change, in response to continued high emissions, began assessing so-called “negative emissions” in its climate scenarios.  Indeed, extraction of CO2 from the air is now almost surely required if global temperature is to be stabilized at a level avoiding disastrous consequences.  Are such negative emissions a plausible assumption?  Will today’s young people be able to afford the cost of negative emissions?

Keith et al. built a pilot plant capturing CO2, which provides the best basis so far for estimating the cost of CO2 extraction.  Their estimated cost range is $94–$232/tCO2, where tCO2 is metric tons of CO2.  This cost appears to be much lower than estimates in an earlier study.  However, it would be a grave misconception to think that the Keith study provides hope for a “get out of jail free card” for the climate problem.

First, note that the $94/tCO2 estimate applied only to a case in which CO2 was processed to a point of being ready for use in production of a carbon-based fuel.  That use of the CO2 does not result in negative emissions when the fuel is burned.  Keith’s cost estimate for cases in which extracted CO2 is prepared for storage is $113–$232/tCO2.

Second, note that Keith does not include the cost of CO2 storage, which has been estimated as $10–$20/tCO2.  Inclusion of storage makes the cost estimate for carbon capture and storage (CCS) $123–$252/tCO2.

Finally, note that costs are often discussed in units of $/tC, where tC is tons of carbon.  A ton of CO2 is 44/12 times heavier than a ton of C.  Thus, the Keith study implies a removal cost of $451–$924/tC.

Hansen et al. used an optimistic cost estimate of $150–$350/tC for CO2 extraction.  Even that lower rate results in a removal cost of $89–$535 trillion over the next 80 years for a growth rate of emissions ranging from 0 (constant emissions) to +2 percent/year.

Global costs may be difficult for individuals to grasp.  In Figure 2A we show the cost of extraction per person for national emissions, based on the lower limit of Keith’s estimated cost $123//tCO2.  The current annual cost to extract all of the annual emissions is of the order of $1,000 per person per year in developed countries, about $600/person/year on global average.  Extracting all current emissions is a realistic approximation of the need, as the allowed carbon budget to keep warming in the range specified by the Paris accord is nearly exhausted.

Figure 2. Per Capita Annual and Cumulative Fossil Fuel Emissions (A and B) Update of Figure 6 of Hansen and Sato.8 Per capita cost for extraction of the emitted CO2 (right scale) assumes an extraction cost of $123/tCO2. (A) 2016 per capita emissions. (B) 1751–2016 cumulative emissions.(Credit: Click to Enlarge.Climate change is proportional to cumulative emissions.  The average citizen in developed countries such as the United States, the United Kingdom, and Germany has a debt of over $100,000 to remove their country’s contribution to climate change via fossil fuel burning (Figure 2B).

Political leaders celebrated the Paris Agreement, as they did the 1997 Kyoto Protocol.  Yet these are precatory agreements, wishful thinking, which do almost nothing to address the fundamental problem summarized so clearly in Figure 1.  The world is using a tremendous amount of energy, over 85% of which is provided by fossil fuels.  Even more energy is needed to raise standards of living globally, which is an underlying requirement for global fertility rates to decline to a sustainable level.

Read more at Cost of Carbon Capture:  Can Young People Bear the Burden?

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