Siphoning excess carbon dioxide from the atmosphere has been suggested as a supplementary measure to contain anthropogenic climate change by the scientific community—and as the only rational measure to control emissions, by those who oppose sustainability restrictions on GHG generating human activities. The problem is that direct capture of CO2 is prohibitively expensive, and it is near impossible to set up adequate capacity at such costs to have a meaningful impact on stalling warming.
Direct air capture, as per a 2011 study by the American Physical Society, cost $600 to pull out 1 tonne of CO2 from the atmosphere—for perspective, human activity dumps nearly 30 billion tonnes of CO2 into the atmosphere every year. Carbon capture or negative emissions technology, therefore, hasn’t been considered central to emissions control so far. However, a study in Joule, by researchers at Carbon Engineering in Calgary, Canada, says that cost of pulling out a tonne of CO2 could be brought down to just $32-94.
While direct capture has relied so far on capture, release in a controlled, contained manner and eventual underground dumping of CO2, Carbon Engineering says it has come up with a method to use the captured CO2 to generate low carbon fuels. This defrays some of the costs, bringing overall spend down to $94. Now, considering carbon capture to just offset emissions by vehicles, a $100 cost per tonne means petro-fuels prices going up by nearly $0.25, as per Nature. Carbon credits and carbon capture/sequestration rewards can help offset some more of the cost.
While this means negative emissions could become more cost-effective in the near future, scientists have warned that these, at best, should be treated as supplementary to actually reducing emissions, given the effects of underground dumping and other disposal are not fully clear. To that end, negative emissions remain one of mankind’s bets, not its only, as some would have it.