Carbon capture options

2020-01-27

in Economics, Photography, Science, The environment

Because the alternative is deep and rapid emissions cuts which countries are unwilling to implement, the IPCC now assumes that stabilizing the climate will involve heavy use of negative emission technologies: “between 100bn and 1trn tonnes of CO2 to be removed from the atmosphere by the end of the century if the Paris goals were to be reached; the median value was 730bn tonnes–that is, more than ten years of global emissions.”

There are numerous possible options. CO2 could be separated from flue gasses from power plants, compressed, and injected underground. If those power plants burn biomass which recently took CO2 out of the atmosphere, that could help draw down the stock of carbon in the atmosphere. That approach is called bioenergy with carbon capture and storage or BECCS. It’s also possible to separate CO2 directly from the air and bury it (direct capture). It’s also worth bearing in mind that sometimes CO2 is injected underground to push up oil to be sold (enhanced oil recovery or EOR). In that case, it likely creates more emissions than it avoids since the same volume of oil is pushed out and then likely burned in a vehicle where it cannot be captured.

All this may be highly questionable as a climate change solution and, indeed, the main push for CCS is from corporations and states that don’t want to give up fossil fuel production. The notion the technology will eventually exist at scale helps justify today’s fossil fuel burning, even though right now we’re buying about 40 million tonnes of CO2 while emitting 43.1 billion tonnes. Burying any substantial fraction of global CO2 emissions would mean compressing and burying many times the total quantity of oil we take out of the ground — with everything that implies about costs, deployment times, and capital requirements — and this whole infrastructure would require energy to run instead of producing it, either requiring us to deploy yet-more climate-safe energy to build and power the equipment or putting us in the self-defeating position of burning more fossil fuels to generate energy to bury the CO2 from the fossil fuels we already burned.

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