Thread by @Peters_Glen

THREAD

We need research, development, & eventual deployment of negative emission technologies, but relying on them at scale is an unjust and high-stakes gamble.

science.sciencemag.org/content/354/63…

The first part of this sentence means that @KevinClimate & I support the great work of @DKeithClimate & colleagues. The second part pissed many people off, particularly people working on these technologies. science.sciencemag.org/content/354/63…

We now have the first detailed engineering cost breakdown of a Direct Air Capture plant (1MtCO₂/yr), putting the levelized costs at $94 to $232 per tonne CO₂. There seems to be some excitement about this, so let's have a look sciencedirect.com/science/articl…

This means it is still he most expensive way to tackle climate change, just less expensive then before. If we have any carbon policy, then all other low- or negative-carbon technologies become relatively more attractive. DAC is still the least attractive (in terms of cost).

These are cost estimates, no one is deploying this technology in anything other than pilot scale. Carbon capture & storage is considerably more advanced, & we still can't get that deployed at any meaningful scale with today's climate policies. What hope for DAC?

A new study put the cost of DAC at $100-300/tCO₂ (hmmm, did they know about the Carbon Engineering's estimates). This makes DAC the most expensive way to remove carbon from the atmosphere, but it *may* have more scale potential then others.
doi.org/10.1088/1748-9…

Integrated Assessment Models love negative emissions, but most don't include DAC. If the cost of DAC goes from the previous $600t/CO₂ to $100-300/tCO₂, then IAMs will deploy even more negative emissions. This will just exacerbate our concerns.
science.sciencemag.org/content/354/63…

Then these is the excitement over "air to fuels". Free & limitless PV/batteries driving DAC with the CO₂ converted to fuels, CO₂ re-emitted on fuel use, & the cycle continues. I love it. I also love Star Wars. Great, but how does this help address climate change?

Air to fuels may have applications in some boutique sectors (say fuel for aviation). There are many ways to produce low-carbon fuels, I think it is a long time before air to fuels is the cheapest or most useful in a climate context.

Hats of to @DKeithClimate & team, but I don't understand the excitement here (not blaming David for this). Are people excited as they see DAC, air to fuels an alternative to mitigation? Frankly, if we continue to belch out 40GtCO₂/yr, then all of this research on DAC is in vain?

Back to the "moral hazard" (sorry @DMReinerCamb). I know this term gets people hot under the collar, but the excitement around CO₂ removal sort of proves the point? We get excited about fancy "save the world" technologies, but don't want to get our hands dirty with mitigation.