by Kevin Kilty

An article in the January 2020 Issue of Physics Today (1) presents an interesting and very readable overview of methods to capture and store away CO₂ emissions. The purpose of this guest blog is to summarize a few key points the paper makes, and add some commentary. WUWT has covered some of this same territory recently here and here.

Motivation

Of course, the motivation for negative emissions technologies (NETs), or CO₂ capture, is to bring atmospheric CO₂ back to safe levels. Although the article fails to mention what safe means in this context, and what levels are unsafe, it alludes to melting polar ice and methane escaping from melting permafrost as consequences of unsafe climate. Nothing unusual here. Despite relegating its case for an unsafe future to such enterprises as the IPCC, the article does provide some insight into the cause of what seems to be the current “crisis” mentality. It is 1.5°C temperature rise goal of the 2015 Paris agreement. As readers of WUWT already know, this is not a 1.5°C increase from now, but rather from an estimated pre-industrial level — meaning that two-thirds of that margin is already gone and we have but 0.5°C left to work with. I suspect most people do not understand this subtle point.

Eventually the article makes a brief excursion into more phenomena by which climate change would become unsafe — forest fires, droughts, and sea level rise. All of this is also familiar to WUWT readers.

Technologies Involved

The best part of the article is its summary of technologies, the NETs, that might be able to remove 10 to 20Gt of CO₂ annually from the air above and beyond the approximately one-half of our 37Gt (Gt = 10¹² kg)annual emissions which will eventually be captured by nature anyway.

Biological solutions (BECCS)

These include policies to prevent deforestation combined with technical efforts at reforestation, afforestation (establishing forests in regions not previously forested), and better agricultural practices. While estimates are that perhaps 3.5Gt of CO₂ could be captured annually with these methods, Stanford’s Rob Jackson and Columbia University’s Julio Friedmann point out the lack of details about land and ecosystems disturbances, water usage, land-owner incentives and needed resources such as energy and nutrients. Once possible negative side effect of forestation the article fails to mention is the potential albedo feedback of darkening a billion hectares of Earth’s surface.

Carbon Capture and Storage (CCS)

Although not discussed specifically in the article, CCS is established in a few instances, and the captured CO₂ used to enhance fossil fuels recovery. David Middleton has written here and here about the technology.

Direct Air Capture (DAC)

These are essentially chemical engineering systems which draw atmospheric air into some sort of solid resin or liquid solution which captures CO₂ in controlled conditions (low temperature or low humidity) and then releases it under altered conditions. Anyone familiar with an ammonia absorption refrigerator would recognize the scheme. Once captured the system stores CO₂ into porous geological reservoirs; or stores it in mineralization such as specialty concrete or in situ subsurface minerals such as olivine.

Jennifer Wilcox of Worcester Polytechnic Institute makes an interesting observation that most of the people promoting DAC are physicists. This reminds me of the energy crisis of the 1970s where physicists promoted, aggressively, a number of advanced energy conversion technologies like MHD, fusion, solar arrays in orbit; which not only couldn’t be made economical, but in some instances couldn’t be made to work.(2)

Incentivizing action

Putting aside the question of the very need for all these activities, the weakest part of the discussion is its failure to specify any realistic means to overcome the principle obstacles: sources of energy, cost, financing of R&D, and paying O&M costs.

The ubiquitous benchmark for all these technologies appears at present to be able to capture and store for about $100 per tonne of CO₂ (1000 kg tonnes). Yet, even $300 per tonne might seem cheap the article suggests if the worst of climate change become reality. A cost of $100 per tonne of CO₂ captured implies a “cost” of burning a gallon of gasoline as about $1.30.(3)

All of the proposed technologies require energy input. If this energy comes from fossil fuels, it simply leads to more CO₂ to capture and costs climb commensurately — to estimates of $1000 per tonne in some instances. Financing the required R&D appear just a matter of enacting a few billion to a few tens of billions of dollars of Federal support, and the O&M costs might be covered by partnerships with industry who have need of the CO2, like the petroleum industry, or covered by the taxpayer in subsidies and production credits, or a carbon tax. The proponents are optimistic. As the article quotes one…

“We know the recipe; we’ve done it over and over again. We have sustained, long-lived R&D programs that drop the price enough that we start making policy. And then we expand policies to align with markets. That is exactly what we did for solar, wind, and nuclear, and batteries.”

The recipe does seem familiar, but not necessarily successful. We have no economical grid scale batteries. Wind and solar have small market penetration so far except in special circumstances. And there is at least a suspicion that rather than align with markets, too much wind and solar undermines markets.

Despite its shortcomings the article is well assembled and informative.

Notes:

• (1) David Kramer, Negative Carbon Dioxide emissions, Physics Today, Vol. 73, No. 1, p.44-51 , January 2020.
• (2) Much of the current climate crisis resembles the energy crisis of the 1970s, especially in the variety of complex solutions being offered, and in a hurry up and do something mania. In the 1970s much of the hurry up policies made problems worse and eventually had to be undone.
• (3) Holman Jenkins in the January 21, 2020 issue of the WSJ wrote that “A carbon tax equivalent to 13 cents per gallon of gasoline would have let Republicans in 2017 realize their fondest tax-reform hopes….” But the costs being considered here show a disparity that green groups would decry. A 13 cents per gallon tax would only be an appetizer.