Carbon Sequestration Capacity is Very Large

Michael Tobis

Michael Tobis, editor-in-chief of Planet3.0 and site cofounder, has always been interested in the interface between science and public policy. He holds a doctorate from the University of Wisconsin - Madison in Atmospheric and Oceanic Sciences where he developed a 3-D ocean model on a custom computing platform. He has been involved in sustainability conversations on the internet since 1992, has been a web software developer since 2000, and has been posting sustainability articles on the web since 2007.

Although there are many hurdles between us and “clean coal” or clean gas for that matter, the capacity of the ground to hold the CO2 for long enough to matter does not appear to be among them, according to a new USGS study.

After taking a look at suitable underground rock formations across the country, scientists with the U.S. Geological Survey say there’s the potential to store more than 500 years’ worth of carbon dioxide emissions, which have been blamed for contributing to global warming.
…
There’s the potential to store between 2,400 and 3,700 metric gigatons of CO2 across the United States, according to the USGS study, which was released in late June. In 2011, the nation emitted about 5.5 metric gigatons of energy-related CO2, while global emissions totaled about 31.6 metric gigatons.

Whether this is cost effective or not is for the marketplace to decide. Whether it is required or not for using carbon is a regulatory issue. But it solves the question of whether carbon neutral power can be made reliable. It can.

Mike Mann argues

“Sequestration is certainly better than no sequestration in most circumstances,” …

“I think there are a number of false premises that underlie the belief that carbon capture and sequestration is some sort of silver bullet in the effort to move toward a carbon-free energy economy,”

and others have taken Myles Allen to task for suggesting that it is a silver bullet. But this enormous capacity is encouraging.

We can electrify everything except air travel, and we can pay a little more for electricity. We can do this with fossil fuels if the fossil fuel interests sequester CO2, which is already technically feasible. Alternatively we can electrify with renewables if they find ways to load balance. Then we can run airplanes on biofuel. We can live more or less normal modern lives with a stable climate, just by adjusting to a one-time increase in energy prices.

Or we can argue and delay ourselves to oblivion. For some reason we are choosing the latter course.

Comments:

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Big reservoirs is good news.

Not just air travel: certain types of road vehicles, most ships, steel and aluminum process emissions, cement production, etc.

At this point the only meaningful hurdle* between us and CCS is that nobody wants to pay for it.

I think that the reason the demonstration projects all die is because there really isn't anything to prove. All the elements have been proved in isolation; there really isn't any reason to run a CCS project unless someone is going to pay for each ton you put away.

*standard disclaimers about unknown unknowns apply.

The "some reason", in my opinion, is the subsidy government gets from fossil fuel users.

There's a lot of room on the surface, too. After the heat of burning 0.171 tonnes of carbon has been converted (33 percent) to 0.514 electrical megawatt-hours, 0.1 of these MWh can be used to pulverize (to 25 microns) two tonnes of a silicate rock that is 50 mass percent forsterite, and 50 kWh to get the dust 5 km above ground level.

In air, 25-micron particles settle 1 km every 16000 s, so lifting them this high allows them to be distributed by the wind for about a day. Thereafter they sit on the soil or get mixed shallowly into it, and take CO2 out of the surface or near-subsurface air for the next few months.

Schuiling and Tickell propose rail transport for the powder, but by the time the world's fossil-profiteering governments feel enough urgency to spend gigadollar one of their petro-trillions on this ... really that should be oleo-trillions, but somehow out of petr-oleum the wrong bit of Latin has taken the meaning ... they're going to want to get the thing done, and as a rock dust distributor, wind is already in position on the required scale.

One-quarter of the pulverization energy is how I recalled the lifting-to-5-km energy, and got the 50 kWh for two tonnes, but a quick mgh calculation, 2000 kg * 9.80665 N/kg * 5000 m, is giving 27.24 kWh. I must have allowed for plenty of inefficiency in the lifting.

Great. I've been waiting for these numbers. But what about the CO2 sequestration potential? And 25µ is the absolute lower limit, otherwise there's some health hazard:

The size of particles is directly linked to their potential for causing health problems. Small particles less than 10 micrometers in diameter pose the greatest problems, because they can get deep into your lungs, and some may even get into your bloodstream.

http://www.epa.gov/pm/health.html

Great. I’ve been waiting for these numbers. But what about the CO2 sequestration potential? And 25µ is the absolute lower limit, otherwise there’s some health hazard:

... Small particles less than 10 micrometers in diameter pose the greatest problems ...

I hadn't been aware you were waiting for the numbers.

The sequestration potential of two tonnes of 50-mass-percent Mg2SiO4 stuff is equal, I forgot to say, to the CO2 production from burning the mentioned 171 kg C.

That's according to this stoichiometry:

Mg2SiO4 + 2 CO2 ---> 2 MgCO3 + SiO2

There are various ways of tweaking the figures; for instance, the two MgCO3s, if they dissolve and run into the sea, will do this:

2 MgCO3 + 2 CO2 + 2 H2O ---> 2 Mg(HCO3)2,

and that would double the effectiveness.

This is likely to get under way after the next two inundations of New York City's subway system, unless such events begin happening very frequently, in which case it may take several.

So particle inhalation risk, unless it's bizarrely large, may not count for much. Recall that a gigatonne removed anywhere is a gigatonne removed everywhere; the dispersal won't be over NYC, maybe not even over Brooklyn.

Fortunately, anyway comminution to 10 microns would much increase the energy cost and extend the particles' wind-riding time unreasonably. A day is plenty. With suitable choice of wind speed and direction, an hour might well be.

Why doesn't someone who can, and isn't me unless I get around to it, work up a well-annotated spreadsheet? So that tweaking the inputs is easy.

Another tweak, for instance: count the energy released by hydrogen that burns along with the carbon.