Legal Commentary

Fun With Carbon Dioxide

By Professor University of Miami School of Law

New materials can selectively capture CO2, scientists say:

Scientists have created metal-organic crystals capable of soaking up carbon dioxide gas like a sponge, which could be used to keep industrial emissions of the gas out of the atmosphere.

Chemists at the University of California Los Angeles said the crystals — which go by the name zeolitic imidazolate frameworks, or ZIFs — can be tailored to absorb and trap specific molecules.

[Prof. Omar] Yaghi and his colleagues describe their findings in the Friday issue of the journal Science.

He said the crystals are non-toxic and would require little extra energy from a power plant, making them an ideal alternative to current methods of CO2 filtering. The porous structures can be heated to high temperatures without decomposing and can be boiled in water or solvents for a week and remain stable, making them suitable for use in hot, energy-producing environments like power plants.

The team of scientists created 25 ZIF crystal structures in a laboratory, three of which showed a particular affinity for capturing carbon dioxide. The highly porous crystals also had what the researchers called “extraordinary capacity for storing CO2”: one litre of the crystals could store about 83 litres of CO2.

How much of this stuff do we need to stop adding carbon dioxide to the atmosphere?

According to Gary W. Harding, How Much of Atmospheric Carbon Dioxide Accumulation Is Anthropogenic?

Today, the atmosphere contains about 720 Gtons of carbon. The concentration of carbon dioxide is about 360 ppm. Regardless of its source, one billion tons of carbon released into the atmosphere as carbon dioxide would increase its concentration by 0.5 ppm (360 / 720) if all of it stayed there. However, scientists estimate that about half of present human carbon emissions are absorbed by the environment. Of the half absorbed, scientists have accounted for where half of that goes. Where the other half goes is the “mystery of the missing carbon” (about 1.8 Gton per year).

A gigaton, by the way, is a thousand million tons. And that’s 1998 data on stocks not flows.

According to Table 3.2 on page 30 of Global Warming: The Complete BriefingWe’re up well past 7.5 GT added annually to the atmosphere due to fossil fuel burning and deforestation.

So to make humans carbon-neutral at present rates of emissions, we need what exactly? Let’s fire up the calculator.

One litre of carbon dioxide at standard atmosphere and pressure weighs 1.965 grams. So 1 GT approximately equals a pentagram (10 to the 15th power).

Divide 7.5 of those penagrams by 1.965 grams and we get a measly 3.82 GT of these crystals. Per year. Assuming fossil fuel use stays flat.

How does this compare to this zany idea?

…a concept … for removing carbon dioxide from the air and turning it back into gasoline.

The idea is simple. Air would be blown over a liquid solution of potassium carbonate, which would absorb the carbon dioxide. The carbon dioxide would then be extracted and subjected to chemical reactions that would turn it into fuel: methanol, gasoline or jet fuel.

…

Even with those improvements, providing the energy to produce gasoline on a commercial scale — say, 750,000 gallons a day — would require a dedicated power plant, preferably a nuclear one, the scientists say.

According to their analysis, their concept, which would cost about $5 billion to build, could produce gasoline at an operating cost of $1.40 a gallon and would turn economically viable when the price at the pump hits $4.60 a gallon, taking into account construction costs and other expenses in getting the gas to the consumer. With some additional technological advances, the break-even price would drop to $3.40 a gallon, they said.

A nuclear reactor is not required technologically. The same chemical processes could also be powered by solar panels, for instance, but the economics become far less favorable.

This is not a small problem.

Full post as published by Discourse.net on February 20, 2008 (boomark / email).