I gave a talk at ICCDU-IX (International Conferences on Carbon dioxide Utilization -IX ) held at Kingston, Canada from July 8-12. I came across a lot of interesting presentations. Below is a summary of the presentations I attended:
1. Stern Review on the economics of climate change: looking at the costs of action vs. costs of inaction (doing nothing).
It concludes that the costs of doing nothing are far worser than acting to stabilize GHG concentrations.
2. Carbon tracker (Pieter Tans, NOAA) : gives CO2 fluxes by region (2001-2005). Measurement of CO2 in the atmosphere becomes critical to enforce any GHG mitigation policy. In a scenario when the actual decrease in GHG concentrations are less than the claimed reductions, the Carbon tracker hopefully can tell us what the actual GHG emissions for a given place are.
3. CO2 utilization: Prof. Beckman (U Pittsburgh) mentioned that CO2 utilization cannot make a meaningful contribution towards reducing CO2 emissions by itself, but rather the idea is to use CO2 in processes that either result in lowered energy consumption (decreasing GHG emissions indirectly) or do not use toxic chemicals like phosgene/Cl2 . Most of the CO2 utilization sessions involved (organic) chemistry that simply went over my head. Most papers were about the the use of CO2 as a reactant (synthesis of aliphatic/aromatic carbonates & copolymerization reactions of CO2) and the use of CO2 as a solvent/reaction medium.
Apart from supercritical CO2, I have also noticed increasing interest in using CO2 expanded liquids (solvents).
4. CO2 capture:
Ionic liquids (IL): Their use and functionalization for tuning their CO2 absorption & selectivity is also a important area of research. (Both of the presentations on ILs mentioned this.) It was interesting to see that ionic liquid by itself absorbs CO2 physically, so heats of absorption are pretty low, amines absorb(complex) chemically, therefore heats of absorption is high, but energy penalty (CO2 stripping from amine & amine volatility) is also high. Therefore, tuning amine functionalized ILs might lower delH while preserving the selectivity for CO2. (I wonder if anyone has done molecular modeling on this stuff to design ionic liquids that have moderate delH as well as good CO2 absorption properties or to atleast understand the cation/anion effects on CO2 absorption).
5. Ideas for the cement industry:
Zeman F.S., Lackner K.S., Zero Emission Kiln, International Cement Review, May 2006
The process produces a pure stream of CO2 gas that does away with the amine capture stage. Basically the idea is similar to oxy-fuel combustion in a thermal power plant, but is a bit more challenging since the end product has to be (clinker, to make) portland cement. (Maintaining normal kiln and cooler operation in a unmodified cement plant is difficult enough already 
. Instead of cooling the clinker with air, in the ZEK process, CO2 is used. This can promote adverse reactions with the hot clinker (surface carbonate formation).
(Another presentation by Zeman that I did not attend was the process study of coupling an atmospheric CO2 capture facility (see below) to the synthesis of syngas by CO2 reforming of CH4.)
For the same industry, Ghosal (McGill U.) showed that concrete can serve as a means to sequester CO2. Carbonated concrete can be used as prestressed concrete blocks. One thing that strikes me now is that how can anyone sequester more CO2 back into concrete than was released due to calcination (and fossil fuel combustion). It now seems a little fishy to me now that I think of carbonating the concrete mixture (assuming the alite and belite mineral phases (tricalcium and dicalcium silicates) are the reactive components. (This shows how attentive I have been )
6. Geologic sequestration: Shell Canada is proposing to build a pipeline to transport CO2 (produced from their oil sands processing Scotford upgrader) near Edmonton to nearby depleted oil & gas wells or a geological storage site. The pipeline is designed for 1.2 million T CO2/year. They find that after their preliminary design stages, their project still does not make economic sense at current CO2 prices (they needed an additional ~ 30-40 $/T CO2 to make the project viable). Therefore, they are looking to the (Canadian) federal government to help facilitate this project by providing tax incentives for the pipeline. (Shell Canada hopes to use this pipeline for carrying CO2 from other producers, like a nearby thermal powerplant.)
7. Geoengineering:
Prof. David Keith (U Calgary) mentioned some of his ideas about large scale geoengineering to control atmospheric CO2 emissions. He showed a lab scale atmospheric CO2 capture system involving NaOH and CaCO3 cycle. Another proposal was the release of reflective photophoretic metal oxide particles into the atmosphere to reflect the incoming visible radiation. (The photophoretic property is needed since otherwise these particles will act as catalysts for ozone layer destruction.) He was however very clear that these approaches are a short term solution, and should not be the main GHG mitigation strategy.
Dr. Herman Ott (Wuppertal Institute, Germany) in his talk about policy challenges of GHG mitigation also mentioned that if we do not reach an agreement as to what would replace Kyoto protocol by the end of this year, and adopt a business as usual approach, we probably will be seeing hectic geoengineering towards the end of 2010-2012 as GHG concentrations continue to rise. It was also mentioned that the prominent mood amongst policymakers was a shift from denial to desperation.In that aspect, I think that the conference did a good job of bringing people from all three aspects of this problem together to make them aware of what is happening.
There were a lot of interesting presentations that I could not attend (we had parallel sessions). A detailed program schedule with the abstracts of presentations is available at the ICCDU-IX website .
