Is Carbon Sequestration Completely Useless?

I have been giving Mark Jaccard and other carbon sequestration enthusiasts a hard time, but does that mean that carbon sequestration is a complete waste of time? Not necessarily, but you have to be aware of the costs and of the niches where the technology is a good fit. At the very least it is a good way to hoist the coal industry on its own petard. They say sequestration will make them as green as other fuels? Fine, you can still sell coal as a fuel as long as you reduce emissions to the level of natural gas. We're not putting you out of business, we just believe you're telling the truth about sequestration, wink, wink.

As I have mentioned before, the concentration of CO₂ in flue gas is so low, and the cost of separating it out is so high both in terms of money and in terms of GHG emissions that it is not worth tackling that problem and probably will never be. It's much better value for money to just stay away from high-carbon fuels as much as possible. It's like the problem with extracting fuel from the tar sands. Right now extracting uses large quantities of natural gas as feedstock and other energy sources to move the stuff and heat it up. You could then add more energy and use it to sequester some of the carbon. But when you do all the math a much simpler solution is staring you in the face: rather than using natural gas to process the tar sand into a fuel, use the natural gas as a fuel directly and leave the tar in the ground. You get to deliver a cleaner fuel to markets, at lower cost and with much lower GHG emissions. And you avoid destroying the entire Athabaska basin. Everybody wins.

Back to carbon sequestration. There are plenty of processes where CO₂ is produced in higher concentration, where the separation cost is much lower. Right now that CO₂ is usually just being released into the air. There are also plenty of processes that consume CO₂ and where customers are willing to pay good money to get a source of it. So much so that there is a market for the drilling of underground CO₂ wells, taking naturally sequestered CO₂ out of the ground to satisfy a market demand. The low-hanging fruit is to bring the two together, to make sure that CO₂ in the ground stays in the ground, and then to make sure that everyone captures the easily captured CO₂ and that any excess that can not be used gets buried.

Some of the easily captured sources of CO₂ include ammonia production for fertilizer, fermentation, lime calcination, detergents, and natural gas wells. Oddly enough, when producing "clean energy" like fuel ethanol or natural gas, a lot of CO₂ get dumped into the atmosphere. Most gas wells contain a lot of CO₂. The industrial processes for preparing the gas for market does the separation of practically pure CO₂ at virtually no additional cost. Don't release it, capture it and make gas even greener. If possible, sell it. If not, back in the ground it goes.

Fermentation, particularly for alcohol, produces a lot of CO₂. That's why beer has bubbles. Actually, that used to be the reason. Often the CO₂ produced is released into the air during fermentation, and other CO₂ is pumped into the beer at the end. Remember that for every molecule of ethanol that you drink or put in your car, a molecule of CO₂ escapes into the atmosphere. Catch it and use it.

Various chemical processes generate CO₂. In some cases, petrochemical plants are already capturing it. There is the famous example of the ethylene glycol plant of Shell Chemicals in Scotford selling CO₂ to Air Liquide, which processes it for the soft drink industry. But larger-scale processes could also capture their CO₂, including the production of ammonia and the calcination of carbonates in lime kilns to make cement. Again, the gas is produced in high concentrations and is easily captured.

Various processes use CO₂. Some use it and sequester it, and some use it and release it, so the same argument applies to them: catch it and recycle it. It's used in the beverage industry. Huge waste - it necessarily gets released into the air. It's used in refrigeration as dry ice or to replace freon. Well, it's better than freon anyway but it is still released into the air. Is it better in terms of CO₂ to use dry ice in refrigeration rather than portable refrigeration units? Not sure. It's used in some chemical processes: urea and ethanol. It's used in enhanced oil recovery. It's pumped into the ground as a solvent. That has the potential to be sequestered, but in actual fact it gets pumped right back out once it's done its job underground and tends to be released into the air. Close but not quite there. It can also be used in greenhouses, for two purposes - as a pesticide since it is after all a poison in high concentration, and to enrich the air. Plants convert it into sugars and such things. Give them a little more in their atmosphere and it replaces some fertilizer, and allows cold countries to reduce their food imports a bit. The processes that use CO₂ already get it in part from the process that produce it, and in part from CO₂ wells. Let's at least put the wells out of business. In relative terms it's not a major part of our total GHG emissions that are affected, but it's a start and it's cheap to do compared to alternatives.

All of this is to say that carbon capture has a role to play in reducing greenhouse gas emissions, particularly by co-locating producers and consumers of CO₂. And you can also often use the synergy to make use of waste heat. Carbon storage also has a role, when all the CO₂ that is easily captured has saturated the market for industrial uses and can be buried relatively cheaply. But extracting it from flue gas to bury it? Only when through conservation and efficiency we have eliminated all the high-carbon fuel use (coal, tar sand, heavy oil, biofuels) that we can. Then when carbon taxes reach $150 a ton it becomes worthwhile to consider extracting CO₂ from flue gas. But that's really a last resort. There is no good reason to ever choose carbon capture and storage over other alternatives, say the experts. Wind, solar, and conservation are a lot cheaper for the same effect.

Tags: Greenhouse Gas Kyoto Protocol Climate Change Energy Carbon Capture Environment

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