I’m doing some work related to Geologic Carbon Sequestration (also called Geologic Capture and Storage): the idea is to capture carbon dioxide from power plants or other industrial sources, and pump it deep underground into geologic formations that will trap it for centuries or millenia. It sounds desperate, and I initially had substantial misgivings, but upon looking into it more I think it is a good idea and we should get started. But there are still some major political, legal, and economic issues that have to be resolved. I’m working on an issue that is on the border between the technical and regulatory spheres:
The State of California will soon be called on to decide whether sequestration should be allowed in some specific places. The government will have to assess the risks and decide whether a particular spot is “safe enough.” Any site that is likely to be proposed will be considered by experts to be highly likely to retain almost all of the CO2 that is pumped into it…but of course, the experts could be wrong. It’s very hard to characterize the subsurface—there could be faults or old boreholes that you don’t know about—so maybe the CO2 could leak out. If it does, bad things can happen.
One bad thing that could happen is that the carbon dioxide could leak into an aquifer and turn the water into something like Perrier. Doesn’t sound so bad—could even be worth a lot of money—but actually it could be a big problem. Carbonated water is acidic (carbonic acid), and could dissolve minerals and leach bad stuff like lead or arsenic into the water. That’s bad if the aquifer supplies drinking water!
One way to assess a site is to look at the “expected loss” or “expected cost” of using the site. For example, suppose the probability that CO2 will leak into the aquifer is 0.001, and if this does happen then the cost (e.g. the cost of purifying the water so people can still drink it) has a Net Present Value of $100 Million. Then the expected loss from this particular failure mode is $100,000.
Here’s the thing: we can estimate the cost, if there is a failure, fairly accurately: you can look at how much it costs to build a filtration plant or to import water from somewhere else, and get it maybe within a factor of 2. But the other part of the equation, the failure probability, is just impossible to answer. Some people will say it’s really high, some will say it’s really low. There’s very little in the way of empirical data, since there are only a few large-scale sequestration sites operating.
If we want to be sure that (probability of failure) x (cost of failure) is low, a common-sense idea is to start with sites where the cost of failure would be low: then it doesn’t matter if the probability of failure is a lot higher than we thought. As more sites are used, and are monitored for a few decades, we’ll learn more about our ability to predict subsurface CO2 behavior — we’ll never know less than we know right now! — and then we can relax the constraint on the (cost of failure) term and start looking at the putative product.
You’re with me so far, right? OK, then here’s where I need help: I need some examples of places where this common-sense idea was EXPLICITLY used in creating regulatory policy. I hope someone who reads this blog can help me here.