While live-blogging the Democratic debate on Sunday night, I took issue with John Edwards's contention that we could reduce the price of gas through tougher regulation of oil refineries. I argued that, since refineries tend to pollute because it's cheaper than not polluting, forcing them to clean up their act would raise production costs and, therefore, gas prices. (I think it's worth doing in any case; it just didn't immediately strike me as a path to cheaper gas.) In response, a diligent Edwards' staffer e-mailed me to note that it is, in fact, possible to reduce pollution while lowering costs. Here's the basic idea: As it stands, the oil refining process tends to release a lot of gas, known as "flare gas," into the atmosphere. In addition to polluting the air, the flare gas is a potentially valuable source of energy, meaning that capturing it could make the refining process a lot more efficient. Fortunately, it turns out that oil refineries can capture the flare gas by installing a piece of equipment known as a recovery compressor. The question, then, is how much does said equipment cost? If the compressors are exorbitantly expensive, then it could take years to accumulate enough savings to offset the upfront expenditure. That would count as an effective cost-increase in my book. If, on the other hand, the compressors were relatively cheap, then the payback time would be short, and it would make sense to talk about flare-gas recovery as a realistic cost-saving measure. So what's the answer? Tough to say, really, since there are so few data points to chew on. But the Edwards campaign does cite one encouraging example: a Shell refinery in the San Francisco area that achieved a 12 percent productivity boost after investing in a variety of technologies, including the recovery compressors. The investment paid for itself in about two years. (See pp. 46-7 of this pdf, and p. 67 of this pdf, for more details.) It's not obvious how typical this scenario can be considered, or even how to isolate the return on the compressors per se (the Shell refinery didn't break the cost and productivity numbers for the compressors out of the overall package), but it certainly points in the right direction. --Noam Scheiber