Over the course of two months, scientists from the University of Alabama had injected 278 tons of carbon dioxide into the Earth. The goal was to keep it there forever, locked in geologic formations. The beer cooler was a key part of that plan. Beneath it sat the delicate electronic components of the monitoring system the scientists were using to make sure none of the captured carbon dioxide found its way out of the mountain. Beer coolers, it turns out, make great low-cost heat protection.

Carbon capture and storage—the process of removing carbon dioxide from factory and power plant emissions and trapping it where it can't reach the atmosphere—is an interesting idea. It has the potential to help us make our current energy systems cleaner as we work on building more sustainable systems for the future. With that in mind, the Department of Energy has seven regional research teams testing carbon capture and storage at sites around the United States.

So far, nobody in the United States has put this full process to the test at the scale that would be necessary in the real world. But, in the past couple of weeks, scientists at the Midwest Geological Sequestration Consortium began pumping carbon dioxide at a new site, one that is going to give us our best picture yet of what full-scale carbon capture and storage (CCS) will be like.

Two hundred and seventy-eight tons might sound like a lot of carbon dioxide. It's not. An average-sized coal power plant will produce 3 million metric tons of CO2 in a year. The infrastructure used at the Alabama site I visited can't be easily scaled up to meet a need like that.

More important, the Alabama project didn't test out the full CCS process. The carbon dioxide stored there didn't come from man-made sources. At least, not like we think of them. Instead, it's naturally occurring CO2, collected by breaking down carbonate rocks. This CO2 is sold for industrial purposes. It's used in some advanced oil and gas recovery techniques. It makes your soda fizzy. And, with exactly two exceptions, it's been the CO2 that's been stored at carbon capture and storage research sites. The Alabama scientists bought CO2, trucked it across the country, compressed it, and pumped it into a hole in the ground.

That sounds a little ridiculous. But there aren't a lot of other options. Big talk and PR aside, the vast majority of coal fired power plants in the United States don't remove carbon dioxide from their emissions. There's no financial incentive to make them want to take on the investment of installing the right equipment.

The new Midwestern carbon storage site, near Decatur, Illinois, is different. First, it's one of the biggest projects ever undertaken. Over the next three years, 1 million metric tons of carbon dioxide will be pumped into rock formations underground. There's only one other site in the country operating at that scale.

Next, the Midwestern site will be the second project, ever, to store carbon dioxide drawn from an actual energy-producing factory. The first, in West Virginia, was much, much smaller. This makes a big difference in how the project operates. Instead of trucking CO2 in from out of state, the carbon dioxide buried beneath Decatur will arrive in a pipeline, sent from a nearby ethanol refinery.

It's not quite the scale of a real-world CCS system. But this is how a real-world system would work. For the first time, instead of just looking at individual parts, we're going to see the whole thing in action.

You take carbon dioxide and you pump it into a hole in the ground. That's the fast explanation. But, in reality, carbon capture and storage is really not that flippant.

For one thing, it's not just any old hole in the ground.

Robert Finley, director of the Advanced Energy Technology Initiative at the Illinois State Geological Survey and one of the scientists working on the Decatur project, says the process of choosing the site began in 2003 with a survey of the entire Illinois Basin. The final site was chosen because of specific geologic features that make it naturally conducive to storing compressed gas.

At Decatur, compressed CO2, in the form of a liquid-like supercritical fluid, is sent down a pipe 7000 feet below ground to a layer of porous sandstone called Mt. Simon Sandstone. The supercritical fluid flows into those pores mingling with and displacing the brine that exists there naturally. If there were nothing but sandstone, you could expect the CO2 to travel back up and out of the Earth. However, above the sandstone sits a caprock. Three caprocks, actually. They're all made from impermeable shale. The sandstone gives the CO2 a place to sit, the shale keeps it there. It's the same kind of features that hold natural gas deposits in place for millions of years.

The CO2 will sit there for somewhere between a few hundred and a few thousand years, Finley says, until it mineralizes. Essentially, it will become the same kind of rock that's broken down today to make the CO2 stored beneath Alabama.

This is where carbon capture and storage gets complicated.

Physically, the risks are not massive, but they do exist. These storage systems are based on how nature stores gas and liquids. They use the same geologic rules. Finley says that you can almost think of it as drilling for oil and natural gas in reverse. Instead of pumping stuff out of these natural reservoirs, we're pumping stuff into them.

It is not common to find natural reservoirs in the United States that have failed, he says. Jed Clampett aside, oil and gas are normally discovered via lots of digging, not because somebody ran across a spot where the oil or gas was seeping out of the Earth. But while it might not be common, it does happen. Western New York state, for instance, is home to multiple "eternal flames," spots where natural gas has escaped its geologic prison and made it to the surface.

The Decatur site was chosen partly because it provides a good opportunity to catch a leak like that before it could do any damage. The carbon dioxide is being stored at 7000 feet underground. The useable groundwater sits at 150 feet down. In between are the caprocks and, at 5500 feet—just above the first caprock—there's a monitoring system, watching for signs of leaks.

So what happens if and when a carbon storage site springs a leak? The primary concerns are really A) groundwater quality and B) that you've just wasted a lot of money capturing and storing carbon dioxide that's now leaking back into the atmosphere.

Most researchers don't think a leak from a reservoir is likely to cause any loss of life. There's a reason for that. When you think, "Carbon dioxide disaster," you probably think about Lake Nyos. In 1986, this volcanic lake essentially burped, releasing a huge bubble of carbon dioxide from the lake bottom that asphyxiated humans and animals for miles around. That's not the kind of leak you get from underground reservoirs. Think of it as the difference between a balloon popping and a balloon slowly deflating over the course of a week. Those natural gas seeps in New York aren't killing people.

When scientists worry about dangerous carbon dioxide leaks from CCS sites, they worry about the piping. If the pipeline going down a well were to catastrophically fail, and if the flow of gas wasn't turned off, and if the prevailing winds and local surface geography were just right, you could, conceivably, end up with a potentially deadly cloud of CO2. This is the point where reasonable people have room to disagree. Some, including Robert Finley, look at all those "ifs" and see an extremely unlikely scenario that can be avoided by good planning and site selection. But not everybody is going to be comforted by that.

Honestly, though, I think the biggest problem with CCS isn't so much physical as it is ideological. The risk is that carbon capture and storage could be pushed as THE solution to our energy problems. And it really, really isn't.

There are a lot of reasons for that, but chief among them is the fact that there is not an unlimited supply of good sites for storing captured CO2. The Decatur site could take a lot more than 1 million metric tons. Finley says there's room for 10s of millions of tons down there. And there are lots of potential sites scattered across the United States. But there are more than 400 coal-fired power plants in the country, as well, each producing several million tons of CO2 per year. Carbon capture and storage is not a license to go on using coal indefinitely. Likewise, there are some parts of the country where finding a good site is going to be difficult. New England, for instance, is sitting on top of a lot of non-porous granite, Finley says.

Think of CCS like a Prius hybrid. It's a cleaner car to drive than, say, a 1978 Impala. Back in 2000, it was really your only choice if you wanted a car and you wanted it to be cleaner. Hybrid cars are a nice way to bridge the gap between all-gas and all-electric. But they aren't the endgame. If we want a more sustainable future, we eventually have to replace the hybrids completely. Same thing here.

Meanwhile, while we're controlling that risk, there's also a risk that you could have a perfectly workable CCS system that never gets used at a commercial scale, leaving dirty coal plants that dirty when they could be a lot cleaner. Why hasn't this technology been used at full-scale yet? It's complicated, but the biggest reason is that there haven't been a lot of companies interested in doing that.

It's telling that Finley gives props to Archer Daniels Midland, the company that owns the ethanol plant, for being interested in working on this project at all and for providing CO2 free of charge. In the past, they've sold that CO2 to make soda and dry ice. Clean coal is an industry buzzword, but it's rare to find coal plants that want to make that happen immediately. About the only place is in Texas' Permian Basin, where some soon-to-be-built power plants have been sited near oil and gas drilling operations, with the goal of selling CO2 to the fossil fuel industry for advance recovery operations.

Industry doesn't have much interest in CCS. And it won't, Finley says, until there's a price on carbon dioxide emissions. That's the thing that will incentivize companies into capturing their carbon. Until then, carbon capture and storage is likely to remain the domain of scientists, something that happens in demonstration projects, but not in the real world.

Image: A flexible tube for carrying CO2 at Germany's "Schwarze Pumpe" power plant. This small demonstration project, which came online in 2008, is the first power plant in the world to remove carbon emissions from its exhaust and bury them in the ground. REUTERS/Hannibal Hanschke

Earlier this week, I told you about a new study tracking radioactive fallout from the nuclear power plant disaster in Fukushima, Japan.

It started with a team of researchers in California, who had been monitoring radioactive sulfur in the atmosphere since 2009. Last spring, after an earthquake and tsunami critically damaged several reactors at the Fukushima Daiichi power plant, those researchers watched the levels of radioactive sulfur skyrocket, relatively speaking. The amounts of radioactive sulfur that reached the California coast weren't high enough to be a threat to humans, but they made a big impact on extremely sensitive monitoring equipment.

Using that data, the researchers were able to figure out where the radioactive sulfur came from and back-calculate how much would have been produced at the site of the disaster—information that can tell us something about how dangerous the disaster really was to people living nearby.

But these researchers weren't the first to collect radioactive isotopes from Fukushima on American shores. And they weren't the first to offer up improved estimations of how much radiation leaked from the damaged power plant in the early days of the disaster. I thought this study was interesting. But, like a lot of you, I was left wondering why it was important.

Then yesterday, I interviewed Antra Priyadarshi, the lead author on the peer-reviewed paper that was published about this study. And I realized I'd gotten the story all wrong. This paper is about radioactive sulfur from the Fukushima disaster. But it isn't about the Fukushima disaster. It's not even about nuclear power. Not really.

In reality, this is a paper about coal. And it's important because of what it can tell us about the sort of air pollution that is much more mundane—and more deadly—than the fallout from a single nuclear disaster.

To get this, you first have to understand who the researchers are and why they've been monitoring radioactive sulfur for so long. It has nothing to do with nuclear power or nuclear weapons.

Antra Priyadarshi is a postdoc—a scientist who has recently earned their Ph.D., but is doing research under the guidance of another, older scientist. You can think of it like an apprenticeship program, in a way. Priyadarshi works in the lab of Mark Thiemens, an atmospheric scientist. The Thiemens Lab is interested in questions of climate systems and the chemical makeup of the atmosphere. In particular, they're interested in ozone.

Ozone is a molecule of three oxygen atoms bound together, and it's the same stuff that makes up the protective ozone layer around there Earth. Way off in the upper atmosphere, ozone is a Good Thing. But context matters. When ozone ends up on our level, where humans can breathe it in, it becomes a problem. That's because ozone can, essentially, give the lining of your lungs a sunburn. The more ozone you inhale, the more damage to your cardiovascular system.

There's a couple of reasons ozone and people come into contact. One is pollution: On hot days, chemicals from car and factory exhaust can turn into ground-level ozone. But ozone from the upper atmosphere can also get transported down to our level naturally. One of the key things the Thiemens Lab is trying to understand is how those natural movements work, why they happen, and what that means for the way pollution-based ozone gets transported from exhaust-rich urban areas to other parts of the world.

This is where the radioactive sulfur comes in, because there's a natural source of that, as well.

In the upper atmosphere, where the naturally occurring ozone is formed, high-energy particles from cosmic rays react with argon to form radioactive sulfur. When air from high altitudes intrudes on our atmospheric level, it brings both ozone and radioactive sulfur along for the ride. Antra Priyadarshi has been monitoring radioactive sulfur both because of the role those isotopes play in climate—there's some evidence that they can serve as points for clouds to condense around and produce raindrops—and because of what the movement of sulfur can tell her about the movement of ozone.

So that explains why Priyadarshi and her colleagues were out there monitoring radioactive sulfur to begin with. But why is this paper important? What does it add to her research?

For that, you have to look to China, and a different form of sulfur.

When we burn coal, one of the things that goes up in smoke is sulfur dioxide. It's not radioactive, but it is dangerous. Sulfur dioxide, like ozone, damages human respiratory and cardiovascular systems. It's a key ingredient in acid rain, which harms crops and other plants, and damages buildings. And it's also a major player in producing particulate matter—tiny grains that get inside your lungs and cause long-term damage.

Particulate matter is also an important factor in climate change. That's because, while particulates are very bad for human health, they also play a role in cooling down the planet. Basically, greenhouse gases in the atmosphere trap heat and particulate matter in the atmosphere prevents heat from the sun from getting in. These two forces work against each other, even though, in man-made terms, they come from the same place—fossil fuel emissions.

When we talk about cleaning up emissions, we're usually talking about reducing the amount of sulfur and particulates produced, but not the amount of greenhouse gases. So, ironically, cleaner tailpipes and smokestacks save lives in the short term, but contribute to a rising global temperature in the long term.

That's why people are watching China. Western countries started scrubbing sulfur out of their emissions decades ago. Our emissions aren't sulfur-free, but they're a lot cleaner than they used to be. China, on the other hand, is rapidly ramping up the amount of coal it burns, and the emissions aren't being cleaned up. It's the world's largest sulfur dioxide polluter today. And scientists are curious about how that sulfur dioxide in the atmosphere is masking the effects of greenhouse gases. When China starts cleaning up its smokestacks, what will happen to the global temperature? How does sulfur dioxide from China affect the rest of the world?

That second question has been very difficult to answer. Think of all the coal that gets burnt everywhere, every day. In order to know something about how sulfur dioxide travels, you have to be able to separate the sulfur dioxide from one factory, or one power plant, and trace it as it moves through the atmosphere. That's like listening to five symphonies playing at once and trying to pick out the work of a single flautist.

Until now.

This is why a study of radioactive sulfur from Fukushima matters. That disaster produced so much radioactive sulfur that it was obvious when the plume from Fukushima reached the shores of California. This signal was loud enough to stand out from the noise. The radioactive sulfur from Fukushima isn't exactly the same thing as the sulfur dioxide from Chinese power plants, but it is close enough that it can serve as a marker. It's a model that can tell scientists some important things about how sulfur travels through the atmosphere and how it crosses great distances, like the Pacific Ocean.

"There are lots of sources of sulfur pollution and a lot of uncertainty in the models," Antra Priyadarshi said. "But this is a case when we can know better how much radioactive sulfur was produced at the source, and how much arrived, and you can neglect the natural background signal. That gives you a better estimation of how much sulfur could be transported over the Pacific."