The industrial age, wrote historian Barbara Freese, ”emerged literally in a haze of coal smoke, and in that smoke we can read much of the history of the modern world.” In boom economies like India’s and China’s, where coal meets about three-quarters of the electrical demand, that haze still hangs heavily. Globally, according to a recent influential study done at MIT and data from the International Energy Agency, in Paris, coal accounts for a quarter of energy consumed and more than two-fifths of ­the electricity generated. That makes it the second leading fuel after oil and the world’s main source of ­greenhouse-gas emissions.

You can add up all the electricity produced in the world from renewable sources plus nuclear reactors, and it doesn’t amount to what coal generates just in the United States and China. It’s impossible to imagine our getting along without coal anytime soon. And yet, with concerns rising sharply about climate change, the general expectation is that governments will increasingly be penalizing carbon emissions by taxing them, regulating them, or forcing companies to trade in them. So burning coal could become radically more expensive unless efficient means are found to capture and permanently store carbon dioxide, which right now is pumped into the atmosphere in astonishing quantities.

In the United States alone, according to MIT, coal-­burning power plants produce about 1.5 ­billion metric tons of CO ₂ a year—roughly a quarter of the world’s total—which is about three times the weight of the total amount of natural gas the country uses each year and nearly twice the volume of oil it consumes annually.

Just capturing the carbon, not to mention finding sound ways of sequestering it, is a job of staggering dimensions and one that the world has just barely begun to address, as the MIT report emphasized. There’s been a lot of talk about it, but hardly anybody is doing anything about it. ”We need large-scale demonstration projects,” a summary of the MIT report said, bluntly.

One company that is doing that kind of demonstration right now is Vattenfall, Sweden’s national energy company, in Stockholm. It’s building a novel clean-coal plant in southeastern Germany, in a town called Schwarze Pumpe. The approach Vattenfall will test and evaluate at the 30-megawatt ­facility—a technology called oxyfuel, or sometimes oxyfiring—is not the one most favored by students of carbon capture. But it appealed to Vattenfall partly because of its disarming simplicity.

In the oxyfuel process, instead of burning coal in air, the nitrogen is first extracted from the air using standard industrial equipment, so that the coal can be combusted in an atmosphere of oxygen and recycled flue gases. The result is a flue-gas stream containing almost none of the nitrogen that otherwise complicates the separation of carbon dioxide. Once the sulfur has been scrubbed using standard procedures, the flue gases consist essentially of just water vapor and carbon dioxide. The water is separated by condensation, and presto, the carbon dioxide is ready to be compressed and liquefied for transport to a final storage site. In this particular case, Vattenfall will have the CO2 trucked to a region called Altmark, where it will be injected into a natural gas reservoir, initially to enhance gas recovery, and ultimately for final disposal.

Why did Vattenfall settle on this somewhat eccentric approach to carbon capture? Back home, as Sweden’s state-owned national utility, it traditionally has produced the country’s electricity in hydropower ­stations and nuclear reactors, which for all practical purposes emit no carbon dioxide. But with the opening of Europe’s ­electricity system to competition in the 1990s, Vattenfall began to expand outside Sweden and is more or less Europe’s fourth largest electricity producer in terms of revenues.