Call it SodaStream for the planet. For three years, Swiss-based Climeworks has carbonated water and pumped it underground. For an astonishingly cheap $30 a metric ton, demonstrated at a geothermal-powered Iceland pilot plant inaugurated on Wednesday, the process ends with basalt rock absorbing the carbon dioxide after two years, eliminating it from the atmosphere for perhaps millions of years. As with many technologies, experts until recently believed efficient climate-cleansing was impossible. Now it’s up to polluters to partner with Climeworks or competing entities to neutralize their carbon footprint for a fee.