nlseaver writes: From a greenhouse gas perspective, coal is one of our dirtiest sources of energy. It's also widely available and cheap, and so it will continue to be a critical source of energy in the twenty-first century. Despite hopes for "clean coal" technology, no clear solution has emerged. Furthermore, because no policy framework (like a carbon tax or incentives to invest in clean technology) yet exists, coal companies are putting into place long-lived "dirty" coal facilities. As the article states: "Within the next few years, power companies are planning to build about 150 coal plants to meet growing electricity demands. Despite expectations that global warming rules are coming, almost none of the plants will be built to capture the thousands of tons of carbon dioxide that burning coal spews into the atmosphere."