[Dr. Scott W. Tinker] Natural gas is methane; an odorless, colorless gas that occurs when plants decay without oxygen, like in a compost bin if you forget to turn it or in the belly of a cow. Livestock makes huge volumes of methane, and so do we. Billions of us emit billions of cubic feet of methane every day. Methane is also found in lakes or ponds, wherever microbes break down plants with limited oxygen. In fact, methane is very common in water. Bubbling up from swamps, off continental shelves, in springs and water wells, there are enormous volumes of methane frozen in water called methane hydrates at the bottom of oceans. But for all of these, they're either not concentrated enough or the technology doesn't exist to harvest them in commercial quantities. But that's starting to happen in some unusual places. Some sewage treatment plants now use digesters to turn organic wastes into methane- in this case, called biogas. We can make crop and livestock waste into methane too. All landfills produce methane, and some are capturing it to run small power plants. But today, to get natural gas and the huge volumes needed to fuel society, we drill into the same reservoirs that produce oil. These conventional reservoirs, like under the Arabian Gulf, are some of the largest natural gas fields in the world. Some countries are drilling into coal to produce methane, and in the U.S. we are drilling horizontal wells into source rocks called shale and fracturing them with high-pressure water injection. This technique, called hydraulic fracturing or fracking, has produced huge new volumes of natural gas in the U.S. and could probably do so around the world. And it could produce some huge new benefits, but we'll first need to address some environmental concerns with fracking, and we'll talk more about both.