Science of Natural Gas – Video

Transcript:

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.

We now know that natural gas is mostly hydrogen. In fact, it’s four hydrogen atoms bound to a carbon atom. This high hydrogen content and simple structure make it incredibly useful. It can be used to make products like acetic acid. Acetic acid is one of the primary ingredients in plastics, and we know that plastics are used in everything. It can also be used to make ammonia. Ammonia is one of the primary ingredients in fertilizers. Modern agriculture depends on ammonia. But the most important use of natural gas is simply to add oxygen. When you oxidize- another name for burning- you get carbon dioxide, water, and a whole lot of heat. This makes natural gas the usual heat source for most industrial equipment like boilers, burners, and kilns, and small residential equipment like water heaters and stoves, and clean enough that it can be burned directly in the house. Power plants burn it to boil water, make steam, and turn turbines. Natural gas makes about a quarter of U.S. electricity and growing, and it’s growing in transportation too. It can be converted to liquid fuel, but more commonly, it’s compressed and burned directly in fleets of buses or taxis that have central fueling stations. Because it’s a gas, transporting methane is more difficult than liquids or solids, and there are environmental impacts of producing and using it but less than coal or oil. With an ability to contribute at a large scale to all areas of energy use- heat, electricity, and transportation- and a growing global supply, natural gas will play an important role in our energy future.