Electricity: From Landfill to Living Room

Texas has an important place in the United States energy industry for many reasons. The discovery of vast oil reserves invited some of the best and brightest engineers to live and work in the Lone Star State. This long tradition has resulted in the extensive energy infrastructure that has taken root in Texas. That infrastructure is currently changing in interesting ways. Large central plants still dominate electricity generation, but there are a lot of smaller plants contributing to fulfill the needs of Texans. For example, your home may someday be powered by the methane produced by landfills. Imagine-instead of digging up coal or drilling for oil to keep your lights on, you could make use of a greenhouse gas that would otherwise go to waste.

Always on the cutting edge of energy, Texans have figured out how to collect the methane created by landfills and how to use it to generate electricity. According to Chris Beattie, writing for the Star Local News, the local government of McKinney has partnered with the company Raytheon. Under this agreement, Raytheon will be able operate five of its sites, in part, with electricity from the landfill.

How do you get Texas electricity from a Texas trash dump? It's far simpler than you think. Much of the material that goes into a landfill is organic: material that was once alive. Orange peels, garden waste, lawn clippings and even paper products comprise a large proportion of what can be found in such facilities. These materials are broken down by the sun, the elements and most importantly, bacteria.

According to the CDC's Agency for Toxic Substances & Disease Registry, organic material undergoes four phases of decomposition. This process creates the methane burned by Texas power plants. During Phase 1, oxygen-consuming bacteria break down carbohydrates, proteins and lipids. (These are kinds of molecules.) Phase 2 is enacted by bacteria that don't consume oxygen; they break the remaining material down into acidic compounds. These acids create nitrogen, phosphorous and other chemicals. As Phase 3 takes effect, other kinds of anaerobic bacteria eat the acids created during Phase 2. This creates a healthy environment for bacteria that give off methane. During Phase 4, the landfill decomposes at a relatively steady rate, giving off, according to the CDC, "approximately 45% to 60% methane by volume, 40% to 60% carbon dioxide, and 2% to 9% other gases, such as sulfides."

Ordinarily, the methane and carbon dioxide produced by landfills is a bad thing. After all, carbon dioxide is the gas most associated with global warming. Too much of it is generally considered a problem. Methane has many of the same effects, in addition to being flammable. The "natural gas" in your home was created millions of years ago; methane is a natural gas that is created all the time. (Cows and other livestock also create quite a bit of methane as they digest food!)

The landfill in Montauk, Texas collects methane before it can escape into the atmosphere. Through the use of collection wells and other traps, the lighter-than-air gas is channeled into a power turbine. There are, of course, a vast series of safety regulations required by state and federal authorities. For instance, landfill officials must monitor methane levels and make sure that they don't get too high. (Obviously, bad things can happen if you have too much of a flammable gas in one place.)

Once collected, the methane is run through a high-voltage generator. Over the course of a year, it's estimated that the landfill will provide Raytheon's North Texas facilities with 24,000 megawatts of electricity; approximately 23% of its total electricity needs. Even better, the Star Local notes that the methane collection plan will reduce "greenhouse gas emissions by 12,000 metric tons."

Renewable energies such as this one are not yet well-established enough to provide 100% of the electricity we all need to maintain a contemporary lifestyle. In fact, landfill methane shares at least one big drawback with other kinds of green electricity generation: the amount of electricity varies according to environmental factors. A solar cell doesn't produce as much electricity when the sky is cloudy, and landfills don't produce as much methane when it's cold outside. (Bacteria reproduce most rapidly in warm and moist environments.)

In spite of these challenges, the creativity of researchers both in Texas and elsewhere will continue to bring us creative solutions to our energy problems. We get electricity from the sun, the wind, the tides…even landfills. Who knows what will be next for Texas energy consumers?