In northeastern Colorado, the cattle living on private and commercial ranches easily outnumber the human population in nearby towns. Gary and Laura Teague own a commercial cattle-feeding business amid the region's rolling grasslands. Faced with rising energy prices and tougher environmental regulations, they are in the vanguard of Colorado ranchers who see animal waste as a promising alternative source of electricity.
"At any given time we'll have somewhere between 15 and 25,000 head of cattle on feed," estimates Gary Teague. "Today, we're somewhere around 19 to 20,000 head of cattle." The Teagues feed their stock a mixture of corn, hay and brewers grain three times a day, with each animal consuming an average of 19 kilos. The result is a lot of animal waste. "We'll generate about 20 semi [trailer] loads of manure every day," says Gary Teague. "Big, full 25-ton loads."
For the past decade, the couple has been turning that waste into compost, selling upwards of 153,000 cubic meters annually -- mainly to area farmers and to wholesale landscapers in Denver. Mr. Teague scoops up a handful and takes a deep breath. "You can smell that wholesome, earthy smell in there," he says. "You can see the wood residuals and feel the dampness. It's an ideal product as a soil amendment."
Gary Teague views himself as a cattle feeder, not an environmental activist. But he is about to embark on a $3 million environmentally friendly project: turning his composting operation into a regional facility for producing organic electricity. He was recruited by Ed Lewis of the Colorado Office of Energy Management and Conservation, who was looking for ranches interested in applying what is called "anaerobic digestion."
An "anaerobic digester" uses naturally occurring bacteria to break down organic waste in an oxygen-free or "anaerobic" environment. The "digestion" process creates methane gas, which is then collected and used to run electrical generators. "For every 10,000 head of feedlot cattle, you can produce about a meg of power," Mr. Lewis estimates. "A meg of power will power about a thousand homes. But if you multiply this across all the country you could produce several gigawatts of power."
Such "digesters" have long been used in China and India and are widespread in Europe. But they have been slow to catch on in the United States, where there are only about 40 in operation. Most of the American facilities employ large, covered pits to collect the methane and break down the waste, making it a very smelly process.
The Teagues will use a series of 380,000-liter stainless steel tanks. This newer design is expected to produce better quality methane and do it less aromatically and in much less time…about five days. Then they will dispose of the waste that remains. "The liquid will be land applied within a matter of hours," says rancher Gary Teague, "and the solid portion will then go into compost and four weeks later it will be composted and put on a truck headed out to Denver or out to a farmer's field."
Initially the Teagues' unit will only handle the electrical needs of their feed yard. But Gary Teague hopes to use cash flow from future electrical sales to add another eight to 10 digesters over the next five years. The goal is to provide electricity to 10,000 nearby homes. "We can take things that were basically going to waste or going into landfills," says Mr. Teague, "and turn them into a renewable source of power…and in the end, wind up with product that is beneficial not only to the homeowner that's using it but also to the farmer who needs a fertilizer source."
"Cow Power" will never replace traditional energy sources such as coal and natural gas. But it could play a more significant role in Colorado's power mix. In November, voters passed Amendment 37, which requires the state's larger utilities to produce more of their power from renewable sources.
