For those who believe using cow manure as a source of energy is a new idea, they are likely forgetting their grade school history classes where they studied how the early pioneers crossing the prairies used the abundant “buffalo chips” as their primary source of fire. That’s right, dried bovine excrement burns easily and cleanly and was an indispensable source of fuel for travelers in the 1800s.
Use as a Biofuel
Biofuel is material that comes from organisms that were recently alive. It's different from fossil fuels, which are obtained from material that has been dead for hundreds of years. Biofuels come from many sources: liquid, gases or solids. The use of manure as a fuel source is referring to a solid. The simplest manner in which to use cow dung as a fuel source is to burn it, just as the pioneers did, but modern technology has provided highly efficient ways to do just that.
When one thinks of renewable energy, generally wind, solar or hydro power comes to mind. But forward thinkers, especially those within the livestock industry, have made remarkable strides by developing ways to use feedlot waste. Home-grown energy, as it is sometimes called, is making some farmers energy self-sufficient by using cow manure to generate electricity. CNN reports in a 2009 article that a Pennsylvania dairy farmer put his 600 cows to work, not only to produce milk, but to power his entire operation, even selling the excess electricity back to the utility company, resulting in an annual savings of $200,000.
How it Works
It all begins with a large containment vault called a digester. The wet manure is loaded into the digester where it is heated for several days, allowing bacteria to break down and releasing methane gas. Methane is highly flammable and burning it produces the energy to turn turbines, which spin generators to make electricity. The heat produced by the spinning generators is in turn used to continue to warm the digester, which continues to break down the manure. A large enough system can also produce enough heat to provide climate control to other on-site buildings.
After the digester has used all the methane from the manure for electric generation, solids remain. These solids are dry and when removed from the digester they can be sold as fertilizer for lawns and gardens. Farm-based operations using digester technology can become nearly self-sufficient.
Although the technology for solid waste generation systems has been around since the 1970s, the cost to build one has always been the biggest deterrent, often times reaching into the millions of dollars for a complete system. Fortunately, partly due to global warming, and partly because of the cost of foreign oil, many states are now offering grants to offset the cost of construction, and when energy savings are factored in, a return on investment of just a few years is not uncommon.