Di China dan India kotoran lembu yang dikeringkan, dipakai penduduk untuk bahan bakar. Energi yang dihasilkan tidak begitu besar.
Lain halnya yang dilakukan oleh Albert Strauss, pemilik peternakan sapi perah di California ini. Dia punya lembu perah 270 ekor. Dengan menggunakan alat methane digester yang dia beli dari departemen pertanian seharga $250,000 (duh, mahalnya) dia menggunakan bakteri untuk menghasilkan proses fermentasi yang mengubah kotoran lembu itu jadi gas methan (CH4 ?). Gas methan itu menghasilkan 1,800 kilowatt-jam, yang cukup untuk keperluan listrik usaha pertaniannya. Sisanya dia pakai untuk merebus 20,000 liter air sampai mencapai suhu 100 derajat celsius untuk keperluan membersihkan bermacam alat meng-UHT susu agar tahan lama. Biaya alatnya mahal memang, tapi kalau harga crude oil nantinya, biaya yang dikeluarkan jadi impas. Salam, RM --------------- OCTOBER 8, 2004 SPECIAL REPORT: ALTERNATIVE ENERGY POWERS UP Turning Manure into Black Gold As oil prices soar, innovative ways of converting livestock waste to fuel, though still in their infancy, could be the new alchemy Albert Straus's basic philosophy has always been that when life serves you a load of manure, you turn it into something good. Like, well, electricity. At his Straus Organic Dairy Farm in Marshall, Calif., 270 milk cows slowly munching on fresh grass produce about 120 pounds of muck a day. Strauss uses some of it to fertilize his fields. Still, plenty more remains, and its disposal has been expensive and problematic -- until recently, when Strauss began converting the stuff into energy. In mid-May, he installed a device called a methane digester. The $250,000 system, built partly with government grants, uses bacteria to ferment the waste and produce methane gas. That gas, in turn, generates 1,800 kilowatt hours of energy a day, which is more than twice what the farm uses. It also heats 5,000 gallons of water to 180 degrees Fahrenheit, so the water can be used for cleaning equipment or pasteurizing milk. Better yet, Straus says with a touch of pride, "When you come onto our farm, you can't smell anything at all." Most self-satisfied gardeners pat themselves on the back for composting kitchen scraps, but a handful of enterprising farmers like Straus are emerging as pioneers in the new era of $50-plus oil. The U.S. alone produces 95 million tons of farm waste a year, according to the Agriculture Dept. SMELLING A PROFIT. Experts have long viewed such refuse as a promising source of renewable energy. It's too early to say how much power it might produce or how much money it might save. But if the Straus venture is any indication, the discard could certainly turn farms into self-sustaining operations. Witness work by Yuanhui Zhang, a professor of bioengineering at the University of Illinois at Urbana-Champaign, who has successfully generated fuel from pig manure. Zhang mixes the fecal matter with water and places it into a specially designed reactor, where it's heated to 550 degrees Fahrenheit and kept under high pressure. Most of the manure breaks down into a goo remarkably similar to crude oil, with a comparable level of British thermal units (Btu) when burned. The rest turns to ash and leaves no animal odor. Zhang can smell a profit, though. He believes a single pig can generate the equivalent of 21 gallons of "oil" every six months -- the average lifespan of a porker these days. The fuel output could add up quickly because many farms raise more than 100,000 pigs at a time. WASTE HEADACHE. They could eventually help meet U.S. oil demand of 800 million gallons a day. Zhang is in talks with several large companies interested in his machine, and he aims to have a pilot plant, based on his technology, up and running within two years. By finding a way to dispose of animal waste, researchers like Zhang could help make the agricultural industry more productive. "Many farms can't grow the size of their herds because they've reached the limit in their ability to manage manure," says Doug Howell, air-quality analyst at the Natural Resources & Parks Dept. in Washington State's King County, which has recently conducted a study on methane digesters. "It's the No. 2 business-viability issue, after milk prices." And that's not the case just for dairy farmers. The current system of agricultural-waste disposal is expensive. Pig farmers pay more than a penny to remove each gallon of manure. Since a pig produces 1.2 gallons of manure a day, the cost quickly adds up. But if farmers let the waste rot on the ground, they run the risk of angry neighbors and regulators. "Eventually, these complaints could push those guys out of business," Howell says. STILL EXPENSIVE. Another outfit is producing fuel from turkey remains. Renewable Environmental Solutions, a joint venture between environmental-services provider Changing World Technologies and food processor ConAgra Foods (CAG ), uses heat and high pressure to generate bubbling crude. Its first plant opened in Carthage, Mo., in May. Every month, it turns 6,000 tons of ConAgra's animal waste into 4,000 barrels of liquid fuel, which can be used to heat boilers. After purification, it even can be used to power cars. This isn't to say everyone will be filling up at the gas pump with fuel made from agricultural refuse next year. The process of turning animal waste into energy still is more expensive than processing crude oil. Some of the entrepreneurs, like Zhang, are also able to produce only relatively small qualities of fuel at a time with their machines. But Brian Appel, chief executive of Changing World, says that gap could soon be eliminated if oil prices were to double again. For now, the recycling process bestows other benefits on the turkey farm. It creates a safe alternative to feeding turkey scraps to animals -- a practice still widespread in the U.S. but abolished in Europe for fear of spreading diseases. These efforts are certainly putting a new spin on the waste problem. Perhaps, as Straus has proven, old adages still hold true: When the cow pie hits the fan, don't panic. Instead, generate positive energy. -------------------------------------------------------------------------------- By Olga Kharif in Portland, Ore. ------------------------ Yahoo! Groups Sponsor --------------------~--> Make a clean sweep of pop-up ads. Yahoo! Companion Toolbar. Now with Pop-Up Blocker. 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