2008 - Volume #32, Issue #4, Page #11[ Sample Stories From This Issue | List of All Stories In This Issue | Print this story | Read this issue]
Small Scale Biogas Replaces Propane
"Our system consists of eight 55-gal. barrels that act as digesters," explains Hoard. "The gas flows through two simple pvc manifolds that æscrub' the gas, draining moisture and serving as shutoff valves. Once scrubbed, gas is stored in a series of tractor tire inner tubes before being piped to the propane line."
The off-grid farmer and his wife use windmills to pump water, a solar panel for electricity, wood to heat the house, gas for cooking, gas for hot water heat, and gas to run his refrigerator and freezer. When his biogas unit is working, the propane flow shuts down.
"I bring the biogas into the propane line at the output side of the regulator," explains Hoard. "Any time the biogas pressure gets over 1/2 lb., it shuts down the propane flow, and everything runs off biogas which is 70 percent methane and 30 percent carbon dioxide. When production drops, the propane runs."
In ideal conditions of 65 degrees, Hoard's biogas system produces 24 hours a day, maintaining about 15 lbs. of pressure. Living in the high country of Nevada, summer nighttime temperatures can drop to 40 degrees, slowing down production. In the winter, the drop off is even faster and more complete.
"As long as the sun is shining, I can produce gas," says Hoard. "My problem is keeping the barrels warm."
He relies on a simple sunroom built from recycled patio doors and a tin roof hinged for easy access. Hoard plans to build a better insulated sunroom that will warm his barrels even more. He also plans to add a few more barrels to the easily expandable system.
"It only cost us about $350," he says. "We've used it since this past November and have had no problems."
Hoard fills each barrel with about 40 gal. of manure slurry. He empties and refills according to gas production. In a warmer climate, he says, each barrel would generate biogas for about 40 days.
Even the spent slurry gets recycled. "It's weed free, high in nitrogen and has very little odor," says Hoard. "It makes great fertilizer."
He says the simple system is one that anyone with some manure or even food waste could set up and use. He's willing to provide detailed descriptions of the system and information on how he set it up for a fee.
Contact: FARM SHOW Followup, HM Ranch, HC 61, Box 6108, Austin, Nevada 89310 (ph or fax 775 217-9264).
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