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Electricity from cow manure!

post #1 of 8
Thread Starter 




this is so great -- turning cow manure into electricity.  see the bolded portion below (of an article from the NY Times) that describes the actual process.  my thought -- why not?!  



FOR years, the cows at Green Mountain Dairy here produced only milk and manure. But recently they have generated something else: electricity.

The farm is part of a growing alternative energy program that converts the methane gas from cow manure into electricity that is sold to the power utility’s grid.

Central Vermont Public Service, which supplies electricity to 158,000 customers around the state, was among the first utilities in the country to draw electricity from cow manure on dairy farms. About 4,000 utility customers participate by agreeing to pay a premium for the electricity.

“We realized we could help meet a customer demand for renewables, help solve a manure management problem and make these farmers more financially secure,” said Steve Costello, a spokesman for Central Vermont Public Service.

Four Vermont dairy farms are producing electricity for the utility, and two more are expected to be online by year’s end, Mr. Costello said. The utility hopes to add six more farms by 2010.

Residents and businesses that get their electricity from the program pay a premium of 4 cents a kilowatt hour above the typical rate of 12.5 cents. Most of that money goes to the farmers, who must purchase their own equipment, which can run up to $2 million per farm. Most farmers expect to make back their investment in 7 to 10 years.

The brothers who own Green Mountain Dairy, Bill and Brian Rowell, were looking to squeeze more profit from their farm, where they have 1,050 cows and have begun acquiring 600 heifers. Milk prices had dipped and they wanted another source of income.

They also thought that the huge amount of waste their cows produced could be used for something other than fertilizer. So they decided to give electricity a try, armed with about $750,000 in federal, state and utility company grants.

“We saw this as an economic and environmental management tool,” Bill Rowell said. “It’s helped to diversify our farm,” which was named the 2008 Vermont Dairy Farm of the Year.

The Rowells’ cows live in a barn where a mechanical scraper sweeps the animals’ waste into a large drain. The waste is then pumped into a huge sealed concrete tank known as a digester, which holds 21 days’ worth of waste and is kept at a temperature of 101 degrees Fahrenheit. Anaerobic bacteria break down the organic matter in the waste, producing a mix of methane and other gases, known as bio-gas. The gas is burned in an engine that runs an electrical generator.

The cow waste produces 250 to 300 kilowatts of electricity daily, enough to power 300 to 350 homes, according to the utility.

“We’re making a resource out of a waste stream,” said Bill Rowell, who is running for the State Senate.

In return, the Rowells receive a payment based on the wholesale cost of power, which averages about 7 cents per kilowatt hour, plus the 4-cent premium. Mr. Rowell said they earned about $200,000 from electricity annually, and with the additional cows should receive $235,000 to $240,000 in revenue from electricity.

The Rowells are also transforming commercial waste. The farm processes about 500,000 gallons of waste and outdated ice cream from Ben & Jerry’s each year and puts it in the digester. The free ice cream, which the company drops off, helps the Rowells generate more electricity and saves Ben & Jerry’s the cost of disposing of it. “We’re improving our processes, and they’re improving theirs,” Mr. Rowell said.

The digester produces more than electricity. After 21 days, the waste is pumped through a separator, which siphons off the liquid into a silo and drops the solids into a barn.

The liquid manure is used as fertilizer, while the solids are used for cow bedding. The bedding saves the Rowells thousands of dollars a month on sawdust, and they sell the excess to garden stores.

Other utilities across the country are purchasing power from farms as part of their renewable energy portfolios. Some, like Central Vermont Public Service, charge their customers a premium, while others do not.

Alliant Energy, which supplies electricity to rural customers in Wisconsin, Iowa and Minnesota, draws power from four digesters and is working to add more. About 20 independent farms in Wisconsin have digesters and sell electricity to various utilities, said William A. Johnson, manager of biofuels development at the utility.

“Our economy is agriculture, and people recognize that supporting the industry is a positive,” Mr. Johnson said. The utility charges 2 cents a kilowatt hour more for cow power.

“Rural customers, in particular, are very excited that something that is considered by some to be a liability, manure, has become, in essence, a resource,” Mr. Johnson said.

In Ohio, Buckeye Power went online with a digester at the end of August and plans to turn waste from a chicken farm into electricity next year.

“We were interested in finding a type of green power that was, No. 1, not intermittent, like wind or solar,” said Steve Oden, a spokesman for Buckeye, which will not charge extra for the power.

Marie Audet’s family farm in Bridport, Vt., was the first in the Central Vermont system and went online in 2005. The family invested $1.3 million and expects to make that back in four years.

“We’re saving money by not using sawdust, reducing original waste by recycling and generating revenue by selling electricity into the grid,” Ms. Audet said.

And many customers here have chosen to pay more for power that is both renewable and supports local farmers.

Maggie Hatch, who owns the Newbury Village Store in Newbury, Vt., operates half of the business with cow power. The renewable power adds $200 to $400 a month to the store’s electric bill, but Ms. Hatch and her husband, Gary, say it is worth it.

“It’s worth it to us to spend that money to help the producers and use power that helps sustain the environment,” Ms. Hatch said. “When you live in a place like we do, which is a beautiful part of the country, you’re really aware of the environment and want to keep it that way.” 

post #2 of 8

Yeah this is a great idea, but not common practice because the initial investment for the equipment is very expensive.  With all the agricultural subsidies in our country, it would be nice to see heavy subsidies specifically for this sort of methane collection for power generation.

post #3 of 8
Thread Starter 

 yes, that would be a great idea!!!  seriously -- i like that specific concept for subsidies.  kills two birds...helps agricultural producers keep up with overhead costs by reducing their electricity bills, but also has positive "eco" externalities....

post #4 of 8

Certainly large enough farms (or cooperatives) can decide not to provide pork, beef, chicken or milk to agribusiness processors who will not co-invest in biogas. This will be a real benefit to rural land value and reduction of CO2. Furhermore, rather than sell extra electric, geothermal, year round hydroponic greenhouses the size of foot ball fields could well be added to give local based agriculture production a year round cycle and extra cash crops...even in New capitalists (?local banks) can be found if necessary.

post #5 of 8

There are companies that use digesters to make on-site power, or even pipe grade natural gas - it is a growing trend, but has a long way to go...  Here in CA they are building a large digester (really big) that will provide a large percentage of the natural gas for one of PG&E's natural gas power plants.  I believe the setup is near Sacramento.  This process can also be used with food processing waste and landfills - different process, but ultimately produces mostly methane which is about 22 times worse than CO2 if released into the atmosphere.  Burning it can make electricity, and releases CO2 as part of the emissions, but waaayyy better than the alternative of just letting the methane loose and not doing a thing with it.

post #6 of 8

Thanks for the straight poop!

post #7 of 8

Since agricultural emissions are no longer exempted from regulation (air, wastewater, solid waste), we are seeing many more operations, especially daries and poultry farms, set up enclosed digesters, gas collection systems and waste-gas power co-generation.    Both thermal and electrical power are being produced, and the byproducts (digested sludge and supernatant water) are recycled.  The most common arrangement currently is for an operating company to install the infrastructure, with the agreement the agricultural operation can buy back power and heat at below-market costs.  Since this is a base load power source, surplus power is distributed to the grid and sold to PG&E or SOCal Edison.  Similar projects are operating at wastewater treatment plants where digester gas is used to co-fire IC engines with waste heat returned to the digester; however most of the power generated is used internally for the big pumps and compressors at typical POTWs.


We have been collecting landfill gas from large mnicipal landfills for the past 10 to 12 years and generating power for distribution to the grid.  This keeps emissions of VOC/NMOC and toxics from being emitted as fugitive emissions and makes productive use of gas that would otherwise be flared.  California wholesale power prices are around $.05 - $.08 /kWh, but household rates with distribution are from $.11 - $.36/kWh.  Most CA power is from natrual gas combusion in combined cycle turbines with nukes and coal being relatively minor players.  Biomass, wind, solar, landfill gas and geothermal are also generating a highe percentage of power here than just about any other State. 


Its pretty cool to be part of these projects that actually produce significant environmental benefits by reducing conventional pollutants like VOC and also lower GW impacts by converting methane to water and CO2.  Keep in mind that while these project have emissions, the carbon sources are from living biomass and organic decomposition rather than fossil sources, and are considered neutral or beneficial in their carbon balance.

post #8 of 8

this tech. is totally scaleable.

i have seen plans for every size, from a lorry inner tyre homemade job for a household plus one cow, to the big industrial units.

farmers in india getting into it hooray! using the gas for home cooking instead of dried dung, will save no end of women and kids from terrible effects of indoor air pollution as well as being more efficient use of resources, as they get to use the poo for energy and still get the soil conditioner at the end.


here's my favourite development ngo, practical action, on digesters. they are currently running a campaign to roll out biolatrines in schools across Kenya, solving the toilet problem and the lighting problem in one.

Edited by gerda - Thu, 08 Jan 2009 19:40:45 GMT
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