Thursday, July 13, 2006

PG&E considers BIOGAS

PG&E considers using a natural energy source that comes from cows -- and it sure isn't milk.

In its quest to tap renewable sources of energy, California has harnessed the wind, the sun, the mighty force of rivers and the steady heat within the Earth.
Now it's looking at cow manure.
Pacific Gas and Electric Co. has signed an agreement to distribute a form of natural gas derived from cow excrement collected at Central Valley dairies.
A small New Hampshire company will produce the gas at individual California farms and deliver it to PG&E's pipeline system, a 40,123-mile web spanning the northern and central part of the state. San Francisco's PG&E might buy the gas or ship it to other buyers -- that hasn't been decided.
The plan has a certain logic.
California relies on natural gas to fuel power plants. Natural gas prices are soaring. A kind of gas, called biogas, can be made from decaying manure. And California -- home to more than 2 million cows -- has an ample supply.
"California, to us, represents the mother lode," said Albert Morales, executive vice president of New Hampshire's Environmental Power Corp. "This is the holy grail."
Many farms use it
The idea isn't exactly new. Farmers scattered throughout the United States and Europe have experimented with similar systems for years, turning manure from cows and pigs into gas and burning it on their premises to generate power. And San Francisco is investigating the feasibility of generating power from pet waste.
"There's truly a track record," Morales said. "It's not a neat idea from a couple of guys in a garage."
PG&E and Environmental Power, however, want the farms' gas to flow throughout the state. It could be bought and sold like regular natural gas, burned in power plants or piped into home furnaces and stoves.
If all goes according to plan, PG&E customers could be using gas from cows in 12 to 18 months.
"There is the potential for a significant renewable resource here," said Bob Howard, PG&E vice president in charge of gas distribution. "This is a big experiment for us to see how a process like this can work."
Cows alone, however, won't solve the state's energy problems. Under Howard's best-case scenario, PG&E might be able to get 5 percent of its gas from farms in 10 to 15 years.
"Compared to the amount of gas we use in California, it's always going to be small-scale," said Peter Lehman, director of the Schatz Energy Research Center at Humboldt State University.
Considering alternatives
He added, however, that the state is in no position to ignore a homemade, renewable source of power.
"There's some fossil fuel we don't have to burn because we've burned the biogas instead," Lehman said. "It's something we need to do."
Turning dairies into the equivalent of gas fields is, in some ways, relatively simple.
Manure is collected and dumped into a tank that removes oxygen and controls the temperature. Bacteria break down the waste and release gas -- mostly methane and carbon dioxide.
Environmental Power's process then removes the carbon dioxide and refines the gas into a product similar enough to natural gas that it can be shipped in the same pipelines.
The carbon dioxide vents into the atmosphere. That compound has been blamed as the key culprit behind global warming.
Despite that, energy researchers tend to view biogas as relatively benign. The manure comes from whatever plants the cows happen to eat, and those plants absorb carbon dioxide from the air, creating a kind of carbon-dioxide loop. In the end, burning biogas leaves less carbon in the atmosphere than burning its fossil-fuel relative.
Environmental benefits
It also consumes methane, a greenhouse gas far more powerful than carbon dioxide. Leave the manure to decompose in an open-air pool -- a common practice on farms -- and the methane ascends into the atmosphere, warming the planet bit by bit.
A subsidiary of Environmental Power plans to sign up individual dairies, install its equipment and build pipes connecting to PG&E's network. PG&E will test the gas daily to ensure its quality.
PG&E has not yet decided to buy Environmental Power's biogas and no money has changed hands between the companies. Prices, presumably, would be based on the open market. Natural gas currently costs more than twice its historic average, the result of supply problems and its rising popularity as a fuel. It remains to be seen if Environmental Power can produce its cow-based fuel at a price that will be competitive with natural gas.
That, to PG&E, is the main reason to give biogas a try. The utility depends on natural gas shipped from out of state. And staunch opposition from environmentalists has prevented California from importing liquefied natural gas, transported in tankers, from elsewhere.
The state, in other words, has few options to get more gas. Other than cows.
"Any new supply has the potential to moderate the price," Howard said. "It's gas we don't have to buy from somewhere else."