Sludge Watch ==> Washington State - using cow manure for methane derived energy

[Maureen Reilly]

Sludgewatch Admin:

Was a time that cow manure was raked out of the barn mixed with straw and 
made a great ammendment to farm fields.  Then came the dairy farms with the 
manure washed into a great wet vat...and the intensive feeding stalls .... 
and the E.coli O157 pathogen from feeding cows on corn-rich diets that 
change the pH in the gut.

So now we have mountains of pathogenically dangerous manures.  In this story 
they turn it into energy.

...............................................................................


Monday, June 11, 2007 12:22


Dairy waste not wasted in Yakima Valley


Published Monday, June 11th, 2007

By Elena Olmstead, Herald Valley bureau

OUTLOOK -- Driving through the George DeRuyter and Sons Dairy on a warm 
afternoon, you wouldn't know the brown-eyed dairy cows staring through the 
fence are producing more than milk.

Their manure is generating electricity.

Since December, the Outlook dairy has been using manure washed from the 
cow's stalls to create power. It produces about 900 kilowatts of electricity 
every hour -- enough to keep the lights on and appliances operating in 500 
homes.

The dairy is one of only two in the state using cow manure to make power. 
Jay Gordon, executive director of the Washington State Dairy Federation, 
said a Lynden dairy has been generating electricity from its 1,500-cow 
operation for a couple of years.


Gordon said the federation would like to see more generators installed as 
they become affordable. He said set-ups that convert methane gas created by 
manure into electricity can range from $1 million for a 1,000-cow dairy to 
several million dollars for larger operations.

It's a cost that can be offset by selling the electricity back to the power 
company, he said. Dairies converting methane from cow manure into 
electricity also earn a carbon credit that can be sold to companies that 
need it.

Adding a generator to the dairy isn't a decision the DeRuyter family made 
overnight. Dan DeRuyter, 39, said his father, George, saw one of the first 
digesters, which heats the waste to extract the methane gas, installed at a 
California dairy. At the time, it was still too expensive an option to bring 
to Outlook.

Then two years ago, DeRuyter said they went to a farm show and discovered 
technology that was appropriate for the farm. But to be sure it would work, 
they took a trip to Wisconsin about a year ago to talk to other operators 
who were already using the digester-based system.

"We figured it was something we could make a little money on and it would be 
a way for us to handle our waste a little better," DeRuyter said.

Although things have become more affordable, DeRuyter said it still cost the 
dairy about $3.8 million to install the equipment needed to make 
electricity. It's a cost he's hoping to recoup over the next 10 years.

To follow how electricity is made, just follow the path of the manure. 
DeRuyter said alleyways in the cow barns are used to collect the manure and 
flush it out to a pit on the southeast side of the dairy four times a day.

DeRuyter said his 3,000 cows create about 130 cubic yards of manure a day. 
That's as much as 13 typical dump trucks hold.

The manure is then pumped through a separator, where solids are separated 
from the liquid. The liquid is recycled into the dairy and reused to flush 
the alley ways.

The sludge goes into a large cement digester -- it's a 300-by-90-foot 
rectangle that's about 16 feet deep. It takes about 21 days for the sludge, 
which is heated to 101 degrees, to make its way through the digester and 
complete the process.

DeRuyter said the high temperature helps anaerobic bacteria go to work on 
the manure sludge, creating methane gas. The gas then rises into large pipes 
that are attached to the digester.

>From the digester, the gas goes into an engine room, where two 
900-horsepower engines work to convert the gas into electricity, which is 
then put directly back onto the power grid. DeRuyter said the dairy doesn't 
tap into any of the power it creates, instead sending it back onto the grid.

DeRuyter said selling electricity back to Pacific Power doesn't provide the 
dairy any savings on its monthly utility bill. Instead, Pacific Power 
routinely sends checks to the dairy to pay for the power -- paying 51/2 
cents per kilowatt hour.

DeRuyter said the dairy has the capacity to create 1,200 kilowatts of 
electricity in an hour. The dairy is currently operating about 75 percent 
capacity. DeRuyter said he plans to be running at 100 percent capacity in 
about a month. He said that's when the dairy will start transporting manure 
from the family's other nearby dairy operation to the Dekker Road site.

Clark Satre with Pacific Power said it's unusual for one of its customers to 
produce enough power that the company can buy it back. He said the Outlook 
dairy is only its third client to do that. The others are in Oregon and 
Utah.

Satre said since the state will soon require large power utilities to 
acquire a certain percentage of their electricity from renewable resources, 
he's happy to see the DeRuyter dairy take this step.

"It's a power source we're not going to have to build," he said.

With green power becoming more common, Satre said he expects more farms to 
begin projects similar to the one at the DeRuyter dairy.

"I do think it's something that will be viable for dairy farmers in the 
future," DeRuyter said. "Most dairy farmers follow up on new technology if 
they think it will work."

And he thinks this is going to work.

http://www.tri-cityherald.com/tch/local/story/8967987p-8883697c.html