                                  T H E

                               Z E P H Y R

                      __     M A G A Z I N E
                     {__]++++++++++++++++++++++++++[]
                     Issue #61                12-5-88

                A weekly electronic magazine for users of
                            THE ZEPHYR II BBS
                        (Mesa, AZ - 602-894-6526)
                    owned and operated by T. H. Smith

                        Editor - Gene B. Williams

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                                (c) 1988

    THIS ISSUE:

       One of our users, Lyle Knox, is involved in agri-business. One
    day he left me a note in private mail about Arizona Dairy and
    some of the things they were doing. It sounded interesting so I
    made a few contacts to see if any magazines would be interested.
    This resulted in an assignment from one called, DAIRY HERD
    MANAGEMENT.
       With the assignment assured, I went to visit the dairy to get
    the information and to take the needed photographs. What I found
    was more than expected.
       I've done articles of this type many times in the past.
    Methane generators have been around for quite a while, but very
    VERY few ever work all that well and often cost more than is
    worth the operation.
       What Arizona Dairy has managed to do is to build one that does
    indeed work. More, it's the largest of its kind in the entire
    world.

       For those of you unfamiliar with the process:
       In a sense, a methane generator is much like a septic tank.
    The animal waste is "digested" by bacteria. The waste product of
    the bacteria (one of the waste products) is methane. And methane,
    also called natural gase or bio-gas, can be burned as a fuel.

       Anyway, what follows is the article I wrote for the magazine,
    with thanks to Lyle.

                          From Waste to Profit

                                   by

                            Gene B. Williams

         With a total herd of 4690 Holstein, Arizona Dairy is the
    largest in the state, but this isn't what makes it unique. On the
    grounds is the world's largest bio-gas (methane) generator of its
    kind. While other dairies are staggering under high electricity
    bills, Arizona Dairy is selling excess power back to the utility
    company.
         Don't let the size throw you off. General manager, Jim
    Tappan, says that he's convinced that the idea can be made to
    work at any dairy with a herd of 100 or more.
         "Actually, we didn't begin with this sort of system in
    mind," says Tappan. "The project began as an attempt to reduce
    the electrical bill. The rest simply evolved from necessity."
         By 1980 they were paying some $15,000 per month, and faced
    the promise of ever higher bills. Owners Kenneth and Marvin
    Morrison and Jim Tappan decided to install a natural gas driven
    generator (Caterpillar G398 NA, producing 475 horsepower and
    generating 320 kw). However, by the time construction was
    complete, the policy of the gas supplier had changed. They wanted
    $100,000 to install the gas line.
         Nearly $250,000 had already been invested in the generator
    and power distribution system. The cost of installing the natural
    gas pipeline caused Tappan and the Morrisons to explore other
    possibilities.
         Conversion of animal wastes into methane gas has been known
    for some time. The problem was that very few have managed to do
    it feasibly on any scale. Even so, it seemed to be a natural
    solution to two problems - supplying the bio-gas to drive the
    generator and handling the manure produced by the cattle.
         Dr. William Jewell of Cornell University in New York had
    been working on a bio-digestion system. His plug-flow design was
    scaled up to meet the needs of the dairy. This would take the
    semi-digested material from the previous tank and feed it to the
    next, resulting in complete and efficient digestion and subse
    quent generation of the bio-gas.
         In 1982 Don Sherman, a graduate of Cornell, came to Arizona
    to oversee the project. The cost came to another $200,000 - about
    twice the cost of installing the gas line - but if the system
    worked, they could greatly reduce or eliminate their staggering
    power bills.
         Five pits were dug. The central three, each 150 feet in
    length, had concrete troughs built around the edges. Large
    plastic tarps were placed over the pits. The plastic was set into
    the troughs and secured with iron bars and rope. When the troughs
    were filled with water, the pits were sealed.
         Each day 50 tons of manure is introduced into the first pit
    by a manure spreader and then mixed with waste water from the
    milking parlors by a lagoon stirrer attached to the PTO of a
    tractor. The mixture is warmed and fed into the first main pit.
    As digestion continues, the manure is pumped into the second and
    third pits. The total process takes approximately 21 days, and
    creates nearly 200,000 cubic feet of methane per day - more than
    enough to supply the 7500 cu. ft. per hour appetite of the
    generator. Heat from the generator goes back to keep the mixture
    at a nominal 110 for more efficient digestion.
         The remaining effluent (12% solids) at the end of the
    process emerges into the fifth pit. This is then pumped to a
    sprayer system set in an open field on the far side of the dairy.
    As the liquid dries it leaves behind an incredibly rich fertil
    izer which Arizona Dairy hopes to one day market commercially.
         The first manure was put into the system in December, 1982.
    Since the system was the largest ever built, testing was needed.
    It began to produce electricity in March of 1983 and about a year
    later reached full capacity.
         There were some initial problems. The original design called
    for the material to be pumped from the top. The heavier sludge
    settled to the bottom, which required that the system be shut
    down occasionally to be cleaned. Cornell suggested that the
    mixture be made thicker to prevent settling. This slowed the
    problem but didn't eliminate it. Output from the system began to
    decline - the symptom that the system has to be shut down and
    cleaned.
         Another suggestion was to bubble the gas back through the
    mixture from the bottom. That also helped, but again didn't solve
    the problem. "It would have been very easy to give up on it,"
    Tappan said.
         It was after this that Tappan saw the solution. The next
    time the pits had to be cleaned, he arranged to modify the design
    so that the drains were at the bottom, "like huge bathtubs." Ever
    since, the system has operated flawlessly and nonstop.
         During the day, when the cost of electricity is higher due
    to public demand, the system produces more power than is needed
    by the dairy. This is sent through a metering system and into the
    power company's lines. The amount is credited to Arizona Dairy's
    power bill.
         Cost of electricity is lower at night. This is when the
    dairy makes its ice and handles other power consuming tasks. In
    essence, they buy power when it's cheapest and sell it back to
    the utility when it's more expensive.
         "The initial cost was high," says Jim Tappan, "but we hoped
    to make it back in four or five years."
         They did just that. Five years have passed since the first
    power came from their generator. Despite some earlier problems
    and the need for design modifications, the entire half million
    cost, and all interest on the loan, is now paid off.
         From here on, the lack of a power bill translates into
    profit for the dairy. "And if we can market the fertilizer, that
    will be an added bonus."

       Seeing it is more fascinating than just reading about it. The
    article will have photos. Since I can't include photos here:

       The building for the generator is on the east end of the field
    and a couple hundred feet away from the pits.
       The first pit is open. Sitting at the side are the manure
    spreader and tractor with the stirrer. Then comes the first
    working pit. Each of the three is about 35 feet wide and 150 feet
    long. Each has a short concrete wall with the trough filled with
    water to make the seal. Over each is the "balloon" of thick black
    plastic to contain the methane. These bags cover the entire pit
    and rise about 12' upwards when full. On the north side there are
    pipes that connect the bags. This way the methane can be drawn
    from any of the three without depleting the other two.
       On the west is the fifth pit, filled with a blackish fluid.
    This is what gets pumped about a half-mile to the south. The
    field in use is about 600 feet wide and nearly a half-mile in
    length. The dried fertilizer is now about 3' thick. It's dry but
    feels kinda soft when you step on it.
       A huge reel (orange, with black 6" flexible pipe wound on it)
    connects to one of two pipes. On the reel is a small gasoline
    engine which winds in the sprayer.
       Amazing!

       Next time around?
       Another job I've covered lately is about a couple in Phoenix
    who collect rocks. But not just ordinary rocks. What they have is
    a complete banquet.
       Yup! Everything in the collection looks just like something
    you'd eat. Hamburger, fries and a pickle. A big "juicy" roast.
    Sirloin steak, chops, fish, rolls, breads, donuts, lemon and
    chocolate pies . . . .

       Arizona is an amazing state if you just open your eyes and
    ears a bit. Lyle suggested this dairy article. Who knows. Maybe
    another of you knows of something strange, unusual or otherwise
    fascinating?

Zephyr Magazine is © Gene Williams. All rights reserved.