Dairy farm in Trenton turns cow poo into profit - WUSF News

Dairy farm in Trenton turns cow poo into profit – WUSF News

Jan Henderson grew up in a farm house. My grandfather was a dairy farmer in western New York. My father was a dairy farmer in western New York. We moved to Florida and moved our dairy farm in 1986.

Henderson is the CEO of Alliance Dairies in Trenton, but you wouldn’t see her in a pantsuit. Alliance is the largest free dairy in the state, with more than 6,500 Holstein cows. Henderson, with her blue jeans and her pickup truck, takes her job very seriously.

“I don’t want to say that cows are more important than people, but, you know, that is your livelihood. So growing or looking after the crops – like feeding, raising, treating and milking the cows – has always been of paramount importance.”

One of her responsibilities in running a farm of this size is to process cow manure. According to the USDA, dairy cows can produce 80 pounds of manure per day. With thousands of cows, all that poo can really add up.

Dr. Sakib Mokhtar is Associate Dean of the University of Florida’s Institute of Food and Agricultural Sciences. He explained that cows have a special organ called the rumen.

In the rumen, microorganisms break down food and release gases. When cows defecate, some of these microbes continue to break down the manure, releasing more gas into the atmosphere, often methane.

Mukhtar said that each molecule of methane is 21 times more powerful than a molecule of carbon dioxide. Greenhouse gases, such as carbon dioxide and methane, contribute to climate change by warming the planet, causing more intense storms and rising sea levels.

“But these effects aren’t always just local, right? With the atmosphere, the gases are really moving in,” Mokhtar said.

Cattle and dairy farms produce about 2% of total greenhouse gas emissions worldwide. according to Climate Monitoring DataIn 2018, it accounted for 2% billion tons of greenhouse gases.

Alliance uses a system called anaerobic digestion to process their manure. From the outside, it looks like a large concrete platform covered with metal tubes. But Del Bottcher, a soil and water engineer who worked on installing Alliance’s digester, said the system is much more than meets the eye.

“You can actually play a game of football inside this thing, it’s so big,” he said. The digester is 140 feet wide and extends 12 feet underground.

Alliance is a dairy free, which means all cows are kept in fan-cooled, water-dampened and sand-filled barns. “So it’s like they’re lying on the beach all day because the sand is very, very comfortable,” Henderson said.

The cows actually prefer to stay in the barn rather than out on pastures because of the Florida heat — the cows don’t sweat, so they enjoy the shade of fog and the cold, Butcher said.

Each barn is built on a one percent slope. When the cows do their work, the water will wash the sand and manure down the slope. The sand is separated and laid out in the sun to dry and reused in the sheds. Pumps push the remaining manure through a metal strainer to remove the water. The water is also recycled and used to re-wash the barns multiple times.

Mokhtar explained that the inside of the digestive system works just like the inside of a cow’s rumen. “So when you have a lack of oxygen in that environment, you have these anaerobic bacteria that start digesting that manure,” he said. But unlike a cow’s rumen, the resulting gas is captured rather than released into the atmosphere.

    The aboveground portion of anaerobic digestion in the middle of the field

Kristen Moorhead

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WUFT News

The above-ground portion of anaerobic digestion is only part of the story: the concrete extends 12 feet underground.

Once the dung enters the digestive system, it remains in an oxygen-free environment while bacteria break it down for about a month. The resulting methane is pumped into a generator that uses gas to generate electricity. This electricity is sent to the power grid. And no matter how much electricity the alliance produces, that much is removed from the dairy’s energy bill, saving dairy money.

When the generator runs, Henderson said, it produces enough electricity to power 425 homes. But the generator often does not work.

She said, “We still had challenges with the generator, in one thing it’s going to break and then we’ll fix it, and then, ‘Oh, darn, something else broke.'”

The main reason for all the malfunctions, Henderson said, is that the gas from digesting cow dung is full of other substances, so it’s not pure. Running this dirty gas through an electric generator can damage device parts faster.

This ongoing repair can be costly. Henderson said the dairy paid $40,000 for a replacement part for a generator that got there 6 months later. During that time, Alliance had to burn methane generated by the digester instead of generating electricity.

Add to that the initial investment to build the system. The cost to build Alliance’s digestive system was $8 million, Henderson said in 2011. The government grant covered 30% of that amount, but the rest was a cost the coalition had to pay up front. This is a cost that many small dairies cannot afford on their own.

according to AgSTAR Anaerobic Digestion Database from the Environmental Protection AgencyThere are 294 anaerobic digesters operating on dairy farms alone in the United States, and of those farms, only 88 have received at least partial USDA funding for construction. This does not include state or local programs, but it still only covers about 30%.

Henderson said one of the goals of the digester when it was built in 2011 was for the entire electricity generated to pay for construction in 10 years. But with ongoing costly repairs, she said, that hasn’t happened yet.

Going forward, Alliance has partnered with TECO Peoples Gas, a natural gas distribution facility serving approximately 425,000 customers in Florida, to build a biogas conditioning facility. This will clean up the methane and turn it into natural gas, which will then be pumped onto an interstate pipeline. This gas could theoretically be used for energy across the country. This can actually make the farm more money.

Butcher says California has a carbon credit program that will pay dairies for natural gas. As long as the coalition gas could theoretically go to California, the California government would give the coalition these credits.

Despite installing a system that reduces methane emissions on her farm, Henderson is skeptical of the environmental movement.

“The farmer needs to be motivated to do this, because if he doesn’t improve his financial situation, there will be no incentive to do it. Because sustainability, you have to be profitable in order to be sustainable,” she said.

Henderson hopes that once Alliance’s natural gas infrastructure is in place, that profit will start to emerge.

Big generator inside a building

Kristen Moorhead

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WUFT News

The generator Alliance uses to generate electricity is not without its problems.

Other solutions

Besides anaerobic digestion, University of Florida researchers are working on another method to reduce methane emissions from livestock. Juan Vargas is a doctoral student at the UF Institute for Food and Agricultural Sciences. He’s working with a team of researchers to explore food alternatives and additives to reduce the methane produced inside the cow.

Some of these experimental feeds are showing promising preliminary results, he said. “Red algae show a 60-80% reduction in methane in the rumen,” Vargas said. Other feed alternatives include nitrates and essential oils that reduce methane by 30% and 10%, respectively.

However, more research still needs to be done to confirm that the additive is safe for both cows and humans.


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