Turning ag waste into energy

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April 13, 2011 - 7:00pm

NET News begins a new reporting project today called NET Quest. Quest is a multimedia series exploring Nebraska science, environment and nature. We begin with a look at science on the farm. About half of Nebraska's farms include livestock and that industry accounts for about half of farm income. But with livestock comes potential environmental and natural resource issues like climate and water that require attention and regulation. In today's Signature story, Perry Stoner reports a unique hog operation in the state that's found a way to turn waste into an energy source.

Danny Kluthe's Methane Digester

By Perry Stoner/NET News

Danny Kluthe runs a family hog operation in rural Dodge, Nebraska. Step inside one of the hog barns and you'll see and hear it's like many hog operations in the state.

"My job is to get the hogs to market", says Kluthe. "Just get them little pigs fat and get em to market."

The little pigs weigh 12 pounds or so when they come to Kluthe's facility. Five or six months later, he's cared for them enough that they are ready to go to market weighing 20 times more than when they arrived. Kluthe says, "These hogs are treated better than humans. I mean their diet is to a T' for their age. Fresh water, fresh air. They sleep with a grin on their face."

With about 7500 hogs typically on hand, a lot goes into fattening them up. That means there's a lot that comes out of them too. It's manure and that's where Kluthe's operation becomes unlike any other in the state.



The waste of hogs, and other farm animals create high levels of the greenhouse gas methane. Methane can last more than a decade in the atmosphere - and is 20 times more powerful than carbon dioxide as a contributor to climate warming. But Kluthe is taking steps to make his farm an environmental game changer.

"I really call this thing a manure processing system with the byproduct being electricity", Kluthe says.

Hogs create an average of more than a gallon of manure each day. All told, Kluthe's hogs generate over 9,000 gallons - enough to fill a gas tanker, every day of the year.

Down the hill from the hog barns is a pit. An underground pipe system uses gravity so the manure flows downhill. Manure collected in a pit is common at hog operations, but what happens in this pit is not. This 14-foot deep airtight tank is called a methane digester.

Kluthe explains what's happening in the tank, "The raw manure goes down to the digester where we've got bacteria-lots of bacteria-and the bacteria in there just multiplies like bacteria does and what the bacteria does is actually breaks the manure down and it comes out liquid. The bacteria in there get fed every day. Every day I feed about a quarter of a pit to the digester and every day the hogs replace it. That is renewable!"

The digester is heated to about 100 degrees. That's the ideal temperature for the bacteria to break down the manure and release methane gas, a process that takes about 3 weeks. The pit traps the methane in its oxygen-free environment. Kluthe then uses the methane as a fuel to run the farm's utilities.

"We capture methane so it's environmentally friendly and green power is pretty awesome, you know, and when I was talking about taking hog manure and feeding this, taking electricity out of it and every day the hogs replace it, now that's as renewable energy as you can get! It runs 24 hours a day, 7 days a week."

Kluthe continues, From the breakdown of the raw manure is methane and that gets sucked up here to the 3306 Cat engine that's running a generator and I always say this Cat engine just purrs on this methane."

The caterpillar engine sits in its own small building. Designed to use either methane or propane as fuel, the engine produces electricity and it's put on the electrical grid, completing the manure to electricity process. Nebraska Public Power buys the energy from Kluthe's family energy company, OLean Energy.

"We actually make enough electricity here to take care of about 45-50 homes a year. I would use about 20% of the production and export 80 or sell 80% so, you know, we're - for a byproduct we've actually got a lot of electricity here. Anybody in Cuming County that turns their lights on doesn't know the difference whether it's coming from Cooper Nuclear or Olean Energy."

For Biological Systems Engineers like Rick Stowell and Crystal Powers with the University of Nebraska-Lincoln, finding ways to utilize what might otherwise be waste is a scientific process. That helps make agriculture more sustainable.

"You're creating greenhouse gases and actually creating a very potent greenhouse gas, says Stowell, "so you don't want that to escape and so it's really important to capture as much of that methane as you can."

Powers says, "In each step of the process from growing your forages and grains for your livestock to feed the animal to within the manure, how do we capture as much energy at each step and anaerobic digesters fit in there because we're figuring out how to get more energy out of the manure before it's ultimately used as fertilizer."

Livestock manure has often been used as fertilizer for crop agriculture. Methane free manure is still used as fertilizer and Kluthe says it also removes most of the odor some find offensive.

In a Biological Systems Engineering lab on the University of Nebraska-Lincoln campus, scientists like Ryan McGhee are examining what happens to the manure at the different stages in Kluthe's process.

"These samples are from the pit which are essentially green, raw manure, very little treatment," McGhee explains pointing to containers of frozen manure, "Then the next step is after it's been digested through the anerobic digester, and then the next sample is the basin, which is the basic flow of treatment at the Kluthe site."

Stowell further explains what the lab work is about, "We are asking them to look at solids content, the organic matter, how that's breaking down that would tell us how well the digester's performing and then we are also very interested in what's the likelihood of gases coming off that would cause odors and the assumption is that the digester is going to break down those odorous gases and other undesirable gases coming off."

Digester technology has evolved, based upon a scientific fact that's been Powers explains has been known for hundreds of years: methane is flammable and can be used as fuel.

"That happened clear back in the 17th Century but it took us up until the late 1800's before we were capturing that to do anything with it and it's only been recently that we've been doing it at a scale to where we can really produce electricity. So there's kind of this slowly finding new pieces of the puzzle to figure out, how can we make this work and how can we balance society's needs with production agricultural needs?"

What happens in sciences labs impacts society in many ways. But the reverse is true too according to Stowell.

"Greenhouse gases have been implicated with climate change and there's science out there for and against that but the idea is that a lot of science is dedicated towards the effect of greenhouse gases on climate change and then we're looking at how much of that greenhouse gas production is produced by agriculture and livestock specifically and then what can we do about that? And, so that all came about really over about a 5 year period here in the United States due to public perceptions and then looking for information and trying to get the facts."

In addition to methane and odor control, the state investigates another way livestock production can have a serious negative environmental impact: Water contamination.

"85% of our population in Nebraska relies on ground water for drinking water", Marty Link is Associate Director at the Nebraska Department of Environmental Quality. "If waste gets into water it's likely to cause a problem that's the whole purpose of our Livestock Permitting Program is to keep livestock waste out of the waters of the state; the groundwater, the streams, the rivers, the lakes and the reservoirs."

Link says harm to drinking water isn't the only concern if livestock waste gets in the water.

"When it runs off into a stream it can cause the algae to get all excited and it gets all this nutrients and it starts growing a lot and so there's an algae bloom. The algae bloom takes up a lot of oxygen. Oxygen is all depleted then from the water and the fish won't have the oxygen in order to breathe and they may die. That's a worst case scenario."

Rick Stowell says that's something being examined at the UN-L lab too.

"You are basically measuring oxygen depletion in a given sample, how much oxygen would that sample deplete in a water body if it got out into a natural water body?"

Link says the goal is zero livestock waste in the state's water ways. "Accidents happen but well managed waste should not make it into the stream and that's what everybody's goal is: to not let the waste make it into the stream."

But generating electricity from hog manure isn't financially what it could be. Customer-generators in Nebraska like Kluthe can produce up to 25 KW. Above that amount they are paid what's called avoided cost from the utility. In simple terms, he's paid the utility's wholesale cost of electricity. The 25 KWs allowed in Nebraska is among the lowest in the nation.

At the state capitol, new legislation could help encourage Kluthe and others to generate more renewable energy. There's $750,000 set aside for zero emissions energy generation, but methane digesters don't qualify, Senator Ken Haar of Malcolm hopes to change that with LB 359.

"This allows methane digesters to take advantage of the tax credit because technically burning methane there is an emission and that's been the glitch in that so this would change it from zero emission tax credit to renewable energy tax credit."

In a recent year, Kluthe would have received less than $400 from the tax credit. Not a lot of money for a system that cost hundreds of thousands of dollars, but renewable energy supporters like Chris Dibbern with the Nebraska Power Association say the change would be small but important.

"In 2006 when this bill first passed the term of art was zero emissions. But today we know that great projects like methane digesters have some emissions but accomplish a great deal of good in producing electricity, reducing odors and recycling animal waste."

Back at Danny Kluthe's operation, he's pleased with how clean a manure operation can be. "The lagoon is odorless so really it's kind of nice pretty lake out there."

Kluthe can still use the manure waste as fertilizer after capturing the methane to be a fuel source. He likes that the digester helps him be a good neighbor. He started dreaming of it in 2003, but wasn't producing electricity until more than two years later due mostly to the permitting process. But now, he's as happy as his pigs about the set up.

"Five years now so we've got a track record and now we've got something that other producers can come and look at and say wow'!"

It's a costly endeavor Kluthe could only make happen with grants that totaled hundreds of thousands of dollars. That's one of the barriers in front of more livestock producers wanting to do what Kluthe has done. But he's not done. Soon he'll install a scrubber that will remove methane impurities and leave propane. He estimates the additional use of the manure byproduct could save him up to $30,000 a year in energy costs. Something he's eager to do.

"I'm excited about the fact that we'll be able to heat our barns, dry our corn, whatever we use propane for now, we're going to be using methane and we'll just solve our oil crisis-probably not-but it's a piece of the puzzle."




More on Kluthe's operation:

Environmental Protection Agency

Western Area Power Administration

Other NET News methane stories:

Methane measurement device

David City methane

David City methane part 2

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