Natural Energy

By Reinsch, Lee Marie

It’s not a pretty topic, but manure’s pretty plentiful in this farm-dominated area.

What better way to make a stink about rising oil prices than to make fuel out of an inevitable agricultural byproduct?

Biogas digestion systems are one of a handful of technologies Wisconsin farmers are using to plow the path toward a greener future.

“Farms are the best places to use renewable energies,” says Don Wichert, director of renewable energy programs for Focus on Energy and Wisconsin Energy Conservation Corp., both nonprofit groups based in Madison. “You have access to solar, wind and biomass [anything natural that can be burned as fuel] probably more so than anybody living in town.”

It makes sense. Farms typically have more space and less risk than city-dwellers of having a five-story parking ramp built next door and blocking the wind or eclipsing the sun.

In the past decade, the number of farmers in the state using renewable resources like the sun, wind, manure and plant waste- based waste pellets to fuel their farms has increased dramatically, according to experts in the field. The last three years have been especially fruitful due to an increase in grant monies available as well as tax credits offered.

How to choose?

When deciding how best to go green, farmers should assess their farm’s size and available resources, says Larry Krom, Focus on Energy’s projects manager for renewable energy programs.

“Renewable energy isn’t one-size-fits-all,” he says.

A farm’s location, type of operation and even the mechanical skill of the farmer should be considered. “I think that every type of renewable technology has a sweet spot,” says Krom.

For example, wind isn’t evenly distributed around the state, so wind energy works best for only some farms, Krom says.

And, reminds John Hippensteel, owner of Lake Michigan Wind & Sun in Sturgeon Bay, wind turbines are machines. They need maintenance.

“If you aren’t a mechanical person who likes to work outside in sub-zero February, then turbines aren’t for you,” he says. “We can only service so many, so the ideal situation is if you can service it yourself.”

Solar units, on the other hand, have few moving parts, so there are fewer parts to break down, Hippensteel says, which is why solar tends to be a better choice for the average homeowner.

Sun exposure is pretty uniform throughout the state with respect to the amount of energy per year one can garner from it, Krom points out. “There are a few exceptions, like lake fog blocking the sunlight, but otherwise, solar energy is evenly distributed around the state,” he says.

But solar hasn’t caught on as fast among Wisconsin farmers as biogas, biomass and wind-energy systems.

Location is a factor for other types of energy generation – biomass, for example. Farmers typically don’t make their own pellets out of sawdust, wood waste or paper pulp, so they have to consider the distance that pellets would need to be transported, Krom says.

And not all farms can make use of their cows’ manure. “If you don’t have a way to collect the manure, it may not work,” says Krom.

Biogas digesters

“Wisconsin cows generate enough manure each year to fill a tank the size of a football field four miles high,” says Wichert, citing a 2005 University of Wisconsin program on agricultural technology.

With that in mind, it’s no wonder some farmers in the state see gold in manure.

Anaerobic digesters are basically chambers that simulate a cow’s digestive system – but instead of eating grass or corn, the tanks eat food that’s already been eaten and digested by the cow. Anaerobic means “without oxygen.”

The digesters use heat and bacteria to break manure down into materials that can be used in everything from animal bedding to liquid fertilizer for crops to methane for heating barns or running farm equipment.

“The fuel is right there and the farmer owns it [unlike with pellet burners or traditional energy systems], and for large farms, they have to do something with it anyway,” says Wichert. Farmers with more than 800 cows have to have some kind of formal manure management program anyway, and biogas is one way to meet that mandate, he adds.

It’s no secret that manure makes a good fertilizer. “It’s a closed system – the cows eat grass, process it, they metabolize it and produce milk from it, and then the wastes go back onto the field and make crops prosper,” says Krom.

Manure is full of nutrients – but too many of the wrong kind can be a bad thing. That’s one reason why large farms have to institute a manure management system, often called a nutrient management system.

One issue is whether the nutrients in the manure are being distributed in the proportion that’s best for the environment, Krom says.

But farmers can’t merely pour manure onto their field and except the field to be fertilized; they need to be smart about it. If it rains, nutrients can be washed away into waterways. Nutrients that demand oxygen to survive can steal it out of the water from the fish, and then fish die. If the ground is frozen when fertilized, it won’t be receptive to nutrients.

Cows produce phosphorous, nitrogen and potassium, enough to take care of most of our fertilizer needs in Wisconsin. One big source of nitrogen not produced by nature is anhydrous ammonia, which comes from natural gas, which comes from fossil fuels.

“There are issues associated with that, such as greenhouse gas, plus it’s a limited resource,” says Krom.

Manure is rich in nitrogen; if soil gets fertilized with anhydrous ammonia-based nitrogen and manure as well, that could create a nutrient imbalance. What to do with the manure of hundreds of cows, then?

“Moving the manure somewhere else can get expensive if it’s too far away; it takes gas to transport it,” says Krom. “So this is a reason people look to anaerobic digestion. It doesn’t make nutrients go away, but it changes the form they are in.”

Processing manure in this way also kills fly eggs, which cause disease, and reduces the odor of manure by 97 percent.

Installing a biogas system for up to 2,500 animals takes an investment of $1 million to $3 million. But within six years, the cost will be recouped in savings on energy bills, Wichert says.

Farmers using these digesters can even save on bedding costs. Processed solids leftover can make a soft, hygienic material for animal bedding.

“You are dealing with a waste problem and you are creating energy,” says Krom. “It’s a different marriage of benefits.”

Typically the farms that do best with biogas are those with at least 500 cows, Krom says. But most farms in Wisconsin are smaller than that, 90 to 95 animals.

One Wisconsin organic dairy farm with 225 cows produces enough manure to justify two digesters, but collecting it is another story. In winter, the cows are in a free stall barn and the manure can be easily gathered to keep two digesters busy. But in summer, the cows are outside grazing and depositing their droppings in the pasture, so only one digester is needed.

Krom says smaller-scale biogas digesters are in the works.

Since 1998, 18 biogas systems have been built on farms in the state, and another 17 are under way, according to Krom.

Wichert believes up to 250 more farms in the state with more than 500 head of cattle could benefit from the Focus on Energy program.

Wind power

As with biogas, wind energy systems work best the larger they are.

A small turbine starts around $50,000 to $60,000, according to Wichert. Even a mid-range turbine can cost $3 million, depending on its mechanism, material and installation variables.

Unfortunately, Hippensteel says, most farms would need a fairly large-sized wind turbine or solar system to generate both their own farm’s needs and see a profit.

“There’s a gap in the market,” he says. “There are small turbines and very large turbines, and the gap in the middle is tough to fill.”

Hippensteel says one turbine can produce enough energy to fuel 300 to 500 houses without the pollution of gas, oil or coal. With large-scale projects, such as the two projects of more than 80 turbines each in Fond du Lac and Dodge counties, wind systems can compete with fossil fuels, he says.

Hippensteel consults with and does wind-energy feasibility studies for a few dozen farmers per year.

Wichert says in the last six years, Focus on Energy has assisted with 45 wind-energy projects in Wisconsin.

Power from the sun

Every year, hundreds of homeowners seek help from Focus on Energy to initiate renewable projects. In the past six years, the nonprofit has enabled 626 Wisconsin residents to install solar electricity or solar hot water systems in their homes. And more businesses are installing solar water or solar electricity because of the tax advantages of doing so, Wichert says.

But solar hasn’t caught on with farmers so far. Solar water heating systems and solar electricity systems have a payback rate of six to seven years, and sometimes the obvious returns on the initial upfront investment can seem rather negligible.

“Farms are leveraged pretty heavily in terms of how much money they owe banks and they might not want to take out additional loans” to do something that will make a marginal difference, says Wichert.

But the power of the sun can be used for a slew of functions, and projects don’t have to cost the moon. Solar power can be used in:

* Electric fencing, to contain and protect farm animals ($100 to $400, depending on the size of the fenced-in area).

* Lighting, which can extend the productivity of daylight hours and also serve to function during a power outage ($50 to $200 per light).

* Water pumping, for watering crops and animals, and helping to use pond water that’s not conveniently located ($1,500 to $7,500, depending on size of the pump).

* Pond aeration, to keep water tanks from freezing over in winter and add oxygen to the water in ponds in summer ($350 to $400).

* Ventilation, via rooftop fans ($200 to $500).

Solar energy can also be used to power gate openers, dashboard chargers for equipment and vehicles, crop dryers, egg incubators and security lighting.

Biomass’ possibilities

Biomass combustion involves almost any type of vegetative material, such as wood scraps, sawdust, or switch grass, which can be made into pellets and burned for fuel.

Because farmers typically don’t have pellet-making and drying facilities on-site, most who use biomass don’t make the pellets themselves. Farmers more commonly sell their crop waste to companies that make pellets for fuel.

Focus on Energy funds non-residential biomass combustion opportunities, and most farmers who would be apt to use biomass would use it as a heating source in their homes, Wichert says. The current most common source of rural hot water or heating is natural gas or propane.

In the past six years, Focus on Energy has assisted with 47 biomass projects, but most are residential or business, Wichert says.

Between its manure and its crops, says Wichert, Wisconsin is the “Saudi Arabia of biomass.”

Copyright ADD, Inc. Jun 10, 2008

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