This article was #21 in PDmag's Top 25 most-well read articles in 2010. Summary: Three years ago, the Brubaker family in Mount Joy, Pennsylvania installed a methane digester on their dairy and poultry farm. With this new technology, they claim the farm is now more than 20 times better for the environment than it was before. Because this article was so popular, we asked the Brubakers a follow-up question:

Q. You mentioned plans to add solar panels as another form to generate renewable energy. How is it working?

A. We installed one of the bigger solar systems in agriculture in Pennsylvania. It is absolutely fantastic; we are very pleased with how it is working. With two grids already in place, we are in the process of adding a third set of solar panels. The panels fit perfectly on the roofs of our barns. We are using a natural resource to make money and we don’t have to work to get it.

The payback is going well and we anticipate it to take about five years. We are using some of the electricity and selling some of it to the local utility. What really makes it pay for itself is selling the solar renewable energy credits (SRECs) to somebody that needs to buy clean energy.

—Luke Brubaker, dairy producer in Mount Joy, Pennsylvania



As you head west from Mount Joy, Pennsylvania, there’s only one way to tell where the city ends and the country begins – the property line that separates a residential home and the Brubaker family’s 750-cow dairy.

When Mike and Tony Brubaker decided to return to the farm to work with their father, Luke, the family realized the dairy needed to expand in order to maintain financial stability for three farm families.

The farm grew and so did the manure output. Following federal and state CAFO regulations, the Brubakers field-applied the manure according to the farm’s nutrient management plan. Yet they wanted to do more.

Although a digester had been on the Brubakers’ minds for some time, it wasn’t until they hosted an ag forum at the farm that they got their first break. The governor and ag secretary at the time came to the forum. While they were there, Luke offered them a tour of the dairy. Luke took them to see the manure pit and shared some of the issues the farm, like many others, faced in terms of manure management. When he mentioned he wanted to build a digester, it sparked an interest in the officials and they offered to find ways to help.

That help came in the form of grants. The Brubakers spent 1 ½ years applying for grants, and it paid off. They received an Energy Harvest grant from the State of Pennsylvania. That, along with loan assistance from the USDA, made their goal of installing a $1 million methane digester a reality.

Without grants, the payback was eight years. With the grants, it’s less than that, says Luke.

The digester started running in December of 2007. Mike, who also oversees nutrition and field operations at the dairy, manages the digester. On a normal day, he spends about 30 minutes monitoring the activity. If there’s an equipment problem or maintenance, like an oil change, it requires some extra time, he says.

With the digester, Mike says the farm is now more than 20 times better for the environment than it was before.

Automatic scrapers deliver the manure to a gravity flow system into the digester. The Brubakers also incorporate dry chicken manure to their digester from the 250,000 broilers they raise each year for Tyson. They can only use a portion of the chicken manure in the digester, otherwise the consistency gets too dry and it is not flowable. The rest of the chicken manure is sold to a nearby mushroom farm.

The Brubakers are also permitted to take food waste and other byproducts, like leftover chocolate from the state’s candy industry. The sugars and fats in the food help the digester make more energy. Soon after start-up they found the digester was capable of making much more gas than their original goal.

After the manure and byproducts are digested, the liquids are hauled to fields by tank and 90 percent are applied no-till.

Liquids from the digester have more nitrogen and less phosphorus, so the Brubakers can apply more liquid to the land to help meet their nitrogen needs while maintaining the maximum phosphorus requirements. In the Chesapeake Bay area, phosphorus levels are a high concern.

According to Mike, the digester also helps to convert some of the nitrogen in the manure from organic to inorganic. The inorganic form is more readily available to the plants and should result in better nitrogen efficiency for the crops.

Hot air from the digester is used to heat water on the farm and to dry down the digested solids. The dairy uses those solids as bedding for the cows. That’s a cost savings of $30,000 a year, reports Luke. The pathogen count is also less than the sawdust they were previously using, resulting in a lower SCC count.

Neighboring farms are using the Brubakers’ digested solids for bedding. With the shavings and sawdust so expensive for the area, they are happy to find a more affordable option.

Non-farm neighbors like the digester, too. Luke recalls a day when they were spreading digested manure on rented land, the land owner came out to say it didn’t hardly smell and was thrilled with the odor reduction, which is 70 to 90 percent less than before.

Brubaker 2

“We are surrounded by 100 or more houses, schools and churches all around our property,” Luke says. “We are always looking for ways to be more friendly to our community.”

The Brubakers don’t like to make their neighbors uncomfortable with their business practices and knew the digester would help, but they didn’t realize it would help as much as it has.

“It’s one of the best things we did, not just for the environment, but also for profitability,” Luke says.

Mike says their digester produces 4 to 5 megawatts a day and powers 150 to 200 homes. About 20 percent of the electricity generated from the digester is used on the farm and the rest is sold to PPL, the local power company.

“PPL has worked with us very well,” Luke says. “They’re required to acquire a certain portion of green energy and we can provide some of that.”

For that reason, the power company is willing to pay a price that helps make it profitable to run the digester.

By reducing the farm’s methane emission, they are able to sell carbon credits to help offset the initial investment into the digester. To do this, the Brubaker family works with Vermont-based energy broker, NativeEnergy, which specializes in farmer-owned, community-based renewable energy projects.

“It’s interesting to see the companies that are buying carbon credits for the emissions they are making or using as they travel,” Luke says, noting Ben & Jerry’s and Dave Matthews Band as partners in NativeEnergy.

Overall, the digester has been a great addition to the Brubakers’ farming operation.

“The digester is one of the greatest opportunities that we’ve ever done,” Luke says. “We were looking for a source of income other than adding cows.”

Having had much success with renewable energy thus far, the Brubakers are taking on another project – installing solar panels on top of a new heifer barn.

“Doing these projects is good for the future of the economy and the environment,” Luke says. PD

PHOTO 1: Adding an anaerobic digester has helped the Brubakers of Mount Joy, Pennsylvania, grow their dairy’s profitability without growing in cow numbers. (Left to right) Mike, Luke and Tony Brubaker have found it also helps with neighborhood relations.

PHOTO 2: Luke Brubaker holds some of the dried manure solids they’ve used to replace bedding on the 750-cow dairy – a cost savings of $30,000 a year. Photos by Karen Lee.

Karen Lee