Touring the Penn State Digester

Joseph Coughlin here with the Penn State Extension Energy team. Welcome to Penn State's dairy complex, home to an incredible piece of technology called an anaerobic digester. Today, we're going to explore how this system turns cow and pig manure into renewable energy, reduces farm odors, and helps make farming more sustainable. Tom Bresnik here with Penn State Extension. So what exactly is an anaerobic digester? It's like a big sealed tank where tiny microorganisms break down organic material like animal manure without oxygen. This process creates biogas, a renewable energy source, and digestate, a nutrient rich liquid that can be used as fertilizer. Here at Penn State, the digester starts manure from over 350 dairy cows and heifers. The barns use sand bedding, which is great for the cows but tricky for the digester. So we use a special system called the McClanahan Sand separator to pull the sand out of the manure. The sand gets cleaned and reused as bedding, and the liquid manure heads to the digester. Once the sand is out, the manure goes into a mixing tank. Soon, we'll also add manure from Penn State’s Swine Farm, which has about 580 pigs. The manure gets stirred up to make sure it's well mixed before entering the digester. Inside the digester, it's heated to about 95°F to help methane producing bacteria do their job. Inside the digester, those bacteria work their magic for about 23 days. The result? Two awesome products, biogas and digestate. The biogas, which is about 55% methane, powers the generator to produce electricity. Enough to generate about 830,000kW a year. That's enough to power hundreds of homes. The heat from the process keeps the digester warm and the nutrient rich digestate is spread on nearby fields as fertilizer. Why did Penn State build this digester? For starters, it makes manure management easier and more efficient. Before manure was trucked to fields, which was time consuming. Plus, the digester cuts down on odors. Important since the dairy complex is right across from Beaver Stadium. It also helps keep birds away from nearby fields, making things safer for planes at the State College airport. It's not just about convenience. The digester supports Penn State's goal to be more sustainable. It reduces greenhouse gases by over 500 metric tons of carbon each year and creates renewable energy. Plus, the recycled sand and digestate make the farm's operations more eco friendly by reusing resources. The Penn State anaerobic digester is a game changer for sustainable farming. It turns waste into energy, reduces odors and helps the environment, all while keeping the farm running smoothly. Want to learn more? Check out Penn State Extension's website for details on anaerobic digesters and sustainable agriculture.