As part of a long-range goal for Michigan State University to consume only renewable energy, the university has broken ground on an unusual project.
The MSU Board of Trustees approved a proposal in April to move forward with an anaerobic digester as part of the university’s energy transition plan, When the researchers involved began work on the anaerobic digester idea, a team led by Dana Kirk, manager of the Anaerobic Digester Research and Education Center at MSU, calculated how much food waste was occurring on campus. They also gathered water usage data and examined whether they could make both processes more efficient.
Kirk said that taking waste and turning it into something usable, something that can also create a positive cash flow, seemed like the logical thing to do.
Before launching the multimillion dollar project, ADREC gained operational experience through the use of a small-scale research digester. Testing began in the fall of 2011 using dairy and poultry manure and food waste from the campus cafeteria in a plug flow configuration. A plug flow configuration moves material down by the introduction of new material without mixing it in the tank. It’s one of four anaerobic digester system types, the others being covered lagoon, municipal complete mix and agricultural complete mix.
MSU’s new system will be a complete digester, which breaks down organic matter in a warm environment with no or very limited oxygen.
The technology behind anaerobic digestion for waste treatment has been around for centuries, and has experienced fluctuations in popularity and use. According to the EPA, the development of anaerobic digesters for livestock manure treatment and energy production has accelerated at a very fast pace over the past few years. The technical reliability of anaerobic digesters through the deployment of successful operating systems over the past five years, growing concern of farm owners about environmental quality, an increasing number of state and federal programs designed to cost share in the development of these systems, the increasing energy costs and the desire for energy security and the emergence of new state energy policies designed to expand growth in reliable renewable energy and green power markets have all affected this rapid pace of growth.
Financial incentives have increased the deployment rate of manure digester systems. For example, grants and loans awarded by USDA Rural Development through the Farm Bill have been one of the primary methods for farms to partially fund installation of commercially proven livestock waste digestion technologies.
Anaerobic digesters reduce greenhouse gas emission reductions in two ways. The first is direct methane emission reduction from the capture and burning of biogas that otherwise would escape into the atmosphere from the waste management system. For projects that generate energy, a second benefit is avoided emissions of greenhouse gases and other pollutants generated by the use of biogas to displace fossil fuels.
ADREC’s pursuit of organic materials for digestion hasn’t stopped with the 1,000 to 1,500 gallons of manure it receives from the dairy farm on campus; the chicken manure; and the pulped food waste from the campus cafeteria. It is also getting preconsumer food waste from the three other dining halls on campus. Kirk explains that part of the process is getting all of the groups — from administration to research to food services — to buy in to the changes that need to happen.
For example, some of the preconsumer food waste comes from the cooks depositing food trimmings in collection bins as they prepare meals. ADREC is also partnering with local food processors and a grease hauler to acquire more organic matter for the digester. One of the system’s byproducts, methane, will be used to help power some of the buildings near the digester, saving money and providing revenue. Other revenue could come from fertilizer sales and tipping fees paid by project partners who would normally pay landfills to dispose of their waste materials. Between the energy produced and the revenue collected, Kirk estimates a 12- to 15-year return rate on the project’s investment — though he noted that it could be less depending on the final outcome of the contract process.
For municipalities and farmers looking at an anaerobic digester system, Kirk recommends that they examine their energy needs and goals and identify where they stand in relation to them today. Municipal planners should also look at the quantities of energy used and the quantity of waste they are working with. In regard to job creation, Kirk said: “There is potential for more system operators, maintenance personnel, designers and engineers. At MSU we are looking at adding a full time operator and a part time operator.” And every ton of organic material that is collected for a digester is a ton that doesn’t wind up in a landfill.