A sustainable Pathway to Achieve Dairy Waste Conversion to Electricity for EV Charging
A research team lead by Prof. Dr. Wei Liao from the Biosystems Engineering Department at Michigan State University (MSU), is focusing on solutions to produce renewable energy from dairy farm waste (manure) integrated with production of electricity to charge electric vehicles (EVs). Dr. Liao brings in his knowledge and more than 20 years of experience to this project, which helps manure management especially in small- and medium-sized dairy farms via climate friendly, carbon-neutral solutions. Dairy is the leading agricultural commodity in Michigan. The dairy industry accounts for nearly 5% of the state's gross domestic product, with $24 billion generated annually and supporting over 111,000 jobs. However, over 90% of dairies are in small- and medium-sized operations (less than 1,000 dairy cows) in Michigan. Challenges such as high capital cost and technological availability of small-scale power generation systems, and electricity buyback rates hurdle the widespread adoption of anaerobic digestion technology on small and medium-sized farms. As the U.S. strives to reduce the carbon footprint and transition towards cleaner and more sustainable energy sources, EVs plays a vital role in achieving these goals. However, for residents and businesses in rural areas, the limited availability of charging stations remains a significant barrier to embracing EV. Dr. Liao believes in linking dairy operations to EV charging can create a rural charging network and address this issue by at least meeting electricity demand of farm operation. He emphasizes the waste to electricity system developed will lead to a win-win-win solution for dairy farms, the EV industry, and rural communities.
Prof. Dr. Wei Liao in MSU dairy farm during the workshop on farm-based renewable energy solutions and EV charging on July 19, 2023.
The project, funded by MSU AgBioResearch, Michigan Economic Development Corporation, MSU Extension, and USDA Agriculture Research Services, involved a proof of concept demonstrating the production of biogas from anaerobic digestion (AD) of manure as the sole feedstock and conversion of biogas to heat and electricity using external combustion engine. The system is developed and built in the Anaerobic Digestion Research and Education Center (ADREC) at MSU, where Dr. Liao serves as the Director. His team of undergraduate and graduate research assistants, Jake Willsea, Carter Monson, and Ben Adams was involved in every stage of the design, construction, and operation in addition to Meicai Xu, who is a Ph.D student in Dr. Liao’s research group. Xu is working with dairy manure as a feedstock for AD and currently investigates methods to exploit organic carbon (C) and nitrogen (N) by modifying traditional AD.
The system to convert manure to electricity has a 2,250 L AD reactor connected to a 10 m3 biogas bag. The manure is fed at a rate of 40 kg wet manure per day, which is equivalent to daily manure management from a single cow. Biogas, which contains around 60% methane, is burned in an external combustion engine (a 6.5 kW PowerGen unit, Qnergy Co.) to produce heat and electricity simultaneously without any biogas quality restrictions.
An average of 4 kWh electricity (15% of biogas energy) generated from the biogas is stored in a battery pack to charge EVs. The amount of electricity can power a Tesla model 3 for 12-15 miles, which is the average distance of a regular daily commute. Monson and Xu’s experiments on the operation of system showed that nearly 80% of the biogas energy heat is used to sustain the temperature of AD reactor at 35℃. The results from the engine efficiency trials and tests point to a temperature increase of 10.12~16.73℃ in 30 minutes for 50 gallons reactor volume.
Operation and Process Flow Chart of the Farm-Based EV Charging Stations Integrated with the AD of Manure.
Dr. Liao’s team continues to work towards building a strong link between agriculture and auto industry, and further make them benefit from each other.
The manager of ADREC, Dr. Sibel Uludag-Demirer, works closely with Dr. Liao in his AD related research projects and she is fascinated by this small scale but highly capable unique system addressing many challenges in AD of manure such as the energy demand to heat the feedstock and reactor and biogas quality requirements for engine. She also finds the installation of EV charging stations innovative as their operation makes the manure management practices closer to being carton neutral.
This project also brought in opportunities for undergraduate researchers. For instance, Carter Monson believes that this project allowed him to build confidence and interest to keep pursuing post-graduate education and training in the biosystems and agriculture engineering field to create a much cleaner and sustainable future for all of us.
The farm based renewable energy production system with EV charging station is planned to be used in research and teaching activities. Dr. Liao invites especially MSU students to witness “the engineering in action” and realize how engineers from different backgrounds can work together to solve real life problems.
MSU-ADREC team, from the left to right: Ben Adam, Meicai Xu, Sibel Uludag-Demirer, and Carter Monson.
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