Making energy from cow manure

February 15, 2013

Experts from the University of Costa Rica’s (UCR) Agricultural Engineering School and Michigan State University, in the United States, are working to produce renewable energy from organic waste using an anaerobic digester.

The project is under way at the UCR’s Fabio Baudrit Moreno Experimental Station in Alajuela, north of the capital, and forms part of an effort by the school to improve technologies that help generate clean energy in rural areas. The program exists throughout Central America and relies mostly on biomass and solar energy. 

The U.S. government is providing Michigan State with $1 million in research funding for clean energy alternatives, through the university’s Biosystems Engineering Department. 

Engineer Daniel Baudrit, technical director of the project and a UCR professor, said participants are not only focused on building a digester, but also on training other professors in the technology, and accumulating more research in the field. 

“The Agriculture Engineering School is changing its studies program to focus on biosystems engineering in the near future. Many universities around the world are making this change,” Baudrit said. 

José Francisco Aguilar, director of the school, said the traditional focus has been on agricultural production. But that’s quickly changing, he said. 

“It’s important to produce, but it’s more important to produce in a sustainable manner that’s environmentally friendly. That’s what’s changing,” he said. 

According to Aguilar, building the anaerobic digester is a way to introduce biosystems into engineering by using organic vegetable and animal waste to produce energy. 

Both students and professors participated in the project’s research and development process. 

The digester is a closed tank in which organic waste is mixed for several days at a temperature of 50 degrees Celsius until bacteria form. The bacteria help produce gas, which is then filtered and passed through biogas generators or a combustion engine that power a generator, which produces electricity. 

The university digester currently is growing bacteria from cow manure, which will take three months. Once that step is complete, other organic waste can be used. 

Eighteen solar panels help keep the digester’s temperature constant around the clock.

Liquid and solid waste left over from the process can then be used to fertilize plants. If treated, the liquid waste can also be used to irrigate crops. 

“This is the first step to creating a research center for agricultural engineering. We’d like to let companies know that this technology is productive, and investment will be repaid in self-sustaining electricity production,” said Mildred Cambronero, a technical assistant on the project who studied the process at Michigan State and helped bring it back to Costa Rica.

The digester costs some $200,000, but in addition to the energy it produces, it can help mitigate environmental damage caused by agriculture activities. 

According to Baudrit, companies already are interested in anaerobic digester technology. The current objective is to resolve the issue of waste management and reduce electricity consumption, he added. With large digesters, companies can generate a significant amount of electricity. 

 “In Michigan, there are digesters that are 30 times the size of ours, and they’re used to generate electricity that is then sold to the state grid,” he added.

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