By Melissa H. Hubbell
The Institute for Energy and the Environment (IEE) in the College of Engineering at New Mexico State University received $120,000 through Gov. Bill Richardson’s Energy Innovation Fund in Solar Energy and Biofuel Production. The funds are for the continued support of an anaerobic bio-digester that converts cow manure into methane used to generate electricity.
IEE is among the first five awardees to receive the Energy Innovation Fund grants.
“These first five grantees have presented ingenious biofuel and solar power projects that will push the envelope of innovation,” Gov. Richardson said. “These public/private partnerships help share the cost of innovation, but our hope is that each project can yield powerful benefits to our state.”
Luz-Elena Mimbela, IEE project manager and a doctoral candidate in environmental engineering, wrote the proposal resulting in the grant. The project is titled “Optimizing an Existing Two-Stage Biofermentation Facility for Methane Rich Biogas Production.”
This two-phase anaerobic (without oxygen) facility, located at Sierra Vista Growers in La Mesa, N.M., converts the carbon in dairy manure, donated by Gonzalez Dairy in neighboring Mesquite, to a methane-rich biogas that can be used in an engine generator for electricity generation. In addition, the resulting solid byproduct is a beneficial soil amendment, superior to existing organic compost, according to Kent Holla, owner of Sierra Vista Growers.
This technology will be an asset to New Mexico, which is ranked seventh in the nation in milk production. The New Mexico Dairy Industry has an annual production of seven billion pounds of milk and $900 million in gross receipt tax. However, the state’s dairy industry is also a source of concern with 328,000 milk cows generating 1.2 millions tons of solid waste a year.
“Currently, manure is either a waste or a very low value soil amendment. With the bio-digester technology in place it can be used for both electricity production and a higher value soil amendment at the same time,” Mimbela said.
The bio-digester consists of two reactors, one solid-phase and one liquid-phase. The liquid-phase reactor is used to grow microorganisms responsible for converting the manure to a methane-rich biogas. The microorganisms are then recycled back to the solid-phase reactor, where most of the biogas production takes place. This minimizes start-up time when a fresh load of manure is added.
Temperature is an important factor in the process and may affect the consumption rate of a particular biomass feedstock and thus the biogas generation rate. Mimbela proposed that a heating system be installed in the solid-phase reactor. Other proposed improvements include an online gas analyzer and instrumentation to monitor key process parameters such as pH, temperature and pressure.
Mimbela hopes this system is used with different types of feedstock such as organic waste from chickens and horses, cotton gin residue, cheese factory residue and municipal waste.
“This is one of IEE’s bioenergy research projects that will provide a substantial increase in the efficiency of dairy manure conversion into methane for electricity generation,” said Abbas Ghassemi, executive director of IEE. “The project helps solve a major waste problem while reducing greenhouse gas emissions in New Mexico.”
Another Energy Innovation Grant for $280,000 was awarded to IEE and Heliodyne Inc. for a project that will demonstrate the use of solar energy to produce electricity for a large building, while using the system’s waste heat to cool and warm the same building.
The Institute for Energy and the Environment consists of WERC: A Consortium for Environmental Education and Technology Development; the Southwest Technology Development Institute, a renewable energy research and development group; and the Carlsbad Environmental Monitoring and Research Center, a nuclear waste management and monitoring center.
For more information contact Ghassemi at (505) 646-2038 or visit or http://iee.nmsu.edu.