Energy innovation grant funds bio-digester

The Institute for Energy and the Environment (IEE) in the NMSU College of Engineering 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.

The 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.

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.