Wednesday, May 27, 2015

How much biogas production potential is there in Iowa?

 Are you interested in the potential anaerobic digestion holds in the state of Iowa? A new, easy to use tool, the Iowa Biomass Asset Mapping Tool (IBAM), may be just what you are looking for (available at IBAM is an economic analysis tool integrated with geographical information systems and was produced as a collaborative product of Dr. Mark Wright of Iowa State University and the Des Moines based company EcoEngineers. 

The model is an online, GIS, interactive map where a user can click on different layers of data to study  the biogas resource potential available or conduct an initial screening of where a potential project could be sited based on both feedstock and infrastructure availability. The IBAM tool provides estimates on production of a wide variety of biogas-based feedstock data including crop residues, manures, and industrial co-products.

The users can assess the potential availability of animal manure, crop residue and determine what co-location opportunities with existing biodiesel, ethanol, food and paper manufacturers exist. In addition to the feedstock data, there is also energy infrastructure data on the locations of natural gas pipelines, electric and gas service territories, and existing power plant locations. This helps users identify potential locations for optimizing substrates available for gas production and for best using the produced biogas.

A complementary tool to the GIS map is a preliminary economic assessment spreadsheet. The downloadable spreadsheet provides users the availability to modify inputs and assumptions to conduct a preliminary economic evaluation for a potential biogas project. Both the IBAM map and spreadsheet will require more robust analysis and engineering designs for any project moving forward, but these publically available tools can help users from the private and government sectors to conduct an initial project screen or quantify the potential for biogas projects in Iowa.

So that’s all great if you are a biogas expert, but really, what is anaerobic digestion?

Anaerobic digestion is a series of biological processes in which microorganisms break down biodegradable material in an environment with no oxygen. As these microbes break down the organic matter they make a mixture carbon dioxide and methane with trace amounts of hydrogen sulfide, ammonia, water vapor, and other gasses that we call biogas. This occurs in a series of three steps: in the first large particles are brown down into things like carbohydrates. Acidogenic bacteria then convert the sugars and amino acids into carbon dioxide, hydrogen, ammonia, and organic acids. Acetogenic bacteria turn those organic acids into acetate, which methanogens convert into methane and carbon dioxide. This is a naturally occurring process, its just when we do it in a digester we are trying to make it happen faster and control where the produced methane goes. So this organic material goes in and what comes out is the methane, which can be combusted to make heat or electricity and stabilized organic matter which still has the fertilizer value (the N, P, and K) it had when it went in.

This almost seems too good to be true right, we still get all our fertilizer value but we can get energy as too! Well, in some cases it can be a great deal, but anaerobic digesters can be expensive to build and sometimes challenging to manage, so they aren’t the right fit everywhere as often times we need an economy of scale to make them cost affordable. Thought not the final solution, hopefully more tools like the IBAM model will help us figure out where anaerobic digestion has the potential to be successful.