Saturday, July 17, 2010

Biomass Energy Agriculture Sustainability - Focus on Water Quality.

When we hear the term "sustainability" for biomass energy feedstocks being discussed or debated, often we really don't know what "specifics" are being proposed. Most of the time it just seems that (1) Project developers' concept of "green" only involves making money; (2) the agenda of many environmental groups (like the Sierra Club) is to kill projects and not find solutions; (3) Legislators don't have a clue on science.

In our collaborative work with the University of Florida and industry scientists, "Advanced Cropping Systems" are being developed, tested, and implemented integrating disciplines of (1) soil science; (2) plant science, (3) engineering science through biomass gasification to create biochar (a stable component of soil organic carbon), and (4) water science.

In today's blog, we will give a brief "science based" discussion on how growing energy crops can integrate into improving and sustaining water quality through a 3 Zone nutrient capture approach.


For example, the concept schematic below illustrates the activity occurring in the yellow Soil Filtration Zone (above). Here, water is filtered through alternating aerobic and anaerobic conditions. This is because certain chemical constituents like N and large carbon-chain molecules such as organic chemicals are broken down under anaerobic conditions initially (nitrate and nitrite are blown off as elemental N in gaseous state; thus they don’t continue in a dissolved state to impact downstream waters). Large carbon-chain molecules are broken down in anaerobic conditions enabling aerobic bacteria to further decompose them. Thus, by running stormwater runoff with P from ag lands through aerobic and anaerobic cycles, more and more of the P and other nutrients are stripped out of the water with each cycle.

In our approach to sustainable agriculture, wood chips, peat and biochar are used to provide the growing media for the bacteria and soil fungi that will aid in the supporting the decomposition and adsorption of constituents. Thus, the system contains the constituents on-site so they don’t leave the biofilter and enter downstream water bodies.

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