Posts Tagged ‘enviromental construction’

Benefits and Challenges of Biogas Technology

October 14, 2010

Biogas Technology

Anaerobic digestion can convert organic wastes into profitable byproducts as well as reduce their environmental pollution potential. Anaerobic digestion offers the following benefits to an animal feeding operation and the surrounding communities:

  • Electric and thermal energy.
  • Stable liquid fertilizer and high-quality solids for soil amendment.
  • Odor reduction.
  • Reduced groundwater and surface water contamination potential.
  • Potential revenue from sales of digested manure (liquid and solids) and excess electricity and/or processing off-site organic waste.
  • Reduction of greenhouse gas emissions; methane is captured and used as a fuel.
  • Revenue from possible reuse of digested solids as livestock bedding.
  • Potential revenue from green energy and carbon credits.

The cost of installing an anaerobic digester depends on the type and size of system, type of livestock operation, and site-specific conditions (EPA AgStar, 2006).  In general, consider the following points when estimating installation/operating costs:

  • Estimate the cost of constructing the system.
  • Estimate the labor and cost of operating the system.
  • Estimate the quantity of gas produced.
  • Estimate the value of the gas produced.
  • Compare operation costs to benefits from operation (include value as a waste-treatment system and the fertilizer value of the sludge and supernatant).

The main financial obligations associated with building an anaerobic digester include capital (equipment and construction and associated site work), project development (technical, legal, and planning consultants; financing; utilities connection; and licensing), operation and maintenance, and training costs.

In making a decision to install a digester, one must realize that the system will require continuous monitoring and routine maintenance and repair that should not be underestimated.  Components should be maintained as recommended by the manufacturers because manure and biogas can be corrosive on metal parts.  In fact, the majority of digester failures over the past few decades were the result of management, not technological, problems.