BENEFITS OF BIOGAS SYSTEMS Reduce odors Provide high-quality fertilizer Reduce surface and groundwater contamination Destroy pathogens and weed seeds Reduce atmospheric emissions of methane, a powerful greenhouse gas Provide on-farm energy Create jobs related to the design, operation, and manufacture of energy recovery systems

Biogas is produced by bacteria that break down organic matter in the absence of oxygen. Biogas, which is 55-75% methane, can be burned directly for heat, or used to power engines that generate electricity.

The fermentation or digestion process that produces biogas consumes the organic matter in the wastewater and can lower the Biological Oxygen Demand (BOD) of the wastewater to safe levels. In addition, the digested slurry that results can be used or sold as fertilizer.

Several digester technologies have been developed to increase the efficiency of this naturally occuring process and to capture the gas for use.

Thailand's primary biogas sources are pig farms and residues from food processing. The country's many pig farms have the combined potential to produce over 50 MW of electricity by producing biogas from manure. The electricity generating potential from cassava processing alone has been estimated at 350 MW. Palm oil also offers significant potential.

Pig Farms

Farms utilizing biogas digesters can solve pollution and odor problems, and reduce the farm's energy costs. Some farms will produce enough biogas to export electricity to the grid for sale to the utility under Thailand's net metering regulations.

The following table shows the distribution of medium-size (60-600 livestock unit) pig farms in Thailand.

Industrial Wastewater

Thailand's food processing industries also offer excellent biogas potential. Most significant are the industrial wastewaters from the palm oil and tapioca starch production, and animal slaughter.