Anaerobic digestion in the food sector

Anaerobic digestion (AD) allows micro-organisms that thrive in an oxygen-free environment to convert bio-degradable materials into biogas that can be used to generate renewable energy (heat and power).  The digestion process involves a series of reactions as illustrated below. 

AD process schematic (simple)-01

Anaerobic digestion is still developing as a technology with opportunities to adapt it to on-site applications that convert residues produced on farm, in rural communities and on food industry sites, into energy for use in the business or the community (or exported).  A key development is the use of biogas to produce upgraded gas (bio-methane) for supply to the gas grid. 


Benefits of on-site plants for food processors

Most food and drink processing residues can be treated with AD.  Larger centralised “merchant” plants can be expensive to build and operate.  Smaller AD plants installed on industrial sites can contribute to site energy demand.  The food industry provides an ideal platform for on-site AD, with a range of feedstocks and the ability to use energy generated from unwanted residues. 

On-site AD will reduce disposal costs, while generating energy that can be used in production processes, reducing the site’s carbon footprint.   Cost savings for on-site AD projects include:

  • Reduced co-product disposal charges - cutting costs of running aerobic plants on site or through a reduction charges for sewer discharge.
  • Reduced costs of sending residual materials off site or disposal of higher COD materials generated in the production process (e.g. whey)
  • Reduced energy costs, as existing fossil fuels (i.e. electricity, fuel oils or natural gas) are replaced by renewable biogas generated on site.