Both the Dry and liquid methods for turning biomass into biogas use anaerobic fermentation. Biomass is fermented to produce biogas, which produces electricity to run a generator and supply the grid and heat, which can be used for other purposes. However, Dry Fermentation has been developed to simulate what happens inside a cow’s stomach.  This means the plant requires less piping, storage capacity and process energy.  It also means that instead of one very large vat the fermentation takes place in a series of smaller vats.

Dry Fermentation achieves the same end product as liquid fermentation but it has many advantages:

• Less manual work is involved – dry fermentation requires one person, with a suitable front loader, for only a half day of work every week, with a four hour, full biomass replacement operation, every four weeks.  This reduces the operating costs of your biogas plant.
  
  
• Processing is totally automated – every step of the process is monitored and controlled from your PC. Also, your production unit vendor, as part of their quality assurance, can monitor and control your plant remotely.  This reduces the operating risk of your biogas plant.
  
  
• No smell – traditional liquid fermentation processing of biomass causes olfactory havoc every time the biomass has to be added to, which is frequently.  However, Dry Fermentation processing requires additional biomass only infrequently and the most odorous parts of the process occur within the plant that cannot be opened during fermentation. No smell means less impact on your immediate environment and less problems with authorisations!
  
  
• No single point of failure – by having a series of smaller fermentation vats, if your biomass does experience an unsuitable acid level, the single vat involved can be cleaned out and replaced, without affecting the rest of your process.
  
  
• No biomass input separation – the Dry Fermentation process can use both wood and plastic.  As such, your raw material does not have to be separated out. This means a lower operating cost.
  
  
• Less water required – Dry Fermentation is just that, dry.  As such the process does not depend on a regular input of water. This reduces input costs and minimises the use of another valuable resource, water.
  
  
• Hygienic Operation – Heat, which is a by-product of the process, can be used to sterilise the plant. No cleaning necessary!
  
  
• Aesthetically unobtrusive – the Dry Fermentation plant, pictures of which you can find on this site, utilise gas-insulated compartments that are housed in what looks like a barn or garage.  It is much less obvious that the usual power plant! This helps in community acceptance and authorisations.
  
  
• Energy can be stored – the input biomass can be stored quite easily.  This is good for supply in winter or in case biomass is needed in a hurry due to any failure in the process.
  
  
• Less processing energy – as the Dry Fermentation plant has only a small requirement for energy to initiate and maintain the process, operation costs are low.  This means a higher ROI for the energy produced.

Simulating the digestion of a cow sounds easy but, Dry Fermentation has taken some time to be developed. Refining the process to its’ current level has made it commercially sound and easy to run.  It does, however, still require some know-how to initiate and maintain the production process.