Products from a Biogas Plant and Their Applications

A biogas plant produces two main products – biogas and digestate; both can be further processed or utilized to produce secondary outputs. Biogas can be used for producing electricity and heat, as a natural gas substitute and also a transportation fuel. On the other hand, the digestate from the anaerobic digestion plant can be used as a soil conditioner.

Below are the different uses of biogas and digestate from a biogas plant:

1. Heat and Power

CHP systems cover a range of technologies but indicative energy outputs per m3 of biogas are approximately 1.7 kWh electricity and 2.5kWh heat. The combined production of electricity and heat is highly desirable because it displaces non-renewable energy demand elsewhere and therefore reduces the amount of carbon dioxide released into the atmosphere.

2. Transportation Fuel

Compressed biogas can be used as a transportation fuel for cars and buses. Biogas can also be upgraded and used in gas supply networks. The use of biogas in solid oxide fuel cells is also being explored.

3. District Heating

The surplus heat energy generated by a biogas plant may be utilized through a district heating network. Thus, there is potential scope for biogas facilities in the proximity of new housing and development areas, particularly if the waste management system could utilise kitchen residuals and green waste from the housing as a supplement to other feedstock.

4. Biofertilizer

Digestate from an anaerobic digestion plant can be further processed to produce liquid fertilizer and soil conditioner. The dewatered slurry from the anaerobic digestion plant is a bulky material with low levels of nutrients and can be used as a soil conditioner. A high proportion of the nutrients remain in the liquor, which can be used as a liquid fertilizer.