Glossary

Anaerobic Digestion (AD): is a biological process in which microorganisms break down biodegradable material in the absence of oxygen creating two important products: biogas and digestate. AD makes the best use of organic materials by producing biogas for the generation of renewable heat, electricity, fuel and fertilizer while closing the nutrients cycle and reducing greenhouse gas emissions.

Ashes: all non-nitrogen nutrients contained in the resulting ash, which are recycled to the producing lands, e.g. forests. To maximize the recycling of nitrogen, all feedstock high in nitrogen should always be treated through AD.

Biogas: the primary product of AD is a methane-rich renewable gas composed of 50 to 65% methane and 35 to 50% carbon dioxide.

Biohydrogen: hydrogen produced biologically by means of fermentation.

Biomethanation: besides methane formed spontaneously during gasification, syngas can be transformed into methane through two catalyst aided reactions: the water-shift reaction (hydrogen and carbon dioxide formed from carbon monoxide and water) and the Sabatier reaction (methane formed from carbon dioxide and hydrogen).

Biomethane: when carbon dioxide and trace gases in biogas are removed, a methane rich renewable natural gas substitute is left in the form of biomethane. Biomethane can be injected into the gas grid, used as a vehicle fuel or used for combined heat and electricity generation.

Biopropane: propane produced from biodiesel side-products or by a biological conversion from starch-containing biomass.

Digestate: remaining part of organic matter treated by AD, rich in nutrients and nitrogen, commonly used as an organic fertilizer in agriculture.

Feedstock: AD can process almost any biogenic material including solid and liquid manure; energy crops; catch crops; agricultural waste and residues; industrial food and beverage waste; and sewage sludge and the organic fraction of municipal solid waste. Gasification can theoretically process any carbon containing material and is a complementary technology to Anaerobic Digestion (AD), since it can treat high-solids feedstock with low anaerobic biodegradability; these include lignocellulosic feedstocks such as wood chips, and non-recyclable waste fractions of biomass origin currently landfilled or incinerated for energy recovery.

P2G: Power-To-Gas technology, where electric energy is used as a reducing agent in chemical or microbiological reactions generating energy-rich gas, namely methane or hydrogen.

Syngas: the primary product of gasification is a mixture of carbon monoxide and hydrogen, with traces of methane and carbon dioxide. It may be used directly for electricity generation, or further transformed to increase its share of methane.

Thermal gasification (Gasification): is a physico-chemical oxygen depleted process in which the carbon containing components of the biomass break down to syngas instead of being completely combusted. It is a complementary technology to anaerobic digestion and greatly amplifies the potential of renewable energy in the form of heat, electricity and vehicle fuel.