Our Technology

BioSNG Technology

BioSNG production generally involves the following steps:

 

  • Fuel preparation: Waste or biomass feedstocks are shredded and dried and recyclates such as metals or dense plastics are removed.
  • Thermal conversion: The prepared feedstock is heated to convert it to a synthesis gas (syngas). The physical and chemical composition of waste and biomass feedstocks means that the syngas is contaminated by tars.
  • Tar treatment: Tars are converted to syngas using thermal, catalytic or plasma treatment or, removed using water or oil based scrubbing.
  • Gas cooling and cleaning: The gas is cooled. Ash and heavy metals are removed along with other contaminants such as acid or alkaline gases.
  • Compression: The syngas is compressed to simplify further processing.
  • Water gas shift: The syngas is reacted with steam over a catalyst bed to increase the ratio of hydrogen to carbon monoxide.
  • Methanation: The syngas is passed over a catalyst bed to convert carbon monoxide and hydrogen to methane and water.
  • Separation: Carbon dioxide is removed to produce methane rich gas.
  • Upgrading: Propane is added to match the calorific value of the BioSNG with the gas grid.

gg-process

The BioSNG pilot and commercial plants in Swindon use oxy-steam fluidised bed gasification and a plasma converter to remove tars and vitrify ash and heavy metals. Wet scrubbing systems are used for bulk removal of acid and alkaline contaminants and a series of guard beds are used for final polishing. A sweet water gas shift is followed by a series of methanation reactors. In the pilot plant a pressure swing adsorbtion system is used to remove carbon dioxide, but in the commercial facility a chemical scrubbing system is used.

There are a number of projects in Europe and the USA that produce BioSNG. The 20 MW GoBiGas facility in Sweden is producing renewable gas from wood residues. ENGIE has committed substantial funds to a facility in France which is nearing completion of the construction phase and a further plant is under development in Holland. Uniquely, our projects are focused on the conversion of waste derived biomass to BioSNG as this is represents the UK’s largest biomass resource.

Further Reading:
GoBiGas Plant
Gaya Project
Alkmaar BioSNG Project

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