BioSNG developments at ECN

ECN developments focus on upstream units such as the gasification process and gas cleaning. The activities can be categorized into the following items:

• Gasification: for the biomass-to-SNG route, indirect gasification has been selected as the best option to produce raw producer gas with high efficiency. Based on the extensive fluidized-bed gasification development work over the past 15 years, ECN has developed a new, superior indirect gasification concept for this purpose, called MILENA. Main features of the MILENA indirect gasification technology (see website) are an essentially N₂-free product gas containing a high CH₄ concentration without having to use oxygen, and 100% biomass conversion. Lab-scale proof-of-principle tests (5 kg/h) and pilot-scale test (150 kg/h). Next step concerns upscaling to ~10MW for CHP and SNG production. Details on its design and operation can be found at ECN-B--10-006. Revealed good process operation under different conditions (bed materials, steam flow, temperature).
  
  
• Tar removal: since indirect gasification produces a gas containing considerable amounts of tar, tar removal is required in a BioSNG process. For this, the ECN patented process called OLGA is foreseen (see website). OLGA is an oil based scrubber technology for the removal of tars above the water dew point. The first version with 2 m_n³/h capacity has been up-scaled to 200 m_n³/h. Our industrial partner Dahlman supplied a 2000 m_n³/h OLGA to a French and a Portuguese customer, which started operation in 2006 and 2010 respectively. OLGA proved to be a robust tar removal technology, able to remove tars from several gasifiers with different tar concentration and tar composition. MILENA gasification and OLGA tar removal have been connected and operated successfully.
  
  
• Selection of gas cleaning: Although ECN would like to rely on existing technology from commercial suppliers, efforts are needed to integrate the units and prove the combination at e.g. lab-scale. Several options exist ranging from physical removal technologies (e.g. scubbing) to sorbent-based cleaning and catalytic conversion. Also cryogenic options are considered.
  
  
• System assessment: system assessment studies are performed continuously to support technology choices (see website). It is calculated that biomass can be converted to SNG with 70-75% energy efficiency. Approximately 40% of the carbon leaves the system as CO₂. If this is captured, a biomass-to-SNG plant could go beyond CO₂-neutral. This is called BECCS: Bio Energy with Carbon Capture and Storage

ECN is very enthusiastic that the SNG technology it is developing receives considerable attention from government and industry. We anticipate that this interest will only increase. The R&D process, with the focus on upscaling and longer-term tests, will pave the way for a successful SNG demo plant within a number of years. A demonstration plant and unique knowledge form the basis for the further commercialisation of SNG technology: a 2^nd generation technology that produces SNG with a 70% yield from biomass and has potential negative CO₂ emissions (carbon sink). The large-scale implementation of SNG will reduce CO₂ emissions, improve supply security and provides business opportunities.