Report Biogas and bio-syngas upgrading Carried out by: Danish Technological Institute Laura Bailón Allegue and Jørgen Hinge Kongsvang Allé 29 DK–8000 Aarhus C Date: December 2012 1 Content 1 Summary ...................................................................................................................... 5 2 Introduction ................................................................................................................. 6 3 Biogas composition .................................................................................................... 7 3.1 Biogas quality versus feedstock composition ............................................................. 9 3.2 Biogas quality versus production process ................................................................. 12 4 Biogas quality for energy uses ................................................................................ 15 4.1 Biogas for only heat production .................................................................................. 16 4.2 Biogas to cogeneration systems (CHP) ...................................................................... 17 4.2.1 Biogas for internal combustion engines ................................................................................... 17 4.2.2 Biogas for Stirling engines ....................................................................................................... 18 4.2.3 Biogas for gas turbines and micro-turbines ............................................................................. 18 4.2.4 Biogas for fuel cells .................................................................................................................. 20 4.3 Biogas into the natural gas grid .................................................................................. 22 4.3.1 Biomethane standards ............................................................................................................. 24 4.4 Biogas as vehicle fuel .................................................................................................. 30 4.5 Biogas as CNG and LNG .............................................................................................. 30 5 Biogas upgrading technologies ............................................................................... 31 5.1 Adsorption .................................................................................................................... 31 5.2 Water Scrubbing ........................................................................................................... 33 5.3 Physical Absorption ..................................................................................................... 36 5.4 Chemical Absorption .................................................................................................... 37 5.5 Membrane Technology ................................................................................................. 38 5.6 Cryogen technique ....................................................................................................... 40 5.7 Biological methane enrichment ................................................................................... 42 5.8 Ecological lung ............................................................................................................. 43 5.9 Summary of upgrading technologies specifications ................................................. 44 6 Biogas cleaning methods ......................................................................................... 49 6.1 Hydrogen sulfide removal ............................................................................................ 49 6.1.1 In-situ (digester) sulfide abatement by addition of iron salts/oxides to the digester slurry ...... 51 6.1.2 In-situ biological H2S reduction by air/oxygen dosing to digester slurry .................................. 52 6.1.3 Adsorption ................................................................................................................................ 53 6.1.4 Absorption/Scrubbing .............................................................................................................. 57 6.1.5 Membrane separation .............................................................................................................. 59 6.1.6 Biofilters and biotrickling filters ................................................................................................ 59 6.1.7 Bioscrubber .............................................................................................................................. 61 6.2 Water removal ............................................................................................................... 62 2 6.2.1 Water condensation ................................................................................................................. 62 6.2.2 Water adsorption ..................................................................................................................... 63 6.2.3 Water absorption ..................................................................................................................... 63 6.3 Siloxanes removal ........................................................................................................ 63 6.4 Halogenated hydrocarbons removal ........................................................................... 65 6.5 Oxygen removal ............................................................................................................ 66 6.6 Nitrogen removal .......................................................................................................... 66 6.7 Ammonia removal ......................................................................................................... 66 6.8 Particle removal ............................................................................................................ 66 7 Overview of system propagation ............................................................................. 67 8 Converting biogas to non-cryogenic liquid fuels ................................................... 71 9 Biogas as feedstock .................................................................................................. 71 10 Gas composition from thermal gasification units ............................................... 72 10.1 Impact from gasifier type ............................................................................................. 72 10.2 Impact on product gas from different types of biomass ............................................ 74 11 Gas quality from thermal gasification plants ...................................................... 75 12 Cleaning process ................................................................................................... 76 12.1 Particulate removal ....................................................................................................... 76 12.2 Tar Conversion ............................................................................................................. 77 12.2.1 Thermal partial oxidation ......................................................................................................... 77 12.2.2 Catalytic oxidation .................................................................................................................... 77 12.2.3 Scrubbing ................................................................................................................................. 78 12.3 Hydrochloric acid, ammonia, and sulfur removal....................................................... 78 12.3.1 Adsorption processes .............................................................................................................. 78 12.3.2 Rectisol and Selexol absorption process ............................................................................. 79 12.3.3 Membrane solutions ................................................................................................................ 79 12.3.4 COS hydrolyses ....................................................................................................................... 79 12.4 Chloride and alkali removal ......................................................................................... 79 12.5 Carbon dioxide removal ............................................................................................... 79 13 Methane production from bio-syngas .................................................................. 81 14 Liquid fuel production from bio-syngas .............................................................. 81 14.1 Methanol ........................................................................................................................ 82 14.2 Fischer-Tropsch process ............................................................................................. 83 15 Biomass thermal gasification ongoing activities ................................................ 84 15.1 Rentech ......................................................................................................................... 84 15.2 The Güssing gasifier .................................................................................................... 85 3 15.3 EON – SNG production, Göteborg Energy .................................................................. 86 15.4 Enerkem .......................................................................................................................