Technologies for Biogas Upgrading

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1 Technologies for Biogas Upgrading Prof. Virendra K. Vijay Head, Centre for Rural Development & Technology, IIT, Delhi

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3 Biogas Production & Utilization (Source: OFGEM, 2011)

4 Upgraded & Bottled Biogas as a Replacement of Existing Petroleum Fuels for Mobility Applications

5 Biogas as an Alternate to Natural Gas! Properties Natural Gas Raw Biogas Upgraded Biogas(CBG/Biomethane) Composition% (v/v) CH % CO % H % N % CH % CO % N % O % CH 4 Min - 90% CO 2 Max (v/v) 4% CO 2 + N 2 + O 2 Max (v/v) 10% O 2 Max (v/v) 0.5 % C 2 H % C 3 H % H 2 S ppm H 2 S mg/m 3 Max 30.3 Moisture mg/m 3 Max -16 Iso-C 4 H % Neo-C 4 H % Iso-C 5 H % Neo-C 5 H % C 6 H % Lower Heating Value MJ/kg 20.5 MJ/kg MJ/kg Relative Density Flame speed (cm/sec) Stoichiometric A/F (kg of Air/ kg of Fuel) Auto-ignition Temperature (⁰C)

6 Raw Biogas Biogas Upgrading: The Gas Separation Problem A low Grade fuel (CH % & CO %) with lower percentage of methane. Mode of utilisation The presence of CO 2 besides being non combustible, restrains its compressibility there by making biogas difficult to be stored in containers. Cleaned/Upgraded Biogas A high grade fuel (CH4 > 90 % and < 10 % other gases) with high percentage of methane. Mode of utilisation Onsite/ Remote applications Methane burns faster hence yields a higher specific output and thermal efficiency compared to raw biogas when used as engine fuel. Upgrading, compression and bottling facilitates easy storage and transportation as a vehicle fuel

7 Utilization of Upgraded Biogas First Biomethane bus in India Biomethane Bus in Sweden Biogas car in Sweden Biogas Train in Sweden

8 Upgraded & Bottled Biogas for Cooking and Vehicular Applications Cascades of Upgraded biogas being transported Biogas Motorcycle in Thailand Biogas Car in India Upgraded and bottled biogas for use as a cooking fuel Bottled biomethane used for power generation

9 Techniques for Biogas Cleaning/Upgrading Absorption Adsorption Membrane Cryogenic Water Scrubbing Pressure Swing Adsorption High Pressure Gas Gas separation Physical Scrubbing Low Pressure Gas Liquid separation Chemical Scrubbing Decide for suitable technology primarily NOT by investment costs Select suitable technology according to: All Technologies are Not Equal. Upgrading capacity The current biogas technologies have different strengths and weaknesses. The established CH4 recovery technologies for the removal of CO 2 from biogas are based on the differences in molecular, thermodynamic Turn down and ratio transport properties of the gaseous components in biogas. Shut down / start up performance and ease of operation Product quality required Chemicals and energy consumption

10 Water Scrubbing Process for Biogas Upgradation Simple process Based on high solubility of CO2 and H2S in water H2S pre-removal is not mandatory Can tolerate ppmv Low investment and operational cost Low methane slip High energy efficiency >96% Best in Medium and Large Applications Proven technology Robust system Regeneration is simple with depressurisation of water Water is recycled

11 Chemical Scrubbing Process for Biogas Upgradation Chemical absorption of CO2 into chemicals MEA/DMEA High selectivity for CO2 Low methane loss Regeneration by heating spent chemical at high temperatures H2S pre-removal is mandatory Otherwise H2S will also be absorbed in the solvent leading to higher heating requirements for regeneration

12 Pressure Swing Adsorption Process for Biogas Upgradation Adsorption on activated carbon or zeolite under pressure Adsorbent is regenerated by sequential decrease in pressu Pre-removal of H2S is mandatory Low biomethane recovery

13 Low investment and operational cost Low methane slip 98% with multi stage systems Compact Simple on/off Simple on/off Best for low and Medium Flows Membrane Cascade Separation System For Biogas Upgradation i) General Design, Ii) Single Stage Configuration, Iii) Two-stage Configuration With A Recirculation Loop, Iv) Two-stage Configuration With Sweep And V) Three-stage Configuration With Sweep

14 Cryo-technology for Biogas Upgradation Liquefied CO 2 Complex Technique High energy requirement for High pressure low temperatures

15 Summary of Biogas Upgrading Technologies Parameter Basis of Gas Pre Working Methane Solvent/ Fate of Heat % Purity N2, O2 Invest Ease of Water scrubbing Operation technology Cleaning is one Pressur of Loss the most Adsorbent widely Split implemented Biogas Require of and CH4 mature in separation technology Cost operation Requirement e during ment Upgraded /Nm3 with over 41% plants out of 503 biogas upgrading plants installed worldwide (IEA, 2017). Method (bar) Upgradatio Gas biogas n Water Scrubbing Physical Not required, 6-10 < 2%, Water No No Cheapest, Based on physical Absorption H 2 absorption of gases in water- no chemical reaction involved. S removed Medium along with CO2 Physical Absorption Chemical Absorption Pressure Swing Adsorption Membrane Separation No pre-cleaning of H 2 S required, since solubility of H 2 S is higher than CO 2, it will also get dissolved Physical in water Not required at high 4-7 pressures. < 4%, Organic Medium,7 > 96, < 93- Absorption High solvents, 0-80C 98% Water is used as a solvent cheap, easily and abundantly available. CH 4 rich (above Regeneration Chemical of Required water & is simple 1 <0.1%, release Amines, of Alkali pressure. 90%) Too high Absorption Recommended Low solutions biomethane gas C No heat requirement during absorption or regeneration stream and CO 2 process. rich (80-90%) No complicated off gas stream Adsorption and complex 4-8 bar equipment <2, 6-10%, Molecular required. with some CH Medium Sieves 4 Easy operation and maintenance. as loss Gas Gas Gas - Liquid Permeation Required & Highly recommended No use of chemicals. Required & Recommended Cheap, Investment cost is less. Simplest No 0.25 Difficult in operation > 98 No 0.28 Difficult in operation No > 96, > 98 Yes 0.26 Extensive process control needed >10-20, High Membranes No 90-92%, Partly Cheap, High 96% Easy Cryogenic Separation Multistage Compression and condensation Recommended 40 Lowest Not required CH4 rich (above 98%) biomethane gas stream and solid CO2 rich (99%) off stream No 99 No , Most expensive Complex, multifaceted

16 State of the Art Water Scrubbing based BioCH 4 and BioCO 2 Production Technology Developed at IIT Delhi, India Awarded: Patent No is granted on 27/06/2017 for A Device and a Process for Conversion of Biogas to a Fuel Gas with enhanced Thermal Efficiency. V.K.Vijay, P.M.V. Subbarao, R.R. Gaur and S.S. Kapdi. Patent Application No. 161/DEL/2006 dated Applied: V.K. Vijay, Rimika Kapoor, P.M.V. Subbarao, A System for Biomethane and Bio Carbon Dioxide Production from Biogas and a Method Thereof. (Indian) Patent Application No.: , Dated: May 21, 2018.

17 Water Scrubbing based BioCH 4 and BioCO 2 Production System at IIT Delhi

18 WS1 WS2 Capacity Gas Flow Rate Quality of Gas Obtained Recovery of Gas WS1 (BioCH4 Production) WS2 (BioCO2 Production) 10Nm 3 /h 5 Nm 3 /h 95% BioCH4 99.9% BioCO2 91% 88.5%

19 Upgraded Biogas Dispensing System at IIT Delhi High Pressure Compressor Two cylinder cascade for bottling of upgraded biogas Dispensing Nozzle - NZ type

20 BioCH 4 Application as Vehicular Fuel

21 BioCO 2 Application Algae Cultivation Grain Fumigation Greenhouses Chemical Manufacturing

22 Mobile Biogas Upgradation System developed at IIT Delhi

23 THANK YOU