7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT Environmental evaluation of difgerent biogas upgrading technologies Lidia Lombardi, Giovanni Francini, Marzio Lasagni lidia.lombardi@unicusano.it
32 nd International Conference on Effjciency, Cost, Summary Optimization, Simulation and Environmental Impact of Energy Systems • Introduction • Objectives • Technologies for upgrading biogas to biomethane • Results - Comparison • Conclusions 7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 2 26-29 June 2019 Heraklion, Crete Island, Greece
32 nd International Conference on Effjciency, Cost, Introduction Optimization, Simulation and Environmental Impact of Energy Systems For 2030: European • Union 40% reduction in Greenhouse Gas (GHG) emissions compared to 1990 levels COM(2014) • COM(2016) at least 27% share of renewable energy consumption Biogas production with consequent bio-fuels and bio-products generation Development of the number of biogas plants in Europe (left), per 1 Mio capita (right). EBA Statistical Report 2018 7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 3 26-29 June 2019 Heraklion, Crete Island, Greece
32 nd International Conference on Effjciency, Cost, Introduction Optimization, Simulation and Environmental Impact of Energy Systems Most of the biogas produced in EU comes from the anaerobic digestion (AD) process Biomethane yield from selected feedstocks. Scarlat et al. 2018 • The biological degradation treatment of AD is suitable for substrates such as source sorted organic fraction of municipal solid waste (SS- OFMSW) The primary product of AD is biogas, characterized by CH 4 (vol, 50-75%) • and CO 2 (vol, 25-45%) as main components 7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 4 26-29 June 2019 Heraklion, Crete Island, Greece
32 nd International Conference on Effjciency, Cost, Introduction Optimization, Simulation and Environmental Impact of Energy Systems In the fjeld of biomass energy conversion techniques, the biogas upgrading technologies can be a solution to use the produced biogas Biomethane CO CH • injection into the distribution network • used in the public and/or private transport 2 4 sector Substitution of fossil fuels for increasing the primary energy savings Development of the number of biomethane plants in Europe (left), number of biomethane plants in European countries (right). EBA Statistical Report 2018 7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 5 26-29 June 2019 Heraklion, Crete Island, Greece
32 nd International Conference on Effjciency, Cost, The case study Optimization, Simulation and Environmental Impact of Energy Systems Italian Government issued the Decree of the Ministry of Economic Development of March 2nd 2018 , introducing a support scheme for biomethane injection into the natural gas grid and for advanced biofuels to be used in the transport sector Case study: San Zeno plant (Arezzo, IT) Future Dry-Batch Anaerobic Digestion able to process 35,000 tonne/year of SS-OFMSW CH 4 , 55% • H 2 S, 100 ppm • CO 2 , • • T emperature, Output of 320 Nm 3 /h 43.7% 35°C biogas N 2 , 1% • • Pression, 0.02 bar O 2 , 0.3% • 7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 6 26-29 June 2019 Heraklion, Crete Island, Greece
32 nd International Conference on Effjciency, Cost, Technologies for upgrading Optimization, Simulation and Environmental Impact of Energy Systems biogas to biomethane Aim of the work is to evaluate the energy and environmental benefjts of the proposed technologies • Pressure swing adsorption (PSA) • Membrane permeation Chemical absorption through inorganic solvent (K 2 CO 3 ) • Data on the considered processes were collected from the main companies ofgering biogas upgrading plants Evaluation methods : • Energy balance CO 2 equivalent emission • balance total primary energy (TPE) CO 2 of each considered energy potential of energy fmows contribution to the impact on the (electric and thermal energy global climate consumptions and energy due to (emission due to electric energy the production of biomethane) requirements, emission due to the 7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT CH 4 slip) 7 26-29 June 2019 Heraklion, Crete Island, Greece
32 nd International Conference on Effjciency, Cost, Pressure swing adsorption Optimization, Simulation and Environmental Impact of Energy Systems p = 9 bar Simplifjed process fmow diagram of a pressure swing adsorption system • Separation of the biogas compounds according to the size of the molecules • Selectively molecular sieve, zeolites or activated carbon Desulfurization step is essential, due to the H 2 S • toxicity for the adsorbent material • T wo phase: a high-pressure adsorption step and a desorption step A low part of CH 4 is not recovered • 7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 8 26-29 June 2019 Heraklion, Crete Island, Greece
32 nd International Conference on Effjciency, Cost, Membrane permeation Optimization, Simulation and Environmental Impact of Energy Systems p = 17 bar Simplifjed process fmow diagram of a membrane permeation system • Selective membrane permeability based on the difgusion and permeation coeffjcients of difgerent gases H 2 S and other contaminants can • damage and corrode the membranes • The well-established membrane permeation process is the three- stage confjguration with sweep biogas stream 7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 9 26-29 June 2019 Heraklion, Crete Island, Greece
32 nd International Conference on Effjciency, Cost, Chemical absorption using Optimization, Simulation and Environmental Impact of Energy Systems inorganic solvent solution T = 70-80 °C T = 120-140 °C p = 8.5 bar Simplifjed process fmow diagram of a K 2 CO 3 chemical CO 2 selective absorption column with a counter- • absorption system current washing through an aqueous solution of potassium carbonate (aqueous solution with 30% of K 2 CO 3 by weight) O 2 , N 2 , H 2 remain predominantly in the • biomethane fmow, that exits from the top of the column Recovery step of CH 4 fractions (fmash tank) • In a regeneration column, CO 2 is released by • stripping with steam produced by an external source of heat 7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 10 26-29 June 2019 Heraklion, Crete Island, Greece
32 nd International Conference on Effjciency, Cost, Operating parameters Optimization, Simulation and Environmental Impact of Energy Systems The specifjc consumptions are referred to the Nm 3 of raw biogas in input to the process Chemical absorption Parameters PSA Membrane with K 2 CO 3 Biomethane production [Nm 3 /h] 182 180 183 CH 4 in the biomethane [%] 96 97 96.25 Electric energy requirements [kWh/Nm 3 ] 0.25 0.34 0.23 Thermal energy requirements [kWh/Nm 3 ] - - 0.48 Heat recovery [kWh/Nm 3 ] 0.15 0.17 0.39 CH 4 slip [%] 1.3 0.8 0.08 Water requirements [kg/Nm 3 ] - - 0.069 Liquid waste to disposal [l/Nm 3 ] 1 0.047 0.039 0.072 Activated carbon requirements [g/Nm 3 ] 2 0.3 0.3 0.3 Chemicals requirements – K 2 CO 3 [m 3 - - 0,005 3 1 a consumption of 0.65 kWh/m 3 was assumed for the process of liquid waste treatment solution/Nm 3 ] 3 Operating hours [h/y] 2 landfjll disposal of the exhausted activated carbon assuming a transportation distance of 30 km 8400 8400 8400 3 aqueous solution with 30% of K 2 CO 3 by weight In order to perform a fair comparison, the same consumption of activated carbons equal to 0.3 g/Nm 3 was assumed in the three cases 7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 11 26-29 June 2019 Heraklion, Crete Island, Greece
32 nd International Conference on Effjciency, Cost, Results Optimization, Simulation and Environmental Impact of Energy Systems Initial assumptions (Reference case): • Thermal source available for the process • Heat recovery not considered Complete regeneration of the K 2 CO 3 solution • Chemical absorption with Energy balance [MWh/y] PSA Membrane K 2 CO 3 Electric energy requirements for upgrading unit 672 914 (+36%) 618 (-8%) Thermal energy requirements for upgrading unit - - 0 Heat recovery 0 0 0 Electric energy requirements for liquid waste 0.082 0.064 0.126 treatment Diesel for the solid waste transportation to 0.003 0.003 0.003 landfjll Biomethane energy -15 947 -15 946 -16 056 (+1%) (+0%) T otal primary energy (TPE) -15 275 -15 031 -15 437 (-1%) (+2%) Chemical absorption with CO 2 equivalent emission balance [tCO 2 /y] PSA Membrane K 2 CO 3 Electric energy requirements for upgrading unit 350 475 (+36%) 322 (-8%) Thermal energy requirements for upgrading unit - - 0 Heat recovery 0 0 0 Electric energy requirements for liquid waste 0.063 0.049 0.096 treatment The percentage in the brackets means the difgerence between membrane or chemical absorption values Solid waste landfjlling and transportation 0.005 0.005 0.005 compared to PSA value CH 4 slip 269 168 (-38%) 16 (-94%) 7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 12 Biomethane production -3287 -3287 -3310 26-29 June 2019 Heraklion, Crete Island, Greece
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