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Environmental evaluation of difgerent biogas upgrading technologies - - PowerPoint PPT Presentation

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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

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7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT

Lidia Lombardi, Giovanni Francini, Marzio Lasagni lidia.lombardi@unicusano.it

Environmental evaluation of difgerent biogas upgrading technologies

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32nd International Conference on Effjciency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 26-29 June 2019 Heraklion, Crete Island, Greece

Summary

  • Introduction
  • Objectives
  • Technologies for upgrading biogas to

biomethane

  • Results - Comparison
  • Conclusions
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32nd International Conference on Effjciency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 26-29 June 2019 Heraklion, Crete Island, Greece

Introduction

European Union COM(2014) COM(2016) For 2030:

  • 40% reduction in Greenhouse Gas (GHG)

emissions compared to 1990 levels

  • 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

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32nd International Conference on Effjciency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 26-29 June 2019 Heraklion, Crete Island, Greece

Introduction

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 CH4 (vol, 50-75%)

and CO2 (vol, 25-45%) as main components

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32nd International Conference on Effjciency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 26-29 June 2019 Heraklion, Crete Island, Greece

Introduction

In the fjeld of biomass energy conversion techniques, the biogas upgrading technologies can be a solution to use the produced biogas

CO

2

CH

4

Biomethane

  • injection into the distribution network
  • used in the public and/or private transport

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

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32nd International Conference on Effjciency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 26-29 June 2019 Heraklion, Crete Island, Greece

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

  • CH4, 55%
  • CO2,

43.7%

  • N2, 1%
  • O2, 0.3%
  • H2S, 100 ppm
  • T

emperature, 35°C

  • Pression,

0.02 bar Output of 320 Nm3/h biogas

The case study

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32nd International Conference on Effjciency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 26-29 June 2019 Heraklion, Crete Island, Greece

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 (K2CO3)

Data on the considered processes were collected from the main companies ofgering biogas upgrading plants Evaluation methods:

  • Energy balance
  • CO2 equivalent emission

balance total primary energy (TPE) energy potential of energy fmows (electric and thermal energy consumptions and energy due to the production of biomethane) CO2 of each considered contribution to the impact on the global climate (emission due to electric energy requirements, emission due to the CH4 slip)

Technologies for upgrading biogas to biomethane

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32nd International Conference on Effjciency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 26-29 June 2019 Heraklion, Crete Island, Greece

Pressure swing adsorption

  • Separation of the biogas compounds according

to the size of the molecules

  • Selectively

molecular sieve, zeolites

  • r

activated carbon

  • Desulfurization step is essential, due to the H2S

toxicity for the adsorbent material

  • T

wo phase: a high-pressure adsorption step and a desorption step

  • A low part of CH4 is not recovered

Simplifjed process fmow diagram of a pressure swing adsorption system

p = 9 bar

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32nd International Conference on Effjciency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 26-29 June 2019 Heraklion, Crete Island, Greece

Membrane permeation

Simplifjed process fmow diagram of a membrane permeation system

  • Selective membrane permeability

based

  • n

the difgusion and permeation coeffjcients of difgerent gases

  • H2S and other contaminants can

damage and corrode the membranes

  • The

well-established membrane permeation process is the three- stage confjguration with sweep biogas stream

p = 17 bar

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32nd International Conference on Effjciency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 26-29 June 2019 Heraklion, Crete Island, Greece

Chemical absorption using inorganic solvent solution

  • CO2 selective absorption column with a counter-

current washing through an aqueous solution of potassium carbonate (aqueous solution with 30% of K2CO3 by weight)

  • O2,

N2, H2 remain predominantly in the biomethane fmow, that exits from the top of the column

  • Recovery step of CH4 fractions (fmash tank)
  • In a regeneration column, CO2 is released by

stripping with steam produced by an external source of heat

Simplifjed process fmow diagram of a K2CO3 chemical absorption system

p = 8.5 bar T = 70-80 °C T = 120-140 °C

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32nd International Conference on Effjciency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 26-29 June 2019 Heraklion, Crete Island, Greece

Parameters PSA Membrane Chemical absorption with K2CO3 Biomethane production [Nm3/h] 182 180 183 CH4 in the biomethane [%] 96 97 96.25 Electric energy requirements [kWh/Nm3] 0.25 0.34 0.23 Thermal energy requirements [kWh/Nm3]

  • 0.48

Heat recovery [kWh/Nm3] 0.15 0.17 0.39 CH4 slip [%] 1.3 0.8 0.08 Water requirements [kg/Nm3]

  • 0.069

Liquid waste to disposal [l/Nm3]1 0.047 0.039 0.072 Activated carbon requirements [g/Nm3]2 0.3 0.3 0.3 Chemicals requirements – K2CO3 [m3 solution/Nm3]3

  • 0,0053

Operating hours [h/y] 8400 8400 8400

1a consumption of 0.65 kWh/m3 was assumed for the process of liquid waste treatment 2landfjll disposal of the exhausted activated carbon assuming a transportation distance of 30 km 3aqueous solution with 30% of K2CO3 by weight

The specifjc consumptions are referred to the Nm3 of raw biogas in input to the process

Operating parameters

In order to perform a fair comparison, the same consumption of activated carbons equal to 0.3 g/Nm3 was assumed in the three cases

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32nd International Conference on Effjciency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 26-29 June 2019 Heraklion, Crete Island, Greece

Energy balance [MWh/y] PSA Membrane Chemical absorption with K2CO3 Electric energy requirements for upgrading unit 672 914 (+36%) 618 (-8%) Thermal energy requirements for upgrading unit

  • Heat recovery

Electric energy requirements for liquid waste treatment 0.082 0.064 0.126 Diesel for the solid waste transportation to landfjll 0.003 0.003 0.003 Biomethane energy

  • 15 947
  • 15 946

(+0%)

  • 16 056 (+1%)

T

  • tal primary energy (TPE)
  • 15 275
  • 15 031

(+2%)

  • 15 437 (-1%)

CO2 equivalent emission balance [tCO2/y] PSA Membrane Chemical absorption with K2CO3 Electric energy requirements for upgrading unit 350 475 (+36%) 322 (-8%) Thermal energy requirements for upgrading unit

  • Heat recovery

Electric energy requirements for liquid waste treatment 0.063 0.049 0.096 Solid waste landfjlling and transportation 0.005 0.005 0.005 CH4 slip 269 168 (-38%) 16 (-94%) Biomethane production

  • 3287
  • 3287
  • 3310

Initial assumptions (Reference case):

  • Thermal source available for the process
  • Heat recovery not considered
  • Complete regeneration of the K2CO3 solution

Results

The percentage in the brackets means the difgerence between membrane or chemical absorption values compared to PSA value

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32nd International Conference on Effjciency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 26-29 June 2019 Heraklion, Crete Island, Greece

Energy balance [MWh/y] PSA Membrane Chemical absorption with K2CO3 Thermal energy requirements for upgrading unit

  • 1291

Heat recovery

  • 229
  • 257 (-12%)
  • 598 (-161%)

CO2 equivalent emission balance [tCO2/y] PSA Membrane Chemical absorption with K2CO3 Thermal energy requirements for upgrading unit

  • 342

Heat recovery

  • 61
  • 68
  • 159

Variation compared to the Reference case:

  • Thermal source not available for the process
  • Heat recovery considered
  • Reintegration
  • f

the K2CO3 solution was evaluated

Sensitivity analysis

Energy balance CO2 equivalent emission balance

+2%

  • 1%

+2% +7% +1% +5% +1%

  • 11%

+1% +1% +1%

  • 2%

The percentage means the difgerence between membrane or chemical absorption values compared to PSA value

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32nd International Conference on Effjciency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 26-29 June 2019 Heraklion, Crete Island, Greece

  • The CO2 balance shows negative results due to the high contribution of

the biomethane production

  • The CO2 equivalent emission due to the methane slip and electric energy

consumptions are key elements for the balances

  • The availability of a thermal source and the possibility to recover thermal

energy (heat) by the upgrading process are key parameters. Its variation may afgect the results

  • Further evaluations referring to difgerent size biogas plants
  • Include other upgrading technologies
  • Economic aspect of the biogas upgrading process (investment and
  • perative costs)
  • Global evaluation through the Life Cycle Assessment and Life Cycle

Costing methods

Conclusions Future perspective

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32nd International Conference on Effjciency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 26-29 June 2019 Heraklion, Crete Island, Greece

Thank you for your attention

lidia.lombardi@unicusano.it

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32nd International Conference on Effjciency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems

7TH INTERNATIONAL CONFERENCE ON SUSTAINABLE SOLID WASTE MANAGEMENT 26-29 June 2019 Heraklion, Crete Island, Greece

Total Primary Energy - Effjciency

Upgrading unit TPE biogas TPE biomethan e TPE

  • ther

contributions

Effjciency [η] PSA Membrane Chemical absorption with K2CO3 Reference case 95% 94% 96% Thermal source not available 95% 94% 89% Thermal source not available + heat recovery 96.5% 95% 92%