Environmental impacts of the CO2methanation value chain

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66thDiscussionForum:LCAofmobilitysolutions:Approachesandfindings30August2017,AlumniPavillon,ETHZürich,Switzerland

SarahWettstein,RenéItten&MatthiasStuckiResearchGroupLifeCycleAssessmentZurichUniversityofAppliedSciences,InstituteofNaturalResourceSciences

Implications on mobility with passenger cars

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Hegemony of diesel finally crumbling?

Power-to-Gasprocessusesexcesspowerfromrenewablesourcestoproducehydrogen(H2).H2 isthenconvertedtosyntheticnaturalgas(SNG,methane)usingtheprocessofmethanation,whichcanbeusedtopowervehicles.

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Production of synthetic natural gas

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NRP70EnergyTurnaround:SustainabilityassessmentoftheCO2 methanationvaluechain:environmentalimpactsandsocio-economicdriversandbarriersNRP70EnergyTurnaround:RenewableMethaneforTransportandMobility(RMTM)Projectpartners:• Hochschule für Technik Rapperswil (HSR),Institut für Energietechnik (IET)• ZurichUniversityofAppliedSciences(ZHAW),InstituteofChemistryandBiotechnology(ICBT)and

InstituteofNaturalResourceSciences(IUNR)• UniversitySt.Gallen,InstituteofOperationsResearchandComputationalFinance• École Polytechnique Fédérale deLausanne(EPFL),Institut desSciencesetIngénierie Chimiques

(ISIC)• SwissFederalLaboratoriesforMaterialsScienceandTechnology(EMPA),DepartmentofMobility,

EnergyandEnvironment

H2

CO2

H2+CO2àCH4Transport

andMobilityTransportationandstorage

4 different vehicle types- Petrolpoweredcar- Dieselpoweredcar- Naturalgaspoweredcar- Electriccar

4 sets of scenarios for production synthetic PtG natural gas- Electricitysource- Hydrogenelectrolysisefficiency- CO2 source- Methanation(workinprogress)

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Goal and scope of the project

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Quantificationoftheenvironmentalimpactsofvehiclespoweredbysyntheticnaturalgas(SNG)incomparisonwithconventionalvehicles

Framework- Geographic:Switzerland- Temporal:Actualstateofresearch,2015

Functional Unit- 1kilometredrivenbycar(1vehiclekilometre)

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Scenarios for synthetic natural gas production

Set of scenarios Scenario

Electricity source

Swiss power mix (grid mix)Poly-Si photovoltaicsCadmium telluride photovoltaicHydropowerMunicipal solid waste incinerationExcess power from photovoltaic production

Hydrogen productionElectrolysis efficiency: 62%Electrolysis efficiency: 70%Electrolysis efficiency: 80%

CO2 sourceIndustrial waste gases (e.g. from cement production)Atmosphere

Methanation CatalyticBiogenic (under revision)

System boundaries and schematic representation of the production system

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Blue:Scenariosetelectricitysource Yellow:ScenariosetCO2 sourceGreen:Scenariosetelectrolysisefficiency Orange:InfrastructureandvehicleGrey:Backgrounddata

systemboundary

hydropower

powerfromphotovoltaics(Poly-Si,CdTe)

powerfromincineration

plant

CO2fromwastegases(cement

industry)

H2fromalkalineelectrolysis(70%

efficiency)

naturalgaspoweredcar

servicestation

ecoinventdatabase(backgrounddata)

CO2fromatmosphere

H2fromalkalineelectrolysis(62%

efficiency)

Swissgridmix

excesspower

H2fromalkalineelectrolysis(80%

efficiency)

infrastructure,electrolyser

methane

infrastructure,reactor

emissions

transport,1km

0.00

0.05

0.10

0.15

0.20

0.25

0.30

Swissgridmix PVPoly-Si PVCdTe Hydropower Incinerationplant Excesspower Petrol Diesel Naturalgas(fossil)

Electric

SNGvehicle Referencevehicles

Greenh

ousegasemissions[kgCO 2-eq./km]

Exhaustemissions Fuelprovision

Distribution Methanation

CO2production H2production

Vehicleandroad

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Greenhouse gas emissions per vehicle kilometre

Errorbarsindicatethevarianceduetochangeinelectrolysisefficiencyfrom70%to64%and80%

- 70%electrolysisefficiency- CO2 fromindustrialwastegases

variance,dependingonpowersupplyforloadingbattery

GreenhousegasemissionspervehiclekilometreareconsiderablylowerforSNGvehiclescomparedtodieselandpetrol

0

50

100

150

200

250

300

350

400

Swissgridmix PVPoly-Si PVCdTe Hydropower Incinerationplant Excesspower Petrol Diesel Naturalgas(fossil)

Electric

SNGvehicle Referencevehicles

Environm

entalimpa

ct[e

copo

ints/km]

Exhaustemissions Fuelprovision

Distribution Methanation

CO2production H2production

Vehicleandroad

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Total environmental impacts according to ecological scarcity 2013

- 70%electrolysisefficiency- CO2 fromindustrialwastegases

variance,dependingonpowersupplyforloadingbattery

Errorbarsindicatethevarianceduetochangeinelectrolysisefficiencyfrom70%to64%and80%

TotalenvironmentalimpactspervehiclekilometrearehigherforSNGvehiclescomparedtoallconventionalfuelsiftheSwissgridmixisusedforH2production

Scenario CO2 source

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TheseparationoftheCO2fromatmosphereonlycausesminorgreenhousegasemissionscomparedtothehydrogenproduction

CO2 collectionfromatmospherecauseshighergreenhousegasemissionsbutenablesdecentralisedmethanation

- SwisselectricitymixatgridforH2 production- 70%electrolysisefficiency

• Mobility fuelled by synthetic natural gas causes lower greenhouse gas emissions per vehicle km than diesel and petrol fuelled vehicles

• Total environmental impacts per vehicle km for synthetic PtGnatural gas are higher compared to conventional natural gas unless excess power is used for methanation

• Depending on the used electricity source, the GHG emissions and the total environmental impacts per vehicle kilometre can be reduced by 42% and 51%, respectively.

• The GHG emissions of the separation of CO2 from the atmosphere are of minor importance for the total greenhouse gas emissions per vehicle kilometre.

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Conclusions

Kommentar:Stromquelle H2-Elektrolyse - für alle gelb markierten Zellen per Dropdown-Menü eine Auswahl treffenWirkungsgrad H2-ElektrolyseCO2-QuelleStromquelle CO2-Bereitstellung

Gutschrift für AbwärmenutzungStromquelle Batterieladung Elektroauto

Ergebnisse für die einzelnen Prozesse (pro Kilometer)

62% Wirkungsgrad

70% Wirkungsgrad

80% Wirkungsgrad

Fahrzeug mit Benzinmotor

Fahrzeug mit Dieselmotor

Erdgas-PKW

Elektro-PKW

62% Wirkungsgrad

70% Wirkungsgrad

80% Wirkungsgrad

Fahrzeug mit Benzinmotor

Fahrzeug mit Dieselmotor

Erdgas-PKW Elektro-PKW

kg CO2-eq kg CO2-eq kg CO2-eq kg CO2-eq kg CO2-eq kg CO2-eq kg CO2-eq UBP UBP UBP UBP UBP UBP UBPH2 Produktion 0.0126 kg 0.09 0.03 0.01 0 0 0 0 233 60 23 0 0 0 0CO2 Produktion 0.06948 kg 0.001 0.001 0.001 0 0 0 0 3 3 3 0 0 0 0Methanisierung 0.0336 m3 0.002 0.002 0.002 0 0 0 0 5 5 5 0 0 0 0Verteilung 0.0336 m3 0.002 0.002 0.002 0 0 0 0 6 6 6 0 0 0 0Treibstoffbereitstellung 1 km 0 0 0 0.04 0.02 0.02 0.03 0 0 0 70 44 20 88Auspuffemissionen 1 km 0.000 0.000 0.000 0.16 0.15 0.068 0.000 0 0 0 83 79 33 0Fahrzeug und Strasse 1 km 0.07 0.07 0.07 0.07 0.07 0.07 0.08 127 127 127 119 119 119 102Gutschrift für Abwärme 1 km 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 0 0 0 0 0 0

Total 1 km 0.161 0.11 0.09 0.269 0.237 0.154 0.112 374 201 163 271 242 171 190

161 107 85 60%

Parameter 62% Wirkungsgrad 70% Wirkungsgrad 80% Wirkungsgrad

Abgase Abgase Abgase62% 70% 80%

CH Strommix CH Strommix CH Strommix

PtG-Fahrzeug PtG-Fahrzeug ecoinvent (adaptiert)ecoinvent (adaptiert)

CH Strommix

Elektro-AutoCH Strommix Photovoltaik CdTe Überschussstrom

Fahrzeug mit DieselmotorFahrzeug mit Benzinmotor Erdgas-Auto

Stromquelle Methanisierung CH Strommix CH Strommix CH Strommixnein nein nein

-100

0

100

200

300

400

500

600

700

62%Wirkungsgrad 70%Wirkungsgrad 80%Wirkungsgrad FahrzeugmitBenzinmotor

FahrzeugmitDieselmotor

Erdgas-PKW Elektro-PKW

PtG-Fahrzeug ecoinvent(adaptiert)

Gesamtumweltbelastung

(UBP

/km)

MethodederökologischenKnappheit GutschriftfürAbwärme

FahrzeugundStrasse

Auspuffemissionen

Treibstoffbereitstellung

Verteilung

Methanisierung

CO2Produktion

H2Produktion

0.00

0.05

0.10

0.15

0.20

0.25

0.30

62%Wirkungsgrad 70%Wirkungsgrad 80%Wirkungsgrad FahrzeugmitBenzinmotor

FahrzeugmitDieselmotor

Erdgas-PKW Elektro-PKW

PtG-Fahrzeug ecoinvent(adaptiert)

Treibh

auspoten

zial(kgCO

2-eq

./km

)

Treibhauspotenzial GutschriftfürAbwärme Auspuffemissionen

Treibstoffbereitstellung Verteilung

Methanisierung CO2Produktion

H2Produktion FahrzeugundStrasse

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Outlook: Calculation tool

• Variableelectricitysource• H2 productionefficiency• CO2 source• Methanationprocess• Creditforwasteheat

• Workinprogress• Availableonrequest,maybe

online

SarahWettstein,RenéItten &MatthiasStuckiResearchGroupLifeCycleAssessmentZurichUniversityofAppliedSciencesInstituteofNaturalResourceSciencesGrüental,P.O.Box,CH-8820Wädenswil

Tel.:+41589345703E-Mail:sarah.wettstein@zhaw.chInternet:www.zhaw.ch/iunr/lca/

Questions?

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References and data sources

• ecoinvent Centre. (2015). Ecoinvent Data v3.2, Swiss Centre for Life Cycle Inventories. Zürich.

• Zah, R., Spielmann, M., & Ruiz, S. (2015). Analyse Der Umwelt-Hotspots von Strombasierten Treibstoffen - Finaler Bericht, (Journal Article), 1–68.

• Vehicle data with real consumption, compiled by Christian Bach, EMPA

• CO2 collecting data from atmosphere,Climeworks AG, Zurich

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