VERSITET Senior adviser Morten Winther AARHUS UNIVERSITY DEPARTMENT OF ENVIRONMENTAL SCIENCE DCE –...

VERSITET

Senior adviser Morten Winther

AARHUS UNIVERSITY

DEPARTMENT OF ENVIRONMENTAL SCIENCE

DCE – DANISH CENTRE for ENVIRONMENT and ENERGY

20 October 2015

UNI

Emissions from heavy duty vehicles using upgraded biogas as a fuel

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20 October 2015Internal DCE seminar 2015

Introduction

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−The project “Biogas for transport - resources, environment and welfare economics” is carried out at DCE from 2014-2016 (Jensen et al., 2015)

−The project is an internal project under the Science Program for Sustainable Energy and Environment

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Introduction

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› The project examines the following questions:

› Is potential biogas production sufficient to fulfil the transport energy demand in a future perspective. What are the emission consequences, and health related and social costs

› Important to understand, in order to create a qualified basis for prioritisation of biogas resources

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Disposition

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−This presentation explains the work made so far in WP3 and 4, dealing with fuel and emission estimates in the project

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Disposition

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−Fuel consumption for trucks and buses in a diesel reference scenario up to 2035

−Some notes on CNG (Compressed Natural Gas) and LNG (Liquefied Natural Gas) vehicles in a biogas scenario

−CH4 emission sources critical for CNG/LNG vehicles

−Calculated GHG (Greenhouse Gas) emission savings in 2035−Some conclusions

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Diesel reference scenario

− HDV’s are grouped into rigid trucks, truck-trailers, articulated

trucks and buses

− FC = Nveh

x Milann

(km) x EFC

(MJ/km)

− Fleet, mileage and speed data: DTU Transport and Danish Road

Directorate

− Fuel factors also split into e.g. EU emission legislation levels:

Conv. and Euro I-VI

Type/size RT 3,5 - 7,5t RT 7,5 - 12t RT 12 - 14 t RT 14 - 20t RT 20 - 26t RT 26 - 28t RT 28 - 32t RT >32t TT/AT 28 - 34t TT/AT 34 - 40t TT/AT 40 - 50t TT/AT 50 - 60t TT/AT >60t Urban Buses <15t Urban Buses 15 - 18t Urban Buses >18t Coaches <15t Coaches 15 - 18t Coaches >18tRT: rigid trucksTT/AT: Truck-trailers, artic. trucks

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− Euro VI enters the fleet and old emission technologies are phased out

− Euro VI dominates fuel totals; 81 %, 95 %, 99 % in 2020, 2025 and 2030, respectively

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− Euro VI vehicles are relevant for natural gas substitution.

− Most fuel expected for 40-50t and 34-40t trucks; 46 % and 21 %, respectively (note the axis scaling!).

− 2035: 45 PJ diesel in total. A full substitution requires 51 PJ of natural gas

Euro VI in closer details

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CNG vehicles – short description

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− CNG: Compressed Natural Gas

− On board storage: Pressure bottles (200-260 bar)

− SI (spark ignition) engine, operates similarly to a gasoline engine

− Euro VI, equipped with a three-way catalyst

− CNG has smaller km range between fuel stops compared to diesel

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− CNG fuel economy vs diesel: Big variations.

− An average of 19 % more MJ/km was found in recent national work1

1COWI/Energistyrelsen: Framework conditions for using

natural gas in heavy duty road transport, 150 pp.,

December 2014 (in Danish: Rammevilkår for gas til tung

vejtransport)

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− NOx and PM (Particulate Matter): No significant emission differences between natural gas and diesel Euro VI, based on the limited measurement data assessed so far1

1COWI/Energistyrelsen: Framework conditions for using

natural gas in heavy duty road transport, 150 pp.,

December 2014 (in Danish: Rammevilkår for gas til tung

vejtransport)

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CNG vehicles – substitution

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− CNG Substitution is made for rigid trucks

Demand for long range is less critical for smaller trucks

Some CNG trucks already for sale in Denmark (up to 320 hp)1, a good precondition

1www.gasbiler.info: Natural gas fueled vehicles for sale

in Denmark, Danish Gas Technology Centre

http://www.gasbiler.info/

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LNG vehicles – short description

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− LNG: Liquefied Natural Gas

− On board storage: Vacuum insulated storage tanks (3-10 bar, -160 oC)

− Dual fuel engine (using 5 % diesel to pilot ignition); operates similarly to a diesel engine

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LNG vehicles – short description

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− Emission performance similar to Euro VI, equipped with SCR and DPF

− Longer km range than CNG, due to more fuel stored

− Fuel economy: Same drawback as for CNG, compared to diesel (ICCT, 2015)

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LNG vehicles – substitution

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− LNG substitution for large trucks (TT/AT trucks)

− LNG fulfills demand for longer km range by large trucks

− Suitable engine capacities already on the market in e.g. the US

− EU directive 2014/94 places on member countries to establish LNG fueling stations along main arterial roads by 2025

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CH4 loss from CNG/LNG vehicles1

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− CNG sources:

− CH4 from exhaust (tail pipe)

− CH4 from the crankcase (So-called ”blow by emissions”, leaks between piston rings and cylinder walls, vented to the atmosphere)

1Delgado, O., Muncrief, R.: Assessment of heavy-duty

natural gas vehicle emissions: Implications and policy

recommendations, The International Council on Clean

Transportation (ICCT), White Paper, 34 pp., July 2015

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CH4 loss from CNG/LNG vehicles1

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− LNG sources:

− CH4 from exhaust (tail pipe)

− CH4 from dynamic venting in the fuel injection system

− CH4 from the fuel tank (”boil off” pressure release for safety reasons)





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CH4 loss from the fueling station1

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− CNG fueling stations CH4 leaks from pipes and fittings

CH4 escape during nozzle connection and disconnection

Compressor loss

− LNG fueling stations

Methane boil-off in storage tanks

Manual venting of vehicle fuel tanks prior to refueling

Spills and escape during nozzle connection/disconnection





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− Calculation for 2035: All heavy duty Euro VI vehicles use CNG/LNG

− Tank-to-wheel greenhouse gas emissions:

For low/high CH4 loss, estimates range between 12 - 22 % of diesel reference case

CO2 originates from the ”5 %” diesel pilot fuel

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− Pump-to-wheel greenhouse gas emissions:

Using low/high CH4 loss, estimates range between 14-25 % of diesel reference case

CO2 originates from the ”5 %” diesel pilot fuel

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Conclusions

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− For CNG/LNG vehicles there a several emission sources of CH4, on board the vehicles as well as at the gas fueling station

− NOx and PM (Particulate Matter): The (scarce) literature data reveals no significant emission differences between natural gas and diesel vehicles for Euro VI

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Conclusions

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− Estimated tank-to-wheel GHG emissions from CNG/LNG vehicles are in the range of 12-22 %, of the diesel reference case

− Including fueling station losses of CH4, estimated ”pump-to-wheel” emissions increase to 14-25 % compared to diesel

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Conclusions

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− Additional CH4 loss is expected during the production of biogas and during distribution

− On the other hand, the CH4 emission savings from manure will be very big

− Both sources are being assessed in the current project; no results yet.

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Thank you for your attention!

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Summary of CH4 loss

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− Conclusions from ICCT (2015) survey: CH4 from exhaust is the same for CNG and LNG

CNG crankcase ~ LNG dynamic venting + fuel tank venting

Fueling station loss, CNG ~ LNG

CH4 loss (% of fuel delivered) low estimate high estimate

Pump-to-tank Fueling station 0,3 0,3Tank-to-wheel Exhaust 0,1 0,9

Crankcase ~ dynamic venting/tank boil off 0,4 0,8

Total Pump-to-Wheel 0,8 2,0Source: ICCT (2015)

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Introduction

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− For overview’s sake, the project consist of 8 WP’s:

› WP1, WP2: Biomass resources and potential biogas production (Jørgensen,

Møller)

› WP3: Future energy demand of the transport sector with a focus on road

transport heavy duty vehicles (HDV); (Jensen)

› WP4: Energy consumption and emissions of different HDV’s powered by

upgraded biogas (Winther)

› WP5: Health-related external costs of air pollution (Brandt)

› WP6, WP7: Life-cycle Analysis and Cost-Benefit Analysis (Thomsen, Cong)

› WP8: Stakeholder involvement and dissemination of results (Jensen)

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