ACV et bilan du puits à la roue (1/2)

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En provenance du cours de École des Ponts ParisTech

Mobilités et véhicules électriques

28 notes

École des Ponts ParisTech

Mobilités et véhicules électriques

28 notes

L’objectif de ce MOOC est d’aider ses apprenants, quel que soit leur profil, leur formation ou leur pays d’origine, à construire une réponse personnelle à des questions comme celles-ci : - Les voitures électriques seront-elles les dernières à circuler dans les métropoles du XXI° siècle ? - Le gain environnemental associé à l’électrification des véhicules justifie-t-il des investissements massifs dans les infrastructures de charge ? - Le véhicule électrique est-il réservé aux riches des pays du Nord ? Grâce à ce MOOC, les participants pourront acquérir des connaissances issues des sciences de l’ingénieur, de la sociologie, des sciences de l’environnement, de l’économie, de la géographie et des sciences politiques pour évaluer, analyser et mettre en œuvre le déploiement des véhicules électriques là où il est pertinent. Le Groupe Renault et les écoles de ParisTech collaborent depuis bientôt 15 ans sur des sujets liés à la mobilité durable. Ensemble, ils ont créé deux Masters (Transport et développement durable en 2004, Mobilité et véhicules électriques en 2010) et l’Institut de la Mobilité Durable (IMD), en 2009, pour accompagner les mutations en cours. Le MOOC Mobilités et véhicules électriques est issu de cette histoire commune et a été élaboré à partir d'un cours délivré au sein du Master Mobilités et Véhicules Électriques, piloté par Arts et Métiers ParisTech en partenariat avec Ensta ParisTech, Mines ParisTech et l’École des Ponts ParisTech. Ce cours est en français, cependant des sous-titres en anglais sont disponibles pour toutes les vidéos et vous pouvez écrire vos messages dans le forum en anglais si vous le désirez./ This course is given in French, nevertheless English subtitles are available for all videos and you can write your posts in the forum in English if desired.

À partir de la leçon

Chapitre 2 - Mobilités électriques et réduction de l'impact environnemental

<p>Dans ce chapitre, nous étudierons les enjeux des changements climatiques puis mènerons une analyse prospective quant aux évolutions des émissions de gaz à effet de serre tout au long du XXI° siècle. <br/>Nous examinerons ensuite le rôle des transports en termes de pollution locale de l'air et de bruit.<br/> Pour pouvoir déterminer la performance environnementale des différents types de véhicules, nous présenterons l'analyse de cycle de vie puis mobiliserons cette méthode pour comparer les performances des véhicules thermiques et électriques en termes de préservation de l'environnement local et global.</p><p>Le chapitre est constitué de 6 vidéos de cours et d'un <em>Point méthode</em> permettant de définir ce qu'est l'analyse de cycle de vie. Il est complété par un entretien avec un expert du groupe Renault pour traiter spécifiquement du sujet des batteries du point de vue de leur impact sur l'environnement. Il se conclut bien entendu par une évaluation sous forme de quiz. Cette évaluation ne porte que sur les vidéos de cours et est notée.</p>

Point méthode - L'analyse de cycle de vie3:01

ACV et bilan du puits à la roue (1/2)10:00

ACV et bilan du puits à la roue (2/2)9:11

ACV comparative des véhicules thermiques et électriques10:50

Rencontrer les enseignants

Virginie BOUTUEIL
Researcher
LVMT (City Mobility Transport Lab), École des Ponts ParisTech
Émeric FORTIN
Head of the Master in Transport and Sustainable Development
Direction of Studies, École des Ponts ParisTech

-This lesson on LCA and well-to-wheel analysis

will be split over two videos. This first video is divided in 2 parts.

The first part will introduce the well-to-wheel analysis,

its principle and associated definitions.

The second part will introduce the different sectors for passenger cars,

conventional and alternative sectors.

Passenger cars have several impacts on the environment.

Materials and energy are required to manufacture them.

They need fuel to run.

Finally, they release greenhouse gas emissions in the atmosphere

such as carbon dioxide or CO2,

but also particle or other pollutant emissions.

When a car reaches the end of its life,

part of the car components can get back in the loop

thanks to recycling. But another part cannot be recycled

and must be disposed of.

If we look at the different steps of a car life cycle,

we can calculate the environmental impacts of each of these steps.

This calculation and analysis of environmental impacts

in each step of a product's life cycle in general,

and in particular for a car, is called life-cycle analysis, LCA.

The life-cycle analysis can be simplified

by only looking at two steps for a passenger car.

First, the step related to fuel or energy source production

that will be used by the car.

This first step is called the "well-to-tank" step or WTT.

The second step is related to the use of the car

and is called the "tank-to-wheel" step or TTW.

This analysis is called the "well-to-wheel" analysis.

It is a simplified analysis of the life cycle

since it only considers two steps of the life cycle

instead of all the steps.

Then, we only look at two environmental indicators:

the primary fossil energy consumption in mega joule of fossil energy

per traveled kilometers made with the car,

and the greenhouse gas emissions in CO2 equivalent grams per kilometer.

CO2 equivalent grams are calculated

based on all the greenhouse gas emissions that are multplied

by an equivalent factor that transforms them into C02 emissions.

In order to calculate these two environmental indicators,

the energy consumption and the greenhouse gas emissions,

we need to look at how much mega joule of fossil energy is consumed

per mega joule of fuel used in the tank

and how much CO2 equivalent grams are emitted

per mega joule of fuel produced.

For instance, in the case of petrol,

we need to quantify these two indicators,

energy and emissions,

for each step from the production until petrol distribution.

Then, for the tank-to-wheel step,

we need to look at fossil energy consumption

and greenhouse gas emissions associated with the use of the car.

To do this, we can use what we call standardized cycles.

The car is tested on a chassis dynanometer

that enables us to measure CO2 emissions and energy consumption.

This chassis dynanometer enables the car to do a standardized driving cycle

such as the NEDC cycle.

Once we know the well-to-tank energy, the tank-to-wheel energy,

the well-to-tank emissions, and the tank-to-wheel emissions,

we can calculate the total well-to-wheel impact.

This impact has two terms.

For energy, first we must calculate

how much mega joules of fossil energy are consumed

for each mega joule of fuel consumed when the car is used.

That is to say, multiply E1 by E2.

Then, we add E2 if E2 is a fossil energy.

This is true for petrol, diesel, natural gas, etc.

Then, for greenhouse gas emissions,

the principle is identical.

A part is associated with greenhouse gas emissions

to produce each mega joule of fuel consumed during use.

Thus, we need to multiply G1 by E2

and then add the tank-to-wheel emissions, G2.

For petrol, we obtain a total energy of 236 MJ per 100 km

and CO2 emissions of 180 gCO2 per km.

We can study several sectors thanks to the well-to-wheel analysis.

A sector is characterized by a fuel and an engine specification.

For instance, the petrol sector is made of petrol as a fuel

and a spark-ignition engine or petrol engine.

The conventional sectors are based on fossil ressources

such as oil and natural gas.

Oil can be used to create petrol or diesel.

Petrol is used in a petrol vehicle with a spark-ignition engine

and diesel is used in a compression ignition engine.

Natural gas is compressed to become a natural gas for vehicles

that is used in a NGV vehicle with a spark-ignition engine

adapted to natural gas.

There are also alternative sectors.

For instance, petrol vehicles with a spark-ignition engine

can use ethanol produced from biomass resources

such as sugar crops, sugar cane or beetroot,

or from lignocellulosic biomass.

The specificity of this ethanol produced from biomass

is that we consider the emissions during use to be zero

because the CO2 emitted during the use of ethanol by the car

is the same CO2 that has been absorbed by the plant during its growth.

This principle is called carbon neutrality.

For diesel vehicles, there are two alternative sectors.

One uses biodiesel produced from vegetable oils or algae.

The other is synthetic diesel produced from coal, natural gas

or wood residues.

For natural gas vehicles,

the alternative sector uses biogas that can be produced

from the methanization of household waste, dedicated cultures or algae.

Biogas also produces zero emissions when used thanks to carbon neutrality.

Another sector can be studied thanks to well-to-wheel analyses:

the electric vehicle sector.

Electricity can be produced from different energy sources:

fossil energy sources such as oil, coal or natural gas,

renewable energies such as solar or wind power, biomass, waste,

or nuclear power.

The electric sector

also produces zero emissions during the use phase

thanks to the use of electricity.

Finally, the last sector we can study is the hydrogen sector

that is used in fuel cell vehicles with an electric engine.

Hydrogen can be produced from natural gas,

biomass gasification

or electricity by water electrolysis.

Now that I introduced the principles and definitions

of the well-to-wheel analyses

and the sectors on which we can make this analysis,

the next video will show you the results obtained with this analysis.

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