Hi. My name is Miquel Estrada, and I'm going to fill you in
on the engineering fundamentals of work, energy and emissions in transportation.
Let's begin identifying the content of this video.
First of all, I'm going to provide you a short introduction to the general terms
Later on,
We are going to move to the definition of the mechanical work
and energy required to move a vehicle.
Later.
We are going to provide an estimation of the energy consumption
based on the vehicle dynamics and operational conditions
we're going to follow with the provision of methods to calculate
emissions using emission factors expressed per vehicle and kilometer
And finally, we are going to conclude identifying and highlighting,
highlighting the key learning concepts and the link to the practical
applications to passenger car and a battery electric bus.
urban
development is closely tied to advances in transportation systems powered
by diverse energy sources from a steam to fossil fuels and now electricity.
Each energy source has shaped our world,
understanding the energy consume and emissions generated
by these systems is crucial for engineers, environmental
analysts and policymakers.
Let's begin with this analysis of the forces
acting on the vehicle because they are fundamental
in understanding the energy requirements and mechanical work done by the vehicle.
We have the driving force that is the the force
generated by the engine or motor transmitted through the
drivetrain to the wheels propelling the vehicle forward.
And we have the resistive resistive forces.
One, the rolling resistance.
The resistance due to friction between the tires and the ground surface
The aerodynamic drag, the resistance caused by the air
acting against the vehicle motion and finally the gradient resistance,
the force required to overcome gravity when moving, moving uphill.
That can also contribute to the driving force.
If the vehicle moves downhill.
The foundation of energy
calculations begins with work in physics.
In physics, mechanical work is the driving force applied to move an object
over a distance measured in Joules.
In vehicles,
we are interested to calculate the work done by the driving force
provided by the vehicle Power train to compensate resistive forces
calculated by the integral from zero to d of the driving force
multiplied by the infinitesimal displacement.
dx. Only for linear
trajectories where the speed is constant along the trip, acceleration is zero,
and therefore, the driving force is in equilibrium with resistive forces.
And we may simplify the estimation of work as the driving force
times the distance. For vehicles, work translate.
This translates to the energy needed to move them: the motion energy.
The motion energy
In real world scenarios,
the driving force and the speed are not constant.
They vary along the trajectory due to changing road
conditions, accelerations and vehicle dynamics.
Power, P(t), is the product of the force and the speed at any given moment
at these factors change or as these factors change, the energy
use over time becomes a summation of these valuable contributions,
which is precisely what an integral computes
by integrating power over time, we account for every small segment
of the journey, capturing the variations in force and velocity.
This allows us to accurately calculate the total energy consumed for motion,
providing crucial insights for vehicle performance, fuel efficiency
and emission analysis.
But how does this energy or power can be provided
by the vehicle engine considering different powertrains?
Let's analyze this topic.
So in
transportation input, energy is the energy content of a fuel
or battery pack. For internal combustion engine vehicles (ICE)
AC This is measured as the heating value of the fuel.
Gasoline contains about 33 MJ/liter, while diesel
is slightly higher at 35 MJ/liter.
For electric vehicles, energy density is critical.
It affects range, weight and performance of these vehicles.
Lithium ion batteries like nickel- Manganese-cobalt offer around 200
to 300 watts-hour per kilogram.
While lithium-ion-Phosphate batteries provide
150 to 200 watts-hour per kilogram.
However, not all input energy is converted into mechanical work.
The total energy consumption that is
the Efuel is therefore calculated by the energy for
Motion, divided by the energy efficiency factor, eta.
Electric vehicles achieve efficiency factors between 70 to 90%, while
internal combustion engines only manage 15 to 25%.
Indeed, ICE vehicles rely on the chemical energy in liquid fuels.
However, inefficiencies like heat dissipation,
friction and incomplete combustion led to significant energy loses.
On the other hand, electric vehicles convert the stored electrical energy
into motion with far greater efficiency thanks to fewer loses,
And regenerative braking.
However, emissions are a
critical part on the energy transition.
Internal combustion engine vehicles rely on the process of oxidation,
where the carbon in fossil fuels is burned to generate energy.
While this combustion powers vehicle, it also produces
undesirable byproducts in the form of exhaust gases.
These emissions include greenhouse gases like carbon dioxide
or methane that contribute to the global warming, and local pollutants
such as nitrogen oxides and particulate matter,
which directly harm human health and degrade the environment.
The real challenge of reduction of reducing
greenhouse gases and minimize minimizing local pollutants
is critical in the transition to cleaner transportation systems.
However, there are also other emissions not linked to the oxidation
process of carbon, such as fuel evaporation, surface friction.
Wear on tires or even wear on brakes.
Meanwhile, electric vehicles shine during operation
but still have these emissions associated with brakes, tires and the manufacturing
and electricity generation processes known as well-to-wheel analysis.
The simplest way to estimate vehicle emissions
for internal combustion engine vehicles is by multiplying the distance traveled,
That is the VKT, either by an individual vehicle
or by multiply, or by the entire fleet by an aggregated emission factor.
This emission factor represents the amount of a specific pollutant
such as CO2 or NOx or particulate matter matter
produced per kilometer traveled. Emission factors
vary depending on the vehicle type, fuel type, engine size and emission
standards such as Pre-Euro or Euro VI classifications.
These are standardized factors are provided by frameworks
like the EMEP EEA, ensuring consistency in emission calculations.
In the reference section you will find a link to the emission EMEP
EEA Air Pollution Emission Inventory Guidebook.
In this video, we have explored several critical concepts
surrounding energy and emissions in transportation.
We started with the mechanical work understanding how force
and displacement combine to drive motion.
We then delve into the energy for motion recognizing how energy inputs,
whether from fossil fuels or batteries power vehicles.
We compared the specific energy of fossil fuels with that of barriers battery
chemistries, highlighting the tradeoff in energy density and performance.
From there, we examined the powertrain efficiency
showing whole internal combustion engines and electric vehicles
differ in converting input energy into usable motion
and the implications for energy consumption.
Beyond energy,
We considered exhaust and a non-exhaustive emissions
focusing on their impacts during the vehicle operation.
And finally, we expanded the discussion to include emissions
from the vehicle production process and energy transformation, emphasizing
the need for a lifecycle perspective when assessing environmental impact.
Applying these principles helps
us estimate energy consumption and emissions for different scenarios.
In the following video, you will see how the concepts presented here
and addressed in the energy performance analysis of an ICE passenger car
versus a 12 meter-long electric bus to demonstrate the stark contrasts
contrast in efficiency and environmental impact.
Thank you for watching.
To learn more, explore the reference below and dive deeper
into energy behind energy and emissions.
Thank you.