2. 2
Nomenclature
(GHG) Greenhouse gasses
(ICE) Internal Combustion Engine
(CO2) Carbon dioxide
(MOT) Ministry of Transport
(HEV) Hybrid Electrical Vehicle
(IMA) Integrated Motor Assist
(HSD) Hybrid Synergy Drive
(CVT) Continuous Variable Transmission
(i-VTEC) Valve Timing & Lifting Electronic Control
(IPU) Intelligent Power Unit
(e-CVT) electronic Continuously Variable Transmission
(PHEVs) Plug-in Hybrid Electric Vehicles
(BEVs) Battery Electric Vehicles
(PHEV) Parallel Hybrid Electric Vehicle
(SHEV) Series Hybrid Electric Vehicle
(WHP) Williams Hybrid Power
3. 3
Table of Contents
Nomenclature .........................................................................................................................................2
Aim..........................................................................................................................................................4
1. Introduction ........................................................................................................................................5
2. Global warming & Greenhouse gas emission .....................................................................................6
2.1The impact of climate change........................................................................................................7
3. Fuel price.............................................................................................................................................9
4. Hybrid technology.............................................................................................................................10
5. Types of (HEV) Hybrid Electric Vehicles............................................................................................11
5.1 Parallel hybrid .............................................................................................................................11
5.2 Series Hybrid...............................................................................................................................12
6. Toyota Prius power split device........................................................................................................14
7. Honda................................................................................................................................................16
8. Ford...................................................................................................................................................17
9. Plug in Hybrids ..................................................................................................................................18
9.1 Battery.........................................................................................................................................19
9.2 Modes of Operation....................................................................................................................21
9.3 Emission performance ................................................................................................................21
9.4 Plug-in hybrid sales .....................................................................................................................21
10. Future technology...........................................................................................................................22
10.1 Transmission system & Operation............................................................................................23
11. Government support ....................................................................................................................256
12. Conclusion.....................................................................................................................................277
4. 4
Aim
The aim of this project is to focus on the hybrid vehicles and find environmental
impact on local and global world, also about the advantages and disadvantages by
using the current and the future technology. The research was done on different
types of hybrids whether hybrid vehicles meet the expectations. Due to high cost it
turns the consumers away and makes the vehicle less attractive in the economic
investment. Hybrid vehicle’s purpose is to reduce and protect the environment from
greenhouse gasses (GHG). It will save the consumer money, zero fuel consumption
when electric system is in operation. In general hybrid technology has a lot of
potential in the near future, but for now they are not a significant improvement over
today’s internal combustion engines (ICE).
5. 5
1. Introduction
The national climate change strategy showed that transport is a fast growing source
of greenhouse gas emission. Due to the predicted continuing rise in CO2 emission
from road transport, there is a need to take action to reduce emission from this
sector. One of the measures that would be of potential interest is increasing the use
of hybrid electric vehicles. This option has the advantage of reducing average
vehicle energy consumption, and hence reducing CO2 emissions.
Robert Anderson of Aberdeen, Scotland built the first electrical vehicle in 1939[1]
. The
vehicle had many problems, the main issue was to recharge the battery power. Over
the years it has been improved and upgraded.
A hybrid vehicle uses two different power sources to drive the vehicle of which one of
them efficient petrol engine and an electric motor. With the electric motor helping out,
the petrol engine works less. There are many types of hybrid systems on the market
to reduce GHG emission, work efficiently and save fuel. Hybrid vehicles are playing
a big role in the near future. The government is supporting and investing into major
automotive manufacturers to develop the hybrid technology.
[1] http://www.odec.ca/projects/2004/guil4m0/public_html/what.html
6. 6
2. Global warming & Greenhouse gas emission
The basic principle of global warming can be understood by considering the radiation
energy from the sun that warms the earth’s surface and the thermal radiation from
the earth and the atmosphere that is radiated out to space. On average these two
radiations must balance. If the balance is disturbed (for instance by an increase in
atmosphere carbon dioxide) it can be restored by an increase in the earth’s surface
temperature.
The gas carbon dioxide has been emitted into the atmosphere in increasing amounts
over the past 200 years and more substantially over the past 50 years because of
the human activities, especially the burning of fossil fuels, coal, oil and gas. Every
year these emissions currently add to the carbon already present in the atmosphere
a further 8000 million tonnes, much of which is likely to remain there for a period of
100 years or more. Because carbon dioxide is a good absorber of heat radiation
coming from the earth’s surface, increased carbon dioxide acts like a blanket over
the surface, keeping it warmer than it would. With the increased temperature the
amount of water vapour in the atmosphere also increases, providing more blanketing
and causing it to be even warmer. The gas methane is also increasing because of
different human activities, which is adding to the problem. An increase in global
temperature will lead to global climate change.
The gases nitrogen (78%) and oxygen (21%) that make up the bulk of the
atmosphere neither absorb nor emit thermal radiation. It is the water vapour, carbon
dioxide and some other minor gases present in the atmosphere in much smaller
quantities that absorb some of the thermal radiation leaving the surface. These
gases are known as greenhouse gases. The greenhouse gases are those gases in
the atmosphere which, by absorbing thermal radiation emitted by the earth’s surface,
have blanketing effect upon it. The added effect is caused by the gases present in
the atmosphere due to human activities such as deforestations and the burning of
the fossil fuels. The important greenhouse gases that are directly influenced by
human activities are carbon dioxide, methane, nitrous oxide, the chlorofluorocarbons
(CFCs) and ozone. The increase in carbon dioxide (CO2) has contributed about 72%
of the enhanced greenhouse effect to date methane (CH4) about 21% and nitrous
oxide (N2O) about 7%.[2]
[2] Global warming, John Houghton, fourth edition,
7. 7
2.1The impact of climate change
The main impacts of climate change will be due to sea level rise, increase in
temperature and heat waves and a more intense hydrological cycle leading on
average to more frequent and intense floods, droughts and storms. We have noticed
this from disasters that have happened in the past years. To respond to climate
change impacts, for instance new sea defences or water supplies. All these will have
a negative impact and involve high cost.
Because of likely rate of climate change, there will also be a serious impact on
natural ecosystems, especially at mid to high latitudes. Forests especially will be
affected by increased climate stress causing substantial dieback and loss of
production. In a warmer world longer periods of heat stress will have an effect on
human health; warmer temperature will also encourage the spread of certain tropical
diseases.
Looking at the local situation. In the UK the fastest rising contributor to climate
change is emission of CO2 from road transportation. The figures below show the
greenhouse gas emission in the UK in 2009. There is not a major different between
2009 and the current condition.
Figure2.1 Total UK GHG emission[3]
Figure2.2 Total UK domestic transport GHG emission[3]
Figure2.1 shows that private road vehicles are the major responsible for the pollution.
More than the half of the CO2 emission is caused by the transport sector. Due to
traffic the level of these greenhouse gases is highest in urban. At the same time this
affects the rural areas as mentioned before. According to the UK government one in
five people are particularly at risk of air pollution. Such as asthma, hay fever,
infections, cancer and so forth. [4]
[3]
http://thelivinglabiesd.wordpress.com/2012/11/05/sustainable-transport-the-impacts-of-
transports-on-the-environment-in-the-uk-2/
[4]
http://www.foe.co.uk/resource/briefings/road_air_pollution_health.pdf
8. 8
The National Asthma Campaign has estimated that asthma costs the UK over £1
billion per year. [5]
Environmental economists have estimated the cost of air pollution
from road transport at £19.7 billion per year. [6]
The two main government targets are:
• Traffic reduction: reducing the volume of domestic transport on the roads.
• Greener cars: ensure that cars pollute less.
This stated that vehicles must continue to get cleaner, quieter and less harmful to the
environment, and that progress made over the last decade needs to continue in the
future. New vehicles are becoming individually cleaner in response to European
emission standards legislation, but total vehicle kilometres are increasing. Overall
emissions of key air pollutants from road transport have fallen by about 50% over the
last decade, despite increases in traffic, and are expected to reduce by a further 25%
or so over the next decade. This is mainly a result of progressively tighter vehicle
emission and fuel standards agreed at European level and set in UK regulations. [7]
There are systems in place to ensure compliance with vehicle emission standards.
Through its Type Approval work, the Vehicle Certification Agency ensures that all
new models of cars coming onto our roads meet EU emissions standards. Almost all
types of vehicles must go through an emission check as part of the annual MOT
testing procedures. In service testing is one of several measures designed to reduce
pollution from vehicle emissions. The MOT tests are kept under review in response
to developments in vehicle technology to ensure an appropriate framework.
[5]
National Asthma Campaign National Asthma Audit 2010
[6]
Madison, Pearce et al The True Costs of Road Transport
[7]
http://www.defra.gov.uk/environment/quality/air/air-quality/approach/
9. 9
3. Fuel price
Figure 3.1 UK fuel price[8]
Fuel price is increasing every year as it is shown on the graph above. Only in 2009
was a huge drop but since then it has always been increasing. The westerns
countries and the US are depended on the Middle Eastern fuel. Due to unrest in the
Middle East and wars that has been taken place the fuel prices have been affected.
Some countries have blocked the world’s oil export. This is causing serious problems
to the countries that are dependent on the fuel. These unexpected actions increase
the fuel price even more. Also not to forget that the fossil fuel is a limited resource.
The Figure 3.2 shows the world oil production decreasing dramatically in the near
future. Therefore, we need to find a new resource in order to satisfy the increasing
demand in energy sector
.
Figure 3.2 world oil production is decreasing over the coming years.[8]
[8]
http://www.housepricecrash.co.uk/forum/index.php?showtopic=175389
10. 10
4. Hybrid technology
In recent years it has been proven that hybrid technology made a considerable
reduction in fuel consumption and emission. Especially the hybrid electrical vehicle
(HEV) proved that improved performance has been achieved by applying a
secondary energy source in a vehicle powertrain system. HEVs are powered by a
combination of electricity and either diesel or petrol. The electricity part is used as an
intermediate energy storage medium to improve the overall efficiency of the vehicle.
There is no need to plug in and recharge the battery. Therefore this cuts down the
amount of fuel needed also it produces less emission and reducing overall fuel cost.
Most hybrid vehicles use regenerative braking system which is recovering of kinetic
energy during braking. In a conventional vehicle majority of the kinetic energy is
converted during friction braking into heat and emitted unused into the environment.
The hybrid vehicles can use the electric motor to recuperate at least a portion of the
kinetic energy for reuse. Ones the brake is applied the vehicles electric motor
switches to generator mode. The wheels transfer the kinetic energy by the drivetrain
to the generator. Through its rotation the generator converts a portion of the kinetic
energy into electrical energy. This energy is stored in a high voltage battery and can
be reused again. This system lowers the fuel consumption, CO2 emission and also
reduces the brake wear.
Figure 4.1 Regenerative braking system.[9]
[9]
http://auto.howstuffworks.com/auto-parts/brakes/brake-types/regenerative-braking6.htm
11. 11
5. Types of (HEV) Hybrid Electric Vehicles
There are two types of HEV one is parallel hybrid and the other one is series hybrid.
5.1 Parallel hybrid
In a parallel hybrid, the ICE and electric source both can be combined to deliver
power directly to the wheels of the vehicle see figure 5.1. Parallel hybrid system is
more complicated compared to the series hybrid because the electrical and internal
combustion system must be mechanically connected to the drive train/shaft. The
engine power drives the axle that can either charge the energy storage or directly
drive the axle. The amount of energy divided among the two depends on the speed
and driving pattern. When acceleration is applied more power is converted to the
drive train than to the batteries. The batteries in parallel hybrids will be charged
through regenerative braking which was explained before on page 10. Examples of
parallel hybrid vehicles are: Honda Civic, Chevrolet Malibu etc. Mild hybrids such as
the Honda Civic IMA have smaller electric engines and have to operate regular
engine continuously to provide power to the wheels.
Advantages:
Engine can be switched off for short distances or during idling.
More suitable for highway driving compared to urban driving.
Directly connected to the wheel less power conversion
Disadvantages:
Complex transmission
Not suitable for driving in cities
Figure 5.1 Schematic diagram of Parallel Hybrid Vehicle.[10]
[10]
http://hevindia.blogspot.co.uk/
12. 12
5.2 Series Hybrid
In a series hybrid, there is no mechanical connection between the engine and the
drive axle. The engine powers the generator which charges the battery. A series
hybrid has a much larger and more powerful electric engine that provides all the
power to the wheels of the vehicle. The vehicle is running from battery energy until it
reaches a limit that they need to be charged again by the power engine. During the
charging process there is no need to increase the speed. The engine can run at its
optimal efficiency zone, this reduces the fuel consumption of the engine and reduces
the emission. The batteries can also be charged during regenerative braking system.
Series hybrids are more expensive due to high cost of the motor and the batteries.
The main advantage is that the series hybrid is suitable for cities. For this reason, the
new London busses and other heavy duty automobiles are running on series hybrid.
Examples of hybrid series are: London busses, Toyota Prius, Chevrolet volt.
Advantages:
Under slow operation
More suitable in urban area
ICE is running at best speed
The ICE can be switched off completely
Low fuel consumption
High fuel efficiency
Disadvantages
Numerous energy conversion which means many losses
Not suitable for urban area
Additional weight and cost due to increased components
Figure 5.2 Schematic diagram of Series Hybrid Vehicle.[11]
[11]
http://hevindia.blogspot.co.uk/
13. 13
In both types of hybrid there is a smaller and more efficient ICE. The batteries used
on hybrid cars should last the lifetime of the as the electric storage, however future
cars are more likely to use super capacitors. Super capacitors can store and release
smaller amount of energy much more quickly and efficiently.
Battery
Engine generator charger converter electric motor
Capacitor
Figure 5.3 Schematic diagram of Series Hybrid Vehicle connected with the super capacitor.
Super capacitors main purpose is to store and supply very small amount of energy
quickly and efficiently, which will affect and improve regenerative braking efficiency
and increased power delivery for an acceleration. The main problem is the high cost
of the super capacitors.
Toyota is a company that is dominating the hybrid vehicle technology. One of the
well-known cars is Toyota Prius which is in series-parallel hybrid. This technology is
named Hybrid Synergy Drive (HSD).
Figure 5.4 Toyota Prius Hybrid[12]
It is having a single power split device, since the power of the engine is split at the
input to the transmission so it is known as input-split.
[12]
http://www.carscoops.com/2011/09/facelifted-2012-toyota-prius-quietly.html
14. 14
6. Toyota Prius power split device
The main part of the Toyota Prius is the power split device. This device connects the
ICE, generator and the electric motor together as you can see on the diagram below.
This gearbox system works as a parallel hybrid or series hybrid system. The ICE and
the electric motor can drive the car individually or together. During the series process
the ICE can charge the batteries or provide power to the vehicle when needed.
Figure 6.1 Toyota Prius Hybrid power split device [13]
The power split device exists of a planetary gear set to provide increased torque to
the wheels. Each of the power sources is rotating the gears in the planetary gear
system, which provides transaxle and acts similar to a Continuous Variable
Transmission (CVT).
The output speed of the gear system
depends on the; generator which is
connected to the sun gear, planet
carrier which is linked to the ICE. The
gears have to work altogether. When
the acceleration is applied, first the
electric motor and the batteries Figure 6.2 planetary gear set [14]
provide all the power. The outer ring gear starts to rotate with the motor. The red part
which is the planetary carrier and its clinked to the ICE, this part is still because the
engine is not running. When the ring gear is rotating, the planets have to spin, which
causes the sun gear and generator to spin. As the vehicle starts to accelerate, the
generator spins at whatever speed it needs to in order for the engine to remain off.
[13]
http://wouldyoudriveit.files.wordpress.com/2009/03/toyota-prius-hybrid-synergy-drive-system-at-low-
speed.jpg
[14]
http://auto.howstuffworks.com/hybrid-car7.htm
15. 15
Advantages of power split device:
ICE can be turned off
ICE speed can be chosen by adjusting generator speed
Lowe emission
ICE runs at efficient speed and load
generator automatically maintains the proper level of charge in the batteries
Disadvantages:
Power vicious cycle may occur leading to low efficiency
Relatively complex
High Cost
Hybrid car sales in 2012
The Toyota Prius has been most successful hybrid on the market. It became very
famous not only because of its excellent fuel economy but also because of its design
see figure 5.4. The future plans will be more fuel economy improvement, bigger cars
and more comfortable and using solar panel on the roof of the vehicle to power the
interior accessories. And it will use the plug in method see page 18. for more
explanation. Also CVTs will be used in the future vehicles such as Toyota Camry
Hybrid XLE.
[15]
http://www.hybridcars.com/dashboard-test/dashboard-december-2012-hybrid-chart/
[16]
http://www.autoguide.com/auto-news/2012/06/11-future-hybrids-heading-to-dealers-soon.html/11
16. 16
7. Honda
Currently Honda Civic Integrated Motor Assist (IMA) is another popular car, it’s using
parallel hybrid. Most of the concepts are the same as Toyota Prius but its
transmission system is made of CVT. The main features are briefly pointed.
Variable Valve Timing & Lifting Electronic Control (i-VTEC) Engine and advantages:
• No need to charge the batteries
• High efficiency
• Light weight
• Electric motor provides extra power to engine
• Intelligent power unit (IPU) powers the electric motor & regulate power supply
• CVT for smooth gear shifting
• Great tax incentive
The steps of the Honda Civic Hybrid's i-VTEC engine and electric motor in different
driving states:
1. Start/acceleration: the engine and the operates at the same time
2. At Low speed: the battery is operating alone
3. During acceleration: the engine and the operates at the same time
4. At high speed: engine is operating without assistance of electric motor
5. Deceleration/braking: recharging the IMA batteries
6. When stopped: automatic idle stop
Disadvantages:
• Problems with batteries in cold weather & needs to be recharged every
second
• High capital cost
Figure 7.1 Honda Civic IMA 2012 [19]
[17]
http://auto.howstuffworks.com/fuel-efficiency/hybrid-technology/honda-civic-hybrid4.htm
[18]
http://www.hybridcars.com/2012-honda-civic-hybrid/
[19]
http://carduzz.com/wp-content/uploads/2012/12/2012-Honda-Civic-Hybrid-4-600x400.jpg
17. 17
8. Ford
2013 Ford Fusion Hybrid is one of the best cars on the market at the moment.
Fusion hybrid gets its propulsion from two sources: an electric motor and gasoline
engine. The electric motor gets its power from a nickel-metal hybrid (NiMH) battery,
and it’s coupled into one single unit with an electronic continuously variable
transmission (e-CVT), a type of transmission that provides better fuel efficiency by
constantly changing through an infinite number of gear ratios. The motor and
transmission are mated to a 2.5liter, 4 cylinder Atkinson-Cycle gasoline engine,
which features late intake valve closing (iVCT) to allow the car to switch smoothly
from electric mode to gas mode and make back again.
What makes the ford Fusion hybrid stand out of is the fact that, the car will travel
under light to normal acceleration up to 60 miles per hour only on electric motor,
much faster than most of its competitors. This could save a lot of fuel. Ford also
claims it’s possible to drive as far as 700 miles on one tank of gas. If you drive in
areas with lower speed limits, like a neighbourhood or busy city streets, you could
potentially take nearly all of the car’s power from electric motor, lowering emission
and saving money. And it captures 90% of energy lose during breaking. The cost of
the car is around $27,000
Figure 8.1 2013 Ford Fusion Hybrid [20]
[20]
http://www.ford.com/cars/fusion/trim/hybrid/
[21]
http://greeneford.files.wordpress.com/2012/08/ford-fusion_hybrid-2013-wallpaper.jpg
18. 18
9. Plug in Hybrids
The next generation such as Toyota Prius and Ford fusion plug in hybrid electric
vehicles (PHEVs) works similarly to conventional hybrid vehicles in that they can
operate using their petrol or diesel engine as well as stored electricity for an electric
motor. A plug-in hybrid operates in the same way as conventional HEV but has a
larger battery pack and gives the driver the option of charging the battery from a
household outlet and then running their vehicle on grid electricity instead of
petroleum. As such, they act as a halfway ground between hybrid electric vehicles
and battery electric vehicles. In addition, most PHEVs (like BEVs and HEVs) would
run a regenerative braking system that puts power from braking back into the battery
system. All of this allows PHEVs to be very efficient, and if driven for relatively short
distances, they could have zero emissions at the point of use.
The benefits of PHEVs are largely similar to those of electric vehicles in that they can,
if kept at a high level of charge, operate the majority of the time on electric power,
thus reducing their emissions to zero at the point of use. They also have the
additional benefits related to electric motors of quiet operation and rapid acceleration.
Because of the additional weight of the battery packs. There are two key types of
PHEV. The first can run indefinitely with the petrol/diesel motor providing the car with
the energy required for motion. The second is effectively a battery electric vehicle
with a small on-board generator to allow the range of the vehicle to be extended.
Figure 9.1 Plug in hybrid powertrain system [23]
[22]
plug in hybrid electric vehicle journal www.csiro.au
[23]
http://commons.wikimedia.org/wiki/File:Plug-in_hybrid_electric_vehicle_(PHEV)_diagram.jpg
19. 19
The illustration on Figure 9.1 shows the general layout of the power system within a
PHEV. It is very similar to that of a series hybrid but with a larger electrical storage
capacity. This enables the greater range available to these types of vehicles before
the combustion engine has to kick in. The type of PHEV which cannot operate
independently of recharging would have a very similar layout, the only difference
being the combustion engine and generator would be insufficient to keep the
electrical storage topped up under normal driving conditions but would slow the rate
of depletion of the power stored in the batteries.
Advantages:
Improvements in fuel consumption
GHG emission reduction – potentially to zero: environmental & public
health benefit
Lower operation cost
Vehicle to grid electricity
Using renewable sources for recharging
Disadvantages:
High capital cost
Lack of availability
Limited range in some types
Emissions can simply be transferred to production sources
9.1 Battery
PHEVs typically require deeper charging and discharging than conventional hybrids.
As the number of full cycles affects battery lifetime, battery life may be less than for
conventional hybrids which do not deplete their batteries as often. Larger battery
package required compared to conventional hybrids.
On-board chargers which are mounted inside the vehicle. The connector to the grid
is standardised, so that the hybrid can be charged at home as well as at charging
stations in the cities. The on-board charger takes place and increases the weight of
the vehicle.
[24]
http://www.toyota.com.au/hybrid-synergy-drive#how-hybrid-works
20. 20
Off-board chargers are much bigger and heavier than on-board chargers, so they
are mounted stationary, for example in the garage. They have more power and can
charge the vehicle's battery faster. Off-board chargers are adapted to the vehicle's
battery voltage, charging method, and need special connectors to the vehicle.
Using electric motor's inverter and inductance has the advantage, that no much
extra space and weight is required. The charging method is on-board, grid flexible
with standard connector, cost efficient and with high power capacity. The electric
machine must be designed for this method, and the inverter needs some extensions.
AC Propulsion for example uses this charging method.
Figure 9.2 Plug in hybrid vehicle using EDF energy [25]
[25]
http://www.hybridcars.com/wp-content/uploads/files/plug-in-prius-610.jpg
21. 21
9.2 Modes of Operation
Charge-depleting mode allows a fully charged PHEV to operate completely on
electric power until the battery state of charge is depleted to a predetermined level,
when ICE fuel cell will be involved. This depends on the vehicle and how hard and
often the acceleration will be applied. This period is the vehicle's all- electric range.
This is the only mode that a battery electric vehicle can operate in, hence their
limited range.
Charge-sustaining mode is used by production hybrid vehicles (HEVs), and
combines the operation of the vehicle's two power sources in such a manner that the
vehicle is operating as efficiently as possible without allowing the battery state of
charge to move outside a predetermined narrow band. Over the course of a trip in a
HEV the state of charge may fluctuate but will have no net change. The battery in a
HEV can thus be thought of as an energy accumulator rather than a fuel storage
device. Once a plug-in hybrid has exhausted its all electric range in charge-depleting
mode, it can switch into charge-sustaining mode automatically.
Mixed mode describes a trip in which combinations of the above modes are utilized.
This contrasts with a charge-depleting trip which would be driven within the limits of
a PHEV's all-electric range. Conversely, the portion of a trip which extends beyond
the all-electric range of a PHEV would be driven primarily in charge-sustaining mode,
as used by a conventional hybrid.
9.3 Emission performance
The combination of the internal combustion engine and the electric motor helps
hybrid cars perform more efficiently, cutting down on fuel use. Plug-in hybrids have
the additional advantage that they can operate purely on electricity from the grid for
short distances, so reducing net emissions significantly over regular hybrids.
9.4 Plug-in hybrid sales
Figure 9.3 Total global PHEV sales 2012/1013 [26]
[26]
http://www.greencarreports.com/news/1082638_feb-plug-in-electric-car-sales-leaf-supply-low-
volt-recovers#.UTEApOgllhQ.email
22. 22
10. Future technology
There are also a number of technologies in the pipeline that may improve efficiency
even further and increase the viability of electrical motors as a power source. Super
capacitors store energy for a short period of time much more efficiently than a
dynamo recharging a battery which was explained on page 13. This technology
could be used to further improve the regenerative braking system. There are also
technologies such as high speed flywheels, which are designed to store energy more
efficiently than charging batteries.
In the recent years the hybrid vehicles are very popular but the second energy
resource is electromechanical batteries. The batteries suffer from economical and
technical disadvantages. One of the main problems with HEVs is associated with the
electromechanical batteries sensitivity to interior and exterior environments that has
got an impact on the batteries performance. The delivery power and the charging
rate significantly affected by their state of charge and temperature conditions.
Especially during the regenerative braking process, a massive power must be taken
by the batteries in a very short of time. Additionally, the batteries do not deliver the
reliability required and must be replaced numerous of times throughout the vehicle’s
life. Some of the companies have proposed to use mechanical power transmission
system and mechanical energy storage instead of batteries, motors, generators and
other electric components. High speed electromechanical composite flywheel is
proposed as an alternative to the electric batteries. Flywheel is cheap, efficient, and
it works perfectly with ICE. The maximum power from a flywheel depends on the
transmission system and the speed and
size of the flywheel. The diagram on the
left shows the specific short duration
peak power and density of various
energy storage technologies. Advanced
flywheel is at the top of the graph as it is
presented.
Figure 10.1 Energy and power densities of different energy storage technology [27]
[27]
http://www.mpoweruk.com/alternatives.htm
[28]
‘’A simple mechanical transmission system for hybrid vehicles incorporation with flywheel’’ journal
2008
23. 23
10.1 Transmission system & Operation
The electric flywheel storage excels in high stressed operation without performance
or lifetime degradation. This unique technology offers easy to package and highly
efficient contentiously recycle of energy. The flywheel is economically beneficial
compared to alternative storage solution for demanding electrified vehicle
applications according to Williams Hybrid Power (WHP).
When the brake is applied, the electricity is generated by attraction motor at the front
or rear axle. This electricity passes down the
cables directly to charge the flywheel which
spins up to very high speed.
Figure 10.2 Electric flywheel system during barking process [30]
Figure 10.3 Electric flywheel system during acceleration process [30]
When the driver accelerates, the whole system works in reverse. The flywheel is
slowed which pushes the electricity back down the same cables proving extra energy
to the wheels. This additional drive energy means that the ICE works less it can save
up to 40% depending on the application. Electric flywheel can be applied on all type
of vehicles.
24. 24
Figure 10.4 Electric flywheel system on a city bus [30]
On a city bus it can save up to 15%. A vehicle continuously starting and stopping
makes the ideal application for WHP flywheel. Some heavy duty vehicles can use
multiple flywheels for higher capacity storage. The flywheel can be fitted on the
busses that are 10 years old. The system is very cheap compared to batteries.
William Hybrid Power is working with some other manufacturing companies to
investigate and use the new electric power flywheel system.
Figure 10.5 Electric flywheel system on a city bus and F- 1 car [30]
[29]
http://www.extremetech.com/extreme/92794-kers-of-the-hybrid-car-flywheels-and-ultracapacitors-give-you-a-
10-second-jolt
[30]
http://www.williamshybridpower.com/technology/the_flywheel/#%2Ftechnology%2Fgreen_credentials
25. 25
Advantages:
Can be used on cars, busses, motor sport, trams, rail and construction
vehicles.
GHG emission reduction: environmental friendly & public health benefit
Lower operation cost compared to electric hybrid
Long life span
No mechanical connection from flywheel
High power and high efficiency 80-90%
Redundancy available to prevent electrical charge and rotational
overcharge
Operate efficiently under ambient temperature, not like capacitors and
batteries which will underperform.
Less complicated
No toxic or chemical products
Multiple flywheels can be used
Disadvantages:
energy capacity is low compared to battery
recycling of the composite casing is a challenge
require durable materials to whitestand the angular momentum
flywheel is rotating at a very high speed
technology advancing very slowly
funding for flywheel technology is less compared to battery
new product does not get much attention, high development cost
26. 26
11. Government support
Several countries have established grants and tax credits for the purchase of new
PEVs generally the economic investments goes to battery sizes and investigations.
The US and the UK offers plug in grant and federal income tax credit up to $7,000.
Many European countries provide tax incentives for electrical chargeable cars. The
incentive consists of tax reduction and bonus payment for the hybrid vehicle buyers.
President Barack Obama’s goal is to place 1 million plug-in hybrid vehicles on the
road by 2015. To achieve the goal the US government is funding about $2 billion for
manufacturing companies to examine advanced batteries and drive mechanisms. Up
to $400 million is invested for transportation electrification demonstration and
deployment projects.
Figure 9.3 President Barack Obama visiting Ford plug in hybrid Company [32]
[31]
http://www.renewableenergyfocus.com/view/1359/uk-government-subsidises-electric-and-plug-in-hybrid-
cars/
[32]
http://blog.toyota.co.uk/toyota-prius-plug-in-hybrid-eligible-for-up-to-5000-uk-government-subsidy
27. 27
12. Conclusion
The question is if the hybrid cars meet the expectations that society suggested.
Presently the Hybrid cars are growing to dominate the near future market and to
reduce the future transportation petroleum consumption. The hybrid cars main
purpose is to reduce GHG emissions and save fuel. At the moment it’s saving fuel up
to 40%. The technology is advancing and has potential but it has to be used correctly
to work effectively. The hybrid cars create much more emission before they are used
on the road. The production of hybrid vehicles is far more harmful than the
production of the today’s regular ICE. Soon the PHEV will be the next generation
hybrid technology which will lead the hybrid market. PHEVs provide potential for
reducing petroleum consumption beyond that of HEV technology. There is a
spectrum of PHEV design options that satisfy performance constraints but there are
still some issues such as high cost, charging areas required in the cities and
suffering of battery systems. Overall hybrid technology is heading in the right
directions, but a lot of work must be done to refine it. Industry needs to be able to
produce hybrids with the same or lower levels of emissions and energy consumption
as conventional cars. Engineers need to develop more effective electric engines with
a greater speed range. Hybrids need to be comparable to conventional cars
pricewise and performance for consumers to start purchasing them in a larger scale.
In the past few years engineers are trying to use mechanical flywheel technology
instead of electric energy. Electric flywheel can also save up to 40% and it’s much
cheaper than the EHV. There’s lack of knowledge about the flywheel and the
technology is improving very slowly because of the high developing cost.
