A hybrid car is an automobile that has an internal combustion engine, usually gasoline, and an electric motor that reduces the effort of the combustion engine and thus reduces fuel consumption and emissions.
As an example, one has a car that combines combustion engine and electric motor in reality is an electric vehicle powered by the kinetic energy coming from the burning of fuel. This is the most widespread model in diesel-electric locomotives and generators.
Although the hybrid car pollutes less than combustion-only cars, its costs are high compared to the difference in pollutant emissions. For now, only expensive cars have this technology.But the forecast is that over time technology becomes cheaper.
The government seeks to deploy this technology in public transport, such as in buses, to improve air quality in large urban centers, which is getting worse. These differ from Trolleybus because they do not have aerial wiring to provide power, and can circulate anywhere; the Trolleybus can only travel where this support exists.
Classification of hybrids
There are three types of hybrid car:
In the first hybrid cars the explosion engine is responsible for the locomotion of the car and the electric was an extra aid to improve the performance of the same. This type is widely used in small cars and is known as parallel-hybrid (eg Honda Insight).
Another method used is the electric motor to be responsible for the locomotion of the automobile, where the engine the explosion only moves a generator responsible for generating the energy necessary for the car to move and to charge the batteries. Generally large automobiles use this system, known as hybrid-series.
The third is the hybrid mixed system, which combines aspects of the system in series with the parallel system, which aims to maximize the benefits of both. This system provides power to the wheels of the vehicle and generate electricity simultaneously using a generator, unlike what occurs in the simple parallel configuration. It is possible to use only the electrical system, depending on the load conditions. It is also permissible for both engines to operate simultaneously (eg Toyota Prius).
Hybrid car benefits
The internal combustion engine of a hybrid car can usually be smaller and lighter than in a corresponding normal car. This is the case when both motors can drive simultaneously if there is a lot of power required. The internal combustion engine can then be dimensioned according to the car’s average power requirement, not according to the car’s maximum power requirement.
When the car slows down, the energy can be converted to electricity, which charges the batteries. In normal cars, this power goes to waste like heat.
Hybrid cars usually have a lower fuel consumption than the equivalent of normal cars. This is especially true when the car is used to drive the city and small and medium-sized vehicles.
The main advantage of hybrid vehicles is the elimination of the defects inherent in the need to start from a standstill (which in conventional endothermic motor vehicles is implemented through friction and first gear) subjected to the physical laws of inertia that requires torque even at speed almost zero while the cyclic thermal engine needs a minimum speed regime to provide a non-zero torque. The steam engine and the electric engine do not present particular problems in starting from a standstill, unlike endothermic engines, which present such criticality (which at the dawn of the automobile represented the greatest brake to its development).
In the car with coupled endothermic engine starting in electric, the two engines are suitable to coexist as they have precisely this complementary characteristics. The internal combustion engine transforms the chemical energy of the fuel (of considerable energy density and easily procured from the supply network) with an acceptable efficiency, in particular in some operating points (at low speeds the electric is more efficient, at high the endothermic).
The electric motor instead converts with a greater efficiency and versatility an energy available on board in smaller quantities. Each electric machine itself is able to work in traction and generation (as well as in both directions) and therefore each hybrid vehicle tries to exploit in slowdowns the ability to “brake” with the electric motor (” counter-electromotive force ” through KERS system), generating energy otherwise dissipated in the form of heat in the brakes. Another advantage is the possibility, even at high speeds for short distances, to support the endothermic engine from the electric one in the acceleration needs.
Electrical energy can be stored with the use of various devices that can also be used simultaneously.
Batteries: they have energy density lower than that of fuel, they can be sized to accumulate maximum energy, to exchange maximum power or with a compromise between the two extremes. The batteries work with electrochemical processes distributed within them and it is not trivial to control all the conditions, for example temperature, to limit as much as possible the decay of electrodes and electrolytes.
Supercapacitors: compared to batteries, they have lower energy density but can yield and receive higher powers. They are based on a more controllable physical process.
Electrically operated flywheels: energy is stored as a kinetic energy of a flywheel driven by an electric machine, it is a completely mechanical process and presents control problems that are still different from the previous ones.
Depending on the degree of hybridization (power of the electric propulsion with respect to the total installed power) and the capacity of the hybrid propulsion system to store electricity, some hybridisation levels are informally defined:
hybridization full (full hybrid), when the electric system is, eg., in alone able to advance the vehicle on a standardized driving cycle, while disregarding the autonomy of the batteries
slight hybridization (mild hybrid), when the purely electric mode of operation is not able to follow for a full driving cycle normalized
minimum hybridization (minimal hybrid), normally confused with the traditional propulsion provided with start and stop system, characterized by a decreasing distance in pure electric mode and by a decreasing degree of hybridization.
Vehicles with stop and start function are also improperly called “micro hybrids”, but this function, typical of many hybrid vehicles, is obtained with traditional components and certainly not with a different propulsion system.
There are two main construction schemes for the integration of a thermal engine and an electric machine: series hybrid and parallel hybrid. The combination of the two gives rise to the mixed hybrid.
This technology, also called “range extender”, is very similar to that used in diesel-electric locomotives. In this type the heat engine is not connected to the wheels, it has the task of generating the current to power the electric motor that transforms it into motion, while the superfluous energy is used to recharge the batteries.
At times when a large amount of energy is required, it is drawn from both the heat engine and the batteries. Since electric motors are able to operate on a vast range of rotational speeds, this structure allows to remove or reduce the need for a complex transmission. For this reason it would allow the use of more efficient turbine engines instead of alternative, in fact the efficiency of alternative internal combustion engines changes with the change in the number of revolutions, in the hybrid systems seriesthe revolutions of the thermal engine are set to obtain maximum efficiency at all times, with no acceleration or deceleration; this property would be exploited with even greater efficiency by the turbine engine. Given this condition and to compensate for the further energy transformation, a thermal engine (generator) can be used that has a very narrow exploitation / operating band compared to the total regimes and for this reason it has a higher efficiency than the classic thermal engines, for at least in that range of regimes, then ideally a turbine engine.
In some prototypes small electric motors are installed for each wheel. The considerable advantage of this configuration is that it can control the power delivered to each wheel. A possible purpose could be to simplify traction control or to insert / deactivate all-wheel drive.
The major disadvantage of the series hybrids is the serious reduction in efficiency compared to the only thermal engines in conditions of high and constant speed (such as making the 130 km / h on the highway). This is caused by the fact that in the thermal-electric-motion conversion part of the energy is lost while it would not happen with a direct transmission. This drawback is not present in the parallel hybrid. The hybrid series are the most efficient for vehicles that require continuous braking-and-go as to urban use vehicles, buses and taxis and some of the heavy work vehicles such as Terex 33-19 “Titan”,Hitachi EH5000 ACII, Liebherr T 282B and BelAZ 75710.
Many models of series hybrids are equipped with a button to turn off the heat engine. The function is used especially for traffic in restricted traffic areas. Autonomy is limited to the battery charge; the heat engine, however, can be reactivated by pressing the same button. The thermal engine is also switched off automatically during stops.
This architecture is among the most used in hybrid cars. It is characterized by a mechanical power coupling node, whereby both motors (electric and thermal) provide torque to the wheels. The heat engine can also be used to recharge the batteries when needed. The construction of the mechanical knot and its position within the propulsion system serve to distinguish parallel pre-transmission hybrids (electric motor upstream of the gearbox), post-transmission (electric motor downstream of the gearbox) and post-wheels (the two axles have two mechanically independent engines, the coupling is therefore made up of the road). The parallel hybridsthey can further be classified according to the balancing of the two engines in providing power. In most cases, for example, the internal combustion engine is the dominant part and the electric motor has the simple function of providing greater power in times of need (mainly at start, under acceleration, and at maximum speed).
Most projects combine a large electric generator and an electric motor in a single unit, often located between the internal combustion engine and the transmission, in place of the flywheel, replacing both the starter motor and the alternator and the flywheel. Usually the gearbox is automatic continuously (consider that because of the electric start in any case the first gear would be eliminated, in many cases the second one, and in the more recent formulations also third and fourth determining a single gear eliminating the need for each type of differential transmission).
The advantage lies in the elimination of low gears (those that consume more fuel) and consumption with wheels that are stationary or slow-moving. It also allows lower displacements as at maximum speed the thermal engine can be supported by the electric one (even if only for a few kilometers). This makes vehicles suitable for city rhythms rather than long motorway journeys.
The mixed hybrids are characterized by a mechanical node, as in the parallel hybrid, and an electrical node, as in the series hybrid. Like the latter, they have two electric machines. The constructive way to realize such double coupling can vary. A relatively simple example is given by the architecture of the Toyota Prius, which realizes the mechanical coupling between the thermal engine, the two electric machines and the final drive shaft through the combination of an epicyclic gear train and a gearbox. The success of the Prius and other Toyota with the same architecture, 10 million cars from 1997 to 2017, makes this scheme the most widespread.
The management of energy flows between the various converters (internal combustion engine, electric motor (s), transmission) and accumulators (batteries, supercapacitors) to respond to a given power demand (torque and speed) by the driver is task of the supervising controller. This controller, typical of hybrid vehicles, is placed, in relation to a traditional torque control structure, in an intermediate position between the driver’s interpretation algorithms (transformation of the position of the acceleration and brake pedals in torque request) and those control of the individual components (engines, transmission, brakes). The management algorithms
The energy management algorithms developed so far belong to two distinct categories, with the possibility of mixed approaches:
Heuristic strategies, based on the translation of specifications at various levels and on empirical rules dictated by the experience of the designers
Optimized strategies based on the application of optimal control mathematical algorithms.
Fuel consumption and emissions reductions
The hybrid vehicle typically achieves greater fuel economy and lower emissions than conventional internal combustion engine vehicles (ICEVs), resulting in fewer emissions being generated. These savings are primarily achieved by three elements of a typical hybrid design:
Relying on both the engine and the electric motors for peak power needs, resulting in a smaller engine size more for average usage rather than peak power usage. A smaller engine can have less internal losses and lower weight.
Having significant battery storage capacity to store and reuse recaptured energy, especially in stop-and-go traffic typical of the city driving cycle.
Recapturing significant amounts of energy during braking that are normally wasted as heat. This regenerative braking reduces vehicle speed by converting some of its kinetic energy into electricity, depending upon the power rating of the motor/generator;
Other techniques that are not necessarily ‘hybrid’ features, but that are frequently found on hybrid vehicles include:
Using Atkinson cycle engines instead of Otto cycle engines for improved fuel economy.
Shutting down the engine during traffic stops or while coasting or during other idle periods.
Improving aerodynamics; (part of the reason that SUVs get such bad fuel economy is the drag on the car. A box shaped car or truck has to exert more force to move through the air causing more stress on the engine making it work harder). Improving the shape and aerodynamics of a car is a good way to help better the fuel economy and also improve vehicle handling at the same time.
Using low rolling resistance tires (tires were often made to give a quiet, smooth ride, high grip, etc., but efficiency was a lower priority). Tires cause mechanical drag, once again making the engine work harder, consuming more fuel. Hybrid cars may use special tires that are more inflated than regular tires and stiffer or by choice of carcass structure and rubber compound have lower rolling resistance while retaining acceptable grip, and so improving fuel economy whatever the power source.
Powering the a/c, power steering, and other auxiliary pumps electrically as and when needed; this reduces mechanical losses when compared with driving them continuously with traditional engine belts.
These features make a hybrid vehicle particularly efficient for city traffic where there are frequent stops, coasting and idling periods. In addition noise emissions are reduced, particularly at idling and low operating speeds, in comparison to conventional engine vehicles. For continuous high speed highway use these features are much less useful in reducing emissions.
Hybrid vehicle emissions
Hybrid vehicle emissions today are getting close to or even lower than the recommended level set by the EPA (Environmental Protection Agency). The recommended levels they suggest for a typical passenger vehicle should be equated to 5.5 metric tons of CO2. The three most popular hybrid vehicles, Honda Civic, Honda Insight and Toyota Prius, set the standards even higher by producing 4.1, 3.5, and 3.5 tons showing a major improvement in carbon dioxide emissions. Hybrid vehicles can reduce air emissions of smog-forming pollutants by up to 90% and cut carbon dioxide emissions in half.
More fossil fuel is needed to build hybrid vehicles than conventional cars but reduced emissions when running the vehicle more than outweigh this.
Environmental impact of hybrid car battery
Though hybrid cars consume less fuel than conventional cars, there is still an issue regarding the environmental damage of the hybrid car battery. Today most hybrid car batteries are one of two types: 1) nickel metal hydride, or 2) lithium ion; both are regarded as more environmentally friendly than lead-based batteries which constitute the bulk of petrol car starter batteries today. There are many types of batteries. Some are far more toxic than others. Lithium ion is the least toxic of the two mentioned above.
The toxicity levels and environmental impact of nickel metal hydride batteries—the type currently used in hybrids—are much lower than batteries like lead acid or nickel cadmium according to one source. Another source claims nickel metal hydride batteries are much more toxic than lead batteries, also that recycling them and disposing of them safely is difficult. In general various soluble and insoluble nickel compounds, such as nickel chloride and nickel oxide, have known carcinogenic effects in chick embryos and rats. The main nickel compound in NiMH batteries is nickel oxyhydroxide (NiOOH), which is used as the positive electrode.
The lithium-ion battery has attracted attention due to its potential for use in hybrid electric vehicles. Hitachi is a leader in its development. In addition to its smaller size and lighter weight, lithium-ion batteries deliver performance that helps to protect the environment with features such as improved charge efficiency without memory effect. The lithium-ion batteries are appealing because they have the highest energy density of any rechargeable batteries and can produce a voltage more than three times that of nickel–metal hydride battery cell while simultaneously storing large quantities of electricity as well. The batteries also produce higher output (boosting vehicle power), higher efficiency (avoiding wasteful use of electricity), and provides excellent durability, compared with the life of the battery being roughly equivalent to the life of the vehicle. Additionally, use of lithium-ion batteries reduces the overall weight of the vehicle and also achieves improved fuel economy of 30% better than petro-powered vehicles with a consequent reduction in CO2 emissions helping to prevent global warming.
There is two different levels of charging. Level one charging is the slower method as it uses a 120 V/15 A single-phase grounded outlet. Level two is a faster method; existing Level 2 equipment offers charging from 208 V or 240 V (at up to 80 A, 19.2 kW). It may require dedicated equipment and a connection installation for home or public units, although vehicles such as the Tesla have the power electronics on board and need only the outlet. The optimum charging window for Lithium ion batteries is 3-4.2 V. Recharging with a 120 volt household outlet takes several hours, a 240 volt charger takes 1–4 hours, and a quick charge takes approximately 30 minutes to achieve 80% charge. Three important factors—distance on charge, cost of charging, and time to charge In order for the hybrid to run on electrical power, the car must perform the action of braking in order to generate some electricity. The electricity then gets discharged most effectively when the car accelerates or climbs up an incline. In 2014, hybrid electric car batteries can run on solely electricity for 70–130 miles (110–210 km) on a single charge. Hybrid battery capacity currently ranges from 4.4 kWh to 85 kWh on a fully electric car. On a hybrid car, the battery packs currently range from 0.6 kWh to 2.4 kWh representing a large difference in use of electricity in hybrid cars.
Raw materials increasing costs
There is an impending increase in the costs of many rare materials used in the manufacture of hybrid cars. For example, the rare earth element dysprosium is required to fabricate many of the advanced electric motors and battery systems in hybrid propulsion systems. Neodymium is another rare earth metal which is a crucial ingredient in high-strength magnets that are found in permanent magnet electric motors.
Nearly all the rare earth elements in the world come from China, and many analysts believe that an overall increase in Chinese electronics manufacturing will consume this entire supply by 2012. In addition, export quotas on Chinese rare earth elements have resulted in an unknown amount of supply.
A few non-Chinese sources such as the advanced Hoidas Lake project in northern Canada as well as Mount Weld in Australia are currently under development; however, the barriers to entry are high and require years to go online.
The fuel economy of hybrid vehicles stems from some factors:
Reducing the Size of Combustion Engines: In the absence of an electric motor, the maximum available power depends on larger motors, which dissipate more power and consume more fuel. On the other hand, when one can rely on an electric motor, one can adopt a combustion engine sized for medium power, and therefore smaller.
Use of the Atkinson Cycle that provides greater energy efficiency than the Otto Cycle.
Regenerative braking part of the braking power is electromagnetic and transforms kinetic energy into electrical energy that can be stored.
Engine shutdown combustion in situations where the power of the electric motor is sufficient (eg traffic jams.), Which prevents the combustion engine be working below the point at which provides low proportion of energy useful (total energy – energy dissipated).
Possibility of capturing solar energy or wind power.
Automakers spend around $US8 million in marketing Hybrid vehicles each year. With combined effort from many car companies, the Hybrid industry has sold millions of Hybrids. Hybrid car companies like Toyota, Honda, Ford and BMW have pulled together to create a movement of Hybrid vehicle sales pushed by Washington lobbyist to lower the worlds emissions and become less reliant on our petroleum consumption. In 2005, sales went beyond 200,000 Hybrids, but in retrospect that only reduced the global use for gasoline consumption by 200,000 gallons per day — a tiny fraction of the 360 million gallons used per day. According to Bradley Berman author of Driving Change—One Hybrid at a time, “Cold economics shows that in real dollars, except for a brief spike in the 1970s, gas prices have remained remarkably steady and cheap. Fuel continues to represent a small part of the overall cost of owning and operating a personal vehicle”. Other marketing tactics include greenwashing which is the “unjustified appropriation of environmental virtue.” Temma Ehrenfeld explained in an article by Newsweek. Hybrids may be more efficient than many other gasoline motors as far as gasoline consumption is concerned but as far as being green and good for the environment is completely inaccurate. Hybrid car companies have a long time to go if they expect to really go green. According to Harvard business professor Theodore Levitt states “managing products” and “meeting customers’ needs”, “you must adapt to consumer expectations and anticipation of future desires.” This means people buy what they want, if they want a fuel efficient car they buy a Hybrid without thinking about the actual efficiency of the product. This “Green Myopia” as Ottman calls it, fails because marketers focus on the greenness of the product and not on the actual effectiveness. Researchers and analysts say people are drawn to the new technology, as well as the convenience of fewer fill ups. Secondly, people find it rewarding to own the better, newer, flashier, and so called greener car. In the beginning of the Hybrid movement car companies reached out to the young people, by using top celebrities, astronauts, and popular TV shows to market Hybrids. This made the new technology of Hybrids a status to obtain for many people and a must to be cool or even the practical choice for the time. With the many benefits and status of owning a Hybrid it is easy to think it’s the right thing to do, but in fact may not be as green as it appears.
In May 2014, the City of São Paulo approved Law 15,997 / 14, which provides that electric cars, hybrids and the hydrogen cell emplaced in the city receive back 50% of the IPVA paid, which corresponds to the part that is the responsibility of the City, since the tax is state. The return of the IPVA is limited to R $ 10,000 and is worth 5 years. The car can not cost more than $ 150,000. These cars with alternative propulsion will also be exempt from the rotation of vehicles of São Paulo. The city hall has 30 days to regulate the law and to detail how it will be fulfilled. The legislation of São Paulo seeks to stimulate the adoption of similar policies in other Brazilian cities. By September 2014 the federal government is still availing options to define a policy that encourages electric and hybrid cars in the country. In July 2013, the National Association of Motor Vehicle Manufacturers (Anfavea) submitted a proposal to enable the sale and development of these models in Brazil to the Ministry of Development, Industry and Foreign Trade (MDIC).
While the adoption rate for hybrids in the US is small today (2.2% of new car sales in 2011), this compares with a 17.1% share of new car sales in Japan in 2011, and it has the potential to be very large over time as more models are offered and incremental costs decline due to learning and scale benefits. However, forecasts vary widely. For instance, Bob Lutz, a long-time skeptic of hybrids, indicated he expects hybrids “will never comprise more than 10% of the US auto market.” Other sources also expect hybrid penetration rates in the US will remain under 10% for many years.
More optimistic views as of 2006 include predictions that hybrids would dominate new car sales in the US and elsewhere over the next 10 to 20 years. Another approach, taken by Saurin Shah, examines the penetration rates (or S-curves) of four analogs (historical and current) to hybrid and electrical vehicles in an attempt to gauge how quickly the vehicle stock could be hybridized and/or electrified in the United States. The analogs are (1) the electric motors in US factories in the early 20th century, (2) diesel electric locomotives on US railways in the 1920–1945 period, (3) a range of new automotive features/technologies introduced in the US over the past fifty years, and 4) e-bike purchases in China over the past few years. These analogs collectively suggest it would take at least 30 years for hybrid and electric vehicles to capture 80% of the US passenger vehicle stock.
European Union 2020 Regulation Standards
The European Parliament, Council and European Commission has reached an agreement which is aimed at reducing the average CO2 passenger car emissions to 95 g/km by 2020, according to a European Commission press release.
According to the release, the key details of the agreement are as follows:
Emissions target: The agreement will reduce average CO2 emissions from new cars to 95 g/km from 2020, as proposed by the Commission. This is a 40% reduction from the mandatory 2015 target of 130 g/km. The target is an average for each manufacturer’s new car fleet; it allows OEMs to build some vehicles that emit less than the average and some that emit more. 2025 target: The Commission is required to propose a further emissions reduction target by end-2015 to take effect in 2025. This target will be in line with the EU’s long-term climate goals. Supercredits for low-emission vehicles: The Regulation will give manufacturers additional incentives to produce cars with CO2 emissions of 50 g/km or less (which will be electric or plug-in hybrid cars). Each of these vehicles will be counted as two vehicles in 2020, 1.67 in 2021, 1.33 in 2022 and then as one vehicle from 2023 onwards. These supercredits will help manufacturers further reduce the average emissions of their new car fleet. However, to prevent the scheme from undermining the environmental integrity of the legislation, there will be a 2.5 g/km cap per manufacturer on the contribution that supercredits can make to their target in any year.
Source from Wikipedia