|
What are EVs?
Stavanger, Norway 13th - 16th May 2009
|
Description - Energy efficiency and energy savings - Other benefits Innovation and technological developments - History - How does it work?
Download the explanatory brochure.
The electric vehicle (or EV) of today has evolved into a reliable and marketable product. The evolution of vehicle technology is ever going forward and the latest developments make electric traction technology suitable for virtually any application. In figures 1 to 4 a few examples of electric cars are shown.
The concept of electric vehicles covers in fact different aspects.
Download the explanatory brochure. Electric Vehicles offer in fact a wide range of possibility combinations. Each of them favouring a well defined application.
Traction batteries with aqueous electrolyte continue to deliver pristine services and are continuously optimised for higher capacity, longer life and lower maintenance. Simple to drive, reliable, totally silent, without any emissions, EVs are ideal for city traffic. However, new battery types such as high-temperature batteries (e.g. AEG Zebra), Nickel Metal-Hydride batteries (e.g Panasonic, SAFT, Varta…), and lithium-based batteries (e.g. 3M, Matsushita, SAFT…) will be available in the coming years. Due to their extremely high energy density, they will offer unprecedented vehicle ranges. The long-range or multi-mission electrically driven vehicle will become a reality through de developments of hybrid drives (e.g. Toyota Prius). Hybrid vehicles combine electric and other drive systems, such as internal combustion engines, gas turbines and fuel cells. The main advantage of this system is the possibility of regenerative braking : recovering energy when braking and storing it in a buffer battery. This energy can be used when accelerating, avoiding that the combustion engine runs at high speed, so consuming more. In some models drivers have the option of running on electricity alone in urban environments, reducing emissions to zero. Different solutions exist and, depending on the battery seizes, some of these vehicles can be connected to the grid for charging the batteries. Various combinations of batteries for energy storage with on-board energy generation facilities give way to specific solutions for each application, and allow minimising energy consumption and emissions. The hybrid technology is now particularly favoured for heavy-duty vehicles such as city-buses. Moreover, it is a fact that all the major car manufacturers now consider the deployment of hybrid drives as the logical way to reduce fuel consumption. The energetic and environmental advantage of hybrid drives becomes even more important when one considers clean on-board electricity generation. The use of fuel cells allows of generating electricity without noxious emissions and with an unprecedented efficiency. Manufacturers worldwide are preparing the fuel-cell vehicle as one of the premier solutions of the future. Energy efficiency and energy savings In-depth studies show that, all figures being equivalent, taking into account the energy efficiency at both production and distribution level, the consumption figures are as follows:
Table 1: Average consumption of conventional cars and electric vehicles [1] [1] G. Maggetto, P. Van den Bossche and J. Van Mierlo, CITELEC report "Force electrique en Wallonie: les vehicules electriques et hybrides en Wallonie, une solution ecologique durable pour la circulation urbaine" These figures show that electric cars, vans or small lories, respectively consume 54%, 47% and 52% of the primary energy needed by internal combustion vehicles. It is clear that electric vehicles are much more energy efficient. This advantage will increase when it will be possible to recharge vehicles by connecting them directly to electricity production sources with a total output efficiency exceeding 50% (plants with combined gas/steam cycle, fuel cells, buffer batteries, etc.). Taking into account an average mileage of 10000 km per year, which is the standard figure for vehicles in urban areas, the energy savings obtained by replacing conventional cars by electric vehicles are:
Table 2: Energy and fuel savings due to electric vehicles When regenerative braking is applied, kinetic energy can be recuperated and sent to the batteries. This can lead to an economy of about 10%. Environmental The introduction of EVs leads to a significant decrease of pollutants in the atmosphere. Taken into account indirect emissions from energy production, we can compare the emission values for each type of car.Figure 5 shows emission values as the total sum of operation-related emissions and emissions associated with final energy supply for Europe in the year 2000, for conventional cars (petrol, diesel and compressed natural gas) and electric cars. Figure 6 shows the CO 2 emissions from the engine and those associated with final energy supply, for European cities.
[2] UNIPEDE 1998 Report From these tables it is clear that EVs pollute less for almost all pollutants. Only for sulphur dioxide, the figure remains larger, because of the number of sulphurous coal plants. This is becoming more and more controlled, and the part associated with electric vehicles is actually rather marginal compared to other polluters. However, this figure should decrease substantially thanks to the improvement in emission control and the use of natural gas in the next few years. The global ecological impact is firmly positive. In figure 6 we see EVs produce less than half as much CO 2 as the other drive variants. Moreover, most of inner city movements are very short. So thermal engines remain in general rather cold, which means that emissions are higher and that efficiency is low. Catalyst converters only work properly at a sufficiently high temperature after some kilometres. In brief, low pollution by EVs is due to the higher efficiency of electric plants. Emissions from EVs are located outside the cities and it is easier to control emissions of one electricity plant than to control thousands of vehicles exhaust pipes. It is clear that EVs have an important role to play in the reduction of CO 2 emissions to avoid climate change and in the targets that have been defined in the Kyoto Protocol. Thermal engines are always rotating, even during a stop. EV motors, on the contrary, are stopped each time the vehicle stops. In traffic jams and at traffic lights EVs neither emit nor consume anything, except for auxiliaries such as lighting and radio. Economic The use of EVs will contribute to a stronger European independence regarding energy supplies,because the market share of diesel and petrol, which are oil products, will become smaller. Social Traffic noise is making the atmosphere of modern cities quite unbearable. Thousands of combustion-engined vehicles are generating an annoying background noise which degrades quality of life in cities. The electric vehicle is virtually silent and allows to rediscover the beauty of a moment of silence and quietness. What about living "windows opened" in the very city centre ? Health Most of the air pollution in today's European cities is caused by automotive traffic. Particularly in adverse climatic conditions, traffic generated emissions are degrading air quality up to the point where the physical health of the citizens is directly threatened. Several cities already had to recur to drastic traffic restrictions. Electric vehicle stands for clean air as iit is effectively zero-emission at its point of use. Furthermore, the emissions due to the generation of electricity are significantly lower than the corresponding vehicle emissions, due to the high efficiency of today's power stations. Mobility and congestion Today's urban traffic is grinding to a halt. Thousands of passenger cars and lorries are stuck in traffic jams which become worse and worse, leading to loss of time and energy, as well as extra pollution. The electric vehicle is ideally suited to be integrated in new traffic management concepts, such as automatic rent-a-car systems and goods distribution centres, which emphasise the complementarity of transport modes and which contribute to the relief of traffic congestion. Cultural Heritage Our European cities have a history of many centuries and can be rightly proud of an unique cultural and architectural heritage. This century however, they have been aggressively invaded by the motor car which through its emissions and through the traffic problems it causes, is forming a real threat to their conservation. The electric vehicle, through its respect for the environment, allows the integration of traffic in sensitive historic areas. Innovation and technological developments in the field All car manufacturers have a very well developed research policy concerning battery, hybrid and fuel-cell vehicles. An important number of auxiliary industries are also deeply involved. The component industry (e.g. battery and electronics manufactures) has a key role to play as well as universities and other R & D institutes. Electricity suppliers are also very interested as there is huge potential for their market. Todays, manufacturers have concept cars which clearly indicate what tomorrow's electric will be like. These vehicles will integrate electric power from the very start of vehicle conception through design to materials chosen. Parallely, continuous research on sophisticated electronic management systems and new generation of batteries allow an increased range. However, it is commonly agreed that pure electric vehicles are a sustainable alternative for commuters and low mileage drivers. In this specific context they have a large potential for niche markets such as city delivery vans, busses or vehicles designed for a specific task (e.g. airports, warehouses, postal services, ...). Hybrid vehicles appear to be the medium term solution and the logical way to reduce the energy consumption of today's conventional cars. Plug-in Hybrid Electric vehicles is a kind of combination between pure electric cars and hybrids. They have in fact a connection to the grid allowing overnight charging as well as a lager battery enabling the vehicle to run full electric on a long distance, like for example in city centre. It results lower environmental impact and reduced dependence on foreign oil sources. Finally, fuel cell vehicles are expected to be the future, offering greatest benefits over future internal combustion engines while offering the same performance. The price and infrastructure problems remain big challenges. The electric vehicle and the conventional automobile have a shared past: indeed, gas-fuelled and electrically-propelled cars were created during the same period, at the end of the last century. Today, the EV is once again in the public eye - this time, as a viable means of preserving the quality of our urban environments. Today, manufacturers are working on the next generation of vehicles, which will be designed specifically for electric power. Just before the end of the century Belgian engineer Camille Jénatzy introduced one of the very first electric vehicles, the surprisingly-designed "Jamais Contente", in 1899. This pioneer vehicle travelled the start-stop kilometer in 47.4 seconds and the launched kilometer in 34. It was the first time an automobile went faster than 100 km/h! 1939-1945: War and Shortages ... Gas-fuelled cars predominated during the first half of the 20th century. The oil shortages of the 1940s, however, led to the renewed interest in the electric vehicle. Car manufacturers quickly developed models such as this convertible Peugeot, baptized VLV (Véhicule Léger de Ville), for light urban use. The 205, emblem of the "energy conservation" years With the support of major energy conservation programs, Saft and Peugeot entered into an EV partnership in 1980. After first testing the nickel-cadmium batteries to equip the first electric 205 - a development which is still driving today's market for electric cars. The beginnings of an industrial production Over the last 15 years of the 20th century, limiting air pollution has become as important as the need to preserve fossil fuels. Consequently, car manufacturers are pursuing their efforts beyond the electric 205, and accelerating their EV industrialization programs. Saft developed partnerships with both French manufacturers - PSA Peugeot Citroën and Renault - as well as with the French government. Objective for this first decade df the millenium Todays, manufacturers have concept cars which clearly indicate what tomorrow's electric will be like. These vehicles will integrate electric power from the very start of vehicle conception through design to materials chosen. Parallely, continuous research on sophisticated electronic management systems and new generation of batteries allow an increased range. However, it is a fact that the larger potential for pure electric vehicles lies in niche markets such as city delivery vans, busses or vehicles designed for a specific task (e.g. airports, warehouses, postal services). Hybrid vehicles appear to be the medium term solution and the logical way to reduce the energy consumption of today's conventional cars. Plug-in Hybrid Electric vehicles will make the bridge between pure electric cars and hybrid “traditional” vehicles. Able to be charged overnight from the electric grid, they have no range limitation. As long as their battery is charged, Plug-in Hybrid Electric vehicle operate like a full electric car, silent, without release of harmful pollutants, including greenhouse gases. As soon as their battery is depleted, after 50 to 80 Kms, they become comparable to regular hybrid vehicles. Finally, in the longer term, fuel cell vehicles are expected to be the future, offering greatestbenefits over future internal combustion engines while offering the same performance. The price and infrastructure problems remain big challenges. There is a fundamental difference between an electric motor and a petrol or diesel engine. Several types of electric motors can be used to propel the vehicles. Essentially, they can be divided in two groups: direct current motors and alternating current motors. Each category has its disadvantages and benefits. Motors can be build in different ways into the vehicle: front or four wheel drive; in wheel mounted motors, ... Traction motors for electric vehicles must be fitted with a device to control the energy transfer between the battery and the motor. Today electronic traction controllers are used, which are characterised by both flexibility of use and high efficiency. Electricians call such controllers "choppers" for direct current drives, or "inverters" for alternating current drives. The traction battery is the "fuel tank" of the electric vehicle, that is where the energy needed for driving is stored. It is also the most critical component of the vehicle. Through the years, several battery types have been developed. Only a small number however can be considered for use in electric vehicles; the most important types are the lead-acid battery and the nickel-cadmium battery. Other types are under development. Cycle life, energy and power density are important characteristics of EV's batteries. The battery charger must transform the AC current from the network in a DC current of the correct voltage to recharge the battery. Volume and weight savings are particularly important for on-board battery chargers. Normal charge is the usual daily charging procedure. For road vehicle applications, it seems interesting to be able to charge the batteries in a much faster way. During subsequent charge and discharge cycles small differences will be emphasised between different battery elements. For this reason, it is necessary to apply a equalising charge at regular intervals. Notably for the battery charge, the electric vehicle needs a specific fixed infrastructure. The electricity must be supplied by the electric mains. For the normal charging one needs an ordinary outlet, present in virtually every house. For larger vehicles, off-board chargers are mostly used. Connecting an electric vehicle to a charging post necessitates the use of a cable and plug. To avoid this manipulation, cable-free inductive charging systems are proposed.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||
