Bosch is one of the all-time great names in car electrics and electronics. However, it is a late starter in commercialising hybrid and electric vehicles, with the lead in especially hybrid cars well and truly belonging to Japan. But Bosch is making giant strides – and now believes the future of powertrains is electric. This is an edited version of a speech presented by Bosch’s Wolf-Henning Scheider, President, Gasoline Systems, at the 59th International Automotive Press Briefing, Boxberg.
Over the next twenty years, the dominance of diesel and gasoline engines in the car will remain unchallenged.
These engines will, however, become more economical: we [at Bosch] believe that fuel consumption for both gasoline and diesel engines could be cut by up to one third. In a few years, a standard series car will be available in the compact to mid-size range that can drive 100 kilometres on just three litres of fuel.
Nonetheless, since we know that fossil-fuel reserves are limited, we must start thinking about alternatives to fossil-fuel powered cars. This is why we have adapted our fuel-injection systems to run on alternative fuels, such as ethanol or bio- and synthetic fuels. We are also working on increasing powertrain electrification, which will increase the efficiency of future cars and reduce their CO2 emissions.
The car of the future will become particularly eco-friendly, especially when it is powered with electricity generated from renewable resources.
It is safe to say that, in the years to come, the range of drivetrain technologies will grow. On the path toward powertrain electrification, our current development activities focus on:
the hybrid engine
purely electric driving
the range extender
The latter is a small combustion engine that powers a generator, which then charges a battery over longer distances. This battery, in turn, delivers energy for an electric motor.
Besides these technologies, we are also working on the fuel cell as an energy converter.
The electric motor is the most efficient means of powering a car. With one kilowatt hour of energy, a conventional combustion engine can cover a distance between 1.5 and 2.5 kilometres. The diesel hybrid, which combines a diesel engine with an electric motor, can cover a maximum of 3.2 kilometres on the same amount of energy. In contrast, a car with an electric motor can get 6.5 kilometres out of one kilowatt hour! This is why we believe that in the distant future, the car will be powered by an electric motor.
Just how soon electric cars become a common sight on our streets depends on a number of factors.
One crucial issue is how the lithium-ion battery develops in terms of cost and capacity. Moreover, rising crude oil prices and legal provisions, such as CO2 emissions standards in the EU and the corporate average fuel economy (CAFE) legislation in the U.S., will also play an important role.
The number of megacities worldwide is growing. According to estimates, more than 500 million people will be living in megacities in seven years time. Electric cars are perfectly suited to the short distances of inner-city travel. And since they are almost emission-free, they easily meet strict emissions standards like those already in place in London.
We see particular potential for electric cars in China’s megacities, where people are showing a growing interest in owning their own automobile. Here, the focus is more on mobility and less on drive technology.
The hybrid drive
With the hybrid drive, the emissions of conventional and commercially available drive technologies can be reduced.
To do this, the mild hybrid uses a start-stop function and can also regenerate electrical energy in the braking process. When the car accelerates, the electric motor delivers torque to boost the process of driving off. This makes it possible to use a smaller combustion engine. As a result, up to 15 percent less fuel is used on average in the NEDC (New European Driving Cycle fuel economy test) than in a gasoline engine with manifold injection.
Depending on the design, such a system, including a small lithium-ion battery, will cost carmakers about the same as a highly efficient diesel engine.
The strong hybrid not only offers all of the benefits of a mild hybrid, it is also able to function exclusively on electrical energy over short distances. For this purpose, strong hybrid cars have a much stronger electric motor and a larger battery. This additional power creates a boost effect, enabling a car to accelerate faster when needed, for instance when overtaking. The strong hybrid uses up to 25 percent less fuel on average in the NEDC, and the additional cost is around one and a half times that of a mild hybrid.
The plug-in hybrid can also be charged from the grid, allowing short distances to be driven emission-free.
In all of these variants, the diesel hybrid shows the greatest potential for reducing CO2 emissions. In our view, the hybrid drive is paving the way for purely electric driving. It is especially efficient for vehicles in urban traffic situations, such as delivery vehicles or courier services, with frequent start-stop intervals. However, integrating an electric motor into strong or plug-in hybrids is an elaborate and expensive process. Moreover, the additional motor makes the hybrid vehicle heavier. In terms of emission-reduction potential, this may make sense for premium-class vehicles. For small and mid-class cars, however, conventional technology is the most cost-effective way to meet future CO2 emissions standards.
The range extender
The range extender is a further technology on the road to electric driving. It is a small, lightweight combustion engine that makes less noise than a conventional engine. With 15 to 35 kilowatts of power, the range extender constantly runs at the optimum operating status. As a result, its fuel consumption is low. If needed, it charges the battery which delivers energy to the electric motor. The main benefit of the range extender is that it requires less technology than the hybrid drive. Without the transmission of a combustion engine or the conventional generator, it is more lightweight and less expensive than the hybrid. Compared with a purely electric vehicle, the battery can be smaller, which also reduces weight and cost. In principle, vehicles equipped with a range extender can cover the same distance as cars with a conventional engine.
Despite all its benefits, the range extender also requires drivers to adapt their driving behaviour. If the battery is running low, the range extender can keep the vehicle going on 28 kilowatts of power – but at a maximum speed of 120 kilometres per hour, fast enough for city driving and over long distances.
The operational profile of the car will therefore determine how powerful the range extender has to be. For higher speeds over longer distances, an engine with power comparable to strong or plug-in hybrids is needed. Since all the components for this type of vehicle also have to be designed to deliver more power, it is heavier and thus less energy-efficient.
Purely electric driving
Before we can drive any reasonable distance purely on electrical power, we must still tackle a number of technological challenges. This is why interim solutions such as the range extender will remain relevant until the electric car can cover longer distances.
The range of an electric car depends on how efficiently it uses the energy at its disposal. This, in turn, calls for a complete rethink of vehicle design. In the future, it will be up to automotive manufacturers to come up with such new concepts. Lightweight construction will play a major role, as will improved aerodynamics and rolling resistance, which can be reduced with low-resistance tires. Moreover, the energy consumption of auxiliary systems, such as heating or air conditioning, must also be minimized.
What will the electric car look like in 2015? It will weigh around 1,000 kilograms. It will have a drag coefficient of 0.34, and its 40-kilowatt motor will be capable of speeds up to 120 kilometres per hour. In Germany today, the average distance covered each day by 90 percent of cars is under 80 kilometres. According to recent surveys, however, drivers want the electric car to have a minimum range of 200 kilometres. To make this possible, our electric car needs a battery with a capacity of 35-kilowatt hours. Based on the technology we expect to be available in 2015, this battery will weigh 250 kilograms and cost around 12,000 euros, or 350 euros per kilowatt hour. Depending on the design of the electric vehicle – how heavy it is, for example – and depending on how the lithium-ion battery develops, the cost of the battery may be slightly lower, at around 8,000 euros.
Clearly, the battery is currently the main obstacle to purely electric driving. It is still too expensive, and cannot provide the same energy density as conventional fuels. Today, one kilogram of gasoline contains 50 to 100 times more energy than can be stored in one kilogram of battery. While cars with gasoline and diesel engines can currently cover 600 to 800 kilometres on one tank of fuel, the battery will not be able to cover comparable distances at a reasonable cost in the foreseeable future.
The lithium-ion battery
Based on what we know today, the lithium-ion battery shows the greatest potential for meeting the high demands of the automobile. Our top priorities are achieving a threefold improvement of its energy density, while at the same time reducing its cost by the same factor. Customers will accept the electric car only if we can increase battery performance and offer it at a lower price. We must also tackle further technical challenges, such as high cycle strength and a service life of more than twelve years. This is because drivers will not tolerate having to change their car batteries after seven years, as is the case with today’s 12-volt starter batteries. What’s more, the battery’s safe functioning must be guaranteed under all operating and climatic conditions.
Although lithium-ion batteries have a proven track record with consumer products such as mobile phones or laptops, a battery for the electric car must meet much higher requirements.
To develop the lithium-ion battery further, we must understand the requirements of the automotive industry and of the car itself. These include production technologies for series production, product lifecycles, temperature fluctuations in the car, and safety requirements, among other things.
We expect the mass market for hybrid and electric drives to develop slowly at first. In 2015, five million of the 85 to 90 million new cars produced will have hybrid drives. Another 500,000 will be plug-in hybrids or electric cars. We believe that the market for electric cars will not start gaining importance until 2020 at the earliest, with six million hybrid vehicles and three million plug-in hybrids and electric vehicles out of 100 million newly produced cars.
We look forward to an exciting future.