Daimler Unveils Emission Free Vehicles: the Electric Smart Fortwo and Mercedes-Benz B-Class F-CELL

 Mercedes-Benz B-Class F-CELL, Image Credit: Daimler

Dr. Dieter Zetsche, Daimler CEO and Head of Mercedes-Benz cars says "As a global supplier of premium cars we want to meet the mobility requirements of our customers all over the world. This is why we are broadly positioned and have developed a modular drive mix to suit different requirements. The smart fortwo electric drive and the Mercedes-Benz B-Class F-CELL are already demonstrating the contribution that electric cars can make to sustainable mobility.

Smart Fortwo

 Image Credit: Daimler

Experts are unanimous in their belief that the "coexistence" of different drive technologies will shape the face of road traffic for years to come. This is why Daimler's approach is to develop vehicle concepts with modular drive technologies which ensure that the focus is always on both customer benefits and environmental compatibility.

In addition to the optimization of vehicles with state-of-the-art combustion engines and further efficiency increases with hybridization tailored to customer needs, the third central focus of development is on fuel cell and battery-powered vehicles that do not produce any local emissions. Dr. Thomas Weber, Daimler AG board member responsible for Group Research and Development at Mercedes-Benz Cars says "Each of these technologies demonstrates its advantages with regard to optimum consumption and emission figures in specific fields of application. We are the only manufacturer worldwide to offer our customers appropriate solutions for all fields of application – from personal mobility to local public transport and goods transport on the roads."

Electric cars are now being delivered to customers

With the electric cars from smart and Mercedes-Benz that are fully suitable for everyday use, zero-emission driving is already a reality. The new smart fortwo electric drive is a pioneer among battery electric vehicles which are primarily suited to use in urban areas. The second generation is already being built and now boasts a highly efficient lithium-ion battery which enables a range of 135 kilometres and impressive performance. Following the start of series production in Hambach, France in mid November 2009, the first small series of 1000 vehicles will be handed over to customers in Berlin on 17 December. The two-seater car will initially be delivered to selected customers in six European countries plus the USA and Canada within the framework of a leasing or rental model. Volume production will start in 2012 and the smart fortwo electric drive will then be available to anyone interested.

Thanks to its range of around 400 kilometres, the Mercedes-Benz B-Class F-CELL is suitable for both zero-emission driving in city traffic and also for travelling longer distances. Small series production of this electric car has also started. Next year the first of approximately 200 vehicles will be delivered to customers in Europe and the USA.

Both electric cars are fully suitable for everyday use. All the main components are housed in a space-saving position between the axles where they are optimally protected, and this means that the interior space is not compromised in the electric versions of the standard cars. Furthermore, the smart – the ultimate city car – has an extremely comfortable range for city driving and it can be charged at any household socket. The B-Class F-CELL offers a large range and is suitable for travelling longer distances as well. As its hydrogen tanks can be fully refuelled in around three minutes it is also the electric car with the shortest charging time.

Infrastructure is essential

An appropriate refueling and electricity charging infrastructure is essential for wide customer acceptance and quick widespread use of electric vehicles. This is why Daimler is committed to setting up a comprehensive network of electricity charging stations and hydrogen filling stations. In September 2009 together with the Federal Ministry of Transport and partners from the energy sector the company presented a plan for establishing a hydrogen infrastructure in Germany. At the same time Daimler reached an agreement with other leading car manufacturers to bring several hundred thousand fuel cell cars to the roads from 2015.

Parallel to this, together with various partners in Europe the Stuttgart car manufacturer is advancing the expansion of a public electricity charging infrastructure. This is because although electric vehicles like the smart fortwo electric drive can easily be charged at a domestic garage socket, around 40 percent of European vehicle owners do not have a parking space of their own. Publicly accessible charging stations are therefore needed. To enable this to be realised Europe-wide as far as possible with standardised framework conditions, Daimler is developing corresponding standards together with other car manufacturers and utility companies.

Electric mobility – an affordable alternative?

New technologies generally entail high investments and costs. This means that at the current stage of development electric cars are still more expensive than comparable models with combustion engines. Daimler is applying all available levers to reduce the costs to a level that is economically acceptable and attractive to customers. For example, by industrializing lithium-ion technology with the company Deutsche Accumotive GmbH and the economies of scale resulting from this.

 Furthermore, in product development Daimler is systematically using a modular E-drive system. This enables synergies to be ideally used between the different vehicle segments. There are also numerous other factors that make electric mobility attractive for customers. Tax relief and other government subsidies are an important aspect. For example, the state of Monaco offers tax relief of up to €9,000 to electric car owners. Other countries have also set up funding programmes for sustainable mobility. France offers a "super environment incentive" of €5000 for vehicles that emit less than 60 grams of CO2 per kilometre. China and Japan have announced subsidies of €6,500 and €11,000 respectively.

Customers benefit from lower running costs

In addition, owners of electric cars can benefit from lower running costs. For example, in Germany the electricity costs for a distance of 100 kilometres currently stand at between two and three euros. And many experts believe that in the long-term the costs for hydrogen will level out at a price that makes it an inexpensive alternative to fossil fuels.

However, the question of the future taxation of new fuels has not yet been clarified. Dr. Thomas Weber says "It would make sense to find a solution that supports the introduction of new drives during the transitional period – for example with temporary tax exemption for electricity and hydrogen, just as various countries offer tax relief today for natural gas used to power vehicles."
For example, electric cars like the smart fortwo electric drive are exempted from the city congestion charge in London, enabling their owners to save considerable sums of money.

Dr. Joachim Schmidt, Head of Sales and Marketing at Mercedes-Benz Cars says "All things considered we see good prospects for electric mobility with fuel cells and batteries. Whilst other companies are still presenting electric show cars, we at smart and Mercedes-Benz are already bringing two vehicles that are fully suitable for everyday use to the roads."

Asahi Glass Carbon Nanotube Fuel Cell Membrane Solves Interlayer Flooding Problem

Asahi Glass Company, Limited (Chiyoda-ku, JP) developed a fuel cell membrane using carbon nanotubes that exhibits superior performance in both humid and low humidity environments. Solid polymer electrolyte fuel cells are required to be operated under a low humidity environment, primarily in their use for automobiles. The nanocarbon material exhibits high proton conductivity in a low humidity environment for a proton-conductive polymer used in a fuel cell membrane electrode assembly, according to U.S. Patent Application 20090291345. Carbon nanofiber is particularly preferred since it is fine and has excellent electron conductivity. The carbon nanofiber may be a vapor-grown carbon fiber, carbon nanotube single wall, double wall, multiwall or cup-laminated type.

By providing an interlayer composed mainly of carbon fiber between the catalyst layer and the gas diffusion layer, water is readily transferred by a capillary phenomenon from the catalyst layer to the interlayer whereby a flooding problem during the operation of the polymer electrolyte fuel cell may readily be solved say inventors Satoru Hommura, Shinji Kinoshita, Hiroshi Shimoda, Susumu Saito, Seigo Kotera, Tetsuji Shimohira and Hideki Nakagawa.

The fiber diameter of the carbon fiber is preferably from 50 to 200 nm, and the fiber length is preferably from 1 to 50 microns. By using such carbon fiber, it entangles with an electron-conductive material (platinum or a platinum alloy, and a carbon carrier) contained in the catalyst layer at the interface between the interlayer 1-84 and the catalyst layer to form a new electroconductive path in addition to an electroconductive path by a point contact with the electroconductive material, whereby the electron conductivity of the catalyst layer will be improved. Further, such carbon fiber is likely to be entangled to form void spaces at the time of applying a coating fluid containing the carbon fiber, whereby such void spaces will function as a gas channel.

The ratio of the carbon material to the proton-conductive polymer (carbon material/proton-conductive polymer) is preferably from 1/0.1 to 1/5 (mass ratio), more preferably from 1/0.2 to 1/1. Within such a range, the dispersibility of the carbon material, the adhesion between the interlayer and the gas diffusion layer, and the gas diffusing property and water-discharging property of the interlayer will be good.

In actual driving of an automobile having a polymer electrolyte fuel cell mounted, the polymer electrolyte membrane will be exposed to various humidity environments. As a test to simulate such a situation, a cycle test (hereinafter referred to as a moistening/drying cycle test) has been proposed wherein the polymer electrolyte membrane is repeatedly exposed to each of a dried environment with a relative humidity of at most 25% and a moistening environment with a relative humidity of 100%. In such a moistening/drying cycle test, the polymer electrolyte membrane swells in the moistening environment and shrinks in the dried environment and thus undergoes swelling and shrinkage repeatedly along with moistening and drying cycles and thus undergoes a dimensional change especially in a planar direction. Therefore, by the moistening/drying cycle test, it is possible to evaluate the mechanical durability of the membrane/electrode assembly in an environment where moistening and drying are repeated.

In order to improve the proton conductivity of the proton-conductive polymer, the ion exchange capacity may be increased. However, if the ion exchange capacity is increased, the water content of the proton-conductive polymer will increase. If the water content of the proton-conductive polymer to be used for the catalyst layer becomes too high, the proton-conductive polymer will swell and clog void spaces in the catalyst layer, thus leading to a problem of a so-called flooding phenomenon. If the flooding phenomenon takes place, the diffusion of the gas supplied to the catalyst layer decreases, whereby the power generation performance of the polymer electrolyte fuel cell will be substantially deteriorated. Asahai Glass says their membrane solves the flooding problem.

An iRAP study identified 3,870 organizations involved in fuel cells, hydrogen energy and related nanotechnology who earned and spent an estimated $8.4 billion in 2008.