Fuel cell vehicle

Fuel cell vehicles are transport vehicles with electric drive, in which the electrical energy required is generated from the conventional fuels, hydrogen or methanol by a fuel cell is converted directly into electric motors in motion or is temporarily buffered in a traction battery. The additional electrical storage allows for a recuperation, for others, it relieves the fuel cell of load changes.

This drive form applies to road vehicles not only as experimental, but is made despite practical limitations in small series. Thus corresponding stations are hardly available and for the longer shutdown a frost-proof room is necessary. Because of the different refueling times, the fuel cell car is usually not seen as competition, but as a complement of the supplied batteries electric cars. These too can achieve as a production vehicle 2013-500 km range.

4.1 compressed hydrogen storage
4.2 metal hydride
4.3 storage in nanotubes
4.4 N- ethylcarbazole
4.5 Chemically bound hydrogen

8.1 passenger cars
8.2 Commercial Vehicles
8.3 ships / boats

Fuel cell drive

A fuel cell can convert chemical energy with an efficiency of up to 60% directly into electrical energy. The so- produced electric energy is stored in the traction batteries and electric motors, often installed without gear directly to two or four wheels ( hub motor ) are converted into kinetic energy. Thus, the fuel cell charged when in use by the traction battery and works as a range extender to increase the range of the vehicle with electric drive.

Operations in the fuel cell

At the anode hydrogen is oxidized, that is, electrons are removed from it. The protons pass through the electrolyte membrane and flow to a cathode. The electrolyte membrane is only permeable for protons, which means that the electrons are forced to take a detour through the current cycle. At the cathode of the air flow down guided oxygen is reduced, that is, the electrons ( which have previously been extracted from the hydrogen) are added. Then the negatively charged oxygen ions strike the protons and react to form water. So that the current circuit is closed. At the same time, heat is released, for example, in the vehicle in winter can be used for heating purposes.

Fuels and fuel

Now only pressure tanks made from carbon fiber reinforced plastic ( 350-800 bar ) can be used for fuel cell car, because the ranges of up to 800 km thus achieved sufficient. The density of compressed gas at 700 bar is already about 75 % of the density of liquid hydrogen zoom.

Cryogenic liquid hydrogen ( -253 ° C, liquid H2) is only used when larger amounts are needed, for example, in fuel cell buses. At conversion loss about 12 % of the energy bound to hydrogen must be expended for the compression to 700 bar, in the liquefaction 28-46 % are to spend. The fueling is similar to refueling with LPG or natural gas.

It is possible different energy- containing substances to be used as fuel. These must be converted for use in the fuel cell before in a reformer chemically into gaseous hydrogen. Immediately use direct methanol fuel cells ( DMFC) the liquid fuel methanol, but they have a low efficiency.

Producing hydrogen

Hydrogen Storage

Compressed hydrogen storage

The problems of storage in pressure vessels are now considered solved. The use of new materials, the effective loss is greatly reduced by diffusion. Goods for the automotive sector by 2000 pressure tank with 200 to 350 bar are used in 2011 and already 700 and 800 -bar tanks with higher capacity are still usual. The complete hydrogen fueling system for a car weighs only 125 kg. For the drive system of a fuel cell vehicle, but also includes not only the pressure tank and the fuel cell, the traction battery as a buffer and the electric drivetrain. The range of a fuel cell vehicle with the pressure tank can be up to 800 km.

Metal hydride

A technology, which is currently still in testing, is the use of metal hydrides. It sets out that certain metal alloys absorb hydrogen by thermal treatment and release them again. Thus, it is stored by hydrogen pressure in the metal powder and released by heating. This method offers advantages in the volume-based storage density. The disadvantage, however, the high material costs and that hydride storage are only absorb about 2 % of its own weight in hydrogen and are therefore very difficult for passenger cars, because these units weigh around 300 kg. The aim of research is to increase the weight-based storage densities by the use of new alloys.

Storage in nanotubes

New Perspectives promised the storage of hydrogen in carbon nano - fibers. Carbon nano - fibers are made of stacked graphite layers, in which the hydrogen is embedded. It was hoped that weight-related energy densities of 8-20 %. In reality, however, only values could be achieved by 2%. The forecasts were wrong due to, among other things Verunreigungen of titanium in the first experiments.

N-ethylcarbazole

An also only recently been explored memory option is the use of N -ethylcarbazole as a storage medium. N- ethylcarbazole can store large amounts of hydrogen chemically and win him back again later. With the hydrogen stored in N -ethylcarbazole a fuel cell could be used to generate electricity in cars. Instead of petrol or power of motorists at the gas station just " charged " energy-rich N- ethylcarbazole ( Perhydro -N -ethylcarbazole or Perhydro - carbazole ) would fill up, and at the same time drain " unloaded " low-energy N- ethylcarbazole. The low-energy N- ethylcarbazole could be locally enriched with energy; ecologically most sense would be directly to places where electricity is produced, such as wind farms in the North Sea. N- ethylcarbazole can be transported in pipelines or stored without pressure in tanks safe and without losses over long distances. Another advantage is the low deterioration of the environment and the atmosphere.

The disadvantage is the duplicity of the supply or disposal. In vehicle two tanks must be available: one for high-energy Perhydro -N -ethylcarbazole and one for unloaded. This can, for example, a double tank with separating membrane be ( LOHC tanks, LOHC called " Liquid Organic Hydrogen Carriers "). The duplicity of the supply and disposal propagates through the gas station up continues in all the logistics. Another problem is that for extraction of the hydrogen from the N-ethylcarbazole usually operating at temperatures of between 100 and 200 degrees Celsius are needed. This would make a temperature management system for controlling the temperature of individual functional units of the system required since the fuel cells operate at around 80 degrees Celsius. In addition, the chemical release of hydrogen from the N- ethylcarbazole without further aids expires comparatively slow, a vehicle acceleration, such as is expected in the automotive industry, can not come about.

Chemically bound hydrogen

A further possibility is to use ethanol for transport. The ethanol is catalytically separated into hydrogen and carbon dioxide and the hydrogen is transferred to a fuel cell. In this method, some problems such as the formation of toxic carbon monoxide in the conversion of ethanol into hydrogen show. This method is no longer used in fuel cell vehicles.

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The Ministry for the Environment, Nature Conservation and Transport of the State of Baden- Württemberg will continue to support the development of a hydrogen infrastructure for a sustainable use of energy and sustainable mobility.

Vehicle manufacturers Toyota, Nissan and Honda have the production cost for hydrogen-powered vehicles now greatly reduced, and plan to launch mass production in Japan in 2015 in connection with the construction of 100 hydrogen fueling stations in the Japanese metropolitan areas.

The price of Daimler BSZ- car should already 2014 only about 20% higher than that of a vehicle with a combustion engine. Daimler wanted to begin no later than 2015 with mass production of hydrogen vehicles. In order to demonstrate the practicality of hydrogen drive, Mercedes -Benz introduced a world tour by multi- cell vehicles of the B-Class. The necessary tank systems for compression of the supplied by Linde AG hydrogen at 700 bar were included as mobile units. Daimler wants to start series production of fuel cell vehicles, contrary to the original plan until 2017, as a competitive price for the vehicles currently can not be realized.

However, building an infrastructure for hydrogen production, hydrogen storage and refueling is still open. It must also be considered from an ecological perspective in addition to how the electric car pollution-free operation of the vehicle (tank -to-wheel ), the generation of the necessary hydrogen ( well-to- tank). The production of hydrogen is carried out at the moment (2012), especially by steam reforming using fossil primary energy, primarily natural gas. The Clean Energy Partnership, a consortium of major car manufacturers and energy suppliers plans to expand both the number of 27 existing, partly non-public hydrogen filling stations 2011, 2015 to a nationwide network of approximately a thousand hydrogen filling stations in Germany. This would mean in Germany, a nationwide network in the radius of 30 kilometers. However, alone, for example, the Berlin hydrogen filling station at the Holzmarktstraße with just over four million euros of taxpayers' money has been funded ..

Potential of hydrogen

Hydrogen (H ) is composed of one proton and one electron. It exists as a colorless, tasteless and odorless, poisonous gas made up of two atoms ( H2). In nature you can not find it practical in free form. It is present there only in a bound form, eg as water (H2O ) into hydrocarbons (oil, gas, coal, biomass) or other organic compounds. Hydrogen is released by applying energy. It is currently (2012 ) obtained almost exclusively from fossil fuels. However, in the production of hydrogen from fossil fuels produces CO2 as a by- product. In terms of climate protection, the goal is quite possible to produce hydrogen without CO2 emissions. The climate-friendly option is to produce hydrogen through the electrolysis of water. Electrolysis is the decomposition of a chemical compound under the action of electric current. Hydrogen is a carbon-free fuel, and can thus contribute to reducing CO2 emissions. However, this potential of the hydrogen can only be exploited if the electricity comes from renewable energy sources. The space required for the electrolysis current can be obtained from energy sources such as solar, wind and water, the economy but is currently not present. About 90 % of the currently used hydrogen produced by steam reforming of fossil sources using the conventional energy mix.

Significant loss of coverage must accept battery-powered vehicles, if they are to drive at low temperatures in northern latitudes such as Germany. Here is also required energy for the heating of the vehicle in the winter, which considerably reduces, in an electrical heating system, the operating range. In a fuel cell vehicle may be able to use the waste heat from the fuel cell for heating.

Fuel cell vehicles today have the same range as those of gasoline, for example, the Toyota FCHV with a range of 830 km. The vehicle is already in commercial use.

Balance of energy supply chain

A comparison of the efficiency of the energy source to the energy supply in the vehicle ( well-to- tank) is obtained for an electric vehicle with fuel cell, a significantly lower efficiency than for an electric vehicle with battery, especially through the necessary hydrogen production and storage. Despite the poorer efficiency in the conversion chain, the advantage of hydrogen is the higher energy density, which can allow a greater range of vehicles and rapid refueling.

Fuel cell concept vehicles

Passenger cars

Honda showed the FCX Clarity in 2007 a production-ready fuel cell car. The first copies were passed by lease to selected customers in California.

On 3 June 2008, the first Toyota FCHV -adv got his street legal in Japan. The vehicle concept is always improved. On 1 September 2008, the Japanese Ministry of Environment leased the first Toyota FCHV -adv for commercial use.

Some manufacturers have already introduced several generations or more different concept vehicles before:

Commercial Vehicles

DaimlerChrysler developed a drive for the sprinters, as well as the 1997 NeBus (O 405 N2 with fuel cell), the 2002 Mercedes -Benz Citaro BZ and presented at the 2009 UITP Congress in Vienna with the Citaro FuelCELL hybrid, the third generation as a hybrid bus with storage battery.
Van Hool and UTC Fuel Cell, ISE Corporation 2005 presented together the Van Hool newA330 Fuel Cell.
Hydrogenics built on the model of Gulliver 520ESP Tecnobus (Italy ) several midi buses with fuel cell drive.
When HHLA in Hamburg harbor a forklift Still (R 60-25 ) with fuel cell drive is running.
CNH Global presented at the Agricultural Exhibition Sima 2009 in Paris the tractor " NH ² " based on the New Holland model " T6000 ". The tractor has 120 horsepower.

Ships / boats

Passenger ship: Passenger ship Hamburg Alster water project Zemships. See also → H2Yacht
Submarine: Submarine Class 212 submarine class 214 DeepC
RoRo ship Undine, fuel cell unit WFC20 of Wärtsilä as an auxiliary drive (20 kW) with methanol feed
The research vessel Solgenia is also supplied via a fuel cell.
The Norwegian Viking Lady is a supply ship, which was also fitted to the diesel-electric drive with a fuel cell in 2009.

Meanwhile, the economical use of fuel cell drive of ships is called into question.

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