Hydrogen is nothing new – it was first identified as an element in the 18th century and has been an important ingredient in the chemical industry for 100 years. Nowadays hydrogen’s potential role as an energy carrier is increasingly the focus, especially in an energy economy underpinned by renewable primary energies. Hydrogen is essential in this context, because it enables the storage and delivery of the primary energy.
In principle, there is more than sufficient renewable energy available, but it is not always available where it is needed and when it is needed. These locational and temporal gaps in supply and demand can be bridged by using hydrogen as an energy carrier. It expands on the transport of energy as electricity, which as a rule is and will remain the medium of choice. However, it is not practical to connect remote locations to the grid or provide for mobile energy use (e.g. cars, goods vehicles and aircraft) this way. Moreover, only limited possibilities exist for storage of electricity and not all renewable sources of energy provide electricity directly (for example biomass).
Using a fuel cell is the optimum way to regain the energy stored in hydrogen. It converts the chemical energy directly to electrical energy and heat in an electrochemical process. By avoiding the intermediate conversion stages (heat for driving a steam turbine and electrical generator) and the thermodynamic limitations that apply to heat engines (Carnot efficiency ceiling) a fuel cell is spectacularly efficient. Fuel cells with thermal cogeneration units achieve efficiency levels of over 80 % by also generating electricity from the heat produced. This is about double the efficiency of conventional combustion engines.
Hydrogen exists on our planet in practically unlimited quantities, but almost exclusively in chemical compounds (water, acids, hydrocarbons and other organic molecules).
At present the majority of hydrogen is produced by the chemical industry as a secondary or by-product of processes and it is subsequently used in other processes where it is required, this is especially the case in the petrochemical industry. The only purposeful production of hydrogen on an industrial scale is mainly extracted at present by reforming natural gas. This process relies on a fossil fuel and so is not sustainable as reserves are limited in the long term and the method involves significant CO2 emissions.
Alternative methods of producing hydrogen are the electrolysis of water from renewable primary energies or from the gasification of biomass. The latter also solves sometimes significant problems connected with the disposal of waste from agriculture and forestry, the organic waste from households and industrial organic waste products.
Hydrogen will also remain an important resource in the chemical industry in the future. However, its role as an energy carrier will become more and more important. According to a study by Shell Germany we can expect that by 2050 around 50 % of global energy demand will be derived from renewable sources (whereby overall demand will increase considerably); and 50 % of that energy is foreseen as being transformed into hydrogen prior to use.
- Stationary uses:
- The energy industry is currently undergoing a transformation to decentralisation of supply. Soon small fuel-cell block systems will be available that can cover the basic needs of a building for power and heating of one or more households. Since the infrastructure is already available, at present they are as a rule fed by natural gas, which is internally converted to hydrogen. Over the longer term, the construction of a hydrogen supply infrastructure can be expected.
- To offset mismatches in supply and demand the power grid can be augmented with electrolyser stations. Instead of switching off renewable power plants in periods of low demand, the excess power generated can be converted to hydrogen, which can either be sold or used to regenerate electricity at a later time. There are already plans to implement this, for example by the Hamburg utility HEW.
- Mobile uses:
- All vehicle manufacturers presently expecting ever tighter restrictions of CO2 emissions and are presently intensively developing fuels and propulsion systems that are still considered alternative.
- All companies are working more on electric vehicles with fuel cells. Die anderen Firmen setzen eher auf Elektrofahrzeuge mit Brennstoffzelle.
- Buses and other commercial vehicles generally use hydrogen as compressed gas or liquefied cryogenic gas.
- Prinzipiell sind auch Passagierflugzeuge möglich, die flüssigen Wasserstoff an Stelle von Kerosin als Treibstoff verwendet (ehemaliges Airbus-Projekt “Cryoplane”).
There are minimal or no emissions connected with the use of hydrogen. The product of burning it is water, from which in principle it is also possible to regain the hydrogen; in this way it is never lost and it is a constantly available energy carrier. Combustion engines that burn it in air do produce small amounts of nitrogen oxide. This problem is removed entirely by fuel cells with much lower operating temperatures. However, emissions do arise in cases where fuel cells are combined with peripheral components (e.g. hydrogen converter from natural gas).
The safe use of hydrogen has long been standard practice in industrial applications. The transportation of hydrogen by road, rail, ship, or through pipelines also pose no major problems. To construct an infrastructure it is necessary to develop devices, equipment and systems suited to everyday use in which existing knowledge is applied.
As a combustible gas in compressed or liquefied cryogenic form, hydrogen is subject to the relevant regulations applicable. Apart from these there are no special hazards associated with hydrogen and in Germany and the EU there are no regulations that relate specifically to hydrogen. The only need for standards in the foreseeable future is mainly concerning its introduction as a fuel in road traffic (licensing regulations). In addition, pressurised tanks made from fibre-reinforced plastic or from other new materials will be used. This will give rise to different safety considerations than for the conventional gas canisters made from steel or aluminium.
The German Hydrogen and Fuel-Cell Association (DWV) is the umbrella organisation for hydrogen and fuel-cell technology in Germany. The DWV coordinates between persons and firms that are interested, disseminates information to technicians, the media and decision-makers in politics, and lobbies for hydrogen technology in Germany. In so doing the DWV works in close cooperation with partner organisations in other countries.