From a chemical point of view, hydrogen is a primary energy carrier , but in nature it is practically not available in free form, but must first be obtained with the help of other energy sources ( fossil energy , nuclear energy or renewable energies ). A hydrogen economy is therefore not automatically sustainable, but only as sustainable as the primary energies from which the hydrogen is obtained. Hydrogen is currently produced primarily on the basis of fossil fuels such as the methane contained in natural gas . Concepts for future hydrogen economies mostly provide for the production of hydrogen from renewable energies, which means that such a hydrogen economy could be emission-free.
While no traditional hydrogen economy has yet been strived for in any country in the world, there are plans to increasingly integrate hydrogen or fuels obtained from hydrogen such as methane or methanol into the existing energy infrastructure as part of the energy transition and the expansion of renewable energies .
- 1874 - the writer Jules Verne described in a dialogue between his fictional characters, when asked what should be burned instead of coal in later times, the first vision of using hydrogen and oxygen as an energy source.
- 1923 - The scientist John Burdon Sanderson Haldane first mentioned the fundamentals of a hydrogen economy in an essay.
- 1970 - Australian electrochemist John Bockris first used the term " hydrogen economy " during a meeting at the General Motors Technical Center in Warren, Michigan. and, after Joseph J. Romm (* 1960), shaped it significantly in the following years.
- 1975 - Together with the physicist Eduard Justi , John Bockris designed the complete concept of a hydrogen economy.
- 1980 - Under the influence of the oil crisis , the physicist Reinhard Dahlberg developed the concept of a hydrogen economy in which hydrogen is generated in desert areas using solar energy and transported to consumers via pipelines. The main motivation was to replace the fossil fuels that were drying up. Dahlberg had not only considered the technical but also the economic aspects of his hydrogen economy.
- 1994 - The German Aerospace Research Institute (DLR) dealt with hydrogen production in the desert. The 350 kW electrolyser operated by solar cells provided evidence at the time that the production of storable and transportable hydrogen is possible. The available solar resources could provide the same amount of energy on one percent of the land area of Saudi Arabia as is exported annually as crude oil.
- 1999 - The Icelandic government included the goal of a hydrogen economy (subject to feasibility and economic viability) in its government program. The focus of Iceland was particularly on hydrogen drives for vehicles and the fishing fleet in order to become independent of oil. The country has no degradable fossil fuels, but is rich in electricity-generating hydropower and geothermal energy. To promote this goal, Icelandic New Energy was founded.
- 2002 - Economist Jeremy Rifkin described the concept of a hydrogen economy in his book The Hydrogen Revolution . For Rifkin, the negative effects on the economy from rising oil prices and the endpoint of fossil fuels as "the most precarious moment in post-industrial history" are an important motivation.
- In 2003, the previous hydrogen proponent Ulf Bossel criticized the low profitability of a hydrogen economy
- In 2006, Joseph J. Romm analyzed the prospects for a hydrogen economy in the USA and said: “When some people pretend that the hydrogen economy is already within reach, they are simply referring to an economic system centered around hydrogen from natural gas and other polluting fossil fuels Fuels. "
- 2007 - The European Parliament, also under the advice of Jeremy Rifkin, adopted a declaration calling for the creation of a hydrogen infrastructure by 2025. The explanation cites global warming and the increasing cost of fossil fuels as justification.
- 2019 - The Hamburg Senator for Economic Affairs Michael Westhagemann announces that a hydrogen plant with a capacity of 100 megawatts is planned in the Port of Hamburg . This would be the largest hydrogen plant in the world.
The levels of an energy industry
The ideas are based on the implementation of hydrogen on all levels of the energy industry:
- Development of required primary energy sources
- Energy generation
- Energy storage
- Use of energy
- Energy trading and distribution
- Distribution and billing
- Guarantee of security of supply
Production of hydrogen
So far, hydrogen has been produced almost exclusively from fossil fuels, primarily from methane. The amount of hydrogen produced worldwide from natural gas and heavy oil was approx. 310 billion m³ in 1999 and approx. 9 billion m³ in Germany. Natural gas and heavy oil are fossil primary energy sources . When producing hydrogen using these substances, carbon dioxide with a high global warming potential is released. This is contrary to the introduction of an environmentally friendly hydrogen economy called for by the European Parliament.
Some of the hydrogen is also produced as a by-product in the chemical industry , e.g. B. in gasoline reforming and ethylene production . However, it is also a by-product of chlor-alkali electrolysis and the production of coke oven gas through coal gasification . In 1999 the chemical industry produced 190 billion m³ in the world and 10 billion m³ in Germany in Germany. Usually the hydrogen produced in this way is used thermally by burning it on site.
Production from electrical energy (electrolysis)
In order to enable a sustainable hydrogen economy, the hydrogen must be obtained from renewable energies. Here come v. a. the wind energy and solar energy ( photovoltaic and solar thermal power plants ) in question, both globally and in Germany have much greater potential than have the biomass. It is assumed that wind and solar energy will cover the main load in a regenerative energy system; some studies even completely dispense with the use of biomass. Most of these concepts only envisage a supplementary role for hydrogen in an electricity-based economy, not a full hydrogen economy in the actual sense.
In a fully regenerative electricity industry, high shares of variable generators such as wind and solar power require additional long-term storage to compensate. For this purpose, chemical storage systems such as hydrogen production, possibly in connection with downstream methanation, come into question. In the case of hydrogen production, storage and subsequent reconversion, the efficiency is currently (2013) a maximum of 43%, in methanation 39%. Sterner et al. indicate efficiency ranges between 34 and 44% for the chain hydrogen production, storage and reconversion. It is assumed that, in perspective, overall electrical efficiencies of up to a maximum of 49 to 55% will be achieved.
This process has been used since October 2011 in a pilot project at Enertrag in Prenzlau , Brandenburg . Electricity that is not required was converted into hydrogen with a 500 kW pressure electrolyser and is thus available for hydrogen filling stations or, if required, is converted into electricity again in a hybrid power plant.
Since October 2011, Greenpeace Energy has also been supplying hydrogen from excess wind power, which is fed into the natural gas network in its pure form or converted into methane.
The Audi AG planned, from 2013, in Lower Saxony Werlte to generate wind power hydrogen. The hydrogen produced should first be converted into CNG to serve as fuel for natural gas vehicles . The hydrogen produced can also be used directly in fuel cell vehicles.
High-temperature electrolysis promises high levels of efficiency because the demand for electrical energy decreases with increasing temperature. The high-temperature electrolysis is of particular interest in solar thermal power plants . The process was in the development stage in 2011.
The Fraunhofer Institute in Leuna is also researching processes for the sustainable and inexpensive production of hydrogen. The electricity required for this is provided by renewable energy sources. The pilot plant for the production of "green" hydrogen is scheduled to go into operation in 2019.
Hydrogen from bioenergy
The production of hydrogen from biomass is largely climate-neutral , because the hydrogen and carbon obtained from the atmosphere / biosphere were previously removed by photosynthesis . However, the effort to generate such. B. fertilizers, pesticides, expenses for transport and processing as well as processing of the biomass are taken into account. The climate neutrality corresponds to the introduction of an environmentally friendly hydrogen economy called for by the European Parliament.
There is no large-scale production of hydrogen from biomass (as of 2011). The procedures are mostly still in the development stage. One example of this is the “ Blue Tower ” project in Herten . The planned plant should produce 150 m³ of hydrogen per hour, the main owner, Solar Millennium AG, went bankrupt at the end of 2011.
Potential and land requirement of energy crops
In Germany, the primary energy demand in 2014 was around 13,000 PJ. According to the federal government's energy scenarios, the area used for the production of biomass can amount to approx. 4 million hectares by 2050 (2011: 1.8 million hectares) without competing with food production . That is only 24% of the land used for agriculture today . From this, a primary energy potential of 740 PJ (18.5 MJ / kg at 10 t / ha) is calculated.
Using the example of the yield values of Miscanthus (18.5 MJ / kg at up to 20 t / ha) , a primary energy potential of 1480 PJ / year is calculated . The value can fluctuate greatly depending on the assumed parameters.
However, the production of hydrogen from biomass, in addition to its direct energetic use, also competes with biomass liquefaction . As an energy carrier, the fuels obtained in this way have a higher energy density than hydrogen and are easier to handle.
Potential of biogenic residues
Biogenic residues from agriculture, landscape conservation wood , forest residues and unpolluted industrial residues can also be used to produce hydrogen. The Federal Environment Ministry estimates the potential of biogenic residues at 900 PJ.
Storage and distribution of hydrogen
In a fully developed infrastructure with corresponding purchase quantities, distribution via pipelines could be significantly more energy-efficient and cost-effective. A large part of the existing natural gas network could be used for this purpose. The natural gas network is suitable for the absorption of hydrogen. Before the switch to natural gas, the German gas networks were operated with town gas , which consisted of 51% hydrogen. Energy is transported over a gas network with significantly fewer losses (<0.1%) than with an electricity network (8%). In the case of pure hydrogen, there is in principle the problem of hydrogen embrittlement , because hydrogen in atomic form can easily migrate into the crystal structure of most metals and there are therefore increased demands on impermeability. The storage capacity of the German natural gas network is more than 200,000 GWh and can temporarily store the energy required for several months. For comparison: the capacity of all German pumped storage power plants is only 40 GWh. The Ministry for the Environment, Nature Conservation and Transport of the State of Baden-Württemberg intends to support the expansion of a hydrogen infrastructure in the future (as of 2011). There is also practical experience with hydrogen pipes:
- A more than 240 km long hydrogen network has been operated in the Ruhr area for decades .
- In Saxony-Anhalt there is a 90 km long, well-developed hydrogen pipeline system operated by Linde-Gas AG in a region with strong industrial gas demand between Rodleben - Bitterfeld - Leuna - Zeitz .
- In 2010 there were more than a thousand kilometers of hydrogen pipelines worldwide. Air Liquide operates 12 pipeline networks with a total length of 1200 km.
There are still problems with long-term storage. Some of the hydrogen evaporates from the cryotank if continuous consumption is not ensured. For example, in the BMW Hydrogen 7 with a liquid hydrogen tank, outgassing began after 17 hours of idle time; after nine days, a half-full tank had evaporated.
Energetic use of hydrogen
The most important element in the use of hydrogen is the fuel cell . It converts the energy contained in hydrogen into heat and electricity.
Use in the house
In the case of domestic electricity generation using fuel cells, as in the case of combined heat and power plant technology, a combined heat and power system can also be implemented, which increases the overall efficiency. Since the focus is on heat production in this mode of operation , these systems are controlled according to the heat demand, with the excess electricity generated being fed into the public power grid.
The theoretically achievable calorific value-related efficiency is approx. 83%. If the efficiency is related to the calorific value , as is customary with thermal power plants and combustion engines, the theoretical maximum efficiency is approx. 98%. The specified system efficiencies are between 40% and 65% depending on the type of fuel cell, although it is unclear whether these are related to calorific value or calorific value.
Use in traffic
A hydrogen powered vehicle has i. A. a pressure tank (e.g. 700 bar) that can be refueled at a hydrogen filling station. In May 2000, BMW presented the first series of 15 hydrogen cars with the type designation 750hL in Berlin . As methods of power generation, either a largely conventional internal combustion engine, similar to driving with natural gas, or a “cold combustion” in a fuel cell is possible. In the fuel cell vehicle, the fuel cell generates electricity that drives an electric motor.
Internal combustion engine
As a combustible gas, hydrogen can be burned in an internal combustion engine (" hydrogen combustion engine "), similar to natural gas-powered vehicles. One example of this application was the BMW Hydrogen 7 . BMW Development Board Member Klaus Draeger announced at the end of 2009 that there would be no new hydrogen test fleet for the time being.
In the fuel cell vehicle , the fuel cell generates electricity that drives an electric motor.
Hydrogen technology is also being tested in buses. The hydrogen buses from 2009 achieved a range of around 250 km with 35 kg of hydrogen. There are now some buses, e.g. B. the Mercedes-Benz Citaro FuelCELL-Hybrid , which work with fuel cells.
Fuel cell cars are much more expensive than electric cars. According to Fritz Henderson ( CEO of General Motors ), such a vehicle will cost around $ 400,000 (as of 2009). The vehicle manufacturers Toyota , Nissan , Mercedes-Benz and Honda have now drastically reduced the production costs for hydrogen-powered vehicles. (The Toyota Mirai, for example, can be bought in Germany for just under € 80,000.) Toyota produces H 2 cars in small series and relies on fuel cells on a large scale.
With the Mercedes B-Class F-Cell and two pre-production vehicles of the Hyundai ix35 Fuel Cell Electric Vehicle (FCEV), ranges of 500 km at maximum speeds of 80 km / h were achieved. In order to demonstrate the suitability for everyday use of the hydrogen drive, Daimler successfully completed a "world tour" with several B-class fuel cell vehicles. 200 series vehicles of this type were delivered to customers in 2010.
With the technology of the Hydrail since 2005, rail vehicles have also come into focus. The Japanese East Railroad Company was one of the first companies to put a hybrid locomotive into operation for test purposes. At the end of 2017, 14 trains with fuel cell drives were ordered from the manufacturer Alstom in Lower Saxony.
The Swiss Federal Railways SBB leads since spring 2014 in its rolling minibars hydrogen-powered fuel cells to get enough energy supply for the built-in espresso machine to have on the road, which is now on the road and the passengers cappuccino can provide. The usual accumulators used up to now would have been too heavy for this energy-consuming task.
Energy chain efficiency
Definition of terms
A distinction must be made between cost efficiency as a measure of the return on money taking into account the costs involved . The more cost-efficient a technology, the higher its profitability . The energy efficiency is a measure of the energy yield in consideration of the energy used. The more energy efficient a technology, the higher its efficiency . The ecological efficiency is a measure of sustainability and environmental compatibility. It is often calculated on the basis of the CO 2 emissions from combustion, for example if fossil fuels are used in production.
Cost efficiency does not necessarily go hand in hand with energy efficiency and ecological efficiency. So has z. For example, a coal-fired power plant with an efficiency of 30–40% has poor energy efficiency when generating electricity, but can be very cost-effective and therefore economical with a low coal price.
Example: The well to tank conversion chain without a pipeline network:
- Electricity from wind power → Electricity transport → Hydrogen from steam reforming → Hydrogen liquefaction → Transport in a tanker → transferring / storing at the filling station
is not particularly energy efficient in terms of technical efficiency. 1 kg of hydrogen cost only 9.50 euros in 2018. This is the hydrogen price that the customer has to pay at the filling station, i.e. including the investments for the construction and operation of the hydrogen filling station , but without taking into account the state subsidies and the higher costs for purchasing the vehicle.
Mineral oil and hydrogen are taxed differently in Germany: No mineral oil or energy tax is levied on hydrogen .
|Vehicle with ...|
|... fuel cell||... traction battery||... gasoline engine|
fuel cell vehicle
|Mercedes-B-Class Electric Drive
with traction battery
with gasoline engine
|Consumption per 100 km||0.97 kg||16 kWh||7 l|
|Fuel price||€ 9.50 / kg||0.30 € / kWh||1.45 € / l (premium gasoline)|
|Cost for 100 km||€ 9.21||4.80 €||€ 10.15|
This means that in terms of fuel consumption, the fuel cell vehicle is more economical in operation than the vehicle with a gasoline engine, despite moderate energy efficiency, but less economical than the direct electric drive with a traction battery .
According to the Hart report , the useful energy costs when using untaxed hydrogen conventionally generated by steam reforming are quite competitive in relation to gasoline. The expected taxation would be offset by rising gasoline prices. The study cited assumes constant prices for hydrogen production.
Efficiency in a hydrogen economy
The assessments of the efficiencies in the sources are sometimes very different because many processes are still under development and their practical production experience is lacking. There is currently no large-scale application, so that the efficiency data for hydrogen production in particular have so far mostly been based on calculations using fossil fuels.
The values assumed for the degrees of efficiency were averaged from the fluctuation range and can in reality deviate upwards or downwards. The calculated overall efficiency can therefore only be approximate values.
|Data from various sources|
|Hydrogen thermochemically from biomass||0.75||The efficiency of the thermochemical production of hydrogen from biomass is given between 69% and 78% depending on the process.|
|Hydrogen from electrolysis||0.80||The efficiency of water electrolysis is given as 70 to 90%. The generation of electrical energy also has an efficiency <100%, which further reduces the overall efficiency with regard to fossil or nuclear primary energy sources as well as biomass. With the internationally dominant efficiency method, this applies to all energy sources to which a calorific value can be assigned. In contrast, in the case of renewable energies to which no calorific value can be assigned (e.g. wind energy or hydropower), an efficiency of 100% is applied in balances, so that here final energy is equal to primary energy.|
|Hydrogen transport in the gas network||0.99||<0.01% losses in the gas network.|
|Electricity and heat from fuel cell heating||0.85||85% efficiency based on the calorific value with reformer. In the case of heating systems , the efficiency can also be related to the calorific value of the fuel used, which can result in efficiencies over 100% because the heat of vaporization recovered is not included in the calorific value.|
|Electric fuel cell||0.60||The electrical efficiency of fuel cells is given between 35% and 90% . The electrical efficiency of a PEM fuel cell is 60%.|
|Lithium-ion battery||0.94||Lithium-ion batteries have an efficiency of 90–98% .|
|Electric motor||0.95||The efficiency of electric motors is given between 94% and 97% . Traction motors are generally very efficient.|
|Hydrogen compression to 700 bar||0.88||The losses during compression are approx. 12% .|
In a hydrogen economy, this results in the energy chain
- Hydrogen from biomass → transport in the gas network → electricity and heat from fuel cell heating
an efficiency of 0.75 × 0.99 × 0.95 = 0.70 .
The energy chain arises for fuel cell vehicles
- Hydrogen from biomass → Transport in the gas network → Compression to 700 bar → Electric fuel cell → Electric motor
with an efficiency of 0.75 × 0.99 × 0.88 × 0.6 × 0.95 = 0.37
For comparison: degrees of efficiency in the fossil energy industry
|Art||Assumed efficiency||Data from various sources|
|Hydrogen from natural gas reform||0.75||Practical values for large-scale reformation and processing|
|Electricity from coal power plants||0.38||38% efficiency on average for German coal-fired power plants. In 2010, the share of hard coal and lignite power plants in German electricity generation was 43% , by 2019 it had fallen to 29.1%, and a little more than 20% is expected for 2020.|
|Power transmission||0.92||8% losses in the power grid|
|Transport and processing of motor gasoline||0.85||The production and provision of fossil fuels such as gasoline and diesel from crude oil takes place with efficiencies of up to 85%.|
|Gasoline engine||0.24||Otto engines have an efficiency of 10–37%|
For electricity from a coal-fired power station, the energy chain results
- Coal-fired power station → electricity transport an efficiency of 0.38 × 0.92 = 0.35 .
For a fuel cell vehicle with fossil hydrogen production by electrolysis, the energy chain is
- Coal-fired power station → electricity transport → electrolysis → compression → BSZ → electric motor an efficiency of 0.38 × 0.92 × 0.8 × 0.88 × 0.6 × 0.95 = 0.14 .
For a fuel cell vehicle with fossil hydrogen production through natural gas reform (currently standard), the result is the energy chain
- Steam reforming → compression → BSZ → battery → electric motor an efficiency of 0.75 × 0.88 × 0.6 × 0.94 × 0.95 = 0.35 .
For a battery-powered electric vehicle charged with pure coal electricity, the result is the energy chain
- Coal-fired power station → power transmission → battery → electric motor an efficiency of 0.38 × 0.92 × 0.94 × 0.95 = 0.31 .
The real electricity mix in Germany increases efficiency depending on the share of electricity producers.
For a vehicle with a gasoline engine, the result is with the energy chain
- Transport and processing of motor gasoline → Otto engine an efficiency of 0.85 × 0.24 = 0.20 .
The comparison shows that the overall efficiency of a hydrogen economy can be higher than that of the established fossil energy economy.
For comparison: efficiency levels in electric vehicles
When charging with green electricity from own generation, the following results:
For battery-powered electric vehicles with the energy chain
- Photovoltaic system / inverter → stationary battery → battery in the vehicle → electric motor
an efficiency of 0.9 × 0.94 × 0.94 × 0.95 = 0.75 .
For electric vehicles with fuel cells with the energy chain
- Photovoltaic system / inverter → stationary battery → electrolysis → compression to 700 bar → fuel cell → electric motor
an efficiency of 0.9 × 0.94 × 0.8 × 0.88 × 0.6 × 0.95 = 0.34 .
This does not take into account the fact that in-house production of hydrogen using photovoltaic direct current on site and maximum compression / refueling for private use, in contrast to private use of electricity, is technically non-existent. In the case of the transport of regenerative electricity via the alternating current network and the necessary transport of the hydrogen to the filling stations and its storage (mostly as liquid hydrogen ), the efficiency of the entire chain for fuel cell vehicles is given as 20 to 25%.
The comparison shows that battery-powered vehicles are more efficient. If there is an additional need for heating / cooling, energy is required for heating / cooling generation. This can reduce the range by up to 50% depending on the battery weight and temperature. Like vehicles with combustion engines, fuel cell vehicles also have significantly higher consumption in winter. However, due to the higher amount of energy carried, this additional consumption does not have as significant an impact on the range as with an electric car.
Environmental and climate protection
The use of renewable energies is often climate-neutral and emission-free. However, when using biomass and burning wood, pollutants can arise. In addition, air pollutants can also arise during gasification to hydrogen or the use of hydrogen, for example nitrogen oxides in the case of lean combustion. The expenditure for cultivation, extraction and processing of the biomass must be taken into account in an ecological consideration , as well as the efficiency of the plant based on the (theoretical) maximum efficiency of the respective process. The use of biomass can also reduce the greenhouse effect: If CO 2 is produced in concentrated form during the production of hydrogen , this can be stored underground and thus withdrawn from the ecosystem.
The incorporation of bio-coke into the field, which is created when the gasification is controlled accordingly, can make the field more fertile and is known as terra preta .
In 2003 scientists at the California Institute of Technology in Pasadena feared, based on simulations, that a comprehensive hydrogen economy could release around 100 million tons of hydrogen into the atmosphere and thus damage the ozone layer .
According to more recent scientific studies by Forschungszentrum Jülich in 2010, this effect will be negligible if realistic assumptions are made. The positive effect of not using fossil fuels predominates. Originally it was assumed that approx. 20% of the hydrogen escapes into the atmosphere. However, due to technological developments, it is now assumed that less than 2% escape. In addition, hydrogen only develops its full ozone-damaging effect in the presence of CFCs . With the decline in CFCs over the next few years, the rebuilding of the ozone layer will predominate.
Accident risk in a hydrogen economy
Is hydrogen, such as B. gasoline or natural gas, extremely flammable . In technical systems, the specific properties of hydrogen must be taken into account. The chemical industry has been using hydrogen in large quantities for over a hundred years, so that there is sufficient experience in handling hydrogen.
Due to its low density, hydrogen is a very volatile gas. In the open air it can evaporate very quickly into higher air layers. However, real accidents are also known in which inflammable hydrogen mixtures accumulated on the ground, because oxygen / hydrogen mixtures with a proportion of less than 10.5 percent by volume of hydrogen are heavier than air and sink to the ground. The segregation does not take place immediately, so that the ignitability is maintained until the 4 volume percent limit is undershot. When handling hydrogen, safety regulations and ventilation systems must take this behavior into account.
The pressure tanks used today (in contrast to petrol tanks) can withstand serious accidents without damage. Hydrogen vehicles with pressure tanks can easily be parked in multi-storey car parks and underground garages. There is no legal provision that restricts this.
In contrast, vehicles with liquid hydrogen must not be parked in closed rooms, as the outgassing can cause explosive gas accumulations.
A hydrogen economy has not yet been realized on a large scale anywhere and its feasibility is controversial. The following statements are questioned: The hydrogen economy is presented as an alternative to the electricity industry. Proponents of a hydrogen economy emphasize the alleged better storage capacity of hydrogen than that of electricity. Hydrogen has the property of good short-term storage in the form of tolerable pressure fluctuations in a pipeline distribution network (the pipeline itself is the storage), as well as long-term storage capacity in caverns (as is currently the case with natural gas). The required electrical energy can be generated from hydrogen on site with the help of fuel cells with an efficiency that is significantly higher than that of German power plants: However, the sources cited for the energy efficiency of fuel cells only consider the conversion of natural gas or hydrogen into electricity, but do not take into account the energy losses generated during the production, storage and distribution of the required hydrogen. The low volume-related energy content is also rarely taken into account: "A 40-ton truck can only transport 350 kilograms of gaseous hydrogen," says Bossel, "and liquid hydrogen is also as light as Styrofoam."
- Jeremy Rifkin : The H2 Revolution. Frankfurt am Main 2005, ISBN 3-596-16029-4 .
- Joseph J. Romm: The hydrogen boom. Desire and reality in the race for climate protection (original title: The Hype About Hydrogen , translated by Jörg G. Moser). Wiley-VCH, Weinheim 2006, ISBN 3-527-31570-5 .
- Alf-Sibrand Rühle: Hydrogen and Economy. Invest in a clean future. Hydrogeit Verlag, Kremmen 2005, ISBN 3-937863-02-8 .
- Nicola Armaroli , Vincenzo Balzani : The Future of Energy Supply: Challenges and Opportunities. In: Angewandte Chemie International Edition . 46, 2007, 52-66, p. 61, doi: 10.1002 / anie.200602373 .
- Jules Verne: The Mysterious Island. 1875. (1999, ISBN 3-401-00260-0 )
- John Burdon Sanderson Haldane: Daedalus or Science and Future. Drei Masken Verlag, Munich 1925.
- History of Hydrogen (Source: New York State Energy Research and Development Authority, accessed August 4, 2011)
- Joseph J. Romm: The hydrogen boom. 1st edition. Wiley-VCH Verlag, 2006, ISBN 3-527-31570-5 .
- John OM Bockris, Eduard W. Justi: Hydrogen. Energy for all time. Concept of a solar-hydrogen economy. Augustus Verlag, 1990, ISBN 3-8043-2591-2 .
- The Hydrogen Guide: History (Source: Hydrogeit)
- ( Page no longer available , search in web archives: Iceland on course for hydrogen. ) (Source: German Hydrogen Association as of October 21, 1999; PDF; 32 kB)
- Jeremy Rifkin: The H2 Revolution . Campus Verlag, Frankfurt am Main 2002, ISBN 3-593-37097-2 .
- Oil crisis is changing globalization (source: Die Zeit, as of June 3, 2008)
- Ulf Bossel: The Future of the Hydrogen Economy: Bright or Bleak? (PDF; 246 kB). April 15, 2003, accessed September 11, 2013.
- Goodbye Hydrogen, Section: Visions for Politics. on: heise.de , May 24, 2007, accessed September 11, 2013.
- Written declaration on the hydrogen economy from February 12, 2007 (source: European Parliament)
- storage: Hamburg wants to build a large hydrogen plant in the port . ISSN 0174-4909 ( faz.net [accessed September 5, 2019]).
- Hydrogeit production of hydrogen (source: Hydrogeit Verlag)
- Volker Quaschning : Regenerative Energy Systems. Technology - calculation - simulation. 8th, updated edition. Munich 2013, p. 49.
- Sarah Becker et al .: Features of a fully renewable US electricity system: Optimized mixes of wind and solar PV and transmission grid extensions. In: Energy . 72, 2014, pp. 443-458, p. 443, doi: 10.1016 / j.energy.2014.05.067 .
- Mark Z. Jacobson , Mark A. Delucchi, Providing all global energy with wind, water, and solar power, Part I: Technologies, energy resources, quantities and areas of infrastructure, and materials. In: Energy Policy . 39, 2011, pp. 1154–1169, doi: 10.1016 / j.enpol.2010.11.040 .
- Volker Quaschning: Regenerative Energy Systems. Technology - calculation - simulation. 8th, updated edition. Munich 2013, p. 373.
- Energy-economical and ecological evaluation of a wind gas offer. ( Memento from December 24, 2014 in the Internet Archive ), p. 18. Fraunhofer IWES . Retrieved November 14, 2014.
- Dan Gao, Dongfang Jiang, Pei Liu, Zheng Li, Sangao Hu, Hong Xu: An integrated energy storage system based on hydrogen storage: Process configuration and case studies with wind power. In: Energy . 66, 2014, pp. 332–341 doi: 10.1016 / j.energy.2014.01.095 .
- Hydrogen hybrid power plant (source: Enertrag as of January 18, 2011; PDF; 37 kB)
- Interview with Enertrag board member Werner Diwald (status: May 12, 2011 source: Autogazette)
- With wind gas into the nuclear phase-out (source: press portal as of March 17, 2011)
- Audi gives Co2 a chance (source: Heise as of May 18, 2011)
- A car manufacturer as an eco-activist (Source: Der Spiegel. As of May 13, 2011)
- Solar hydrogen (source: Research Association for Renewable Energies Status: 2002; PDF; 289 kB)
- Fraunhofer CBP press release: Green hydrogen. Fraunhofer Center for Chemical-Biotechnological Processes CBP, October 21, 2016, accessed on January 29, 2018 .
- PDF website of the Federal Ministry of Economics. Retrieved July 8, 2015.
- Result of the federal government's energy scenarios (source: Informationsdienst Wissenschaft IDW as of April 28, 2011)
- Ulf Bossel: Hydrogen does not solve any energy problems. In: Technology Assessment - Theory and Practice. April 2006, accessed September 24, 2014.
- Pipeline Technology. (PDF; 1.2 MB). In: Biohydrogenmagazin. 18th edition, p. 33.
- Adding hydrogen to the natural gas network (source: German Gas and Water Association as of October 2010; PDF; 180 kB)
- Natural gas pipelines as storage for wind energy (source: Heise as of April 18, 2011)
- hydrogen transport (source: H2 Works)
- Stuart Island Energy Initiative. Retrieved April 19, 2019 .
- green electricity as natural gas (source: Fraunhofer Institute, as of April 26, 2010)
- A hydrogen infrastructure is to be built in the country for future-proof energy use and sustainable mobility. ( Memento from January 23, 2011 in the Internet Archive ) (Source: Ministry for the Environment, Climate Protection and Energy, Baden-Württemberg as of January 19, 2011)
- Germany on the way to the hydrogen economy. ( Memento from September 23, 2015 in the Internet Archive )
- Hydrogen via the pipeline from the industrial site Leuna ( Memento from January 10, 2014 in the Internet Archive )
- Hydrogen - the new energy carrier. ( Memento from October 25, 2007 in the Internet Archive ) German Hydrogen and Fuel Cell Association e. V. Internet: dwv-info.de
- Michael Bertram: Industry: Fraunhofer-Gesellschaft invests six million euros in Leuna . In: Mitteldeutsche Zeitung . November 18, 2015 ( mz-web.de [accessed January 29, 2018]).
- Transport of hydrogen (source: TÜV Süd)
- Hydrogen as an energy carrier. ( Memento of February 5, 2009 in the Internet Archive ) (Source: Air Liquide)
- On the way in the hydrogen 7 Series , in: heise online, November 22, 2006, accessed on February 8, 2012.
- Fuel cell- data and facts. ( Memento of February 28, 2013 in the Internet Archive ) (Source: Vaillant Group; PDF; 83 kB)
- Richard Herbrik: Energy and heat technology. 2nd Edition. BG Teubner Stuttgart 1993, chapter 4.1.
- Functional principle of fuel cells (source: Network Fuel Cell and Hydrogen NRW)
- Knowledge of fuel cells (source: Hydrogeit Verlag)
- CleanEnergy World Tour 2001 final in Berlin. BMW Group, November 8, 2001, accessed April 19, 2019 (press release).
- Markus Fasse: Car manufacturer: BMW is losing faith in hydrogen propulsion. Handelsblatt , December 7, 2009, accessed on April 19, 2019 .
- scale test in Hamburg - new fuel cell bus from Mercedes uses 50% less hydrogen. ( Memento of December 13, 2010 in the Internet Archive ) In: ATZ Online. November 19, 2009, inserted February 15, 2012.
- GM CEO: electric cars require teamwork; hydrogen cars 10x more expensive than Volt ( Memento from January 1, 2010 in the Internet Archive ) October 30, 2009 (Source: Washington Post)
- Michael Specht: Fuel cells as a drive: Why Toyota is switching to hydrogen . In: Spiegel Online . November 19, 2017 ( spiegel.de [accessed November 19, 2017]).
- J. Wilms: Hydrogen cars on world record drive . In: The time. April 26, 2012.
- Mercedes B-Class F-Cell on a world tour (source: Heise as of January 31, 2011)
- future of railways: hydrail.org
- Development of the World's First Fuel Cell Hybrid Railcar . (April 11, 2006) East Japan Railway Company. Retrieved June 18, 2013.
- Minister Lies: The future begins in Lower Saxony. (No longer available online.) Archived from the original on November 10, 2017 ; accessed on November 10, 2017 .
- Andreas Wilkens: Fuel cell trains should replace diesel locomotives in Lower Saxony. Heise online, November 10, 2017, accessed on November 10, 2017 .
- Benedikt Vogel: SBB Minibar: Thanks to fuel cells, now also cappuccino. ( Memento of May 8, 2014 in the Internet Archive ) on behalf of the Swiss Federal Office of Energy, SFOE, accessed on May 8, 2014.
- Federal government and industry set up a network of 50 hydrogen filling stations. ( Memento from December 2, 2013 in the Internet Archive ) (Source: Federal Ministry of Transport, Building and Urban Development, as of June 20, 2012)
- watt gehtab.com, March 21, 2011: Mercedes-Benz is building series production for fuel cells. ( Memento from September 12, 2013 in the Internet Archive )
- caranddriver.com, March 2013: 2014 Mercedes-Benz B-class Electric Drive , accessed September 11, 2013.
- The Economics of a European Hydrogen Infrastructure for Automotive ( Memento from January 25, 2012 in the Internet Archive ) (Source: International Hydrogen Day Status: February 24, 2005; PDF; 149 kB)
- Hydrogen production from biomass (Section II. Efficiency) (Source: H2 Works)
- Hydrogen high-performance electrolyser (source: Hydrogeit Verlag)
- Viktor Wesselak , Thomas Schabbach , Thomas Link, Joachim Fischer, Handbuch Regenerative Energietechnik , Berlin / Heidelberg 2017, p. 6.
- Test drive in the Toyota FCHV adv (source: Heise, as of July 29, 2011)
- Efficiency... of various energy chains. ( Memento from November 1, 2012 in the Internet Archive ) (Source: Hydrogen Center Austria, status: 2009; PDF; 178 kB)
- Range of electric cars drops drastically in winter (source: Heise.de as of December 14, 2011)
- Hydrogen as an ozone killer? (Source: Umweltdialog.de Mediengruppe macondo as of September 30, 2003)
- Hydrogen is not a threat to the ozone layer (source: Energie Agentur NRW as of February 25, 2010)
- German Hydrogen and Fuel Cell Association: Hydrogen - the new energy carrier. ( Memento from January 31, 2012 in the Internet Archive ) (PDF; 153 kB), as of March 22, 2004.
- Media forum German Hydrogen Day, Axel Stepken: Hydrogen - As safe as gasoline (PDF; 704 kB).
- ( Page no longer available , search in web archives: Dr. Henry Portz, fire experts determine the mysterious cause of the fire. ) ZDF Adventure Knowledge from July 11, 2007, inserted on February 9, 2012.
- Spectacular test shows: Hydrogen in the car doesn't have to be more dangerous than gasoline. ( Memento from May 29, 2012 in the Internet Archive )
- Safetywhen using hydrogen. ( Memento from March 6, 2012 in the Internet Archive )
- Video: University of Miami crash test
- The myth of hydrogen. In: time online. October 7, 2004.
- Ulf Bossel: Hydrogen does not solve any energy problems. In: Technology Assessment - Theory and Practice. 15th year, No. 1, April 2006. ( tatup-journal.de , PDF)
- Fa Gennex: Fuel cell module for highly efficient power generation ( Memento from July 10, 2015 in the Internet Archive ) (Source: Ceramic Fuel Cells GmbH Status: April 2010; PDF; 362 kB)
- ( Page no longer available , search in web archives: Fuel Cell Power Modules from HYDROGENICS ) (Source: Hydrogenics GmbH as of 2009; PDF; 2.3 MB)
- Energy efficiency in power generation. ( Memento from September 15, 2012 in the web archive archive.today ) (Source: Federal Environment Agency as of July 2009)
- Technology Assessment, Theory and Practice, No. 1, Volume 15 - April 2006, pp. 27–33: Hydrogen does not solve energy problems , accessed August 14, 2012.
- heise.de, May 24, 2007: Goodbye hydrogen, section: Storage destroys energy , accessed September 11, 2013.