1) Pathways for the production and utilization of hydrogen
2) Production of hydrogen
3) Storage of hydrogen
4) Delivery of hydrogen
5) Applications of hydrogen
6) Some examples
7) The challenges
8) Useful Links
Other than biofuels (such as bio-ethanol and biodiesel), it is difficult to convert renewable energy (such as solar energy, wind energy, hydro energy) into a form suitable for propelling vehicles. One possible way is to make use of renewable-source electricity to produce hydrogen gas through electrolysis of water, and to utilize the hydrogen gas so produced as vehicle fuel. In this way, the hydrogen gas functions as an energy carrier, to store up the energy derived from renewable energy, for use in transportation vehicles or other purposes.
Other than functioning as an energy carrier with high energy content per kilogram weight, hydrogen has the further advantage of being a zero-emission fuel. In contrast to fossil fuels, the conversion of hydrogen into mechanical or electrical power will not cause the emission of greenhouse gas or other atmospheric pollutants.
Hydrogen economy is an economic structure in which hydrogen is widely used as an energy carrier to help address concerns about air pollution, global warming and energy security.
Other than producing hydrogen using renewable energy, hydrogen can also be produced from feedstock including fossil fuels and chemicals. When using hydrogen produced from fossil fuels, the principal advantage is to reduce urban pollution caused by fuel combustion in vehicles. On the other hand, when using hydrogen produced from renewable energy, we can reap the dual benefits of eliminating the use of fossil fuels as well as reducing urban pollution.
As shown in the diagram below, hydrogen can be derived from various sources including fossil fuels, renewable energy sources and nuclear energy. Currently, most of the hydrogen produced in the world is from fossil sources such as steam reforming of natural gas. However, producing hydrogen from fossil sources still consumes the precious non-renewable natural resources and causes the emission of greenhouse gas and pollutants. It is only through the use of renewable energy to produce hydrogen that the whole process from production to consumption can be nearly emission-free.
|Abbreviations:||LPG - Liquified Petroleium Gas,||FTD - Fischer Tropsch Distillates,||CG - Conventional Gasoline|
|LH2 - Liquified Hydrogen Gas,||CH2 - Compressed Hydrogen Gas,||ICE - International Combustion Engine|
|FC - Fuel Cell|
The table below illustrates the status of development of various technologies for producing hydrogen, and the energy consumption, efficiency, and relative cost figures.
|Cost Relative to SMR|
|Steam methane reforming (SMR)||0.78||2-2.5||Mature||70-80||1|
|Methane / natural gas pyrolysis||R&D to mature||72 - 54||0.9|
|H2S methane reforming||1.5||-||R&D||50||<1|
|Landfill gas dry reformation||R&D||47-58||~1|
|Partial oxidation of heavy oil||0.94||4.9||mature||70||1.8|
|Steam reforming of waste oil||R&D||75||<1|
|Coal gasification (TEXACO)||1.01||8.6||mature||60||1.4-2.6|
|Partial oxidation of coal||mature||55|
|Steam- iron process||R&D||46||1.9|
|Grid electrolysis of water||3.54||4.9||R&D||27||3-10|
|Solar & PV-electrolysis of water||R&D to mature||10||> 3|
|High-temp. electrolysis of water||R&D||48||2.2|
|Thermochemical water splitting||Early R&D||35-45||6|
|Photolysis of water||Early R&D||<10|
|Photoelectrochemical decomposition of water||Early R&D|
|Photocatalytic decomposition of water||Early R&D|
Hydrogen from steam reforming of natural gas is a few times more costly than fossil fuels. PV electrolysis of water is three times more costly than steam reforming, as given in above table. The cost of hydrogen produced from renewable sources is therefore relatively high as compared to the costs of fossil fuels.
Hydrogen can be stored in liquid form or compressed gas form in cylinders, or stored in metal hydride. Stationary applications of hydrogen stored in cylinders in industrial processes are common. However, storage of hydrogen for automotive applications remains a challenge.
One of the major challenges is the ability to carry enough hydrogen on-board a vehicle to enable a sufficient driving range without adding too much weight. Storage of hydrogen under high pressure of several hundred bars inside high-strength cylinders on-board cars or buses has already been demonstrated to be technically feasible. Research and development on various other hydrogen storage technologies such as advanced high-capacity metal hydrides, carbon-based and high surface area sorbents, chemical hydrogen storage, as well as other new materials and concepts are underway.
A delivery infrastructure is required for establishing a hydrogen economy. Other than transporting hydrogen in cylinders by trucks or ships, pipelines can also be used as it is the most economical way of delivering hydrogen from the production site to end-users in large quantity. The existing delivery infrastructure for fossil fuels is not suitable for the delivery of hydrogen due to the potential embrittlement of the steel and welds by hydrogen, and the potential of leakage as hydrogen molecules are very small.
Hydrogen can be utilized in many different ways, either for stationery or for automotive applications. Hydrogen combines with oxygen to form water and generates electricity in fuel cells. Fuel cells can be used to power devices from portable computers to automobiles and buildings. Hydrogen-powered internal combustion engines and turbines also make up potentially viable, low-emission motive systems. Hydrogen-rich gas can be directly used as a fuel gas for cooking and in boilers.
Iceland's hydrogen economy
Being the first country to make effort to become free from imported fossil fuels, Iceland is trying to poineer the hydrogen economy and aiming to transform into the world's first hydrogen economy in year 2050, with electricity from hydro-electric power and geothermal power to produce hydrogen by electrolysis. Hydrogen has been used in a fleet of city buses since year 2003 and the application of hydrogen for ocean vessels is under research. Iceland aims is to have hydrogen powering all cars and buses and the fishing fleet in the future.
Clean Urban Transport for Europe (CUTE) project in Europe
CUTE is a European Union project to test fuel cell buses in nine cities in Europe during November 2001 to May 2006. The aim of the project is to demonstrate the feasibility of a public transport system using hydrogen as the fuel. Funding is granted to pilot the operation of 27 purpose-designed fuel cell powered buses in 9 European cities as well as the establishment of regional hydrogen production and refueling infrastructures.
CUTE was succeeded by HyFLEET:CUTE with more fuel cell (FC) buses and with hydrogen-fuelled internal combustion engine (ICE) buses. Cities outside Europe (Beijing and Perth) also involved. The project will examine the ecological and economical advantages and disadvantages of FC bus and hydrogen-fuelled ICE bus technologies. For more information, please visit:
This web page has hyperlinks which may transfer you to third-party website.http://www.global-hydrogen-bus-platform.com/
Above: Fuel cell bus in London (February 2006)
Components of the hydrogen economy are still under an early stage of development. Technological advances in the production, storage, delivery and utilization of hydrogen as a fuel, to bring down the costs, are crucial for the development of the hydrogen economy. In addition, public acceptance of hydrogen as a fuel also need to be addressed.
The International Partnership for the Hydrogen Economy
The International Partnership for the Hydrogen Economy was established in 2003 as an international institution to accelerate the transition to a hydrogen economy. It provides a mechanism for partner countries to organize, coordinate and implement effective, efficient, and focused international research, development, demonstration and commercial utilization activities related to hydrogen and fuel cell technologies.
Link: This web page has hyperlinks which may transfer you to third-party website.http://www.iphe.net/
Hydrogen World Council
The aim of the Hydrogen World Council is to promote hydrogen throughout the world by encouraging people to campaign for the changes necessary in their own country and learning about what is happening in other countries.
Link: This web page has hyperlinks which may transfer you to third-party website.http://www.hydrogen.co.uk/
Hydrogen Program, the US Department of Energy
The DOE Hydrogen Program works in partnership with industry, academia, national laboratories, federal and international agencies to:
- Overcome technical barriers through research and development of hydrogen production, delivery, and storage technologies, as well as fuel cell technologies for transportation, distributed stationary power, and portable power applications,
- Address safety concerns and develop model codes and standards,
- Validate and demonstrate hydrogen and fuel cell technologies in real-world conditions, and
- Educate key stakeholders whose acceptance of these technologies will determine their success in the marketplace.