Clean Tech 101

Hydrogen Energy - The Perfect Energy Source for the Future?

What is Hydrogen?
Hydrogen as an Energy Carrier
How is Hydrogen Produced?
Uses of Hydrogen
Hydrogen Fuel Cell
The Future of Hydrogen


Hydrogen can be considered as a clean energy carrier similar to electricity. Hydrogen can be produced from various domestic resources such as renewable energy and nuclear energy. In the long-term, hydrogen will simultaneously reduce the dependence on foreign oil and the emission of greenhouse gases and other pollutants.

What is Hydrogen?

Hydrogen can be considered as the simplest element in existence. Hydrogen is also one of the most abundant elements in the earth’s crust. Hydrogen as a gas is not found naturally on Earth and must be manufactured. This is because hydrogen gas is lighter than air and rises into the atmosphere as a result. Natural hydrogen is always associated with other elements in compound form such as water, coal and petroleum.

Hydrogen has the highest energy content of any common fuel by weight. On the other hand, hydrogen has the lowest energy content by volume. It is the lightest element, and it is a gas at normal temperature and pressure.

Hydrogen as an Energy Carrier

Hydrogen is considered as a secondary source of energy, commonly referred to as an energy carrier. Energy carriers are used to move, store and deliver energy in a form that can be easily used. Electricity is the most well-known example of an energy carrier.

Hydrogen as an important energy carrier in the future has a number of advantages. For example, a large volume of hydrogen can be easily stored in a number of different ways. Hydrogen is also considered as a high efficiency, low polluting fuel that can be used for transportation, heating, and power generation in places where it is difficult to use electricity. In some instances, it is cheaper to ship hydrogen by pipeline than sending electricity over long distances by wire.

How is Hydrogen Produced?

Since hydrogen does not exist on Earth as a gas, it must be separated from other compounds. Two of the most common methods used for the production of hydrogen are electrolysis or water splitting and steam reforming.

Steam reforming is currently the least expensive method for producing hydrogen. It is used in industries to separate hydrogen atoms from carbon atoms in methane. Because methane is a fossil fuel, the process of steam reforming results in greenhouse gas emissions which is linked to global warming.

The other method for the production of hydrogen is electrolysis. Electrolysis involves passing an electric current through water to separate water into its basic elements, hydrogen and oxygen. Hydrogen is then collected at the negatively charged cathode and oxygen at the positive anode. Hydrogen produced by electrolysis is extremely pure, and results in no emissions since electricity from renewable energy sources can be used. Unfortunately, electrolysis is currently a very expensive process.

There are also several experimental methods of producing hydrogen such as photo-electrolysis and biomass gasification. Scientists have also discovered that some algae and bacteria produce hydrogen under certain conditions, using sunlight as their energy source.

Uses of Hydrogen

Currently, hydrogen is mainly used as a fuel in the NASA space program. Liquid hydrogen is used to propel space shuttle and other rockets, while hydrogen fuel cells power the electrical systems of the shuttle. The hydrogen fuel cell is also used to produce pure water for the shuttle crew.

Hydrogen Fuel Cell

Fuel cells directly convert the chemical energy in hydrogen to electricity, with pure water and heat as the only byproducts. Hydrogen-powered fuel cells are not only pollution-free, but a two to three fold increase in the efficiency can be experienced when compared to traditional combustion technologies.

Figure 1. Hydrogen Fuel Cell (Image source U.S. Dept. of Energy)

Fuel cells can power almost any portable devices that normally use batteries. Fuel cells can also power transportation such as vehicles, trucks, buses, and marine vessels, as well as provide auxiliary power to traditional transportation technologies. Hydrogen can play a particularly important role in the future by replacing the imported petroleum we currently use in our cars and trucks.

The Future of Hydrogen

In the future, hydrogen will join electricity as an important energy carrier, since it can be made safely from renewable energy sources and is virtually non-polluting. It will also be used as a fuel for ‘zero-emissions’ vehicles, to heat homes and offices, to produce electricity, and to fuel aircraft.

Hydrogen has great potential as a way to reduce reliance on imported energy sources such as oil. Before hydrogen can play a bigger energy role and become a widely used alternative to gasoline, many new facilities and systems must be built.

Figure 2. Future hydrogen energy infrastructure. The hydrogen is produced through a wind electrolysis system. The hydrogen is compressed up to pipeline pressure, and then fed into a transmission pipeline. The pipeline transports the hydrogen to a compressed gas terminal where the hydrogen is loaded into compressed gas tube trailers. A truck delivers the tube trailers to a forecourt station where the hydrogen is further compressed, stored, and dispensed to fuel cell vehicles. (Image source U.S. Dept. of Energy)

Source: AZoCleantech
Last Update 13th January 2008


  1. Richard Kenna Richard Kenna United States says:

    I have been thinking of a system that would be of value in a rural setting that would use wind power to generate hydrogen which could be used as a fuel for internal combustion generators. I have been told that hydrogen has a potential problem in that it is prone to leaking. One article went so far as to suggest that if you had several pipes, each carrying a different product, that you should have hydrogen on top to avoid it from contaminating the product above it. That suggests a very potent leakage and penetration problem. Your article doesn't get into this problem at all. I would be most interested in any comments.

    • Ritu Aggarwal Ritu Aggarwal India says:

      This is really not a big issue with Hydrogen. With proper pipes, it can be avoided. It might have been a bad experience with a person from which you read it.

      What is more worrying is that Hydrogen is dangerous because it is highly flammable (it has a low ignition temoerature). Hydrogen is described as 'safe' here which is not the case. This is also the reason why Hydrogen run vehicles could not be used.

      • Peter Carr Peter Carr United Kingdom says:

        But they are already in use in Japan, and in Scotland, where buses in Aberdeen have been in use since 2015.

      • Richard Richard Richard Richard Canada says:

        Hydrogen is dangerous only if mixed with air. The cooling agent for big alternators is Hydrogen do to its high heat capacity.
        If you get a leak, hydrogen is so light that it goes up so fast and is not even retain by earth gravity. It is actually less dangerous than gasoline which collect under the car if there is a leak and will burn the whole car.

  2. jack jack jack jack United States says:

    You know there are other plans that just run power to gas stations and have the electrolysis happen there eliminating the need for pipelines and trucks.

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