Can Hydrogen Fulfill its Potential?

Over the last decade there has been a general craze for hydrogen, a future energy vector. While its many advantages make it capable of meeting the planet's energy challenges, there are many technological and economic challenges that must be overcome before a real hydrogen revolution can happen.

CUTE project  (2006/2009) - hydrogen-powered buses in Europe

Future Opportunities...

Hydrogen is not an energy in and of itself, but an energy vector, like the electrons in electricity. It provides energy when it is part of a chemical reaction, for example in a fuel cell or during combustion.

Its use as an energy vector presents a number of advantages:

   • Diverse primary energy sources can be used to obtain hydrogen, including fossil fuels (natural gas, etc.), biomass (wood, etc.) and water.

   • Less environmental impact - Producing hydrogen through electrolysis, for example, does not cause any greenhouse gas emissions. 

Hydrogen technology is not yet at the stage where it can be used in large-scale applications.

However, hydrogen technology is not yet at the stage where it can be used in large-scale applications. Fifty years after the first tests were carried out on hydrogen vehicle engines, we are still testing and building prototypes.

Hydrogen-powered buses are being tested all over the world.

True. Launched in 2001, the Cute project (Clean Urban Transport for Europe) is extending the use of hydrogen-powered buses in public transport systems all over the world. These buses are being currently used in 10 cities in Europe (Amsterdam, Barcelona, Hamburg, London, Luxembourg, Madrid, and Reykjavik) and wider afield - Beijing in China and Perth in Australia, with a total of 47 buses in circulation. These buses have dedicated service stations - see http://www.global-hydrogen-bus-platform.com/

... Obstacles to Overcome

Hydrogen is used in the chemical industry, in particular in refineries and to produce fertilizer. In this case, hydrogen is mainly produced through steam reforming¹ (where molecules are separated under the effect of steam). This process requires natural gas.

Aside from the chemical industry, hydrogen's primary uses in the future are likely to include the following:
 
   • Residential or industrial cogeneration (electricity and heat production)

   • Electricity generation for portable electrical devices

and

   • Vehicle propulsion.

The obstacles that hydrogen applications have yet to overcome are as follows:

   • Storage^2-3-4: It is difficult to store large quantities of hydrogen in small volumes because of its density. 5-7kg of hydrogen is enough to power a vehicle for about 500km, but at ambient temperatures the volume of 1kg is 12m³! Possible solutions involve compressing it, liquefying it or storing it as metal crystals^5-6 (e.g. nickel can absorb and restore hydrogen). Hydrogen is stored at over 600 bars in some vehicle prototypes. Solutions still need to be developed to manufacture light, safe tanks that can both maintain pressure and retain hydrogen.

   • Producing large quantities of hydrogen is energy-intensive: Non-polluting energies need to be used so as not to cancel out the positive effect of using it. Thus, it has been calculated that replacing oil with hydrogen in the US road transportation industry would require the construction of almost 800 production plants⁷. However, biomass technology (wood energy, plant energy, etc.) is not sufficiently developed to meet the level of demand production on this scale would require. Therefore, natural gas, a fossil fuel, would have to be used.

   • Hydrogen's tiny molecules can penetrate and weaken materials. Its use in industrial applications therefore requires the use of special materials that are rare and costly- such as platinum, which is used in some fuel cells.

   • Cost: It currently costs 1000 euros to produce one kW for one fuel cell. This price needs to be brought down to 50 euros per kW to compete with the internal combustion engine in cars⁸.

   • Life span: For a fuel cell to be profitable, it must have a longer life span than the current few thousand hours.

Hydrogen fuel cells are very energy efficient.

True. Energy efficiency is the rate of energy produced in proportion to the energy required for production. For example, 15% for photovoltaics (converting light into electricity), 33% for nuclear energy (converting the fuel's energy into electricity), and 60% for wind energy (converting mechanical energy into electricity). It is about 50% for hydrogen fuel cells^9-10-11.

In 2009, Japanese companies developed a 3kW fuel cell that produces electricity using oxygen from the air and hydrogen from gas mains. This fuel cell registered efficiency of 56% for several thousand hours, peaking at 59%¹².

This fuel cell model is expected to be developed for uses in supermarkets and restaurants by 2011-2012. Before this can happen, the fuel cell's resistance must be increased to several tens of thousands of hours to meet user requirements.

[1] http://www.unige.ch/cuepe/html/biblio/pdf/ActesJcuepe2005.pdf p.27
[2] http://www.senat.fr/rap/r05-426/r05-426_mono.html#toc603
[3] http://www.cea.fr/content/download/2816/12618/file/pac.pdf p.9
[4] http://www.enpc.fr/fr/formations/ecole_virt/trav-eleves/cc/cc0304/hydrogene/H2.htm
[5] http://www.unige.ch/cuepe/html/biblio/pdf/ActesJcuepe2005.pdf p.39
[6] http://a-o-p.net/energiachallenge/wp-content/uploads/2009/10/Energiachallenge2009SchottFlorian.pdf p.8
[7] http://www.senat.fr/rap/r05-426/r05-426_mono.html#toc603
[8] http://www.afh2.org/uploads/memento/Fiche%205.2.1%20PAC%20rev.%20avril%202008.pdf
[9] http://www.afh2.org/uploads/memento/pdf/fiche_3_2_1.pdf p.4
[10] http://www.unige.ch/cuepe/html/biblio/pdf/ActesJcuepe2005.pdf p.29 p.3
[11] http://www.cea.fr/content/download/3112/14773/file/061a063pehr.pdf p.4
[12] http://www.bulletins-electroniques.com/actualites/59106.htm