Wednesday, July 9, 2008

Hydrogen production

Methods of hydrogen production:

Note: Consideration in the sense of economical competitiveness and environmental effect in relative to gasoline in order to be feasible.

1. Steam reforming of natural gas, sometimes referred to as steam methane reforming (SMR)

1.1 Most commonly used, least inexpensive, high temperature (700 – 1100 °C) and in the presence of a metal-based catalyst (nickel)

1.2 steam reacts with methane to yield carbon monoxide and hydrogen
CH4 + H2O → CO + 3 H2

1.3 Additional hydrogen can be recovered by a lower-temperature gas-shift reaction with the carbon monoxide produced.
CO + H2O → CO2 + H2

1.4 Efficiency of 70%. Require CCS (Carbon Capure and Storage or Sequestration)


2. Electrolisis of water

2.1 Electrolisis is splitting water molecules into hydrogen and oxygen using electricity from energy sources such as nuclear and renewable energy like hydropower and wind turbine.

2.2 Considering a power plant that converts the heat of nuclear reactions into hydrogen via electrolysis, the total efficiency may be closer to 30–45% for converting electrical energy into hydrogen's chemical energy.

2.3 Now researchers at GE say they've come up with a prototype version of an easy-to-manufacture apparatus (electolizer) that they believe could lead to a commercial machine able to produce hydrogen via electrolysis for about $3 per kilogram -- a quantity roughly comparable to a gallon of gasoline -- down from today's $8 per kilogram. That could make it economically practical for future fuel-cell vehicles that run on hydrogen.

2.4 "You can only make it so much more efficient; there isn't a lot you can do. So we've attacked the capital costs," says Richard Bourgeois, an electrolysis project leader at GE Global Research in Niskayuna, NY.

2.5 Electorlisis of water is emerging trend due to its sustainability.


3. Biological production

3.1 Bio-hydrogen can be produced in an algae bioreactor. In the late 1990s it was discovered that if the algae is deprived of sulfur it will switch from the production of oxygen, i.e. normal photosynthesis, to the production of hydrogen.

No comments: