Next-Generation Nuclear for H₂ Too

14 September 2004

Chemical and Engineering News features the multiple approaches to next-generation nuclear power and provides a useful framework for understanding the differences. (Overview chart at right from DOE. Click to enlarge.)

In the US, the longer-term focus seems to be on Very High Temperature Reactors (VHTR)—generation IV systems as compared to the mostly generations I and II currently in service—with their concomitant ability to produce hydrogen for fuel purposes.

VHTR, helium- and lead-cooled fast reactors, and the molten salt reactor are all designed to generate electricity and also to operate at sufficiently high temperatures to produce hydrogen by thermochemical water cracking. At present [in the US], about 97% of hydrogen is produced from fossil fuels by steam reformation of methane. Around 3% is produced by electrolysis of water, but the electricity costs for the process are relatively high.

“The direct thermal decomposition of water is impractical, as it requires temperatures in excess of 2,500 °C,” [Tim J.] Abram [manager of advanced reactor systems at British Nuclear Fuels] says.

THERMOCHEMICAL hydrogen production, on the other hand, can be achieved at temperatures of less than 900 °C. “The only feeds to the process are water and high-temperature heat, typically 900 °C, and the only products are hydrogen, oxygen, and low-grade heat,” Abram explains. “Nuclear power is particularly well suited to hydrogen production by such a process because of its near-zero emissions.”

DOE, although supporting research on several generation IV reactor concepts, is giving priority to VHTR technology, notes William D. Magwood IV, director of the DOE Office of Nuclear Energy and chairman of the GIF policy group. The technology is known as the Next Generation Nuclear Plant (NGNP).

“The NGNP would be able to make both electricity and hydrogen at very high levels of efficiency,” Magwood says.

“The base concept of the NGNP is that of a very-high-temperature, gas-cooled reactor system coupled with an advanced, high-efficiency turbine generator and an even more advanced thermochemical hydrogen production system,” he continues. “We have very high expectations for this technology.”

Resources:

• DOE Nuclear Power 2010 Program

• INEEL Generation IV Initiative

• DOE Generation IV Nuclear Power Systems

• Nuclear Hydrogen Initiative

• Thermochemical Production of Hydrogen