Right now the consensus is at 30 square kilometer, which is a lot less than the initially promised 400 and considerably less than even the current 100 on the Steam page.
"Economics dictates that 95% of current U.S. hydrogen is produced by steam-methane re-forming of non-renewable natural gas, " Michael K. Heiman, professor of environmental studies at Dickinson College, wrote in a study of the proposed hydrogen economy last year.
Abengoa said the project will improve its current solar thermal technology, which uses mirrors to concentrate and direct the sunlight for producing steam.