A process combining dark fermentation and photofermentation for production of hydrogen is interesting due to its potential of producing hydrogen at a high yields. In this study, the hydrogen process is compared to a 2nd generation ethanol process with respect to cost and with the aim of increasing our understanding of the pros and cons and giving a clear picture of the present status of the two processes. The hydrogen production cost was found to be about 20 times higher than the ethanol production cost, 421.7 (sic)/GJ compared to 19.5 (sic)/GJ. The main drawbacks of the hydrogen process are its low productivity, low energy efficiency, and the high cost of buffer and base required to control the pH. (C) 2011 Elsevier Ltd. All rights reserved.