초록
<P>The green alga <I>Chlamydomonas reinhardtii</I> has the ability to produce molecular hydrogen (H<SUB>2</SUB>), a clean and renewable fuel, through the biophotolysis of water under sulphur-deprived anaerobic conditions. The aim of this study was to advance the development of a practical and scalable biophotolytic H<SUB>2</SUB> production process. Experiments were carried out using a purpose-built flat-plate photobioreactor, designed to facilitate green algal H<SUB>2</SUB> production at the laboratory scale and equipped with a membrane-inlet mass spectrometry system to accurately measure H<SUB>2</SUB> production rates in real time. The nutrient control method of sulphur deprivation was used to achieve spontaneous H<SUB>2</SUB> production following algal growth. Sulphur dilution and sulphur feed techniques were used to extend algal lifetime in order to increase the duration of H<SUB>2</SUB> production. The sulphur dilution technique proved effective at encouraging cyclic H<SUB>2</SUB> production, resulting in alternating <I>Chlamydomonas reinhardtii</I> recovery and H<SUB>2</SUB> production stages. The sulphur feed technique enabled photobioreactor operation in chemostat mode, resulting in a small improvement in H<SUB>2</SUB> production duration. A conceptual design for a large-scale photobioreactor was proposed based on these experimental results. This photobioreactor has the capacity to enable continuous and economical H<SUB>2</SUB> and biomass production using green algae. The success of these complementary approaches demonstrate that engineering advances can lead to improvements in the scalability and affordability of biophotolytic H<SUB>2</SUB> production, giving increased confidence that H<SUB>2</SUB> can fulfil its potential as a sustainable fuel of the future.</P><BR><BR><P>Graphic Abstract</P><P>(1) Green algal cultures are grown in custom photobioreactors. (2) They are placed under anaerobic conditions to initiate H<SUB>2</SUB> production, but this leads to algal cell death. (3) Sulphur re-insertion is used to encourage algal culture recovery. Steps (2) and (3) are repeated, resulting in cyclic H<SUB>2</SUB> and biomass production.<BR><IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3cp51866c'><BR></P>