Swedish Study Offers Hope for Hydrogen Production with Algae

A study conducted by a group of researchers at Uppsala University (Sweden) suggests that efficient production of hydrogen gas using the photosynthetic machinery of green algae is possible, contrary to previous skeptical views. Published in the journal PNAS, the study provides insights into the low efficiency problem and how it could be solved.

Hydrogen is one of the most promising renewable fuels which can be produced by splitting water molecule. The natural process of photosynthesis in green algae, which harnesses the energy of the sun to split water, is one biological way to produce hydrogen. The hydrogen ions generated from water splitting can later be formed into hydrogen gas through the work of a special class of enzymes called hydrogenases coupled to the photosynthetic electron transport machinery.

While it is known that green algae can produce hydrogen gas under certain conditions, previous studies have suggested poor commercial prospects due to very low efficiency. One skeptical view is that most of the hydrogen gas production in green algae is not directly powered by sunlight through photosynthesis but comes from other metabolic paths, making the green algae a poor hydrogen producer.

The focus of the Uppsala University study is the protein complex involved in light capture and photosynthetic electron transport, called Photosystem II or PSII. The researchers measured how the amount and activity of PSII varies in a wild type and a mutant strain of the green algae Chlamydomonas reinhardtii under different conditions, and thereby affects hydrogen production.

The researchers highlighted the finding that most of the electrons delivered to the hydrogenases (about 80 percent) originated from water splitting by PSII. This means that most of the hydrogen production is driven directly by solar energy, in contrast to popular views. This finding opens up a way to further improve hydrogen gas production in green algae through genetic engineering approaches that seek to preserve and enhance the function of PSII.