A designer proton-channel transgenic alga for photobiological hydrogen production that is specifically designed for production of molecular hydrogen (H2) through photosynthetic water splitting. The designer transgenic alga includes proton-conductive channels that are expressed to produce such uncoupler proteins in an amount sufficient to increase the algal H2 productivity. In one embodiment the designer proton-channel transgene is a nucleic acid construct (300) including a PCR forward primer (302), an externally inducible promoter (304), a transit targeting sequence (306), a designer proton-channel encoding sequence (308), a transcription and translation terminator (310), and a PCR reverse primer (312). In various embodiments, the designer proton-channel transgenic algae are used with a gas-separation system (500) and a gas-products-separation and utilization system (600) for photobiological H2 production.