The way in which a photosynthetic protein can be used in an integrated photobiofuel cell is reported in a study published in Nature Communications this week. The work illustrates how illumination of the cell results in the formation of electricity, without the need of sacrificial reagents. Itamar Willner and co-workers attached the photosynthetic protein photosystem II to the surface of an electrode and used this photoanode to assemble a photobiofuel cell. They report that illumination of the photoanode results in the oxidation of water to O2 and the transfer of electrons through the external circuit to the cathode, where O2 is re-reduced to water. This direct coupling of cathode and anode reactions without the need for a sacrificial reagent reduces waste, and further work could lead to the development of useful electrochemical devices.