Biodegradable prototype batteries constructed from biopolymers from crustaceans and algae could be fuelled successfully by different sources of sugar, including sugared water, glucose, still soft drinks and tree saps. The sugar was oxidized into electrons and protons by enzymes called dehydrogenases. It was claimed that these batteries could provide power for more than three times as long as the batteries in common use now, and that they would be refillable, either using prefilled cartridges or any suitable sugary liquid.