Hydrogen remains a controversial renewable energy as producing the gas releases carbon dioxide, but scientists continue to find ways around that. The University of Central Florida was able to efficiently and cheaply generate hydrogen from seawater with nanomaterial that captures the sun’s energy. A recent study from Columbia also uses seawater and sunlight, but takes the carbon emissions out completely in the process.
Led by Daniel Esposito, an assistant professor in the Columbia Engineering department, his group of scientists have been able to create floating rig that goes through water electrolysis. It’s a process that separates oxygen and hydrogen with electricity from a solar photovoltaic source. While hydrogen gas only produces water when burned itself, much of it is currently produced with natural gas that emits carbon.
There have been attempts to capture these emissions, such as startup FuelCell Energy’s generators that are geared toward microgrids. However, Esposito and his team have found a different approach that doesn’t use natural gas. Mimicking the design of an oil rig, this floating device has solar panels that powers the process of water electrolysis instead.
One issue that’s limited this process in the past is using expensive membranes that separate hydrogen and oxygen, but can deteriorate over time. Columbia’s prototype instead collects and separates these substances using bubbles in the water. Even more impressive, hydrogen created from this process is 99 percent pure.
Jack Davis, a PhD student working with Esposito, compares the process to photosynthesis in a school report: “These solar fuels generators are essentially artificial photosynthesis systems, doing the same thing that plants do with photosynthesis, so our device may open up all kinds of opportunities to generate clean, renewable energy.”
At the moment, the prototype is simply a small-scale device in the lab. Further studies will need to be done in order to determine if a bigger version of the product would be functional and what challenges would lie ahead. Immediate goals are to increase efficiency and limit the crossover between electrodes.
Esposito’s group uses a high-speed video camera that observes the hydrogen gas and oxygen bubbles between electrodes, which is the crossover effect. This decreases purity and would require additional separation equipment that would make the process more expensive. These cameras are able to capture video at 500 frames per second, a rate over 16 times more fast than standard smartphone cameras.
“We are especially excited about the potential of solar fuels technologies because of the tremendous amount of solar energy that is available,” Esposito said in the Columbia report. “Our challenge is to find scalable and economical technologies that convert sunlight into a useful form of energy that can also be stored for times when the sun is not shining.”
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