Renewable energy of the future: seawater

There’s no doubt about it, global warming is a real, and growing crisis. While some are choosing to ignore the signs and the information given to them, others are looking towards a move into renewable and clean energy. A few researchers at Osaka University have found a way to make renewable energy that uses one of the largest resources on earth, seawater.

The Problem

Solar energy is a major source of renewable energy. But how can we use solar energy when the sun is hiding? One answer is to turn solar energy into chemical energy that can be used as fuel. By doing this conversion, it can be stored and moved around. Hydrogen (H2) is a potential candidate for the conversion. It can be produced by splitting water molecules (H2O) using a process called “photocatalysis”. Photocatalysis is when sunlight gives energy to another substance which then acts as a “catalyst”. A catalyst speeds up the rate at which a chemical reaction happens. Photocatalysis occurs all around us, sunlight hits a plant’s chlorophyll (a catalyst) in their plant cells, which allows to them produce oxygen, and glucose which is a source of energy. 

However, as the researchers noted in their paper, “the low solar energy conversion efficiency of H2 production and the storage problem of gaseous H2 have precluded the practical use of H2 as a solar fuel.”

The Solution

Enter hydrogen peroxide (H2O2). As American Energy Independence notes, “Hydrogen peroxide, when used to produce energy, creates only pure water and oxygen as a by-product, so it is considered a clean energy like hydrogen. However, unlike hydrogen, H2O2  [hydrogen peroxide] exists in liquid form at room temperature, so it can be easily stored and transported.” The problem was that the previous way to make hydrogen peroxide used photocatalysis on pure water. Pure water is as clean as it gets. With the amount of pure water used in the process, means that it isn’t a feasible way to create sustainable energy.

Here’s where seawater comes in. Given what seawater is made up of, the researchers used it in photocatalysis. The result was an amount of hydrogen peroxide that was high enough to run a hydrogen peroxide fuel cell (a fuel cell is like a battery, only it needs a continuous stream of fuel to run.)  

This method of creating hydrogen peroxide for fuel is a budding project with room to grow. There is still the question of cost-efficiency, and using it on a larger-scale, rather than just as a fuel cell. One of the researchers involved, Shunichi Fukuzumi, was noted in an article saying, “In the future, we plan to work on developing a method for the low-cost, large-scale production of H2O2 from seawater,” Fukuzumi said, “This may replace the current high-cost production of H2O2 from H2 (mainly from natural gas) and O2.”