There has been plenty of research on how hydrogen can fit among renewable energy technologies. Hydrogen can combust like fossil fuels, but the only products are water vapor and heat, making it a zero-emissions fuel. The main limitation has been that hydrogen production consumes a lot of energy, and therefore it cannot compete with fossil fuels yet. However, the growth of solar power has created a unique opportunity to deploy hydrogen in energy storage technologies.
Electrolysis is a process where electricity is used to separate water into hydrogen and oxygen. Solar power is ideal for electrolysis, for two main reasons:
Although hydrogen combustion comes with risks, the gas can also be used in a fuel cell reaction, where it is combined back with oxygen to produce water. This reaction provides both electricity and heat, and both outputs are useful in buildings.
The energy output of a hydrogen fuel cell is around 40% electricity and 60% heat, and both outputs are simultaneous when the unit operates – producing only electricity is not possible. As a result, hydrogen electrolysis is a very inefficient energy storage method when only electric power is used, but highly efficient when heat and electricity are required simultaneously.
Japan has taken a leadership role in the deployment of hydrogen technologies, and they plan to equip 5.3 million households with hydrogen fuel cells by 2030. The East Japan Railway Company also has plans for hydrogen technology, and they will equip their Musashi-Mizonokuchi station with a hybrid system that combines solar power and hydrogen generation. A similar system was deployed at the Henn na Hotel in Nagasaki, Kyushu. All these projects represent ideal applications for hydrogen fuel cells, since electricity is required along with space heating or water heating, ensuring the heat output of a fuel cell is not wasted.
Being the continent with the highest solar radiation per square meter, Australia can also benefit from solar-powered hydrogen generators and fuel cells. If the hydrogen economy grows and it becomes a commodity traded around the world, it would even provide a way for Australia to “export” its abundant solar energy.
For Australian energy companies, hydrogen fuel cells can accomplish the same function as any other energy storage system: absorbing surplus generation from solar and wind power, while compensating for peaks in demand that occur when renewable generation is offline.
Property owners have the option of exporting surplus solar energy to the grid, but consider that the feed-in tariff is much smaller than the kilowatt-hour retail price, so it makes sense to maximise solar energy usage. Hydrogen fuel cells are a promising alternative in buildings where heat and electricity are used at the same time and stabilising the energy market.