Hydrogen is a battery, not an energy source. To make hydrogen with truly zero emissions it has to start with green electricity anyway, only it squanders more than half of that energy as waste in the energy conversion. In short, hydrogen is electrification, but a roundabout and very inefficient way of doing it. If we do hydrogen for the majority of the energy economy, it doubles or triples the amount of clean energy we have to produce. It is an expensive sideshow to the main event: electrification. Yes, a small amount of hydrogen, but let’s not get carried away. Beware! There are obvious reasons the gas industry likes to lobby for this idea. Australia is dangerously addicted to the Hydrogen narrative, and we should be more realistic about its role in Australia’s future.
Many people believe hydrogen is the answer we need for decarbonization. But hydrogen is not a source of energy. You don’t discover hydrogen; it is a battery in the form of a gaseous fuel. The fossil fuel industry is happy to promote the hydrogen fiction as the majority of hydrogen sold today is actually a by-product of the natural gas industry. Only a tiny amount of hydrogen exists naturally as a gas on Earth. To make hydrogen and store it we first have to create electricity to power a chemical process called electrolysis, which is not highly efficient. Then we’d have to capture the hydrogen gas and compress it, which consumes about 10-15% more energy. Then we’d have to decompress the gas and burn it or put it through a fuel cell. More losses.
As a battery, hydrogen is pretty ordinary; for the one unit of electricity you put in at the beginning, you probably only get 50% out at the other side. This is called ``round--trip efficiency.'' To run the world off hydrogen, we’d have to produce twice the amount of electricity, already a monumental challenge. Chemical batteries typically have 95% or so round-trip efficiency, pumped hydro 85-90%.
Germany and Japan invested heavily in hydrogen because they don’t have domestic natural gas. They want something with the energy density of gasoline. In theory, hydrogen has about three times more energy per kilogram than gasoline (123 MJ/kg as compared to 44). You have to compress it and store it in a tank made of exotic materials. The tank weighs much more than the hydrogen gas itself. If you include the tank in your calculations, hydrogen ends up being about a quarter of the energy density of gasoline and only a little bit higher energy density than batteries.
Saul Griffth: “I started a company called Volute that built better CNG and hydrogen tanks and the technology is now licensed into both of those industries, so even as someone who would profit greatly from a hydrogen economy, I’m pretty confident it will only end up being a niche player. We can argue about the size of the niche. Hydrogen can be the high-temperature gas for industrial processes such as steelmaking and can solve some niche transportation problems. Hydrogen will be useful, but it is not the answer.“