Discover more from Transportist
Transportist: The Hydrogen Economy
Another post about hot air
The Hydrogen Economy
To be buzzword-compliant in Australia is to talk about the ‘Hydrogen Economy’. While private vehicle electrification is here, and will take some time to roll out (despite the disinformation campaign from various sources), there are some technologies which are less amenable to electrification than others. City cars are more amenable than intercity trucks e.g. Cars have a shorter range, their load is smaller, so batteries are more feasible.
As the load gets heavier and the range is longer, more batteries are required. THIS MAKES ALL EXISTING ON-BOARD BATTERIES LESS EFFICIENT. This is because the batteries use more and more of their stored power moving other batteries around. (This affects fuel as well, but because the energy density of fuel is higher, the problem is not as salient).
Solutions include fast recharging (so smaller batteries can be used without spending too much time recharging), battery swapping [which has been tried multiple times since 1900], overhead wires as used for streetcars (trams) and electric trains, and has been proposed for trucks, or even dynamic in-road charging (or discharging) which seems most practical for buses with their frequent stops at specific locations (i.e. bus stops), so most batteries and stopping for charging can both be avoided.
But the energy density of batteries remains lower than liquid fuels, it has been estimated that “1kg of hydrogen contains 130 times more energy than 1kg of batteries.”
Yet the efficiency of batteries is significantly higher. This from Volkswagen (not an unbiased source).
The most interesting part of the study remains: Which energy has the best efficiency and is the most cost-effective for driving e-cars? Battery or hydrogen operation?
With battery-powered e-cars, only eight percent of the energy is lost during transport before the electricity is stored in the batteries of the vehicles. When the electrical energy used to drive the electric motor is converted, another 18 percent is lost. This gives the battery-operated electric car an efficiency level of between 70 to 80 percent, depending on the model.
With the hydrogen-powered electric car, the losses are significantly greater: 45 percent of the energy is already lost during the production of hydrogen through electrolysis. Of this remaining 55 percent of the original energy, another 55 percent is lost when hydrogen is converted into electricity in the vehicle. This means that the hydrogen-powered electric car only achieves an efficiency of between 25 to 35 percent, depending on the model. For the sake of completeness: when alternative fuels are burned, the efficiency is even worse: only 10 to 20 percent overall efficiency.
Australia is apparently swimming in Hydrogen. (Arguably the universe is swimming in Hydrogen), so the desire to make Hydrogen a thing remains, even if it’s not the best choice for passenger cars, maybe buses, or trucks, or trains will have a different outcome.
The colour adjective on hydrogen indicates how it was made
Grey hydrogen - natural gas
Brown hydrogen - lignite coal
Black hydrogen - bituminous coal
Green hydrogen - zero-carbon electricity
Blue hydrogen, is produced like grey, brown, or black hydrogen, but uses Carbon Capture and Storage (CCS) to minimise the impact, and may be less expensive than Green Hydrogen.
You may be skeptical of blue hydrogen. You would not be alone.
But there is the also the question of whether any of this economically feasible. We have been down this path before, with fuel cells, more than two decades ago, when Fuel Cells were being promoted as the future of transport energy. As has been quipped about Fusion and Brazil: maybe it’s true that:
Fuel cells are the future and always will be.
In the end fuel cells lose a lot of energy in all the transformations, and hydrogen is an inefficient energy carrier.
What airplanes especially, and to a lesser extent trucks, buses, and trains need is a higher energy density than today’s batteries can provide. Two points:
One, tomorrow’s batteries may have higher density, especially if solid state batteries work as promised.
Second, enter biofuels. Many people are working on the problem of producing biofuels at scale in a way that doesn’t consume all the croplands presently used for food.
There are big bets being placed on different technological trajectories, and no one needs to commit to deployment yet. But, just as with fossil fuel in the last century, the more entrenched batteries get, the harder it will be to unseat them as the dominant energy carrier for transport.