Name: The Truth about Hydrogen
Uploaded: 2021-04-12T12:02:22.000Z
Duration: 14 min 58 s
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This episode of Real Engineering is brought to you by Skillshare, home to over twenty

thousand classes that could teach you a new life skill.

As the world grapples to eliminate fossil fuels from our energy diet, electric cars

have seen an incredible boom over the past few years.

Last year, over one million electric cars were sold around the world.

The number of Nissan Leafs, Teslas, and other electric vehicles in circulation worldwide

And while there are many brands of electric car to choose from, there are only two choices

when it comes to powering electric vehicles: fuel cells or batteries.

Both produce electricity to drive electric motors, eliminating the pollution and inefficiencies

of the fossil fuel powered internal combustion engine.

Both hydrogen and electricity for batteries can be produced from low­ or zero ­carbon

sources, including renewable energy like solar and wind, and therefore both are being pursued

by car manufacturers and researchers as the possible future of electric vehicles.

However, a great debate is being waged by supporters of each technology.

Elon Musk has called hydrogen fuel cell technology “incredibly dumb,” claiming they're

more of a marketing ploy for automakers than a long-term solution.

In contrast, Japan has announced its intention to become the world's first hydrogen society,

with the Japanese government and the auto industry working together to introduce 160

hydrogen stations and 40,000 fuel-cell vehicles by March 2021.

At first glance, hydrogen seems like an extremely clever way to power a car.

Compressed hydrogen has a specific energy (aka energy per unit mass) of neary 40,000

Lithium ion batteries at best have a specific energy of just 278 wh/kg, but most fall around

That's 236 times as much energy per kg for hydrogen.

And because of its energy density and lightweight nature, compressed hydrogen and fuel cells

can power cars for extended ranges without adding much weight, which as we saw in our

last video is a gigantic road block for incorporating the technology into the aviation industry.

The designers of electric vehicles are caught in a catch 22 with energy density and range.

Each extra kilogram of battery weight to increase range requires extra structural weight, heavier

brakes, a higher torque motor, and in turn more batteries to carry around this extra

mass, This weight compounding limits how far a battery powered vehicle can travel, until

new technology can help reduce the weight of the batteries.

For hydrogen fuel cell vehicles, this weight compounding is not an issue.

Additionally, a hydrogen fuel cell vehicle can be refueled in under 5 minutes, where

a battery powered electric vehicle, like the Tesla model S, takes over 3 hours to fully

When looking at the range and refuel times hydrogen can offer, you can see why some car

manufacturers are investing in this technology.

Hydrogen is a clear winner, but it falls behind when we start considering the end-to-end production

While both batteries and hydrogen fuel cells are both forms of electricity storage, the

Fully charging a Tesla Model 3 with a 75 kiloWatt hour battery, costs between 10-12 dollars

With a rated range of 500 kilometers, that's between 2 and 2.4 cent per kilometer.

In a previous video, I visited a petrol station that introduced a hydrogen pump, fed by its

which used off-peak electricity to produce hydrogen.

The hydrogen from this station cost $85 dollars to fill the 5 kg tank of the Toyota Mirais

That's 17.7 cent per kilometer, 8 times the price.

And here lies the problem, Hydrogen simply requires more energy to produce.

To understand the economic viability of hydrogen let's dig deeper into the production process.

Before any hydrogen vehicle can hit the road, you first need to produce the hydrogen, but

hydrogen is not a readily available energy source.

Even though hydrogen is the most abundant element in the universe, it is usually stored

in water, hydrocarbons, such as methane, and other organic matter.

One of the challenges of using hydrogen as an energy storage mechanism comes from being

able to efficiently extract it from these compounds.

In the US, the majority of hydrogen is produced through a process called steam reforming.

Steam reforming is the process of combining high-temperature steam with natural gas to

While steam reforming is the most common method of industrial hydrogen production, it requires

a good deal of heat and is wildly inefficient.

Hydrogen produced by steam reforming actually has less energy than the natural gas that

And while hydrogen fuel cells themselves don't produce pollution, this process does.

So if we want to assume a future scenario with as little carbon emission as possible,

Another method to produce hydrogen is electrolysis - separating the hydrogen out of water using

While the electricity needed for this process can be provided from renewable sources, it

requires even more energy input than steam reforming.

You end up losing 30% of the energy from the original energy put in from the renewables

So we are sitting at 70% energy efficiency from hydrogen fuel cells if traditional electrolysis

is used, before the car even starts its engine.

A slightly more efficient method of producing hydrogen is polymer exchange membrane electrolysis.

Using this method, energy efficiencies can reach up to 80%, with the added benefit of

being produced on site, which we will get to in a moment.

But this is still a 20% loss of energy from the original electricity from the renewables.

Some experts say the efficiency of PEM electrolysis is expected to reach 82-86% before 2030, which

is a great improvement, but still well short of batteries charging efficiency at 99%.

[1] A 19% difference in production costs doesn't explain the difference in costs yet, so where

The next hurdle in getting hydrogen fuel cell vehicles on the road is the transport and

If we assume the hydrogen is produced on site, like it was for this petrol station, then

we eliminate one energy sink, but the cost of storage is just as problematic.

Hydrogen is extremely low density as a gas and liquid, and so in order to achieve adequate

energy density, we have to increase its actual density.

We can compress the hydrogen to 790 times atmospheric pressure, but that takes energy,

about 13% of the total energy content of the hydrogen itself.

Alternatively we can turn hydrogen into liquid, cryogenically.