Is hydrogen the perfect energy source for the future?

Hydrogen is the most abundant element in the universe. It can be made safely from

renewable energy sources and can be used as a fuel for vehicles, to heat buildings,

to produce electricity, and to fuel aircraft. It is hence often stated that hydrogen is the

fuel of the future. Thanks to it, we are going to power clean planes, clean cars, clean

boats... In short, we can get rid of our polluted world in no time, while preserving all

the advantages we have so far.

Wonderful solution. But is it?

The first problem is that hydrogen as a gas cannot be found naturally on Earth. It is

always associated with other elements and must be manufactured. Long story short,

to be able to exploit hydrogen, you have to separate it from the other atom it is linked

to. Take the example of water (hydrogen + oxygen). To obtain hydrogen, the liaison

between the atoms must be broken, which costs the same amount of energy that

what will be gained in the end. This could be interesting. However, including all the

intermediary losses, it costs more energy to dissociate H and O2 than what will be

gained by combusting hydrogen in the end.

Secondly, almost all of the hydrogen is produced from hydrocarbons such as natural

gas and coal. As a consequence, in 2018, the global production of 70 million tons of

hydrogen generated the emission of 800 million tons of CO2, a figure comparable to

the emissions of commercial air transport (918 million tons in 2018), or the combined

CO2 emissions of the United Kingdom and France.

For instance, Hydrogen is created daily in our world, as its indispensable in the

synthesis of ammonia (NH3: Nitrogen + Hydrogen), to produce nitrogenous

fertilizers. In this equation, nitrogen, also known as azote, is recuperated from the

air. Hydrogen is recuperated from natural gas by heating water to a certain point

hence creating hydrogen and CO2. We do get hydrogen gas in this case, but also...

CO2. It comes both from the chemical reaction itself, but also from the combustion of

the natural gas that provided the energy for this reaction. For every tone of H2

produced, 10 tones of CO2 go into the air. As a result, a car using hydrogen

produced this way would emit around 120g/km of CO2 over its lifetime. In

comparison, the average new petrol car would emit between 120 to 130 grams of

CO2 per kilometre. Instead of being created in the car engine, CO2 is created in the

upstream production of hydrogen.

The hydrogen defenders argue that this amount of emission can be brought

significantly down when hydrogen is produced from renewables, even mentioning

sometimes that if renewable energy is used, the gas has a zero- carbon footprint.

First, it is important to recall that renewable energies are not carbon neutral. A wind

turbine produces 10g of CO2/kwh before storage, and a solar panel produces 50g of

CO2/kwh before storage. Some would say that this is still less than gas, which

produces 400g of CO2/Kwh. But it is still not carbon neutral. And maybe in 2020, we

can stop doing less bad and start doing more good.

Additionally, for hydrogen to be "green", water must be electrolysed with low-carbon

electricity (nuclear, wind or hydraulic energy). But there is a small magnitude

problem: in France, to replace all our fuels by hydrogen obtained by electrolysis from

wind power, we would have to multiply by 15 the number of modern windmills

installed in France, and double the total electricity production... This may be hard to

sustain…

In Conclusion, hydrogen presents several challenges that need to be addressed

before being able to say that it is the perfect energy source for the future. Its

defenders welcome the decrease in the costs of renewable electricity, in particular

solar photovoltaic and wind energy, to promote the efficiency and the capability of

Hydrogen to become the energy platform of the future. Even if some new studies

show that new means, like the power-to-gas systems harnessing renewable energy,

could produce cleaner, cost-effective hydrogen for industry, there is still a long time

to go before being able to fly from Berlin to Tokyo without polluting.