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Hydrogen feeds the world

Fertilizer production requires large amounts of hydrogen. Today, 95 percent of this hydrogen is produced from fossil fuels, leading to colossal greenhouse gas emissions of CO₂. To save the Earth from more than 2 °C of global warming, politicians are using economic incentives to get the fertilizer industry to switch from fossil hydrogen to clean hydrogen produced by electrolyzers. This makes the fertilizer industry one of the largest markets for electrolyzers. In this blog post, we take a closer look at this little-known market, which, given its size, is more interesting than many of the more well-known ones.

Which mod­ern inven­tion has meant the most to human­i­ty? The steam engine, train, air­plane, car, space rock­et, nuclear pow­er, radio, tele­vi­sion, com­put­er, AI, …? The list of con­tenders is long. But none of them can match…

Sound a fan­fare, please!

…the Haber-Bosch process.

Haber & Bosch

Haber and Bosch!? What have Peter Haber and Har­ry Bosch done for human­i­ty? you ask in disbelief.

Well, they have enter­tained us. At least a few of us. Peter Haber is a Swedish actor best known for play­ing Mar­tin Beck, and Har­ry Bosch is a fic­tion­al char­ac­ter in Michael Connelly’s nov­els. But they are, of course, not the Haber and Bosch behind the mod­ern inven­tion that has meant the most to humanity.

The Haber and Bosch I am talk­ing about are the Ger­man chemists Fritz Haber and Carl Bosch. They devel­oped a chem­i­cal process in the ear­ly 20th cen­tu­ry that now car­ries their name. This process has been jus­ti­fi­ably described as “the most impor­tant inven­tion of the twen­ti­eth century.”

But before we dig into what the process does and why it deserves the first spot above all oth­er con­tenders, we need to take a deep breath and get some context.

Nitrogen

The breath we just took con­tained 78 per­cent nitro­gen gas (N2). 78.1 per­cent, to be exact. That makes nitro­gen (N), by far, the most com­mon ele­ment in the air we breathe. It is also one of the most com­mon  ele­ments in the whole universe.

Nitro­gen is also one of the build­ing blocks of life. Lit­er­al­ly. It’s in amino acids, pro­teins, DNA, RNA and ATP. (The lat­ter is the fuel that our cells run on.)

But it’s not by breath­ing air that your body gets the nitro­gen it needs.

The nutrient source of nitrogen

You get nitro­gen by eat­ing plants, or by eat­ing ani­mals that have pre­vi­ous­ly eat­en plants, or by eat­ing ani­mals that have pre­vi­ous­ly eat­en oth­er ani­mals that have pre­vi­ous­ly eaten…

Ok, you get the pic­ture. The food chain. The point is that plants are ulti­mate­ly our source of nitro­gen intake.

But how does the nitro­gen get into the plants?

Sim­ple: their roots absorb it from the soil they grow in.

But how does the nitro­gen end up in the soil? you ask relentlessly.

Today, the pri­ma­ry source is nitro­gen fer­til­iz­er that farm­ers spread on fields. But let’s hold off on that. We start by look­ing at how nature does it with­out the help of humans.

Nitrogen fixation

Enter the scene: Diazotrophs.

What?

Dia­zotrophs is a col­lec­tive name for bac­te­ria and oth­er microor­gan­isms that con­vert nitro­gen in the air into nitro­gen com­pounds, main­ly ammo­nia (NH3), which plants can take up. This process is called nitro­gen fix­a­tion.

Nitrogen’s circle of life

When plants die, bac­te­ria and fun­gi sink their teeth into the remains. (Fig­u­ra­tive­ly speak­ing, of course; bac­te­ria and fun­gi have no teeth.) The same thing even­tu­al­ly hap­pens to ani­mals and humans as well. Their remains con­tain nitro­gen com­pounds (pro­teins, DNA, RNA, and so on). Some microbes can break these down, releas­ing nitro­gen into the atmos­phere. This process is called den­i­tri­fi­ca­tion.Nitro­gen fix­a­tion and den­i­tri­fi­ca­tion are thus part of the great cir­cle of life, which Mufasa teach­es young Sim­ba in the movie The Lion King. This cycle is known in sci­ence as the nitro­gen cycle.

Lis­ten to the song Cir­cle Of Life from the movie The Lion King.

Need for fertilizers

Does the nitro­gen cycle go by itself?

If nature is left to take care of itself, the nitro­gen cycle ticks along with­out any prob­lems. But as soon as human­i­ty put the plow in the ground and start­ed farm­ing, the bal­ance was disturbed.

If crops are grown in the same place over a few years, the plants take up more nitro­gen from the soil than nat­ur­al process­es can restore. This is why humans have come up with strate­gies such as slash-and-burn agri­cul­ture, crop rota­tion, and fertilization.

The prac­tice of fer­til­iza­tion dates back to ancient times, with ear­ly civ­i­liza­tions such as the Sume­ri­ans and Egyp­tians using manure to enrich soil around 2000 BCE. This ear­ly form of fer­til­iza­tion helped improve crop yields, show­cas­ing human­i­ty’s ini­tial under­stand­ing of enhanc­ing soil fer­til­i­ty for agri­cul­tur­al purposes.

Father of the fertilizer industry

Manure and humus have been used as fer­til­iz­ers since the time of the Sume­ri­ans and the Egyp­tians. How­ev­er, the idea of cre­at­ing a syn­thet­ic fer­til­iz­er was not born until the 19th century.

In his ground­break­ing book Die organ­is­che Chemie in ihrer Anwen­dung auf Agri­cul­tur und Phys­i­olo­gie, first pub­lished in 1840, the Ger­man chemist Jus­tus von Liebig argued that nitro­gen com­pounds, such as ammo­nia, were need­ed to grow the health­i­est crops pos­si­ble. This earned him the epi­thet “father of the fer­til­iz­er industry.”

Jus­tus von Liebig’s the­o­ry led to a rush for nitro­gen at the end of the 19th cen­tu­ry. Salt­peter was mined with an unprece­dent­ed fren­zy, and trop­i­cal rocks were scraped for guano.

Watch the video to learn about how the demand for guano led the U.S. to pass a law giv­ing Amer­i­can cit­i­zens exclu­sive rights to guano on unclaimed islands.

Sources of nitrogen fertilizers

But salt­peter mines and bird poop only went so far.

At the end of the 19th cen­tu­ry, it was real­ized that nat­ur­al sources were not suf­fi­cient to meet future needs. This sparked the idea of some­how extract­ing nitro­gen direct­ly from thin air.

Sev­er­al meth­ods were devel­oped to fix the nitro­gen in the air. But it was not until the begin­ning of the next cen­tu­ry that the real break­through came, albeit with a hum­ble beginning.

Ammonia from thin air

In 1905, Fritz Haber pro­duced a small amount of ammo­nia by mix­ing nitro­gen and hydro­gen at 1,000 °C in the pres­ence of an iron cat­a­lyst. How­ev­er, the high tem­per­a­ture made the method impractical.

Over the next few years, Fritz Haber refined his tech­nique. In March 1909, he pre­sent­ed a method in which the tem­per­a­ture had been reduced to the more man­age­able range of 500–600 °C. This was accom­plished with high pres­sure. The process requires almost 200 times the air pres­sure (20 MPa).

But there was a caveat. The ammo­nia was pro­duced drop by drop; it took 8 hours to pro­duce a sin­gle liter of ammo­nia. Nev­er­the­less, Fritz Haber had demon­strat­ed a viable solu­tion for extract­ing nitro­gen from the air and fix­ing it as ammonia.

Watch the video for more infor­ma­tion on Fritz Haber.

Haber-Bosch process

The Ger­man chem­i­cal com­pa­ny BASF pur­chased the rights to the process and tasked Carl Bosch with scal­ing up Haber’s table­top machine to indus­tri­al scale. Four years lat­er, the BASF fac­to­ry in Oppau pro­duced five tons of ammo­nia – per day.

This is why the process is named after the two men: The Haber-Bosch process.

Haber and Bosch were award­ed the Nobel Prize in 1918 and 1931, respec­tive­ly, for their work in solv­ing the chem­i­cal and engi­neer­ing prob­lems of large-scale, con­tin­u­ous flow and high-pres­sure technology.

Fritz Haber Carl Bosch
Fritz Haber and Carl Bosch.

Telling correlation

Ini­tial­ly, Haber-Bosch process was main­ly used to pro­duce ammo­nia for the mil­i­tary and indus­try, but after the Sec­ond World War, the use of ammo­nia as a nitro­gen fer­til­iz­er in agri­cul­ture exploded.

The increased use of syn­thet­ic nitro­gen fer­til­iz­er led to high­er yields that sup­port­ed a rapid­ly grow­ing pop­u­la­tion. That’s why Pro­fes­sor Vaclav Smil wrote in the pres­ti­gious sci­en­tif­ic jour­nal Nature that the Haber-Bosch process ”is the most impor­tant inven­tion of the twen­ti­eth century.”

Global World Population And Fertiliser Use
Source: N. Alexan­dratos and J. Bru­ins­ma, World Agri­cul­ture Towards 20302050: The 2012 Revi­sion, Food and Agri­cul­ture Orga­ni­za­tion of the Unit­ed Nations, ESA Work­ing Paper No. 12–03, June 2012.

High cost for feeding the world

An often-quot­ed sta­tis­tic is that nitro­gen fer­til­iz­ers are respon­si­ble for feed­ing half the world’s population.

Since this fer­til­iz­er is pro­duced through the Haber-Bosch process by con­vert­ing hydro­gen, I think it’s fair to say that hydro­gen feeds the world.

Don’t you agree?

But the mass adop­tion of syn­thet­ic fer­til­iz­ers has come at a high cost to the envi­ron­ment: harm­ful algal blooms, soil acid­i­fi­ca­tion, and mas­sive green­house gas emissions.

Greenhouse effect

A study esti­mates that the pro­duc­tion and use of nitro­gen fer­til­iz­ers, both organ­ic and syn­thet­ic, in food-grow­ing accounts for around 5 per­cent of glob­al green­house gas emis­sions and that this could threat­en efforts to keep glob­al warm­ing below 2 °C.

Nitro­gen fer­til­iz­ers con­tribute to the green­house effect in many ways.

One issue is that far from all fer­til­iz­er is absorbed by plants, and what remains is bro­ken down by microbes in the soil, pro­duc­ing laugh­ing gas (N2O).

That’s not fun­ny at all. (Pun intend­ed, of course.)

Laugh­ing gas, or nitrous oxide, which is its chem­i­cal name, is a green­house gas almost 300 times more potent than car­bon diox­ide (CO2).

But anoth­er major source is the pro­duc­tion itself. The man­u­fac­ture of arti­fi­cial fer­til­iz­ers is respon­si­ble for almost 1.5 per­cent of total glob­al CO2 emissions.

Energy-hungry monster

The Haber-Bosch process is car­ried out at high tem­per­a­tures and pres­sure, turn­ing the pro­duc­tion plants into ener­gy-hun­gry mon­sters. The ener­gy comes from burn­ing nat­ur­al gas.

Nat­ur­al gas is also used to pro­duce gray hydro­gen, which is the feed­stock in the Haber-Bosch process. Much hydro­gen is need­ed. Remem­ber that form­ing ammo­nia takes three hydro­gen atoms per nitro­gen atom (NH3).

About 40 per­cent of the fos­sil gas input into the process is burned to fuel the reac­tion, with the remain­ing 60 per­cent being used as feedstock.

Pro­duc­ing ammo­nia fer­til­iz­ers is respon­si­ble for about 1 per­cent of all glob­al ener­gy use and 1.4 per­cent of CO2 emissions.

Carbon dioxide polluter

More than 180 mil­lion met­ric tons of ammo­nia are pro­duced annu­al­ly. Near­ly 90 per­cent of ammo­nia is used to pro­duce syn­thet­ic nitro­gen fer­til­iz­ers (includ­ing urea, ammo­ni­um nitrate, and ammo­ni­um phosphate).

Pro­duc­ing this mas­sive amount of ammo­nia requires more than 32 mil­lion met­ric tons of hydro­gen. Today, more than 95 per­cent of this hydro­gen is pro­duced from nat­ur­al gas and coal.

To pro­duce 32 mil­lion tons of hydro­gen by steam methane reform­ing (SMR), the most com­mon method, approx­i­mate­ly 80 mil­lion tons of nat­ur­al gas are required, assum­ing an effi­cien­cy rate of 80 per­cent for the SMR process.

Thus, we can cal­cu­late that 68 mil­lion tons of nat­ur­al gas are need­ed just as a feed­stock in the pro­duc­tion of nitrite fer­til­iz­er. The Haber-Bosch process con­sumes an addi­tion­al 45 mil­lion tons of nat­ur­al gas as fuel. In total, 113 mil­lion tons of nat­ur­al gas are need­ed annu­al­ly to pro­duce syn­thet­ic nitro­gen fertilizers.

When all this nat­ur­al gas is used, more than a stag­ger­ing 310 mil­lion met­ric tons of car­bon diox­ide (CO2) are released into the atmosphere.

Oops!

Need for PEM-electrolyzers

For hydro­gen to con­tin­ue to feed half the world while keep­ing glob­al warm­ing below 2 °C, the pro­duc­tion of syn­thet­ic nitro­gen fer­til­iz­ers must switch from fos­sil-based hydro­gen to fos­sil-free hydro­gen rather quickly.

How­ev­er, this requires many PEM-elec­trolyz­ers to pro­duce the fos­sil-free hydrogen.

Smoltek’s role

Whether an elec­trolyz­er pro­duces hydro­gen to feed the world or pow­er a sports car, there is a problem.

The cell mate­r­i­al in a PEM-elec­trolyz­er con­tains irid­i­um. Today, 2.0 mil­ligrams of irid­i­um are used per square cen­time­ter. That doesn’t sound like much, but it is a lot, giv­en that irid­i­um is a scarce met­al prac­ti­cal­ly only mined in South Africa. (Some are also mined in Cana­da and Russia.)

The price of irid­i­um is sky-high and expect­ed to rise sharply with the increased demand, as it is prac­ti­cal­ly impos­si­ble to extract more per year than already done.

This is why all man­u­fac­tur­ers and buy­ers of PEM elec­trolyz­ers want to reduce the amount of irid­i­um from the cur­rent 2.0 to an ambi­tious 0.1 mil­ligrams per square centimeter.

Researchers and devel­op­ers world­wide are work­ing fran­ti­cal­ly to reach this dream goal. So are we. And I would say that we are ahead of the game thanks to our unfair advan­tage.So, if you ever had doubts about the deci­sion to pur­sue the hydro­gen mar­ket in par­al­lel with the semi­con­duc­tor mar­ket, it’s time to stop doubt­ing. Don’t you agree?

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