Originally posted May 20, 2010 by Matt

What is your quest?

So the last post was scary, both in length and content. But, seriously, haven’t we been hearing this doom and gloom of global warming for a while? How about we reframe this conversation in a more positive light? Let’s discuss what science is truly capable of accomplishing. Let’s transform CO₂ from a problem into a commodity waiting to be used.

What we would like to do is come up with an efficient way to convert the CO₂ in our atmosphere into desirable materials (alcohols, plastics, a pony, what have you). We will need to create a market for CO₂. The crucial question is: Can we make this cheap, abundant, atmospheric gas valuable? (Come on, there’s a market for reprocessed cow manure—why not CO₂?)

We’ll need a) some science b) some policy and c) a way to make the science and the policy play nicely.

Granted, these are daunting tasks with no easily accessible answers. However, there is a historic precedent for converting an atmospheric gas into commodity chemicals. In the current post, we will take a look at this example to gain a little perspective on what needs to be done in order to exploit the untapped value of CO₂.

N₂ and CO₂ — Holy Grails

Scientists love searching for the next “Holy Grail”—the big technological push of each generation. Maybe it’s that we like to think that, in pursuing our scientific quests, we’re as brave and dashing as Indiana Jones. (I mean seriously when it comes to scientist rock stars, Indiana Jones is the clear #1, with NCIS’ Abby Sciuto a notable runner-up.) But I digress … Holy Grail is a term that makes our quest for scientific knowledge sound significant and hints at the excitement of discovering and deciphering the mysteries of our natural world. And to think that some people believe that scientists don’t have a way with words! Some scientific quests, however, are more worthy of the term than others. When considering societal impact on a global level, nitrogen fixation (turning nitrogen or N₂ —an inert gas making up approximately 80% of our atmosphere— into chemicals used in farming and explosives) and CO₂ conversion (alcohol, plastics, ponies, etc.) are top of mind in any conversation of what might be considered a scientific Holy Grail.

Maybe the secret to CO₂ conversion is in the Castle Anthrax.

Our last post introduced some of the issues surrounding CO₂ emission, including the need to come up with novel ways to reduce emissions or use CO₂ as a resource. We would like to discuss in this post how the drive to reduce CO₂ in the atmosphere can be likened to previous efforts focused on N₂ fixation, a fully-realized technology. N₂ and CO₂ are both gasses found in the atmosphere. Neither is reactive with other chemicals. And notably, both represent an inexpensive resource for valuable commodity chemicals. In looking at the history of N₂ fixation, we hope to draw meaningful comparisons that will help us make sense of the complex research process and the unresolved issues impeding the development of CO₂ conversion technologies.

History of N₂ fixation

In the early 1900s it was evident that standard agricultural techniques were not going to be able to keep up with the growth of the global population. Farmable land was being stripped of its nutrients, specifically, sources of fixed nitrogen such as nitrates (NO₃^–). The best fertilizers, including guano (“Forget MiracleGro, try our organic bat poop!”), which had been overharvested, and nitrates from the Atacama Desert, which were subject to unstable markets and supply chains, were declining in their availability. These nitrates were also crucially important for making explosives. Any country that had a stranglehold on the nitrate market would be dominant in agriculture, economic security, and military power. Scientists (particularly German scientists) thus started to look for a chemical method to mix nitrogen and hydrogen gasses so that they would form ammonia (NH₃).

Bat poop! Get your bat poop!

A scientific call-to-arms went out in 1898 from the incoming president of the British Academy of Sciences, Sir William Crookes. He warned of the impending doom (sound familiar?) that without new fertilizers current crop yields would not be able to keep up with population growth. A new form of fixed nitrogen had to be found. “It is a chemist,” he said, “who must come to the rescue.” The goal then, was to turn N₂, this abundant and useless gas, into nitrates or ammonia (both sources of fixed nitrogen). The list of those who searched for an answer includes a group of some of the most regarded chemists in history: Joseph Priestly, Henry Louis Le Chatelier, Henry Cavendish, Wilhelm Ostwald, and Walther Nernst. (What do you mean you’ve never heard of them?). They tried many different methods. My favorite is one that tried to “bottle lightning.” Lightning is the one physical force, not chemical or biological, in the natural world capable of turning N₂ and O₂ into nitrates. So researchers used huge arcs of electricity to try to fix N₂. Unfortunately, this method was way too expensive to be useful.

The technique that was ultimately successful involved making ammonia from pressurized N₂ and H₂ gasses passed over iron particles—a catalyst—at a high temperature. Wilhelm Ostwald, one of the founders of the field of physical chemistry, came tantalizingly close to discovering this. He saw the idea of N₂ fixation not as the Holy Grail, but a true Philosopher’s Stone (that’s the Sorcerer’s Stone to you American Harry Potter fans). N₂ fixation was like the Philosopher’s Stone in that the process could provide eternal life (i.e. the earth could sustain more life than it would otherwise) and that the quest for its discovery drove many people to near madness (including Ostwald himself).

The Alchymist, In Search of the Philosopher’s Stone, Discovers Phosphorus by Joseph Wright of Derby

Where Ostwald and others had failed, Fritz Haber finally succeeded. Haber, an established chemist at a mid-tier German University, was the first person to show how ammonia could be produced from N₂ and H₂ in profitable manner. Chemists’ persistence sometimes amazes me. Ammonia is such a noxious chemical! If you’ve ever driven by (or worked on) a poultry farm, you are well aware of the pungent aroma of NH₃. It burns the nostrils. That anyone would want to produce millions of tons of this stuff on their home soil defies explanation.

Ultimately, Haber’s achievement was due to his desire to prove himself as a top-tier scientist, his ability to understand and build off of the work of others (notably Le Chatelier and Ostwald), and the assistance of his partner Robert Le Rossingol in fabrication of the high-pressure equipment. Haber’s techniques relied on three basic chemical principles: 1) chemical transformations occur faster at higher temperatures, 2) chemical reactions are more efficient if you continuously add starting materials while simultaneously removing the final products, and 3) catalysts will speed up the rate of reaction. Combining these three principles with the ability of Le Rossingol to create fundamentally new reaction vessels, Haber was able to produce an efficient method for creating ammonia. He patented his discoveries and sold them to the German firm BASF (which originally stood for Badische Anilin- und Soda-Fabrik).

Fritz Haber

For BASF, the discovery and rights to Haber’s work had the potential to yield huge profits. The problem was, in order to make it work on an industrial scale, entirely new processes would have to be invented. New high-pressure reaction containers would have to be built. New ways of supplying high-pressure, pure sources of N₂ and H₂ would have to be developed. New materials for handling these chemicals would have to be made. The man they put in charge of the industrialization was Carl Bosch. Bosch oversaw every aspect of the technological conversion. He managed a huge team of trained scientists (*note) in what would later become the model for how all modern chemical companies perform industrial research. The industrial processes that BASF designed for nitrogen fixation are still used today and have become a bedrock for the field of chemical engineering.

Carl Bosch

For their work, Haber and Bosch were awarded the Nobel Prize in 1918 and 1931, respectively. The Haber-Bosch cycle remains critically important to the global economy and global nutrition. The industrial application of the Haber-Bosch process currently uses roughly 1% of the global energy consumption and produces around 100 million tons of fertilizer per year. This was truly a scientific achievement with vast global (and olfactory) consequences.

What lessons can we apply to CO₂ conversion?

The drive to find technologies for CO₂ sequestration and conversion has the potential to mimic some of the accomplishments of N₂ fixation: establishment of a new industry, direct promotion of human welfare, and creation of valuable chemicals from a cheap and abundant feedstock. The basic premise is the same as N₂ fixation: CO₂ will be condensed from the atmosphere, carried through state-of-the-art reaction vessels, reacted with other chemicals, and converted into commodity materials. Like with N₂ fixation, the discovery will require dedicated and focused scientists. Unlike N₂ fixation, CO₂ conversion will not aid in Nazi Germany’s rise to power. Commercialization has the potential to revolutionize industrial processes, and patent rights for CO₂ technologies will generate considerable profits. The conversion of CO₂ into valuable products will reduce the presence of this greenhouse gas in the atmosphere.

Before any of this can be achieved, however, there are several key components of CO₂ conversion that need to be resolved. We will talk about each of these points in more detail in later posts, but will outline them now.

– N₂ fixation relied on the ready ability to condense N₂ from the atmosphere. These technologies need to be developed for bulk CO₂ condensation and sequestration from the atmosphere or from industrial smoke stacks.
– CO₂ has already found a use as a feedstock in industrial processes. Urea, methanol and salicylic acid are all value-based chemicals that are synthesized on the order of millions of tons per year. Unfortunately, industry is currently producing billions of tons of CO₂ every year. New materials and new conversion techniques need to be developed.
– N₂ fixation brought great wealth and power to Germany. The lab-oriented, engineering, and blue-collar jobs created from the development of CO₂ technologies will bring wealth and security to the nation that best accomplishes these tasks. US policy will need to be enacted to support CO₂ conversion technologies if we are to be players in this global market.

The next posts in this series will explore past and current CO₂ policy. Future posts will look at some of the existing and emerging technologies and will even delve into understanding how nature uses light as an energy source for CO₂conversion into sugars and other value-based chemicals.

General References and notes:

Most of the historical content and some of the technical content concerning N₂ fixation found in this piece were compiled from two sources: The Alchemy of Air by Thomas Hager, published by Harmony Books of New York and Enriching the Earth by Vaclav Smil, published by The MIT Press of Cambridge, MA. Both are wonderful reads in their own rights, bringing to life the historical background of N₂ fixation. The Alchemy of Air takes a closer look at Haber and Bosch and discusses how the German state they helped to advance affected them in different ways. Enriching the Earth takes a more technical approach to the history of nitrogen fixation. We highly recommend reading both of these books if you are interested in these topics.

Sir William Crookes’ remarks on N₂ fixation were similar in tone to those of major researchers today speaking about CO₂conversion. To read more of his speech and the arguments from the scientific and public community, click here.

*Note One of the most amazing aspects of the industrialization of N₂ fixation involves the testing of catalysts. Alwin Mittasch led this process. He ran over 6500 tests over the course of 3 years. By today’s standards, this is a small amount. However, running this number of experiments in such a short amount of time was a monumental task in 1910.