Understanding the Relationship Between Chemical Feedstocks and Dangerous Fossil Fuels.
Recently in this space, I posted a very esoteric piece - so esoteric that it understandably provoked no comment - on the preparation of p-xylene from dimethylfuran, a chemical that is accessible from biomass such as straw.
The Conversion of Cellulosic Biomass Into Aromatic Compounds.
In so doing, I failed to apply a lesson I often - albeit with very limited success - try to evoke whenever one hears these "feel good/sound good" bits of environmental wishful thinking - which is to think about scale. For instance, the scale of world energy consumption as of 2016 was 576 exajoules per year - fraction of which that is derived from dangerous fossil fuels has been rising not falling throughout the 21st century - and all of the endless hype about the solar industry's "percent" growth is merely an attempt to bury the issue of scale. Wind and solar energy combined, despite all the cheering, did not produce 10 exajoules of energy in 2016 and thus has been insignificant, is insignificant, and always will be insignificant.
A recent publication in one of my favorite journals Environmental Science and Technology has served for my inattention to issues of scale in referencing a lab scale process as significant; there's a long way between "there" - "there" being significance - and "here," "here" being a world in which the collapse of the planetary atmosphere is accelerating and not as popularly imagined, even remotely being addressed. The paper is this one, about the role that dangerous fossil fuels play in the chemical industry, the chemical industry being at the very core of and essential to our way of life, pretty much involved in everything a modern bourgeois person - such as I am - does. Here is the paper: Mapping Global Flows of Chemicals: From Fossil Fuel Feedstocks to Chemical Products (Levi and Cullen, Environ. Sci. Technol., 2018, 52 (4), pp 1725–1734)
This graphic from the paper shows pretty much everything you need to know about it:
(Similar types of flow diagrams for energy are widely available from the Lawrence Livermore Laboratory and other places. I sometimes post a particular version here and there showing the energy flow diagram for Denmark, that offshore oil and gas hellhole showing how trivial its much ballyhooed and hyped wind industry is.)
Anyway.
From this diagram, one can discern the world requirement for "BTX" (Benzene, Toluene and Xylenes) is on the order of 80 million tons, of which roughly 70 million tons is carbon. This compares to the average annual average amount of carbon dioxide that is routinely dumped into the atmosphere while we wait for the grand super duper renewable energy nirvana that never comes, roughly 35 billion tons of CO2, corresponding to about 15 billion tons of carbon.
70 million tons may be accessible via "waste" biomass. Over on another website where I was banned for telling the truth, I roughly calculated from available references that the total carbon content of all the straw in China is roughly 267 million tons.
This of course does not account for transporting and processing all the straw in China, of course, just so I'm not encouraging false optimism.
According to the cited paper, the world chemical industry's contribution to climate change from direct by products of the chemicals themselves as carbon dioxide, is relatively small, 267 million tons, or less than 1%. More serious is the release of methane, and probably less serious, but significant all the same, is the contribution to climate change from nitrous oxide, a side product of the ammonia industry on which our food supply depends:
However this ignores the energy input of chemical processing, which is far more significant.
From the opening text of the paper we have these remarks from the authors:
In performing this pivotal role, the chemical sector exerts a large environmental burden. It is responsible for approximately 7% of global anthropogenic global greenhouse gas (GHG) emissions, and 5.5% when only counting CO2 emissions.(1) The sector’s final energy consumption is the largest among industrial sectors: 42.5 EJ in 2014, of which 25 EJ is feedstock energy.(2) Other sources of emissions include those stemming directly from the chemical transformations mobilized in reactors (process emissions), and from energy conversion in the transformation sector (indirect emissions). In addition to these gaseous emissions, chemical products can spawn pernicious aqueous discharges. The oft-publicised problem of fertilizer runoff contributing to hypertrophication,(3) and the more recent exposition of plastic waste ending up in the world’s oceans(4, 5) and organisms(6) are notable examples.
Returning to the issue of the ammonia industry, it is worth noting that 55 million tons, graphically it seems to be on the order of 1/3 of the total, comes from coal, the most dangerous of the three dangerous fossil fuels. Coal is often reported as being "dead," which is nonsense; reports of its death are greatly exaggerated, to steal a Twainism. Between 2000 and 2016 coal was the fastest growing source of primary energy on this planet, increasing by 2/3 of the amount used in 2000 (roughly 90 exajoules worth) by 60 additional exajoules. The contribution that coal makes to ammonia synthesis may be trivial in comparison to its use in the energy and steel industry, but it is real and significant.
I found this paper thought provoking, and it served for a useful refocusing on the realities of our increasingly dire environmental situation.
If we want to be serious - and there's no way that we are even remotely so in any country or even in any political party in any country - scale is the most important thing of which we can think.
I hope you're having a pleasant weekend.
