Environment & Energy
Related: About this forumNice listing of the putative carbon intensity of biobased chemicals.
It's become increasingly clear to me in recent years that all efforts to address climate change have failed miserably, as we can see by looking at the Mauna Loa carbon dioxide data, at least until the Republicans either destroy the carbon dioxide observatory outright or begin to fudge the data, neither of which will have any bearing whatsoever on the truth itself, other than to obscure it.
Thus, among the many burdens we have placed on all future generations is the likely need they will have, in order to stabilize the climate, for the need to actually remove carbon dioxide - our waste, not theirs necessarily - directly from the atmosphere.
This is an almost impossibly difficult engineering task, although there are many scientists who refuse to give up hope that it is an engineering challenge that can be met. (One of my personal favorites is Christopher Jones's group at Georgia Tech.)
I question it, but I believe that if it is possible at all, biobased chemicals, which theoretically could sequester carbon in an economically viable way inasmuch as the carbon would not be sequestered in the oft imagined waste dumps, but as products, useful products, in particular polymers.
As I catch up on some reading, I came accross an interesting paper in the relatively new, but rich, journal, ACS Sustainable Chemistry and Engineering which gives a very nice table of the carbon intensity of a broad range of biobased chemicals from a number of biological feedstocks.
The paper in question is this: Meta-Analysis of Life Cycle Energy and Greenhouse Gas Emissions for Priority Biobased Chemicals (ACS Sustainable Chem. Eng. 2016, 4, 6443?6454). While the parent paper may be behind a firewall, the "Supplementary Information" which actually contains the data tables on the carbon cost (or benefit) of biobased fuels is not and can be accessed by the general public.
Supporting Information, Meta-Analysis of Life Cycle Energy and Greenhouse Gas Emissions for Priority Biobased Chemicals
If one looks at the table, one will see that many of the chemicals actually release more carbon dioxide than they sequester. While this may seem to make the situation hopeless, it actually need not always be so, since these calculated values assume certain process parameters.
In many cases one of the inputs for processing is heat and currently heat is often provided by the use of dangerous fossil fuels. It is possible however for this heat to be obtained in other ways, notably with the use of high temperature nuclear reactors of types being evaluated all over the world by nuclear engineers. This may offer an avenue to making some of those processes (most notably those involving reformation) that are marginally carbon positive, carbon negative.
Some excerpts of the full paper's text:
50 million tons is a trivial amount, given that we now irreversibly dump more than 30 billion tons of carbon dioxide into our favorite waste dump, the atmosphere now, and - while we wait like Godot for the solar and wind miracle that never comes - the dumping is rising in volume, not falling. Still, one hopes that we can make progress.
Some other text, later in the paper:
Another paper along these lines in the same issue of the same journal that strikes me as interesting is this one: Reductive Catalytic Fractionation of Corn Stover Lignin (ACS Sustainable Chem. Eng. 2016, 4, 6940?6950)
Here's a graphic from the paper's abstract:
The cellulosic ethanol business has failed commercially, and the plants built to make it commercially viable have all failed. These were fermentation systems, inherently batch processes, batch processes, particularly water based batch processes are seldom successful to make commodity chemicals.
But the process here is thermal, and thus quite different, far more amenable to continuous flow.
The stover, irrespective of the failure of the cellulose to ethanol processes, is still carbon captured from the air. Perhaps it's not wise to throw the baby out with the bathwater.
The chemicals shown here in the graphic are hydrogenated ("saturated), but the intermediates (shown in the full text but not shown here) are unsaturated, meaning that they are potential precursors to polymers. What is interesting about these putative polymers (which are not discussed in the paper) is that they are highly functionalized and could in theory be utilized to make resins like commercially important peptide synthesis resins, but more importantly, I think, a whole host of functionalized resins designed to remove dilute and sometimes toxic (or commercially desired) elements from very dilute streams, for example mercury from coal plants now found in all the world's water supplies, or lead, from coal and other sources.
I'd like to think there's still some hope for the future, even in times that seem hopeless.
Esoteric but interesting, I think.
Enjoy the remainder of the weekend.
eppur_se_muova
(36,305 posts)certainly as opposed to not working at all, which is my present situation.