Figure 1. Global supply of liquid hydrocarbons from all fossil resources and associated costs in dollars (top) and GHG emissions (bottom). EOR is enhanced oil recovery, GTL and CTL are gas- and coal-derived synthetic liquid fuels. The CTL and GTL quantities are theoretical maxima because they assume all gas and coal are used as feedstock for SCPs and none for other puposes. The lightly shaded portions of the graph represent less certain resources. GHG emissions in the lower figure are separated into fuel combustion (downstream) and production and processing (upstream) emissions by a dashed line. Results are based on costs and conversion efficiencies of current technologies available in the open literature. Gas hydrates are ignored due to a lack of reliable data. The GTL cost estimates assume a range of $0.5 to $2 per MBTU.
See Brandt and Farrell (2006) for details. (Brandt A R and Farrell A E 2006 Scraping the bottom of the barrel: CO2 emissions consequences of a transition to low-quality and synthetic petroleum resources Clim. Change)
5 comments:
The figure is used in both the 2006 Environmental Research Letters and the 2007 Climatic Change paper (I think it's the same figure in both).
The text in the 2006 paper discusses ignoring the gas hydrates (the exclusion noted in the figure caption in your blog post).
"For each resource type, the quantity of liquid hydrocarbon fuels that could be produced with current technologies is plotted on the horizontal axis, accounting for losses in conversion to liquid fuel. The dark portion of each resource segment represents a conservative estimate of the amount of that resource available (typically, reserves), while the lighter portion represents a less certain estimate. The CTL and GTL quantities are theoretical maxima because they assume all gas and coal are used as feedstock for SCPs and none for other purposes. Nonetheless, this figure illustrates that synfuels represent a larger `backstop' to conventional oil production than does oil shale, even if only a modest fraction of global gas and coal resources were used for this purpose. We ignore methane hydrates due to a lack of reliable data, but if technologies for producing these resources were developed, the potential for liquid hydrocarbon production would be greatly extended.
The monetary and GHG `costs' are plotted for each resource on the vertical axis, given in dollars per barrel (top) and carbon emissions in grams of carbon equivalent emitted per megajoule of refined product (gCeq MJ–1, bottom). The vertical dimension for each segment of the curve represents the range of variability or the uncertainty associated with the implications of utilizing each resource. "
In contrast, the CC text seems not to discuss hydrates and seems to frequently refer to estimates as "upper bounds."
(I say "seems" because i haven't read this carefully, just looked to see if I could see what they said about methane hydrates.)
Maybe I'm just missing something, or is there something at stake in this difference?
Even if I missed something above, if we just look at the 2006 paper, I'd like to make the following comment.
I like graphs with a lot of info, but I always get nervous when the *visual* thing itself does not *visualize* important disclaimers about what it is ignoring.
It's like, say, a graph of hidden costs of fossil fuels that doesn't make *visual* the part about how it doesn't try to estimate costs from GHGs or mercury, say, just some of the costs from some of the damage from some of the other pollutants.
Or a graph about sea level rise projections that doesn't make visual the fact that it is ignoring ice sheet dynamics, or something.
I'm no good at making graphs, but I wonder if "someone" couldn't come up with some kind of graphic language to make such assumptions, such "ignorings," visible.
Maybe with some kind of shading (or maybe animation) or something I can't even imagine.
Has anyone seen any really good examples of this?
Shoot, I'm not sure where my first comment went? Maybe it will appear.
It was about how the 2006 paper mentioned ignoring methane hydrates (as the figure caption notes):
"We ignore methane hydrates due to a lack of reliable data, but if technologies for producing these resources were developed, the potential for liquid hydrocarbon production would be greatly extended."
But the 2007 paper doesn't seem to explain this? But maybe I'm just missing something.
I can't imagine why the spam filter liked that one...
Heh. You made me read through the first comment again to see if I could guess what it could have been.
***
Speaking of reading through, not really sure why I didn't see this earlier, but the figure caption of the 2007 paper does (of course) also touch on not including methane hydrates, although it's a bit less clear:
"Rogner’s (1997) estimate of natural gas resources in categories I–VI. Categories VII and VIII were not included because they are of dubious economic viability and contain large amounts of methane hydrate resources, which are very uncertain."
But, either way: any ideas for how to *visually* represent the fact that methane hydrates are ignored, while indicating the possible size of the related emissions, so as to make visible the significance of that which is being ignored (in a graph that features information based on so ignoring)?
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