More scare chemistry: on the use of “solvents” in extracting oil sands

As a Chemist I am often asked to comment on “scare chemistry” stories. That would be stories that use the public’s lack of knowledge of chemistry to scare us into doing something that may not be good for us. This fear-mongering is common in the food industry and has created a backlash in the form of the dihydrogen monoxide (DHMO) movement. For those not chemically inclined DHMO is the formal chemical name for water and the DHMO folks have been parodying fear-mongering in the food industry by convincing unknowing foils to agree to try and ban DHMO in foodstuffs etc…

This week’s in scare chemistry, I have been repeatedly directed to a Pembina Institute blog post about the use of “solvents” in the extraction of oil sands. The article “Using solvents in the oilsands: The good, the bad and the ugly” relies heavily on readers not understanding bitumen geochemistry and having a fear of “solvents” to try and scare us about the idea of using “solvents” to make the extraction of bitumen from oil sands more effective and less environmentally damaging.

Now I will admit, having watched way too many procedural cop shows on TV. So even I can sometimes see the word “solvent” and think of a scene in a show where the detective reports that the evidence was destroyed when the body was submerged in solvents. Then after about a millisecond my chemistry education cuts in and I remember that most solvents are pretty benign. Every morning I start my day by running a hot solvent through crushed coffee beans to extract a caffeine mix to which I subsequently add dry fructose and a non-dairy creamer (I am lactose intolerant). I then use the resulting solution to address the fact that I have young children who get up way too early. You see our most effective solvent is one of the most common chemicals out there, yes that would be the pretty innocuous DHMO. DHMO is what we call a polar solvent, because the individual molecules of water (H2O) have an arrangement where the hydrogen and oxygen atoms don’t share electrons evenly. This gives the hydrogen end a slight positive charge and oxygen a slight negative charge. Run heated water through coffee beans and you extract a caffeine-rich solution otherwise known as your morning cup of coffee.

In chemistry we have a simple rule about solvents: like dissolves like. What that means is that a polar solvent will dissolve a polar compound. That is why water dissolves fructose (sugar) so well but does not dissolve oils, which are typically non-polar. This is also why, when you have been cutting garlic, running cold water over your hands will not remove the garlic oil. But put a wee bit of vegetable oil on your hands, rub together vigorously and wash with soap and you, too, can leave the house without being told off by your kids.

Returning to the topic of this post let’s consider how they currently get bitumen out of the ground. Most outsiders knows that the earliest bitumen was mined from surface formations. However, most of the bitumen in Alberta is located deep underground and needs to be extracted using in situ methods. One of the most popular of these is steam-assisted gravity drainage (SAGD). In SAGD two wells pipes are drilled close together one above the other. Steam is pumped through the top pipe which heats the bitumen to a temperature at which it flows down into the lower pipe and is extracted. The process gets the job done but has some serious drawbacks. It uses a lot of energy since it takes a lot of energy to generate all that steam, it uses a lot of water (as steam) and it uses a solvent DHMO that (from a chemical perspective) is about as unlike the bitumen as it can be.

Needless to say Alberta has its fair share of chemists and they long-ago recognized the limitations of this technology. Way back in the early 1980’s scientists in Alberta started experimenting by using hydrocarbons (like ethane) as a solvent in SAGD. By using solvents made of hydrocarbons (i.e. ethane or natural gas liquids) the oil companies could make use of the “like dissolves like” rule in chemistry to enhance the process. While I don’t have time to go into why it has taken so long to go from pilot project to full-scale usage there are now a number projects that use the process and doing so has great benefits. To start, using either pure hydrocarbon solvents in SAGD or a steam-solvent cogeneration has the potential to reduce costs for the production of oil sands oil while cutting the costs per barrel and substantially reducing the greenhouse gas emissions per barrel. As the Expert Panel of the Potential for New and Emerging Technologies to Reduce the Environmental Impacts of Oil Sands Development (Oil Sands Expert Panel) notes:

Several operators are experimenting with solvent-based technologies that do not require steam, which could potentially reduce GHGs related to energy use by 90% and bring per barrel emissions (KgCO2e) to well below the level of U.S. average crude and other international sources.

This new technology has the potential of being a big win-win. Looking at the Oil Sands Expert Report you can’t help but get excited if you are a pragmatic environmentalist. Here we have a technology that could let the oil sands keep operating while keeping us below our Paris Agreement emission commitments. So, what could activists have against it? Well let’s look at the “bad” in the Pembina Institute story. Specifically, the Pembina Institute article points out:

One lingering concern is the potential for surface or subsurface contamination from the injected solvent. Solvent-assisted techniques leave residual solvent underground after bitumen is extracted (between 30 per cent and 50 per cent in the case of Imperial Oil’s technology tested at Cold Lake). While an operation is productive, the subsurface is monitored and the operation is designed to detect any foreseeable solvent loss. How solvent loss is mitigated after detection is not well understood. Furthermore, after production ceases, there is still a risk of solvent leakage, which could contaminate subsurface zones or, in the extreme, release the solvent to surface. This issue is particularly important to those living in the Lower Athabasca Region, where the liability of tailings production steadily increases as projects are developed without proper mitigation measures.  

So let’s unpack this paragraph shall we. In the article the word “solvent” is used in its scariest, freak-out-the-public form. To make it less scary try reading the same paragraph but replace the term “solvent” with “natural gas liquids”. Now for those of you who didn’t click on the link, natural gas liquids can literally come from the exact same formations as the bitumen.

Reading the same paragraph using “natural gas liquids” if I told you that some of those liquids would remain in the formation (back where they came from) would you be as concerned? Now as for leakage, well the reason the bitumen is in that formation is because it is locked in that geological space. It isn’t coming out because that is where it is stuck. If the liquids that naturally occur in those formations was going to be released into the environment, it would have started tens of millions of years ago and would be ongoing today. Fears that the stuff is going to escape ring pretty hollow. Similarly, fears that the liquids are going to get stuck in the formation ring equally hollow. Yes, it would be a waste of good hydrocarbons, but it is not really an environmental concern. Ultimately, by reading that passage using “natural gas liquids” instead of “solvents” it becomes clear the only reason anyone has any reason for fear is because it includes that scary word “solvent”. Try reading this follow-up JWN Energy story on the topic: Here’s what Pembina doesn’t like about solvents in the oilsands using the trick and see how it reads. There really isn’t anything to be afraid of is there.

Ultimately reading back on what I have written I can only be sad to recognize that once again the public’s chemical IQ is still way too low. It is still far too easy for activists to frighten the public. More frustratingly, a lot of the instances of people being scared are by authors who themselves do not have strong chemical understanding. They may not even mean to do so, but by using a loaded term like “solvent” they can freak us out. In this case it is clear that solvent-aided bitumen extraction seems like the sort of technological advance that would address many of the biggest concerns about oil sands extraction and should be something everyone is pushing. It should not be something the general public should be fighting.

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18 Responses to More scare chemistry: on the use of “solvents” in extracting oil sands

  1. Tired of paid scientists says:

    Sincerely, who care of your explanation? The real question is about how wrong are tar sands and you just elude it by explaining why a fucking solvent is not that bad… The whole thing is bad, destroying entire regions, polluting water and generating GES more than we need. Period.


    • Blair says:

      Except for a few minor errors like: I am not paid to say this stuff. The area is underlain by bitumen, as such the area is already affected by these compounds and has been for millions of years. Water would not be affected because the area being addressed if SAGD is below the active aquifers. Finally we will need hydrocarbons to continue to function as a society as we migrate to a fossil fuel-free status so we had better learn how to get those hydrocarbons as efficiently as possible.

      Liked by 1 person

    • Martin Kral says:

      I do. The man is a chemist, not a politician. Why do you have to be such a prick about his explanation. He already answered your non-question. Link to it and read and learn.


    • Maggie Bart says:

      Try decaf dude.

      And whatever you do avoid the CO2 enhanced version of DHMO . . . Your constitution can’t handle it.


  2. Martin Kral says:

    Great chemistry lesson. Question: Using in situ methods and “like dissolves like” rule, what would the solvent be to extract uranium?


    • Blair says:

      Uranium does not naturally occur in a form that is appropriate for in situ removal. It is bound into rock (rather than coating sand particles). As such it needs to be removed, crushed to increase surface area then extracted using acids which will break the chemical bonds between the uranium oxides and the neighbouring rock.


      • Martin Kral says:

        Then what have I been reading about. The term in situ has been referenced in article as a cleaner way to extract uranium. So you are saying that uranium always has to be mined?


  3. Martin Kral says:

    Blair, how much uranium to you think is in that ocean solvent – saline water?


    • Martin Kral says:

      Answer: enough to power the world for 6.5 billions years. How many more years before the earth gets swallowed up by the sun? 5.4 billions. Do the math and we can agree that the world will never run out of energy sources.


      • actinideage says:

        I’ve read these and a few other papers on the subject.

        On the evidence to date, seawater uranium recovery is a viable, scalable method of harvesting nuclear fuel from the ocean at uranium ore prices above about $300/kg. That ore cost would raise the per kWh price of enriched uranium fuel for light water reactors by a few tenths of a US cent – practically negligible. But considering the equilibrium between terrestrial uranium and that dissolved in oceans, it is a practically unending energy source on any human scale.

        Liked by 1 person

      • Martin Kral says:

        I didn’t mean to redirect the topic to uranium, but I wanted to stress that ‘in situ’ was a reasonable approach to extraction at the tar sands. Thanks for the references. They will help Blair justify his original article.


  4. HLP says:

    Thank you for relaying “solvent” in such a clear manner and summarising some of the benefits of using it. I work in SAGD, and we come up against this sort of miscommunication all. the. time.


  5. Harvey Crone says:

    Thank you for the calm and detailed description- the use of natural gas liquids could be an important tool for extraction of the bitumen in with considerably less effect on the environment. Given Canadian natural gas supplies there is a ready source.


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