This is new. This is nice ! I have been in contact with the Real World. On scientific congresses, we scientists all tell each other that should engage with the public and actively participate in the public debate. And we all nod and concur, and in the end, I am not entirely convinced this will be the case. Until recently…
Not too long ago, I received a mail with two questions on our work, by someone who signed as a “Concerned Layman”. I was intrigued by the mail, its contents and the writer. I read the questions several times, and started formulating the answers in my head, being excited that someone had taken the effort to send me questions about my research. I know this may sound silly, but I really got excited about this. In my opinion, this is what everyone should actually do when they consider themselves “Concerned Lay(wo)man” about a scientific subject, be it climate change, medical research or quantum physics. In many cases, academic scientists are payed with taxpayers’ money. So it only seems reasonable that we scientists reserve some time to answer questions arising from the public, doesn’t it ? On a personal level, I think this is exactly how society should function nowadays, especially with the endless possibilities of connecting to one another. If you have a question about a specific subject, why not contact a specialist to clear matters up ?
Because I wanted to take some time to answer the questions in a clear and understandable way, I immediately mailed the person back, saying I would take a day or two. What followed was a nice exchange of emails, which left both of us a lot wiser. The wisdom I gained by answering the questions of our Concerned Layman resides in being shown which questions arise in the Real World in response to scientists generating knowledge. Issues that may be entirely obvious to us -working in a particular field and being immersed in that knowledge on a daily basis- , may be at least a cause for concern in others that find themselves outside of that bubble. Therefore I would like to thank the first Concerned Layman for contacting me, and initiating what is the first of hopefully many Question and Answering (Q&A) sessions. I sincerely hope we are setting a trend for those who puzzle over certain subjects, and so lower the threshold for contacting your “local” scientist.
With the explicit consent of our “Concerned Layman”, I decided to publish the questions and my answers, as I believe these are both relevant and contemporary, and may be playing in more people’s minds.
Q1 – “If ordinary electrical power sources, such as coal fired power plants, were used to transport and grind olivine, would the amount of CO2 neutralized be more than the CO2 emitted by the plant?”
A1 – In principle, yes. That is the entire thought behind this approach, to capture (far) more CO2 than is emitted during the grinding and transport process [of the olivine]. In fact, the CO2 “penalty” should be as low as possible to allow for actual atmospheric CO2 uptake (that is, thát CO2 that was already in the atmosphere to begin with, before grinding a gram of olivine…). In a scientific publication by Hangx and Spiers from 2009 (both University of Utrecht, The Netherlands at that time), the authors show a graph (Fig. 4, page 762, bottom right corner) where the CO2 cost of grinding is set against the final grain size. Smaller olivine grain sizes facilitate a faster dissolution reaction, due to higher surface area per unit volume. In another publication by German and British colleagues (Moosdorf et al. 2014), the proportion of CO2 costs for each “activity” during the mining, grinding and transport is calculated, based on publicly available information, showing a very low contribution to the CO2 penalty by mining and transport, and a relatively high contribution by the grinding process. Even so, after accounting for the penalties, more than 60% of the capability of olivine to capture CO2 would still be available to do just that, capture CO2. The issue is the speed with which that chemical reaction occurs.
Q2 – “If the [olivine dissolution] reaction was done in a separate pool where the water could be heated to start an exothermically sustained reaction, could that speed up the CO2 uptake, whereby the material could then be dumped into the sea?“
A2 – The (geo)chemical dissolution reaction of olivine is already an exothermic reaction. Once initiated, and although very slow, it will sustain itself, without extra addition of energy. In fact, the reaction releases a little energy, in the form of (minute) heat. For more specific information on this, see the work of Prigiobbe et al. (2009).
The matter of warmer water to speed up the process is indeed a matter under investigation. We suspect (following simple physics and chemistry) that olivine would indeed dissolve faster in warmer waters. Regarding the use of a separate warm pool, I can tell you that the pool would have to be very large in order to start making a difference. To answer your question correctly, I assume that by “the material”, you mean the water (of the heated pool, as you proposed in your question) in which olivine has dissolved and of which the alkalinity [= the acid-buffering capacity] has (dramatically) increased. The point is then to have large volumes of olivine dissolve in our warm pool, and subsequently dump that high-alkalinity water into the sea, in order to neutralise the ocean acidification. Seawater with lower acidity (due to olivine neutralisation) can then act again as a sink or sponge for atmospheric CO2 (as it has been doing forever), and start taking up more. That is what we have measured (time and again) in our own experiments. Now, to use a pool as a preparatory step, means that there is an outflow into the ocean. And this outflow will be immediately diluted, once it runs into the ocean, much like as if you would run a hot-water faucet directly into an outside pool in winter, in the hope of creating a warm jacuzzi. Eventually, after adding a lot of warm water and if your winters are not too strong, you might even manage to increase the temperature of your pool. If you leave the hot water on for weeks or even years, you might even get yourself a warm pool. But at tremendous costs in terms of water, heat (CO2) and money. You see here the problem of upscaling. In order for the higher-alkaline “pool” water to have immediate climatic effect on our acidified ocean, we would need a “pool” that is so big, with a large stirrer to keep the water mixed and the olivine dissolving, and with such an enormous outflow, that it would become 1) very costly 2) energy consuming (and thus CO2) and 3) logistically difficult to manage. That is why we are trying to find out how effective and ecosystem-friendly it would be if we would introduce large volumes of olivine directly into the marine environment, and let nature do the work for us. We discuss these ideas and issues in a recent publication. We are trying to find this out in controlled, experimental environments, and are doing modelling exercises between numerous scientists, each with their own expertise.