Perhaps it would be helpful to have an Open Thread here on the Forum. It would give a space for miscellaneous comments, and stimulate discussions which could be spun off to more specific threads. Besides, it might be fun.
Post by Roger Clifton on Jul 30, 2017 14:21:05 GMT 9.5
That's good, grunty poetry, Huon. Fits in with the four-second guideline for noisy gatherings.… Someone says, "What can we do about it?"
You say: "Lithium, uranium and silver!"
They say: "Eh?"
You say: "Yes, lithium batteries for cars, uranium for baseload to charge them, and silver coins to tax the carbon sinners!"
The four seconds are over. The someone sips his beer. Bad music and drunken chatter wash over the timeslot as though no brains had been active there at all. Perhaps the message will echo. We did our bit.
Post by Roger Clifton on Aug 25, 2017 15:44:24 GMT 9.5
Environmentalists can point to the high carbon intensity of all mining. Overwhelmingly, the emissions are due to diesel. Modern mining techniques rely heavily on diesel, for cutting, trucking and minesite power for ore processing etc. However, electrification of the entire operation can greatly reduce, if not eliminate the high diesel content:
Very interesting post, RC. Your "solution" was prescient.
I recently read an article about two Silicon Valley entrepreneurs who are developing a 2 MWe micro-reactor that can be transported by truck to mining sites or other remote locations. The reactor is fast and cooled with liquid metal. Here's how they came up with the idea:
"The Macro: So how did Oklo, formerly known as UPower, start? ...
"We had a series of conversations with friends and contacts who were working in power development for remote communities--for projects like mining and gas. They'd talk about how much a pain in the rear it was to get power to these remote places they were working on. The common thing to use is diesel, but it's a big problem: There are often no roads to deliver the fuel, it's quite unwieldy, the weather can be so severe that it will freeze, and so on.
"These people would say, 'Well, diesel is the most energy-dense fuel we know.' But nuclear is 2 million times as energy dense. We'd ask them, what if there was a small enough reactor that you could bring out on a job site? They all said, 'Whoa, who makes that? We would buy that in a second. As many as you could make.'"
Most of the uranium, thorium, gold, and silver in the universe may well have been produced by the merger of neutron stars. And now gravitational wave observatories in the US and Italy may have detected such an event for the first time. The discovery is just rumors at this point, but the rumors have some weight.
I was sorry to see that the BNC main site is now closed to comments. Perhaps we can take up some of the slack here on the BNC Forum. But in any event, I'd like to express thanks to Professor Brook for both sites. They have certainly helped me and have, I'll bet, made no small difference for the environment.
Post by Roger Clifton on Sept 22, 2017 10:50:52 GMT 9.5
Hi Huon, you gave this thread a quite good enough name, as it invites free commentary. Seeing as potential thoughtful commenters would find these Forum pages while browsing the web, they would be more likely to be attracted if they were finding keywords of interest to them. A few provocative posts from us might help!
Thanks David B. Benson and Roger Clifton for your helpful comments about starting an Open Thread 26 (or 27!) in the "BNC Blog Post Comments" section. For now I guess the status quo is fine, with the other remaining an option. But either way, I hope an open thread is popular, and that it inspires further comments in the specific topic threads.
"Rosatom estimates that the current closed fuel cycle - in which reprocessed uranium (RepU) and plutonium are only used once - can at best use about 21% of used light water reactor fuel, with the remaining 79% - mostly uranium-238 - going into storage. The new nuclear fuel cycle could use a further 77%, with only 2% of used fuel then requiring disposal as waste, Zalimskaya said."
Post by David B. Benson on Sept 27, 2017 0:50:16 GMT 9.5
If someone knows how to contact Peter Lang there is a matter that he and I might discuss here on the BNC Forum. The subject came up on the Energy Matters blog but about half of my post attempts there never make it. So here, somewhere on the Forum, would be preferable.
Post by Roger Clifton on Oct 4, 2017 18:37:10 GMT 9.5
Currently, global consumption of carbon-based fuels is dumping about 40 gigatons of CO2 into the atmosphere-ocean system annually. In an imaginary world with copious cheap noncarbon energy, the same rate of CO2 could be captured from the atmosphere and turned back into fuels to undercut and replace extraction of fossil fuels. Because the stuff is about to be burnt again as soon as it is produced, we don't have to store vast quantities in hiding places we don't have. Apart from the fictional conversion, life would be much as it is today. The greenhouse concentration would be stable and industry would go about business as usual.
Removing the backlog of accumulated emissions is quite another matter. It is about 50 times one year's current emissions. We have somehow to bring down and convert about 2000 gigatons of CO2 into solids that we're going to have to share the surface of the earth with. If "we" consists of 10 billion people, we only have to provide each of us with 200 tons or so of various stuff that he and she would be delighted to have underfoot.
Now we can issue an invitation to the imagination of our science fiction writers. After all, they have just created a vast industrial petrochemical industry that converts the ghastly gas into gasoline. Now they can create factories (now several times bigger than just the fuel refineries) to capture CO2 and output carbon-based materials to replace plastics, building materials, road base, concrete, soil improver and where it has been lost, soil itself.
But then, you might have something more realistic in mind...
... to capture CO2 and (convert it to) carbon-based materials to replace plastics, building materials, road base, concrete, soil improver and where it has been lost, soil itself.
Nope, the stuff wouldn't be dense enough for road base (vibration) or massive concrete (needs weight). In fact, we wouldn't want it put somewhere where (heavier) soil had just been washed away. Finally, people would sooner or later discover that they can save on electric heating bills by instead burning all those old building materials that have been cluttering up the place for years and years.
All is not lost--at least not yet. According to Dr. James Hansen, "If phasedown of fossil fuel emissions begins soon, improved agricultural and forestry practices, including reforestation and steps to improve soil fertility and increase its carbon content, may provide much of the necessary CO2 extraction."
Post by Roger Clifton on Oct 6, 2017 17:47:38 GMT 9.5
I conclude that removing 2000 gigatons of CO2 from the atmosphere is effectively impossible, not least because there is simply nowhere else to put that much stuff. However removing the annual increase of 40 gigatons is a requirement of the Paris Agreement, where we must end up with "no net emissions" at all. The word "net" allows us to emit as much as we would, as long as we remove that much as fast as it enters the atmosphere.
The industry that turns over 40 gigatons per year would not have to be impossibly big. After all, the oil in "coal, oil and gas" is currently being passed through a large global and petrochemical industry before it is turned into emissions by its consumers. So, the capture-and-convert industry would have to be something like four or five times as big. Oh, and have a couple of dozen terawatts of non-carbon power supplied.
The new petrochemical industry would inevitably evolve out of the old one and inherit many of its functions. These would include feedstock for plastics and so on. One current activity is the provision of carbon anodes for the aluminium smelters. In a coke-free world, similar anodes would probably also have to be produced, in greater quantity for the smelting of iron.
Post by Roger Clifton on Oct 6, 2017 18:15:05 GMT 9.5
Oops, sorry Huon , I took too long to compose that!
In saying, "may provide much of the necessary CO2 extraction", Dr Hansen has backed down from his earlier belief that reforestation would be able to bring down all of the carbon excess.
In the couple of decades since he proposed reforestation, the world has grown hotter and periods of desiccation have increased worldwide. At the same time increasing CO2 has enhanced the growth of the C4 grasses, increasing the fuel burden in the forests. We have watched forests explode into flame in Portugal, Norway, Russia and Australia. And burning continues in the Amazon, the Congo and Indonesia. Soil carbon decreases every time agricultural land is ploughed, while the area of agricultural land increases at the expense of forest. Far from presenting a sink for carbon, the world's forests have become a source of emissions.
For me, Dr Hansen's proposals now fall in the category of token reductions, along with wind, solar, kelp farming, et cetera.
We have a nuclear-sized problem. We need a nuclear-sized solution.
RC, your conclusion was spot-on and nicely expressed: "We have a nuclear-sized problem. We need a nuclear-sized solution." But there are a few details to clear up. I'd like to start with the number of gigatons of CO2 (Gt CO2) in the atmosphere--and then consider how many gigatons we need to take out. If one googles 'weight co2 in atmosphere' one gets an answer of around 3,000 Gt. OK?
Post by Roger Clifton on Oct 7, 2017 17:35:23 GMT 9.5
Huon challenges: how many gigatons of CO2 are in excess?
You could make an estimate from the Keeling curve, the continuous measurements of atmospheric CO2 made since 1957. Currently it is (*) 405 ppmv, increasing at ~2.8 ppmv per annum. Figures quoted several years ago are always several years out of date, but you can always look it up at www.esrl.noaa.gov/gmd/webdata/ccgg/trends/co2_trend_gl.pdf. Extrapolating back from the start of the curve to subtract the preindustrial concentration, is arguable, but there are earlier measurements. Convention takes it as 280 ppmv. Subtracting it leaves 125 ppmv, the cause of current AGW.
Consider that each ppmv is 16 g/m² and that the area of the earth is 510 Mm2 (that's 510 x 10^12 m²). Multiplying the three quantities gives the first estimate, of 1000 gigatons of CO2. But if you somehow vanished that (enormous) quantity of stuff from the atmosphere, more CO2 would begin to emanate back out of the oceans to restore the recent equilibrium.
The greatest uncertainty here is how much of past CO2 has been absorbed (from the atmosphere) into the ocean. In the mid-1980s, an oceanographer told me that the oceans had been absorbing half to two thirds of the CO2 that had been emitted. Meanwhile the oceans have been warming and becoming more acid, so its capacity to absorb CO2 has been decreasing. Currently we read that about one third to one half is being taken up by the oceans – so if you say "a half", you're in the ballpark. Hence 2000 Gt total excess. We just don't know how much would come bubbling out and the risk is not only that all of it would come out, but that much of it would be converted to CH4 on the way.
Clearly it would be good to find somebody who has done all the accountancy of how many emissions have been made and when. But the only figure at hand for me is not the accumulation but its rate, of 40 gigatons per annum. This too is rubbery, as it has to include emissions from land use change. A conservative figure I read recently was 34 gigatons per annum, but considering how fast it is increasing, it is probably sufficient just to say 40 gigatons per annum and shrug. I then guessed historical emissions amounted to about 50 years worth of the current emission rate, implying (again) 2000 gigatons of excess CO2.
(*) yes, 405 ppmv multiplies as above to 3300 Gt, an update on the Wikipedia entry
Thanks, RC, for mentioning the Wikipedia article (Carbon dioxide in Earth's atmosphere). Section 2 (Current concentration) contains this description:
"Each part per million by volume of CO2 in the atmosphere contains approximately 2.13 gigatonnes of carbon. Currently CO2 constitutes about 0.041% (equal to 410 ppm) by volume of the atmosphere, which corresponds to approximately 3200 gigatons of CO2, which includes approximately 870 gigatons of carbon."
Now, Hansen has set a target of 350 ppm (or, ideally, less). So we need to get rid of about 60 ppm of CO2. at least. Multiplying by 2.13 gives about 128 gigatonnes of carbon, which equals about 470 Gt CO2. This is a good first approximation of our task.
Post by Roger Clifton on Oct 8, 2017 13:13:26 GMT 9.5
(Re: Hansen's target of lowering atmospheric CO2 by 60 ppmv)
Removing 470 gigatons of CO2 as liquid would require pressurised storage of approximately 470 km³. Just one cubic kilometre is an impossibly large volume to permanently hide. We have returned to the critical question: where would you put the waste?
Actually more than 470 gigatons would have to be removed to lower the atmospheric concentration by 60 ppmv, because the similar amount in the ocean surface would progressively emerge as we took it out of the atmosphere.
To be fair to Dr Hansen, he was proposing an activity in an unlikely future world – where all carbon emissions had been stopped. Because that would require a revolution on the scale of a global war effort, resources and political will for a cleanup effort on the necessary scale would already have been mobilised.
Post by David B. Benson on Oct 8, 2017 15:39:42 GMT 9.5
Chemically react the carbon dioxide with mafic rock to permanently remove it. I live on top of an edge of the Columbia Basalts, a large and deep expanse of suitable rock for this. There are also the Deccan Traps of India and the Siberian Traps. There is even more available under the ocean.
Less permanently, use irrigated afforestation of the Sahara desert and the Australian outback to remove about 2--3 ppm per annum, less ocean giveback.
Post by Roger Clifton on Oct 9, 2017 10:23:25 GMT 9.5
Without artificial acceleration, the weathering rate of rock increases with temperature and with CO2 concentration, so it provides a long-term negative feedback, the only one I know of among the carbon forces. Somewhere short of a hundred thousand years from now, most of the anthropogenic CO2 will end up absorbed in the weathering of rock from the continents. That assumes, of course, that we all stop emitting tomorrow and never touch fossil carbon again.
How fast it would restore the greenhouse levels, and how closely, is unclear to me. Even in the hot, wet Amazonian Basin, the weathering rates vary considerably. See Figure 7 in core.ac.uk/download/pdf/12041599.pdf. The scale on the figure goes up to 0.300 moles of CO2 per square metre per year.
Under the figure the text estimates the world continental average absorption rate as 0.161 moles per square metre per year. That's 7 g/m²/a. This is swamped by our current rate of emissions of about 260 g/m²/a (continental). And there's the ~13000 g/m² (~2000 Gt) of backlog to be absorbed. Might take a while...