Well I hope everyone had a good Christmas/Kwanzaa/Hanukkah/Holiday Season/Time off Work/Overtime shift or anything else I might have missed.
Today we are back on the train of how to undo the damage done to our environment by hundreds of years of bad kids getting coal in their stockings for Christmas. First the bad news. Just stopping burning fossil fuels won’t save us. Even if we magically got batteries powerful enough to run every car, and plane, and ship and enough zero-carbon energy to power the whole world it still won’t save the environment in time to prevent horrendous damage.
Now the good news. We’ve known how to pull CO2 out of the air for well over 40 years. Here’s a short list of some of the ways we can do this. (Thanks Wikipedia!)
Stuff like this has been used in submarines, spaceships, and even smokestack scrubbing in more recent years. So why aren’t we using it to clean up our atmosphere? The common answer is that it’s too expensive. The accurate answer is that we don’t have the energy to do it. And the fundamental answer is that the laws of thermodynamics won’t let us clean up our atmosphere until we start using zero-carbon sources to do it.
Think about it. CO2 is a by-product of making energy with fossil fuels. So it doesn’t cost any energy to put it into the atmosphere. In fact it gives us energy to put it there. And here’s where Thermodynamics rears its ugly head, the second law to be precise. A good high temperature steam turbine will harvest about 45% of the energy in burning fossil fuels as electricity. Therefore, the remaining 55% of that energy is, effectively, leftover heat used by the exhaust gases to disperse themselves throughout the atmosphere. So even in a perfect system, we would need to use 122% of the total energy of that one power plant (55%/45%) to pull in all the CO2 released from that power plant from a perfect dispersion.
That’s a huge amount of energy when you start talking about Gigawatt scale coal plants, and that’s completely ignoring the fact that you need more power than that plant outputs in order to negate that plants output, and if you use another fossil fuel plant to make that energy then it only compounds the problem.
Now, if you catch the CO2 before it has a chance to enter the atmosphere proper, like right in the exhaust stack, you can prevent a huge majority of the CO2 from getting out into the world. and in fact a great many fossil fuel plants have stack scrubbers… for particulates, NOx, and SOx gases. The chemistry is a bit easier for those items than for CO2 so only very new “clean coal” plants have CO2 stack scrubbers. But the energy to run these scrubbers comes from the coal plant which lowers their output which makes their energy cost more, and really only slows down the release.
And then there is still all the other anthropogenic CO2 in the atmosphere, several hundred billion tonnes of it. All the CO2 from all the power plants that humanity has ever made, whether it’s a grid power plant or a car engine or a plane or a tanker ship. So to get all that out of the atmosphere, we need a power source that can produce huge amounts of energy if we want to have the power to clean this up in our lifetimes, it has to be able to operate continuously because CO2 doesn’t go away when it’s dark out, and it also has to be zero-carbon itself.
Even with nuclear energy it will still take an enormous effort to clean up our environment of all our garbage CO2. Current estimates put the energy cost of pulling CO2 out of the air at 0.66 GJ/tonne. Luckily people smarter, and with access to more data than I have already taken all the stages of carbon capture into account to arrive at that value. So lets assume we have a CANDU reactor powering a Direct Air Capture (DAC) system capable of using all of it’s power, it would be able to extract approximately 1 tonne of CO2 per second.
Current data (11 years out of date) gives us a value for the mass of CO2 in the atmosphere at approximately 3 Trillion tonnes and we are currently adding approximately 40 Billion more tonnes every year. That is if you can believe this guy:
Now in 1 year there are about 31,536,000 seconds. So Just to keep up with the CO2 we are pumping into the air we would need almost 1270 CANDU reactors doing nothing but running CO2 capture all day every day. Lets assume that you only fit 3 reactors per power plant giving us about 423 power plants (several larger plants can have 4-6, rarely more). That would just about double the current worldwide fleet of nuclear power plants (currently ~429, just in case it comes up on Jeopardy later and you want to impress your family). Sure we wouldn’t be putting any CO2 into the atmosphere but that would be it. No other benefit from all that energy other than effectively a stopgap that would get less and less effective because lets face it, if the world found out that we had the ability to pull out CO2 at the same rate we were putting it into the atmosphere, they would just start burning more coal because it’s Cheap and energy poverty is something that no one wants to have to suffer through against their will.
So lets assume that we are suddenly in a zero-carbon world but we still have all this garbage in our atmosphere that we want to get rid of. Just to get back to the amount of CO2 we had in 1960 would require the removal of almost 100 ppm, or 750 Billion tonnes. Now lets say we want to get back to that number by 2050, almost in keeping with the Paris Agreement. that gives us 31 years to do so. Using the previous numbers for 1 CANDU = 1 tonne of CO2 per second, we would require 770 reactors (about 222 new power plants) to produce enough power to hit that deadline.
Now this is an almost grotesque over simplification, it doesn’t take into account build times, rate accelerations, logistic chain growth or even the work in building the actual CO2 harvesting machinery. Like everything to do with Climate Change, this kind of project would be an enormous undertaking. But there honestly aren’t any other options. No other energy source has the chutzpah to even dream of being able to tackle a problem on this scale.
The question then becomes, assuming we can actually pull all this CO2 out of the atmosphere… what do we do with it? We obviously have to put it somewhere or it will just leak back out into the air. Here’s the best part about this whole thing. There is a method of sequestering carbon that is self-replicating, aesthetic, gives homes to wild animals, rejuvenates the environment, and is tasty.
Disclaimer, I am not an environmental/agricultural/biological scientist. I am simply putting together disparate pieces of information that I have found into a potentially feasible plan. If anyone in the relevant fields wants to tell me I am full of wishful dreams/giant piles of bullshit I invite you to tear a strip out of me on twitter @AlbertaNuclear.
Stage 1 of what to do with the CO2 is do what these guys are doing. Sell the CO2 to greenhouses and industrial agriculture companies so they can increase the CO2 concentrations in the farming areas to boost crop yields without fertilizers.
Stage 2 is use the waste material from organic items such as these healthy vegetables grown in the vertical farm that your children refuse to eat and pyrolize it all into biochar. And then basically dump the biochar all over every available field, forest, range, or wetland that needs a little boost in mineral content and watch as the plants start growing like preteens that sleep all day. (That’s right, nuclear can go hand in hand with Growing our natural environments and expanding the areas that they cover by reducing the area required for our power generation, take That Wind and Solar)
Stage 3 ????
Stage 4 Profit!
Ideally you would also do the same with purpose grown lumber and start feeding a feedback cycle of pyrolizing discarded wood to feed back into the tree farms. Basically start working under the assumption that everything organic that we throw away should be turned into biochar and used to supplement everything that we grow as a way of carbon sequestration. The more we can help the biosphere grow by using the carbon that we pull out of the air, the faster we can grow more plants that will Also pull CO2 out of the air, and give ourselves some very nice campsites and hiking trails at the same time.
Finally, since this is Alberta Nuclear Nucleus, I would be a bit remiss if I didn’t showcase what my own province was doing to help sequester CO2. First there is the Alberta Carbon Trunk Line Project which is designed to gather CO2 from locations all around the province and pump it to an underground repository at a rate of 14.6 million tonnes per year. It may not be as long term efficient as using carbon sequestered in effectively fertilizer to grow plants to sequester more carbon but it has the benefit of being immediately useful in preventing CO2 emissions. It is expected to come online in 2019 and will be the single largest Carbon Sequestration program in the world.
The other is the Quest Carbon Capture and Storage Project which operates a small sequestration field in a porous rock formation and is capable of storing 1 million tonnes of CO2 per year and has been in operation since 2015.
Discalimer #2 I am not, and never have been, in the pay of any oil company operating in, or outside of Alberta and am not acting on their behalf as some form of positive press. However if any oil company would like to give me money under the strict agreement that I will continue to point out how nuclear energy is better than all fossil fuels in every way I invite you to get in touch with me at firstname.lastname@example.org My rates are quite affordable.