Proposed Sizewell C Nuclear Plant Plans to Utilize Waste Heat for Direct Air Capture of CO2.
Direct Air Capture of CO2 from the atmosphere is an energetically expensive process. As I often note, all of the heat released in dumping this dangerous fossil fuel waste in the first place must be added to reduce it to a stable material or product, as well as additional energy to overcome the entropy of mixing associated with the act of dumping it.
What this means is that to reduce the concentration of CO2 by capturing it from the air, a future generation would need to have all the energy we have used, plus the energy they need to live, plus the thermodynamic penalty associated with the dumping itself.
As I often note, this is a fool's errand unless the energy utilized to accomplish the task is obtained using energy that would otherwise be lost, that is, if additional energy, exergy, is recovered by raising efficiency. (The task of raising efficiency is not to reduce energy use, but consistent with Jevon's paradox, to increase energy use to do things that need doing - such as eliminating poverty for just one example - but can't be done without energy.) Direct air capture requires energy. Period. No discussion.
I do not know the technical details of the plan described in the article below, although I have been following direct air capture (and seawater capture schemes) for many years. I am aware of those that require relatively low temperatures, and this may be such a program.
Here's the article for what it's worth:
‘Megatonne’ CO2 capture plant plan for Sizewell C
Those behind the project - EDF’s Sizewell C, University of Nottingham, Strata Technology, Atkins and Doosan Babcock - gave an upbeat assessment of progress made in phase 1 of the UK’s Department for Business, Energy and Industrial Strategy (BEIS) Greenhouse Gas Removal innovation competition.
They say that a heat-powered direct air capture technology can be developed and in the future scaled up and integrated with the Sizewell C power plant, offering increased efficiency and less reliance on electricity compared with existing direct air capture technology and "could utilise up to 400 megawatt therma of heat from the power plant to capture 1.5 million tonnes of CO2 per year, which is enough to almost offset the UK’s entire emissions from railway transport".
The idea is to utilise heat (steam) from the turbine installation at Sizewell C power station when it is operational, removing CO2 from the ambient air where the concentration is around 400ppm by placing large volumes of air in contact with chemicals known as sorbents using an adsorption system, where the CO2 adheres to the solid surface of the sorbent material. The sorbents are then treated so that the CO2 is released from them and compressed for storage or reuse, while the adsorbent materials can also be re-used.
The consortium is among the bidders for phase 2 funding from the BEIS contest, and says "the experiments performed using a lab-based pilot plant have enabled the process design" for a 100 tonnes of CO2 per year demonstration plant to be completed...
The announced figure, 1.5 million tons is a drop in the bucket. Current fossil fuel waste is dumped at a rate of 35 billion tons per year, with additional CO2, about 10 billion tons, being added by land use changes each year.
Of course, the plant will also avoid the release of dangerous fossil fuel waste merely by displacing it with clean energy, so there's that.
The world has built and operated over 500 nuclear reactors, well more than 400 currently operate. At very high efficiency, for which I advocate, we might save the world with a few thousand reactors. If each thousand reactors were to remove 1.5 million tons per year, should this technology be practiced, we would be removing 1.5 billion tons per year, as well as preventing the dumping of new waste.
I can't imagine that this process is the best process. Sizewell C is proposed as an EPR, a pressurized water reactor, not a very high temperature reactor of the type of which I am fond. This said, one is encouraged to see the basic idea, using waste heat for environmental purposes, being proposed.
Our next generation engineers, I expect, will do great things. Our indifference and our willingness to dump responsibility for our mistakes on their lap will mean that the will have to do great things. We have left them with no choice, much to our disgrace.
Have a nice evening.
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