It has that great word "could."

Fifty years of "coulds" about hydrogen from so called "renewable energy," another three car Monty game by which the fossil fuel industry pretends to be "green," has nonetheless left us with a burned planet.

Oddly enough, monthly data from MLO don't seem to be reflecting a decline in atmospheric CO2 content from all that "carbon capture".

...carbon capture and utilization. It will however be marginal. Just before he died, the Nobel Laureate George Olah published a beautiful paper on the topic, closed carbon cycles. It was presented not as a solution but as an aspiration. The caveat is that this approach would involve carbon free energy, which I am known for claiming exists in only one form.

I believe that direct air (or better seawater capture) lies at the edge of feasibility.

There is, in my opinion, a set of carbon based materials that would be or could be - there's that word "could" again - environmentally sustainable. In use, carbon is sequstered. Obviously however, some carbon based materials that have resulted in an environmental disaster, traditional plastics.

Hand waving will not do. Doing these things is not easy. On the contrary, they are difficult. The problem is cultural. We do not do the hard things because we have been lulled into complacency by believing too much in what the handwavers advertise.

Last edited Thu Aug 29, 2024, 04:42 PM - Edit history (1)

... wouldn't that make them a carbon sink? ( Assuming the fuel used to carry these plastics to their final resting place in landfills was "carbon neutral." )

Concrete and other building materials could also be carbon sinks with nuclear power inputs.

We keep pretending some magical technical solution will come along and displace coal, oil, and gas.

It's not going to happen until we truly decide to quit fossil fuels. Quitting fossil fuels is the step that comes first, the rest follows. Pick some dates and stick to them. No more new fossil fuel power plants, starting today. We start tearing down fossil fuel power plants starting next year. And so on. That's the only way any "transition" happens.

The trouble is that nobody wants to be inconvenienced in any way, most especially the more affluent citizens of this world who somehow still believe they'll be insulated from the worst impacts of global warming up until the day they discover their insurance (or their money) is worthless.

Consider polyethylene, which is the most common plastic in the world, with an annual production rate of roughly 100 million tons per year.

It is definitely accessible by the hydrogenation of CO₂ to methanol, followed by the well known "MTO" - methanol to olefins - process. Polyethylene is just shy of 90% carbon, slightly lower, but let's use that number as a first approximation, meaning about 90 million tons. The ratio between the molecular weight of CO₂ to carbon is roughly 3.66, meaning 100 million tons of PE containing 90 million tons of carbon would involve the reduction of 90X10⁶ * 3.66 = 330 million tons of carbon dioxide. This is less than 1% of the amount of carbon dioxide emitted each year, roughly 35 billion tons, while we all wait for the "renewable energy" nirvana that didn't come, isn't here and won't come.

Moreover, the polyethylene will be overwhelmingly discarded after a single use. If - this is a good idea - we reform municipal waste with nuclear generated steam or supercritical water, this carbon would be continuously recycled. If recycling were a hundred percent efficient - it won't come close - it is unlikely, at least theoretically, that much new carbon would be required. Where polyethylene is not recycled - only a very tiny amount actually is - it is becoming a huge environmental problem.

A better case can be made for some permanent, long term use plastics, for instance methacrylate, and related hard permanent plastics used as structural materials, furniture, certain types of tough glass and similar uses. There are carbon fibers of course, which if they can be made less expensive would also sequester carbon, and certainly carbides like the refractory silicon carbide, and metallic carbides. The electrochemical reduction of CO₂ is well known, but as electricity is thermodynamically degraded, exploiting a Boudouard type system involving disproportionation of CO also offers some application, possibly thermodynamically superior, where industrial carbon is required.

Concrete is another possibility, depending on the source of lime. Right now concrete is a net contributor to extreme global heating; in theory it might be a sink.

The point is though that the solution is not easy. It is difficult because of scale. I do think we need to consider carbon based structural materials as permanent sequestration tools, but it might take centuries to undo the damage already done, even in an ideal nuclear powered world.

Thanks for your comment.