Sounds like bullshit. Doesn't most of CO2 (in aluminum production) come from all the production of electricity that you need to smelt?
The electricity in Iceland is almost exclusively 'sustainable' energy (hydro and geothermal) and the Icelandic power system is one of the least carbon intensive in the world. At present it is #2 (https://www.electricitymap.org) in the world behind Norway at 28 gCO2e/kWh. Smelting aluminium in Iceland instead of say, the USA (~ 400 gCO2e/kWh), is already a great way to reduce the carbon intensity of aluminium products.
This article is discussing the CO2 emissions related to some integral processes within the smelter, and it is a big deal. No, it wont save the world, but also no, it is not bullshit. These are the sort of small incermental improvements that we require in ALL industries in order to dent global carbon emissions.
[1] https://energy.mit.edu/wp-content/uploads/2006/11/MITEI-The-...
Also, aluminum and bauxite can be shipped to/from where it makes the most sense to process it.
However... what people fail to realize over and over is that the route for most of the worlds aluminum is from China to Iceland to China again. In tankers burning fuel like there is no tomorrow.
The biggest gain would be in how to refine the aluminum without shipping across the world twice.
Of course, China wouldn't have to use coal if they chose not to, and cargo ship bunker fuel produces some very nasty pollution besides CO2, but in the world we live in it is far better for carbon emissions and probably for the environment in general, to use Iceland as the aluminum smelting hub.
Yes, that'd be nice. People are working on solutions, but the only economically viable way to refine the material is to use a highly intensive electrolysis process. My quick google search is showing 17,000 kWh/ton of aluminum [1].
It's currently economically viable to refine in Iceland, but China is the #1 producer of raw aluminum [1] [2]. Iceland only has 3 smelters, and the combined capacity is less than the 9 largest smelters in the world, 2 of which are in China.
Citation [1] also has mentions of how much better the process of smelting has become.
>So, within 60 years, by improving the technology, fluoride emissions have been reduced more than 15 times (Table 2) and annual amounts of fluorinated residues have decreased from 1500 ton after WWII to 60 ton today.
From a purely energy standpoint, raw aluminum production has become vastly more efficient [4], with kWh/kg dropping from ~27 in 1940 to ~17 in 2000. The theoretical minimum is 5.99 kWh/kg [5]
[1] https://www.sciencedirect.com/topics/engineering/aluminum-pr...
[2] https://en.wikipedia.org/wiki/List_of_countries_by_primary_a...
[3] https://en.wikipedia.org/wiki/List_of_aluminium_smelters
[4] https://www1.eere.energy.gov/manufacturing/resources/aluminu... (page 40 of the PDF, numbered 25 on the page)
[5] https://www.aceee.org/files/proceedings/2003/data/papers/SS0...
Great post, saved it for future reference!
Do you know how China powers their much larger smelters?
And do you know if these possible difference in aluminum smelting is considered when the carbon footprint for something like a mostly-aluminum Tesla is made?
Looks like largely coal. [1] This surprises me, as China has some truly massive hydroelectric generation stations which would be ideal for smelting.
>And do you know if these possible difference in aluminum smelting is considered when the carbon footprint for something like a mostly-aluminum Tesla is made?
I'm sure it's considered, but really don't know more than that. There is a big push in the manufacturing field to get ISO 14001 (environmental) certification. Many large manufacturers are requiring that of their suppliers. I'm unfamiliar how well the certification would allow tracing back emissions. Even if there were a higher carbon footprint on production, some of that can be cancelled out by better energy efficiency of the vehicles. The cost per pound and cost of repairs can be higher on aluminum.
Tesla, in its push to be economical, appears to be going with steel on the Model 3 (compared to aluminum on Model S).
>Chowdhry highlighted the key advantages of steel over aluminum as being the lower production equipment costs, the lower worker training/skill needed to work/operate steel, the lower compensation and cost savings of steel workers versus aluminum workers, and the lower repair costs. [2]
We've seen significant increases in aluminum per vehicle [3], though much slower than estimates from 40 years ago would have said. The CAFE standards implemented in the Obama era seemed to kick things into gear, notably with the Ford F-150 switching much if not all of its body to aluminum.
[1] http://www.world-aluminium.org/statistics/primary-aluminium-...
[2] https://evannex.com/blogs/news/112953413-tesla-model-s-vs-te...
[3] https://www.statista.com/statistics/496185/pounds-of-aluminu...
[4] https://en.wikipedia.org/wiki/Corporate_average_fuel_economy
I keep seeing this about "shipping" being a major contributor to greenhouse emissions but some brief googling shows it's only 2.2%. This seems very little considering how much is shipping across the oceans and compared to electricity generation and ground-based transport.
In slightly more (but still high school level!) detail, the raw material for aluminum refining is Al2O3. That is dissolved in a bath of molten salt, where the ions dissociate. The 2 Al3+ is electroplated out by adding electrons at the cathode. The 3 O2- comes out by withdrawing electrons at the anode; usually, the anode is carbon [1], and the reaction is:
2 O2- + C -> CO2 + 4 e-
The innovation here is to use an inert anode, so the reaction is:
2 O2- -> O2 + 4 e-
The fundamental chemistry of this is pretty obvious, so presumably there are good practical reasons why everyone was using carbon anode before.
EDIT It seems [2] that the process is using the carbon to do some of the energetic work of reducing the oxygen (carbon loves to reduce oxygen even when it doesn't have two extra electrons, a fact exploited in an earlier industrial process [3]), therefore requiring less electrical energy. This is sort of a way to stealthily burn some carbon to produce energy.
[1] https://en.wikipedia.org/wiki/Prebaked_Consumable_Carbon_Ano...
[2] https://chemistry.stackexchange.com/questions/6774/why-do-th...
When neutral carbon and oxygen react, the carbon reduces the oxygen because it gives it a fractional share of its electrons when they form a bond. But when oxygen is charged, it already has lots of electrons. In this reaction the carbon is helping oxidise the oxide ions.
That is what makes it economical to ship bauxite from all over the world there, and have it manufactured to aluminum, and exported.
So this is a nice topping on the cake, to have even some of the last bits of CO2 from the process eliminated.
I don't see why this wouldn't apply to other sites elsewhere. How they generate their elictricity is another matter.
And it sounds like a great idea to me. It's just not particularly interesting from the perspective of aluminum smelting.
https://royalsociety.org/topics-policy/projects/low-carbon-e...
I think it is in there where he mentions an interesting trade off between the environmental cost of making aluminium vs the long term savings of making, for example, car parts out of aluminium rather than say cast iron which they would have been made from in the past.
Which is to say, it's not immediately clear that increasing the cost of aluminium to encompass the externalities of shipping it is actually a net benefit to the planet as a whole.