However, a bigger concern upon a glance is that this process does produce NOx emissions...
The hydrogen is used for reducing the iron oxides, that's the whole point of the process! That is,
FeXOY + H2 => Fe + H2O
Depends on how we define 'waste' and at what part of the process.
When they start with the rock from the ground/pit, the rocks/etc are often crushed, running through some sort of slurry while basically separating the 'ore' out from silicates/etc that will be around them. I'm guessing this is already done close to the site, since transport cost could be fairly high even by past standards.
What you wind up Iron ores that are considered 'worth' mining, the actual Iron content is anywhere from ~48% to ~72%. They'll typically have Oxygen, Possibly also Carbon or hydrogen as the 'impurities'.
So, there's still a lot of potential waste in transporting all of that.
[0] - Also, that would theoretically be useful in filling the pit back up, one would hope. But not sure on that one.
In the mining of iron ore there is a step called "beneficiation" which involves the wet processing of minerals - this is not unique to iron ore and is common to many mining operations for a wide variety of materials, wet processing produces a waste slurry known as "tailings" which are typically stored in a dam or similar (https://en.wikipedia.org/wiki/Tailings_dam) - tailings dams have been the cause of major environmental issues in the past. Such as the Brazilian Dam failure in 2019 which killed 250+ people.
After beneficiation Iron ore is transported to a steelworks where it is smelted. The smelting process produces a further waste product "slag" (https://en.wikipedia.org/wiki/Slag) how much slag is generated depends on a few factors such as the efficiency of the plant and the quality of the raw materials. Steelmaking slags can have some further use, for example it can be used in the concrete and cement industry and as a road base but how much if any of it is recycled very much depends on the country and the steelworks in some countries, particularly those with looser environmental restrictions slag is sent to landfill.
In finding the source for this, https://en.wikipedia.org/wiki/Energy_in_Iceland aluminum was the thing of note there. I was aware that this was the main power consumption (tangent to reading Artemis by Andy Weir).
> ... This trend continued and increases in the production of hydroelectric power are directly related to industrial development. In 2005, Landsvirkjun produced 7,143 GWh of electricity total of which 6,676 GWh or 93% was produced via hydroelectric power plants. 5,193 GWh or 72% was used for power-intensive industries like aluminum smelting.
We are currently importing all the natural gas in Europe, and both the price and carbon footrpint are more than double of what pipeline delivered from Russia.
You could build a pipeline from the middle east to Europe for hydrogen. We are already building powerplants in Sahara to export energy to EU. But I do not see why you should ever need to.
Iron ore and Aluminium ore is literally everywhere. We could move all of primary metal refining close to equator for solar power. China is close enough to equator, and produces huge quantities of Iron. Australia could be producing iron, they have plenty of sun.
Or Europe could produce hydrogen in the summer and store for the winter to keep refineries running.
50kg of hydrogen should be equivalent to like ~600kg of ammonia (if I did my math right). So there's a substantial mass difference in one way shipping of 600kg of ammonia versus two way shipping of ~1000kg of solids to consider. In addition, since the tanker is empty on the return trip, if we were willing to play the travel time game, we could reduce tanker return speeds to try to compensate for running faster while carrying.
So I don't think it's completely cut and dry that shipping the iron ore/steel makes more sense.
What?
your point is kinda silly, if thats the point you were trying to make.
Australia has a lot of high grade coal, which can be used for steel making (unlike low grade coal). And Australia has enormous quantities of high grade iron ore (as in you can weld to the rocks found in some parts of the country). Yet to the frustration of many Australian's we don't make steel. Instead we export the coal and ore to countries that make the steel, and they export the finished product back to us.
Plus doing anything else might see Australia benefiting from their natural resources. Last time a government tried that, the CIA and Britain delivered a new one.
If you have a big wind power or solar complex like the ones being built in the North Sea or Australia you might be better off using hydrogen directly.