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The contribution of mining enough metal to make a kettle to environmental degradation pales into insignificance next to the destruction wrought by your selfish insistence on having hot drinks

Not finding much direct comparisons in a quick search, anyone here have opinions/facts about the environmental impact of titanium vs aluminum mining and processing? Basically I'm just trying to decide between an anodized alu kettle and and a titanium one. I know the right answer is steel, but humour me.

@withered_preacher I can answer this. I just needed to check my figures before replying.

Titanium alloy e.g. Ti64

Primary production:
Embodied energy 600-740 MJ/kg
CO2 footprint 38-44 kg/kg

Processing:
Embodied energy 5-6 MJ/kg
CO2 footprint 0.3-0.5 kg/kg

Recycled material:
Embodied energy 228-281 MJ/kg
CO2 footprint 14.4-16.7 kg/kg

Aluminium alloy (typical)

Primary production:
Embodied energy 200-240 MJ/kg
CO2 footprint 11-13 kg/kg

Processing:
Embodied energy 2.5-3 MJ/kg
CO2 footprint 0.15-0.25 kg/kg

Recycled material:
Embodied energy 18-21 MJ/kg
CO2 footprint 1.1-1.2 kg/kg

Figures are from Materials and the Environment (2009) by Michael F. Ashby.

About the ores. As with aluminium ore, titanium ore is fairly abundant and mined in quite large quantities as titanium dioxide. Most of it is used as white paint pigment. Most of the remainder goes to the aerospace industry as titanium alloys. It doesn't come from any dubious parts of the world, so I don't think there are any social issues relating to its mining and extraction (e.g. crime, forced labour, child labour etc). It is very energy-intensive to process into metal - this is where the high embodied energy and high CO2 figures come from, and therefore the high cost. It is also very energy-intensive to recycle, despite the fact that the bulk of titanium is actually recycled from the huge amounts of waste from aerospace machining.

Aluminium is quite energy-intensive to produce as a virgin material (compared to other normal material like steel and glass), but takes very little energy to recycle (around 10% compared to primary production). A very high proportion of aluminium is recycled unless the application specifically requires very pure aluminium for its mechanical properties (e.g. car bodies, drinks cans).

So depending how much recycled material is in there, consider it's going to be at least 3x more energy intensive and 3x higher in terms of CO2. Your decision may be a functional one - will the titanium kettle far outlast the aluminium one? Will you value it more and look after it to ensure it lasts? How many aluminium kettles will you end up using in the same lifetime?

As Tester mentioned, the bulk of the environmental impact in its lifetime is going to be in the heating of the water for drinks.