You could use it for district heating of buildings in winter, but that's about it.
As the article mentions, you need to get above the phase transition between liquid and gas at high pressure (they mention 150c) to be able to reliably and quickly convert the thermal energy into kinetic, then into electrical inductance (gas expansion moving a turbine, moving a dynamo).
Maybe if you went into business making pot roast, you could cook meat low and slow, or set up massive dehydrators.
Running it under a shallow drying bed might make salt extraction from water evaporation faster, too.
Sadly, none of those things tend to be very close to mines.
That's not true at all. If any other liquids were more useful they would have been used long time ago, even in places where the cost is not of primary concern, such as nuclear submarines.
Nuclear submarines have no use for a working fluid that boils below 100 C. Indeed, they pressurize the water so that the boiling point is well above that point, because they have no difficulty heating water well above that.
Steam is used everywhere despite that it is quite corrosive, mainly because it is cheap.
You clearly don't know what you are talking about. Water steam is a perfect medium for turbines because of its favorable thermodynamic properties, mainly high specific heat allowing water steam to absorb large amount of thermal energy. Also water steam is not corrosive because water itself is not corrosive. It's the dissolved minerals making it corrosive and that's why water used for turbines is purified first.
Yet, steam turbines attached to nuke and coal plants spend 10-20% of their time offline, being overhauled mainly because of high-temperature/high-pressure steam's corrosiveness.
Cold distilled water is not corrosive. Superheated steam, howsoever pure, little resembles cold liquid water in any detail. Furthermore, hot water will pick up minerals from whatever it runs through.
Many materials that are not especially corrosive as cold liquids behave quite differently at extreme pressure and temperature. Water has uncommon valuable thermodynamic properties, but not uniquely so; its chief virtue is that it is good enough and cheap.
Ideal thermodynamic efficiency is 1-Tcold/Thot in an absolute temperature scale. This means given a perfect mechanism to turn heat into work this is the upper bound of how much of the heat can be turned into useful work.
Say ambient air is 20 deg C, with your 90 deg C heat source then you get 1-293/363 which is about 20%. So it's not to say you can't get work out of this system, but it's not great compared to having something nice and not.
And even then, you can't push a turbine with a hot liquid so your energy extraction technique now gets complicated.
would it be possible to use a heat pump to increase the temperature to a more efficient range? Or would all of the efficiency gained be lost by operating the heat pump?
I have wondered about this as well... If your heat pump uses say 1kW, and they usually provide 4x-5x heat out, so say 5kW of heat out and your able to extract 50% of that as energy using say a turbine, you would get 2.5kW out? or maybe 1.5kW (subtracting the initial 1kW used to run it?) so maybe not great but maybe possible?
given perfect heat pumps/engines in that circumstance, you would get exactly as much energy out as you put in. Theoretically perfect heat engines are called 'reversable' for that reason: they give you the best possible exchange between heat and work. Said another way: heat pumps can give you 4-5x the heat out as work you put in precisely for the same reason you can't get much work out of that heat: the temperature increase is small. If you were to heat something up to a temperature where you could more efficiently extract work from it, it would require more energy to do so.
Yes you can use a heat pump, but that requires work to run. Think compressors and whatnot. So even with a perfectly efficient heat pump that limit still holds because you are using some of the energy gained from your new hot temperature to run the heat pump.
As the article mentions, you need to get above the phase transition between liquid and gas at high pressure (they mention 150c) to be able to reliably and quickly convert the thermal energy into kinetic, then into electrical inductance (gas expansion moving a turbine, moving a dynamo).
Maybe if you went into business making pot roast, you could cook meat low and slow, or set up massive dehydrators.
Running it under a shallow drying bed might make salt extraction from water evaporation faster, too.
Sadly, none of those things tend to be very close to mines.