So, them being 'black' isn't really the point. The point is the potential to get steam from water at lower temperatures, in less time.
If you are dealing with A LOT of water (if you were to scale this to power-plant scale), you are dealing with large 'thermal mass'. This means you need a lot of heat over time to raise all the water to a high enough temperature to create electricity.
If you run a power plant, you want flexibility. You want to switch on your power plant fast, and then shut it down when you want, without cost. This lets you speculate on the electricity market, and be more available if there is a sudden spike in electricity demand. If you're dealing with large thermal mass, you don't have this flexibility.
Also lots of advantages of lower cost - not needing heat exchangers etc but I'll leave it there.
How exactly would you scale this direct absorption? Glass tubes? Under pressure? Oops, now we're at the air-receiver dream. Never gonna happen. Also, can you guarantee that particles don't get entrained in the steam flow? I'm not sure Siemens is gonna warrantee that turbine. Sorry to be a pessimist, but it's gonna take a while longer for tech like this to make sense to me.
But it isn't hard to separate a small mass of water with low thermal mass from your "a LOT of water", is it? If your nanoparticle solution boils ten liters of water in the first minute, pour out ten liters of water over your black heat absorber, and it will boil in about a minute, too.
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how long do you have? :)
So, them being 'black' isn't really the point. The point is the potential to get steam from water at lower temperatures, in less time.
If you are dealing with A LOT of water (if you were to scale this to power-plant scale), you are dealing with large 'thermal mass'. This means you need a lot of heat over time to raise all the water to a high enough temperature to create electricity.
If you run a power plant, you want flexibility. You want to switch on your power plant fast, and then shut it down when you want, without cost. This lets you speculate on the electricity market, and be more available if there is a sudden spike in electricity demand. If you're dealing with large thermal mass, you don't have this flexibility.
Also lots of advantages of lower cost - not needing heat exchangers etc but I'll leave it there.
How exactly would you scale this direct absorption? Glass tubes? Under pressure? Oops, now we're at the air-receiver dream. Never gonna happen. Also, can you guarantee that particles don't get entrained in the steam flow? I'm not sure Siemens is gonna warrantee that turbine. Sorry to be a pessimist, but it's gonna take a while longer for tech like this to make sense to me.
But it isn't hard to separate a small mass of water with low thermal mass from your "a LOT of water", is it? If your nanoparticle solution boils ten liters of water in the first minute, pour out ten liters of water over your black heat absorber, and it will boil in about a minute, too.