Re: Solar electric at 50% efficiency?



Alex wrote:

On 1 Mar, 23:45, Eeyore <rabbitsfriendsandrelati...@xxxxxxxxxxx>
wrote:
Alex wrote:
Just a thought ...

Has anyone tried using solar thermal power as a pre-heater for thermal
power stations (gas or coal?)

Imagine a 20 Hectare solar collector field supplying about 200MW of
heat. This is used to preheat air and natural gas, prior to combustion
in gas turbines.

Input: 200MW solar and 800MW gas
Output: 500MW electric

Advantages:

- The heat is converted to electricity at an effective efficiency of
that of the plant, about 50% for gas turbines.
- The circulatory fluid is only heated to about 200-300C - quite
manageable with limited losses
- The heat can be stored in a molten salt and released when there's no
sun

Any problems with this?

Yes, the heat is low temperature and no use for the application.

Power stations actually need to GET RID of 'low grade' heat !

Yes, they need to get rid of 50 degrees C or so out the back end. If
you've got a good coastal site it could even be worth pumping cold
water up for 50m below.

But preheating your input gases to 200-300 degrees means you can
increase the air:fuel ratio and still get the same temperature in the
combustion chamber.

How do you propose to get significant amounts of 200-300 degree heat ?

Graham


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