This was taken last week, but I have been working on it since for a camera club competition.
The ruins of the building are of the old cornish boiler house with original chimney. The boiler would have been coal fired, likely by hand generating steam for use in pumping and dirving the lift.
The sky was what was seen, but has been worked to darken areas and increase contrast
A very interesting old building and works well in monochrome. My only comment is it looks as if you have upped the clarity or sharpening a bit too much. You will notice a slight halo around the building that I am sure the judge will notice. If you haven't had the competition yet, just tweak these small points before submitting.
Intriguing read.