While I agree that this isn't a great image for a B&W conversion it's still important to understand that going B&W isn't just about removing color. B&W photography is about expressing color (hues) in levels of luminosity, not just desaturating. Ansel Adams' work is so effective because he knew what color filter to stick on the front of the lens when he was shooting to get the contrasting luminosities he wanted for an impactful shot.
For example, let's take you color image (lo-res) and convert it 3 ways in Photoshop...
Grayscale (this simply desaturates):
B&W Adjustment Layer (default) (this is similar, but attempts to apply some level of luminance balancing for colors):
B&W Adjustment Layer (tweaked) (colors are made brighter or darker - luminance adjusted - and then masked out as desired):
As you can see the first two are rather flat, while the last shows some features in the foreground (gained from the color luminance adjustments) while retaining the sky from the default (which I masked out).
Similarly look at this color image and then the two conversions, the first a desaturation and the second adjusted for luminance (it was
really good before I sized it down and got the ring around the yellow)...
B&W is an art form that needs to be practiced.