De or het kolenvergassing?

The correct Dutch article is:

de kolenvergassing

Rule Words ending in -ing: almost always de. See the rule

How to use kolenvergassing

the kolenvergassingde kolenvergassing
this kolenvergassingdeze kolenvergassing
that kolenvergassingdie kolenvergassing
our kolenvergassingonze kolenvergassing
your kolenvergassingjouw kolenvergassing
every kolenvergassingelke kolenvergassing
which kolenvergassing?welke kolenvergassing?
a big kolenvergassing / the big kolenvergassingeen grote kolenvergassing, de grote kolenvergassing