To give the air a sugary smell, a sergeant poured a can of nonalcoholic beer on the hot, volcanic rocks.

After years of trying and failing to jump-start sales of alcohol-free beer, the world’s largest brewers are expanding their nonalcoholic offerings with renewed zeal.

Light refreshments, including snacks from a candy bar and nonalcoholic drinks, are included; beer, wine and “patriotic cocktails” are available for extra.