manhole cover with steam escaping

airing atmosphere breach catacomb cavity chamber channel conduit construction conveyer cooler cover duct ecology efficient energy environment environmental equipment exertion exhaust factory fans flames flow force freshening fuel fume fumes funnel gas global gorge hollow hood hose hot industrial industry intake light main manhole manufacturing passage pipe pipeline pipes plant pollution power production purifying refinery shaft smoke space spout steam steamy steel system technology trough tube tunnel underground underneath vent ventilation vessel void warm warming winterair