"A tank is enough to get you around the region for the day, but you have to plan ahead," Martin Risberg, a county engineer, said as he filled a biogas Volvo.

“一个油箱就足够让你在这一地区转上一天，但你必须提前计划。”该县工程师马丁·里斯伯格一边给一辆沼气沃尔沃加满油，一边说。