Investigation of selective catalytic reduction for control of nitrogen oxides in full-scale dairy energy production

► Selective catalytic reduction reduced NOx emissions from a dairy biogas-fueled engine. ► NOx production during combustion of dairy biogas was variable. ► Performance was improved by real-time data collection and automated process control. ► Air-fuel ratio impacted NOx removal; other engine conditions were less influential. ► Catalysts demonstrated stable performance.