While hydrogen or biogas options can be either zero carbon or net zero carbon, the fuel infrastructure will be dominated by kerosene type liquid fuels for the foreseeable future.
Very strict, ultralow emission standards such as EPA Tier 5 and EU Stage 6 require extensive and expensive aftertreatment technology involving complex catalytic reduction to reduce oxides of nitrogen, supplementary ammonia injection, as well as particulate filtration which itself requires high heat regeneration cycles. Catalysts and filters are heated, and to address this power demand, the Cummins engine uses a 48 V alternator to deliver increased current with moderately sized cabling. Test 15L-class engines are going to Walmart later this month for field testing on natural gas.
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