An aftertreatment system comprises a liquid exhaust reductant tank. A heat exchanger is positioned downstream of the preheater. The heat exchanger heats the liquid exhaust reductant to a second temperature. The second temperature is sufficient to decompose the liquid exhaust reductant and produce ammonia gas. A storage tank is positioned downstream of the heat exchanger and is structured to store the ammonia gas at a predetermined pressure. The aftertreatment system also includes a selective catalytic reduction system positioned downstream of the storage tank. The aftertreatment system can also include a preheater positioned downstream of the liquid exhaust reductant tank and upstream of the heat exchanger.